ALBERT

Description: Efforts to date have not advanced Indigenous participation, capacity building and knowledge in Arctic environmental science in Canada because Arctic environmental science has yet to acknowledge, or truly practice decolonizing research. The expanding literature on decolonizing and Indigenous research provides guidance towards these alternative research approaches, but less has been written about how you do this in practice and the potential role for non-Indigenous research partners in supporting Inuit self-determination in research. This paper describes the decolonizing methodology of a non-Indigenous researcher partner and presents a co-developed approach, called the Sikumiut model, for Inuit and non-Indigenous researchers interested in supporting Inuit self-determination. In this model the roles of Inuit and non-Indigenous research partners were redefined, with Inuit governing the research and non-Indigenous research partners training and mentoring Inuit youth to conduct the research themselves. The Sikumiut model shows how having Inuit in decision-making positions ensured Inuit data ownership, accessibility, and control over how their Inuit Qaujimajatuqangit is documented, communicated, and respected for its own scientific merit. It examines the benefits and potential to build on the existing research capacity of Inuit youth and describes the guidance and lessons learned from a non-Indigenous researcher in supporting Inuit self-determination in research. Pinasuktaujut maannamut pivaallirtittisimangimmata nunaqarqaarsimajunik ilautitauninginnik, pijunnarsivallianirmik ammalu qaujimajaujunik ukiurtartumi avatilirinikkut kiklisiniarnikkut kanata pijjutigillugu ukiurtartumi avatilirinikkut kiklisiniarnikkut ilisarsisimangimmata, uvaluunniit piliringimmata issaktausimangittunik silataanit qaujisarnirmut. Uqalimaagait issaktausimangittunit silataanit ammalu nunaqarqaarsimajut qaujisarningit piviqartittikmata tukimuagutaujunnarlutik asiagut qaujisarnikkut, kisiani titirartauqattanginnirsaukmat qanuq pilirigajarmangaata ammalu ilautitauningit nunaqarqaarsimangittut qaujisarnirmut ikajurtuilutik Inuit nangminiq qaujisaqattarnirmut. Taanna titirarsimajuq uqausiqartuq issaktausimangillutik iliqusiujumik nunaqarqaarsimangittut qaujisartiujut ammalu saqittillutik ikajurtigiiklutik pigiartittinirmik, taijaujuq sikumiut aturtanga, inungnut ammalu nunaqarqaarsimangittunut qaujisartinut pijumajunut ikajurtuilutik Inuit nangminiq qaujisarnirmut. Tavani aturtaujumi piliriaksangit Inuit ammalu nunaqarqaarsimangittut qaujisartiujut tukisinarsititaullutik, Inuit aulattillutik qaujisarnirmik ammalu nunaqarqaarsimangittut qausartit ilinniartittillutik ammalu pilimmaksaillutik makkuktunik inungnik nangminiq qaujisarunnarniarmata. Sikumiunut aturtaujuq takuksaujuq qanuq Inuit aaqiksuijiullutik Inuit pisimajiuniarlutik tinngirartaujunik, takujaujunnarningit ammalu aulatauningit qanuq inuit qaujimajatuqangit titirartaukmangaata, tusaumajjutaukmangaata ammaluikpigijaulutik kiklisiniarnikkut atuutiqarninginnik. Takunangniujuq pivaalliutaujunnartunik ammalu pirurpalliagajartunik maanna qaujisarniujumik pijunnarsiqullugit makkuktut Inuit ammalu uqausiulluni tukimuagutaujunnartut ammalu ilitausimajut nunaqarqaarsimangittunit qausartinit ikajurtuilutik inuit nangminiq qaujisarnirmut.

Description: A total of 344 soil cores were taken in annually cropped fields of Alberta, Saskatchewan, Manitoba, and Ontario from 2011 to 2013 in areas where the field shapes, or obstacles within fields, required the driving pattern of farm operations to overlap. Soil nitrate-N concentrations in overlapping areas were 60% greater, soil Olsen-P concentrations were 23% greater, and pH was 0.5 units greater at 0–15 cm depth compared with non-overlapping areas, suggesting smaller nutrient use efficiency and potential for greater nutrient loss.

Description: Differences in soil water retention (SWR) characteristics between soil types and the factors driving those differences provide important information for land management, particularly in regions such as the Colombian Andes, which have limited water-storage infrastructure and where soils provide plant-available water and other ecosystem services. The objective of this study was to explore relationships between SWR and physical, chemical, and mineralogical properties of Andisols and Inceptisols through a case study of two watersheds in the Colombian Andes. This study identified a complex relationship between total carbon (TC), short-range order (SRO) minerals, and SWR. Both soil types had high SWR, with volumetric water content at permanent wilting point between 39% and 53%. Principal component analysis showed association of SWR with TC, SRO minerals, and % clay in both soil types. The Andisols of this study were coarse textured, allophanic (rich in allophane and imogolite — up to 17% in the B horizon), and with up to 15% TC in the A horizon. In contrast, the Inceptisols were fine textured (〉30% clay) and higher in ferrihydrite than the Andisols. The formation of organo-metallic complexes was observed in A horizons; however, TC was lower under pasture than forest in both soil types. The addition of organic matter to soils with SRO minerals, such as the soils of this study, may foster the formation of organo-metallic complexes, stabilize soil C, and enhance SWR. Consequently, both study sites may benefit from management practices that increase soil organic matter.

Description: This study investigated differences in forest structure, organic layer thickness, soil organic carbon, and permafrost depth between late successional (LS) and post fire (PF, 90 to 120 years since burn) plots under black spruce (Picea mariana (Mill.) BSP) on fine-textured, poorly drained lacustrine sediments in the Copper River Basin, Alaska. We found that although live stem and seedling density and organic layer thickness (OLT) was not significantly different between PF and LS plots (28 ± 7 cm and 31 ± 10 cm, respectively), soil organic carbon (SOC) stocks (30 ± 10 kg m-2 and 46 ± 12 kg m-2, respectively), and permafrost depth (90 ± 28 cm and 56 ± 12 cm, respectively) remain significantly different. OLT was linearly related to 1 m SOC stocks for LS plots but not for PF plots, and LS plots had a greater proportion of highly decomposed (humic) material in the organic layer. Soil properties on PF plots appear to be on a trajectory of recovery towards LS plots with respect to SOC stocks, permafrost depth, and organic layer composition, but remain different despite nearly 100 years since fire disturbance and therefore potentially sensitive to changes in future fire frequency or climate.

Description: Global change-driven droughts are triggering worldwide forest dieback which are predicted to increase even further. Here, we combined genome-wide single nucleotide polymorphisms (SNPs) and dendrochronological approaches to assess genetically-based individual tree vulnerability to past extreme droughts that caused massive mortality of Nothofagus dombeyi forests in northern Patagonia. We collected fresh leaves and wood cores from pairs of Healthy Crown (HC) and Partially Affected crown (PA) trees at four sites impacted by 1998, 2008 and 2014 droughts. We used dendrochronological techniques to estimate parameters in terms of growth trends due to drought and genomic analysis to assess its relationship with water stress. While 5,155 neutral loci did not discriminate PA from HC trees, a set of 33 adaptive SNPs did so, 8 of which were related to hydric stress. Association analysis between genomic variants and dendrophenotypic traits yielded 6 SNPs that were associated with a growth measure as resilience to cope with drought. Our preliminary results indicate that susceptibility to drought in N. dombeyi could be determined at the genomic level. The combination of both approaches provides a framework for the identification and analysis of candidate genes for stress response in non-model species.

Description: A 42-year sequence (1976–2017) of Scots pine tree diameter measurements using band dendrometers at the Aukštaitija National Park (Lithuania) study site was analysed. We have evaluated the intra- and inter annual growth dynamics of tree’s diameters and their response to meteorological forcing, as well as the long-term annual and monthly growth-rate changes in tree diameter in the study area. On average, the largest tree-diameter growth was found to have taken place during the month of June (35% of the annual increase). After June 24, the diameter growth rate decreased very strongly. The pine growth in May and August was mostly affected by the temperature of the previous month. The precipitation amount was the main driver that determined tree growth in June‒August. Heavy precipitation events had the largest impact on short-term tree-diameter increases. As a consequence of air temperature rise, we have determined the largest positive Scots pine tree diameter growth-rate changes in May and June during the period from 1976 to 2017.

Description: Factors that limit the range expansion of introduced species can offer insights into the basic ecology of these species and inform conservation of associated endemic species. North American red squirrels (Tamiasciurus hudsonicus (Erxleben, 1777)) were recently introduced to the island of Newfoundland, Canada, where they have been implicated in the decline of two endemic bird subspecies. During the summers of 2016 (following conifer masting) and 2017 (following nonmasting), we conducted surveys with 1960 point counts and playback to assess red squirrel distribution and habitat use across a 257 km2 montane landscape in western Newfoundland. We used generalized additive models with stepwise model selection to assess the relationship between land cover and red squirrel occurrence each summer. Red squirrels were most common at low elevations and were not detected at elevations above ∼500 m. Their occurrence was negatively associated with the presence of water, coniferous scrub, and 10- to 30-year-old fir–spruce but positively associated with the presence of 30- to 70-year-old fir–spruce and 〉70-year-old fir. Red squirrel presence was related to more land cover variables in 2016, after a masting year. The absence of red squirrels from forests at higher elevations apparently resulted from lack of suitable habitat rather than incomplete range expansion. Climate- or silviculture-induced changes in vegetation may alter mid- and upper-elevation habitat suitability.

Description: Ditch network maintenance promotes forest growth in drained peatland forests but increases nutrient and sediment loads, which are detrimental to water quality. Society needs to balance the harvest revenue from improved forest growth against deteriorating water quality. We examine socially optimal even-aged forest management in drained peatlands when harvesting and ditch network maintenance cause nutrient and sediment loading. The means to reduce loading include establishing overland flow fields and abstaining from ditch network maintenance. We characterize this choice analytically in a rotation framework and examine, in a numerical model, the key factors affecting the choice of forest management and water protection measures. We choose a drained peatland forest site located in northeastern Finland in the vicinity of ecologically vulnerable forest headwater streams. On the given drained forest site, we find a set of parameters under which implementing ditch network maintenance is privately but not socially optimal.

Description: Shadow fractions can be overestimated because of topographic shadows, which can occupy a significant area on aerial photographs of mountainous terrain. In this study, we first used high-dynamic-range (HDR) image analysis techniques to extract the original canopy shadow from the topographic shadows on aerial photographs. Subsequently, we applied the shadow fraction method to estimate selected forest attributes (stand height, basal area, and stem volume). In this paper, we discuss the effects of tree shadow fraction normalization, auxiliary spectral information, and forest type on forest attribute estimation. HDR image analysis successfully extracted canopy shadow information from topographic shadows. The tree shadow fraction normalization method had no obvious effect. The shadow fraction enhanced spectral information to estimate stand attributes. Using shadow fractions resulted in better estimates of stand height for mixed-hardwood forest ([Formula: see text] = 0.45), basal area for mixed-hardwood forest ([Formula: see text] = 0.50), and stem volume for conifer–hardwood forest ([Formula: see text] = 0.43). This difference in estimated results is related to the shade patterns produced by stand structures in the different forest types.

Description: Forest supply chain planning must deal with many natural disturbance uncertainties such as fires, insects, and windthrow. One important consideration is wood infestation by invasive insects, as it causes environmental and economic harm. An example of invasive insects in Eastern Canada is the spruce budworm (Choristoneura fumiferana (Clemens)), which is the most destructive insect in North America’s conifer stands. In 2017, more than 5 million ha of forest were defoliated by spruce budworm in Quebec. Repeated defoliation causes tree mortality, reduction of growth rates, and reduced lumber quality. Consequently, different wood qualities with greatly varied values are found in the forest. Changes in the outbreak intensity impact wood values throughout the forest. One of the common actions to mitigate the economic and environmental damages is salvage harvesting. However, because of the large uncertainties and lack of detailed information, it is a difficult problem to model. We propose a multistage stochastic mixed-integer programming model for harvest scheduling under various outbreak intensities. The objective is to maximize revenues of wood value minus logistic costs while satisfying demand for wood in the industry. The results show that when there is an outbreak throughout the forest, the priority for salvage harvesting is to focus on forest areas with the lowest level of infestation.

Description: Simple sequence repeat (SSR) and single nucleotide polymorphism (SNP) genotypes on the same plant samples of Chrysolepis chrysophylla (Douglas ex Hook.) Hjelmq. (Fagaceae; golden chinquapin) from 22 sites were used to determine genetic diversity and population structure. One site of C. sempervirens (Kellogg) Hjelmq. allowed interspecific vs. intraspecific comparisons. SSRs and SNPs yielded many similar results. Among-site variation contributed 13% to 17% of the genetic variation and Fst estimates of 0.14 to 0.17 were in the range expected among Fagaceae species rather than among populations within a species. The northern sites tended to group separately on the first two axes of multivariate scatterplots from southern sites. Sites in two geographically isolated areas were divergent: (i) the Hood Canal, Washington population was relatively more genetically distant from other golden chinquapin sites than was our C. sempervirens site; (ii) three coastal southern California sites were moderately diverged. The Hood Canal site had a negative inbreeding coefficient, fewer alleles, lower heterozygosity, and differed from the Skamania County, Washington site as well as all other sites. Hood Canal trees are distinguished by disjunct geography and by these molecular results. This suggests that the golden chinquapin near Hood Canal be treated as a management unit, and potential conservation actions are discussed.

Description: The gravity model was used in this paper to clarify the influencing factors of the export value of non-timber forest products (NTFPs) for Vietnam from 2003 to 2017. The estimates of this model indicate the importance of the size of economies, distance, common borders, exchange rates, average forest area, natural forest closing (NFC) policy of the Vietnamese government, sanitary and phytosanitary measures (SPS), and the interaction of SPS and importers’ GDP (SPS-GDP) as determinants of NTFP export of Vietnam. The main result of this study is the distinct and contradictory effect of NFC policy and SPS measures. While, the NFC policy increase the value of Vietnam's NTFP exports, SPS measures significantly decrease the exportation. Using the SPS-GDP interaction variable yields a noticeable result: the negative impact of SPS on NTFP trade decreases with increasing income of NTFP importers. Furthermore, the NFC needs to continue to implement policies to increase investments in the NTFPs trade, increase the quality of NTFP products from planting, harvesting, to processing, to meet the requirements of future importers. The findings offer several implications both in theory and in practice for trade policies, economic development theory based on Vietnam's forest resources.

Description: The pine-wood nematode, Bursaphelenchusxylophilus (Steiner and Buhrer), was most commonly extracted from Cerambycidae emerging from nematode-infested pines in Minnesota and Wisconsin during 1981 and 1982. The greatest number of nematodes were extracted from Monochamusscutellatus (Say) and Monochamuscarolinensis (Olivier). Low numbers of B. xylophilus were found in some buprestids but no nematodes were found in the curulionid and scolytid beetles examined. Two species of Cerambycidae, Monochamusmannorator (Kiby.) and M. scutellatus were associated with B. xylophilus from balsam fir in Minnesota. Bursaphelenchusxylophilus from insects associated with balsam fir were morphologically different from insects associated with pine. Dauer larvae of B. xylophilus were concentrated in the thoracic segments of M. scutellatus and Monochamusmutator (Lec.) examined. Bursaphelenchusxylophilus was transmitted to twigs during maturation feeding and to logs during oviposition by M. carolinensis, M. mutator, and M. scutellatus.

Description: Alnusrubra Bong, dominates the first 65 – 80 years of a sere that is initiated naturally on the terraces of the Hoh River. Stands of 14, 24, and 65 years were studied to determine to what extent the Alnus stage enriched the nitrogen inventory of the site. Bare sandbars deposited by the river had a mean of 783 kg/ha nitrogen. Alnus communities caused an increase in the nitrogen inventory so that, by 65 years, total community nitrogen was 4659 kg/ha, soils held 3594 kg/ha N in the upper 45 cm, and Alnus trees held 942 kg/ha N. The nitrogen contents of the soil, Alnus wood, bark, and branches, grasses, total aboveground biomass, total belowground biomass, and sticks less than 1 cm diameter all showed significant increases from 14 to 65 years. The A. rubra stage is an important link in the nutrient inventory between unvegetated, recently deposited sandbars and the climax coniferous forests dominated by Tsugaheterophylla (Raf.) Sarg. and Piceasitchensis (Bong.) Carr.

Description: Forest management, characterized in many northern countries by the predominance of clear cutting and growing even-aged and -sized trees, has simplified the structure of boreal forests. Consequences include alterations in cultural ecosystem services such as forest attractiveness, i.e., combined aesthetic and recreational values. Continuous-cover forestry might mitigate these effects through the use of selection and gap cutting, but these methods have been little studied, particularly from the attractiveness viewpoint. We used photo surveys to assess Finnish citizens’ perceptions of attractiveness of in-stand scenery of Scots pine (Pinus sylvestris L.) forests logged using different methods. (i) The attractiveness scores, given by respondents, declined steadily from unharvested forest through continuous-cover methods to seed-tree and clear-cut methods. (ii) Respondents with a negative attitude to forest management gave lower scores than respondents with a positive attitude, but the declining slopes of attractiveness against logging intensity were similar. (iii) In unharvested and less intensively managed stands, summer photos received higher scores than corresponding winter photos. (iv) Background variables (gender, education, living environment, memberships in recreational or nature NGOs, forestry profession, and forest ownership) had negligible effects on the scores. We recommend the use of continuous-cover logging methods in settlement and recreational areas.

Description: The world’s forests are highly fragmented by linear disturbances, and many forests have failed to recover decades after abandonment. Lack of recovery is common in unproductive forests, such as treed peatlands, because of conditions that limit tree growth, including simplification of microtopography (loss of microsites). The persistence of these features affects biodiversity, but of particular concern in Canada is the detrimental effects on threatened woodland caribou. Although natural regeneration of trees in peatlands occurs in some places, it is not an effective recovery strategy for restoring the habitat of woodland caribou. This has led to restoration activities with costs exceeding CAD$12 500/km. However, current restoration does not consider wildfires, which can destroy planted trees but also initiate early seral conditions that favor natural regeneration. Here we compared tree regeneration on seismic lines and adjacent forest controls for burnt (75 sites) and unburnt (68 sites) treed peatlands in northeast Alberta, Canada. Tree regeneration (stems with a DBH 〈 1 cm/ha) varied from 28 500 in burnt lines, 11 440 in unburnt lines, and 18 210 in burnt forest, to 9520 in unburnt forest. Wildfires promoted denser regeneration in sites with a greater proportion of serotinous species and water table depth. Microtopography and terrain wetness explained regeneration on burnt lines, but not unburnt lines. In burnt and unburnt lines, sunlight, microtopography, and depth of water table most affected tree regeneration patterns.

Description: Because of the very high complexity of modern optimization models based on single trees, uncertainties are often disregarded. In this study, we present a modelling approach that allows partial harvesting but is still simple enough to consider risk. Our modelling approach investigates whether the inclusion of timber price uncertainty influences the harvesting schedule. The model considers positive growth response to the density reduction that follows harvesting. Testing the impact of uncertainty, we define the discounted net revenues of each harvest operation as random variables. We compare harvest scheduling both with and without the inclusion of uncertainty. We first model growth response based on a partial-harvest schedule, without integrating uncertainty from timber price fluctuations. The results show that harvesting tree cohorts at different times is financially optimal. We run the same model again, including the risk of timber price fluctuations. The inclusion of risk leads to slightly greater differences in recommended harvest timings. Because of the small difference observed, we conclude that it is unlikely that risk arising from fluctuating timber prices would strongly affect the results for more complex forest economic models concerning the optimal harvest schedules.

Description: Flooding for 30 days induced several changes in Quercusmacrocarpa Michx. seedlings, with stomatal closure among the earliest responses. Stomata remained more closed in flooded than in unflooded plants during the entire experimental period. Leaf water potential was consistently higher in flooded than in unflooded plants. Other responses to flooding included acceleration of ethylene production by stems; formation of hypertrophied lenticels on submerged portions of stems; growth inhibition, with greatest reduction in roots; and formation of a few adventitious roots on submerged portions of the stem above the soil line. Some of the morphological responses to flooding, especially formation of hypertrophied lenticels, appeared to be associated with increased ethylene production. Quercusmacrocarpa seedlings adapted poorly to flooding as shown by failure of stomata to reopen after an early period of flooding and low capacity for production of adventitious roots. The much greater inhibition of root growth than shoot growth by flooding will reduce drought tolerance after floodwaters recede.

Description: Once dominant across the United States (US) Southeastern Coastal Plain, the longleaf pine (Pinus palustris Mill.) ecosystem covers a fraction of its historic geographic range. Restoration efforts have largely occurred on public lands, while most private forests feature alternative pine species. A better understanding of public interest in ecological restoration is critical to sustained efforts and successes. This research examines both forest landowner and general public interest in longleaf pine restoration. Results contribute to research on the social dimensions of ecological restoration, much of which has focused on small-scale projects rather than landscape-scale initiatives. In addition, this study addresses the lack of knowledge regarding factors driving attitudes towards ecological restoration other than demographic and psychometric variables. We employed a telephone survey of 2700 participants across eight states in the southeastern US in the historical range of longleaf pine. A majority of respondents supported restoration as a general goal and were supportive of the use of prescribed fire as a restoration practice. Place attachment, knowledge about longleaf pine, and age were among the significant predictors of restoration support. Findings have implications for future research focusing on sociocultural influences of restoration projects, as well as expanded public support for restoration of fire-maintained ecosystems.

Description: Coarse woody debris (CWD) in the form of logs, downed wood, stumps and large tree limbs is an important structural habitat feature for many small mammal species, including the American marten (Martes americana). At a long-term experimental trial in northern temperate hemlock-cedar forests of British Columbia, Canada, we analysed the impact of varying amounts of overstory basal area retention: 0% (clearcut), 40%, 70%, and 100% (unharvested) on CWD volume, decay class, and inputs from windthrow over 27 years. We used CWD attributes (diameter, length, decay class, and height above the ground) known to be favourable for martens to create an index for assessing the impact of harvesting intensity on CWD habitat features. Stands with 70% retention had CWD attributes that resulted in CWD habitat features similar to unharvested stands. Clearcuts contained pieces that were smaller, more decayed, and closer to the ground, which contributed to a habitat that was less valuable, compared with stands that had higher retention. Over the 27-year period, windthrown trees were the majority of CWD inputs, and volume change was positively related to percent retention. Our results highlight that forest management influences CWD size and input dynamics over multiple decades, and the need for consideration of these impacts when undertaking long-term multiple-use forestry planning.

Description: Fire is an important disturbance agent in the boreal forests of China. The aggressive fire suppression policy of China since 1988 has resulted in a large financial investment in support of fire brigade capabilities and the maintenance of fire management infrastructure. We developed a spatially explicit burn probability (BP) model to evaluate the effectiveness of improved fire management in Daxing’anling, China. The BP model can emulate the burn probability of the forest landscape by simulating daily wildfire occurrences, spread, and suppression for simulated years. Two scenarios were used for fire simulations in this study. The base scenario used the infrastructure data and parameters of fire suppression capability from the 1968–1987 period, and the intensive scenario used the data and parameters from the 1988–2012 period. The simulated annual burned areas for 1968–2012 showed a fluctuating trend similar to the historical fire records. Compared with the base scenario, the burn probability decreased by 73.6% under the intensive scenario, which suggests that improved fire management could significantly reduce the burn probability. This study shows that the BP model can model the effects of fire management activities on the forest landscape level and evaluate the effectiveness of fire management strategies or management measures.

Description: The impact of climate change on tree stability is often associated with a higher risk of windthrow due to higher frequency and greater magnitude of extreme climatic conditions. Higher lateral loads due to an increase in maximum wind and rainfall reduce tree anchorage because of a decrease in soil matric suction and consequently the overall strength in the system of trunk, root, and soil. This study compared the mechanical response of trees with different root architectures using static loading tests conducted in the field and numerical analysis of laser-scanned root systems. For this case, mature trees of Khaya senegalensis (Desr.) A. Juss., Samanea saman (Jacq.) Merr., and Syzygium grande (Wight) Wight ex Walp. were tested and analyzed. The root system models consisted of root system architectures obtained using 3-D laser scanning. A parametric analysis was conducted by varying the modulus of elasticity of the soil (Es) from 2.5 to 25 MPa, and the results were compared with those of the static loading tests to obtain the overall mechanical responses of the root–soil systems. The results showed important dependencies of the mechanical responses of the root–soil system on the root architecture in withstanding the lateral load. The numerical models also allowed estimation of the effective leeward and windward anchorage zones with different soil elastic moduli and rooting architectures to define the extent of the tree root protection zones.

Description: Habitat loss is one of the main consequences of landscape transformation by humans. Monitoring biodiversity changes in areas under different management strategies is fundamental for species conservation. Our study is the first to assess the role of forest disturbance history on spider (Araneae) biodiversity in the westernmost portion of the Atlantic Forest. We analyzed taxonomic and functional aspects of spider assemblages in understories in a large forest fragment in southwestern Brazil. Spiders were sampled in five 30 m × 5 m plots over three seasons in three areas with different management histories: clear-cutting, selective logging, or native plots. We also characterized tree basal area, tree density, and canopy openness. The clear-cut plots showed more canopy openness and low habitat heterogeneity due to the high density of one pioneer native tree species. Forest structure in selective logging and native plots was similar. Spider richness, abundance, and functional richness were affected only by the season. Species composition also differed among the areas depending on the season. The abundance of web-building species was mainly associated with clear-cut areas in winter and spring. These results highlight the importance of natural regeneration in the Atlantic Forest after disturbance for the conservation of regional spider biodiversity.

Description: In Europe, mixed mountain forests, primarily comprised of Norway spruce (Picea abies (L.) Karst.), silver fir (Abies alba Mill.), and European beech (Fagus sylvatica L.), cover about 10 × 106 ha at elevations between ∼600 and 1600 m a.s.l. These forests provide invaluable ecosystem services. However, the growth of these forests and the competition among their main species are expected to be strongly affected by climate warming. In this study, we analyzed the growth development of spruce, fir, and beech in moist mixed mountain forests in Europe over the last 300 years. Based on tree-ring analyses on long-term observational plots, we found for all three species (i) a nondecelerating, linear diameter growth trend spanning more than 300 years; (ii) increased growth levels and trends, the latter being particularly pronounced for fir and beech; and (iii) an elevation-dependent change of fir and beech growth. Whereas in the past, the growth was highest at lower elevations, today’s growth is superior at higher elevations. This spatiotemporal pattern indicates significant changes in the growth and interspecific competition at the expense of spruce in mixed mountain forests. We discuss possible causes, consequences, and silvicultural implications of these distinct growth changes in mixed mountain forests.

Description: Root elongation of greenhouse-grown Alaskan taiga tree seedlings increased with increasing root temperature in all six species examined and was most temperature sensitive in warm-adapted aspen (Populustremuloides Michx.). Root elongation was slower in fine than large roots and in black spruce (Piceamariana (Mill.) B.S.P.) was less temperature sensitive in fine than in large roots. Root elongation in the laboratory was slowest in black spruce, which has an inherently slow growth rate, and most rapid in poplar (Populusbalsamifera L.) and aspen, which grow more rapidly. In contrast, field root elongation rates tended to be highest in black spruce from cold wet sites, suggesting that site factors other than soil temperature (e.g., moisture) predominated over genetic differences among species in determining field root elongation rates. The seasonal pattern of root elongation was closely correlated with soil temperature and reached maximum rates in July for all tree species (except aspen medium-sized roots). Most roots of each species were in the top 20 cm of soil. However, root growth penetrated to greater depth in warm compared with cold sites. Root biomass in a 130-year black spruce forest (1230 g/m2) comprised only 15% of total tree biomass. Root biomass of 25-year aspen and 60-year poplar sites (517 and 5385 g/m2, respectively) comprised a greater proportion (57% in poplar) of total tree biomass than in spruce.

Description: The patterns of translocation of carbon in different-age tissues of four common moss species in a black spruce (Piceamariana (Mill.) B.S.P.) dominated forest near Fairbanks, Alaska, were studied by 14C labelling and carbohydrate analysis. A simple, in-vial combustion technique was developed for combustion of small (

Description: To assess the impacts of uncertainty and environmental objectives on the configuration of timber supply networks, we develop a generic multi-period, mixed-integer fuzzy linear programming model with demand uncertainty and two objectives of minimizing total transportation cost and greenhouse gas (GHG) emissions. We then use the triangular fuzzy number method to define the uncertain demands and convert the model into its equivalent auxiliary crisp counterpart. To derive Pareto solutions more efficiently, we propose the nondominated sorting genetic algorithm (NSGA-II) to solve the model. Finally, we apply the model framework and solution method to a real-world case of regional timber supply in Fujian, China, to demonstrate their applicability. The simulation results of the model show that trade-offs exist between total cost and GHG emissions and that the proper selection of the number and locations of distribution centers can help reduce both the cost and GHG emissions. Demand uncertainty and supply fluctuations across different time periods can increase the cost and GHG emissions. Our empirical results provide useful insights into the design and management of regional timber supply networks, and our generic model is applicable to the analysis of regional supply networks of other products or materials besides timber.

Description: Water stress of subalpine conifer species may be measured with the pressure chamber after several hours of tissue storage. Tissue samples stored in cool, humid vials exhibited very little change in xylem pressure potential over a 4-h period. However, xylem pressure potential declined steadily when a source of water vapor was not available. Xylem pressure potentials of current-year and 1-year-old needles of lodgepole pine (Pinuscontorta var. latifolia Engelm.) were slightly lower than those of older needles.

Description: Recent interest in continuous cover forest management of longleaf pine (Pinus palustris Mill.) ecosystems raises questions of long-term sustainability because of uncertainty in rates of canopy recruitment of longleaf pine trees. We destructively sampled 130 naturally regenerated, midstory longleaf pines across an 11 300 ha, second-growth longleaf pine landscape in southwestern Georgia, United States, to reconstruct individual tree height growth patterns. We tested effects of stand density (using a competition index) and site quality (based on two site classifications: mesic and xeric) on height growth and demographics of midstory trees. We also compared height growth of paired midstory and overstory trees to infer stand regeneration and recruitment dynamics. In low-density stands, midstory trees were younger and grew at greater rates than trees within high-density stands. Midstory trees in low-density stands were mostly from a younger regeneration cohort than their paired overstory trees, whereas midstory–overstory pairs in high-density stands were mostly of the same cohort. Our results highlight the importance of releasing midstory longleaf pine trees from local competition for sustained height growth in partial-harvesting management systems. They also demonstrate patterns of long-term persistence in high-density stands, indicating flexibility in the canopy recruitment process of this shade-intolerant tree species.

Description: Fire refugia — locations that burn less severely or less frequently than surrounding areas — support late-successional and old-growth forest structure and function. This study investigates the influence of topography and fuels on the probability of forest fire refugia under varying fire weather conditions. We focused on recent large fires in Oregon and Washington, United States (n = 39 fires 〉 400 ha, 2004–2014). Our objectives were to (1) map fire refugia as a component of the burn severity gradient, (2) quantify the predictability of fire refugia as a function of prefire fuels and topography under moderate and high fire weather conditions, and (3) map the conditional probability of fire refugia to illustrate their spatial patterns in old-growth forests. Fire refugia exhibited higher predictability under relatively moderate fire weather conditions. Prefire live fuels were strong predictors of fire refugia, with higher refugia probability in forests with higher prefire biomass. In addition, fire refugia probability was higher in topographic settings with relatively northern aspects, steep catchment slopes, and concave topographic positions. Conditional probability maps revealed consistently higher fire refugia probability under moderate versus high fire weather scenarios. Results from this study inform conservation planning by determining late-successional forests most likely to persist as fire refugia despite increasing regional fire activity.

Description: The sampling intensity of a national forest inventory is usually low. Forest dynamics models can be used to update plots from past inventory campaigns to enhance the precision of the estimate on smaller areas. By doing this, however, the inference relies not only on the sampling design, but also on the model. In this study, the contribution of model predictions to the variance of enhanced small-area estimates was assessed through a case study. The French national forest inventory provided different annual campaigns for a particular region and department of France. Three past campaigns were updated using a forest dynamics model, and estimates of the standing volumes were obtained through two methods: a modified multiple imputation and the Bayesian method. The update greatly increased the precision of the estimate, and the gain was similar between the two methods. The sampling-related variance represented the largest share of the total variance in all cases. This study suggests that plot updating provides more precise estimates as long as (i) the forest dynamics model exhibits no systematic lack of fit and was fitted to a large data set and (ii) the sampling-related variance clearly outweighs the model-related variance.

Description: This study was carried out in the northern region of Burkina Faso under Sahelian climatic conditions. The area was particularly affected by the 1970s–1980s droughts that led to the degradation of land and vegetation. Since the early 1990s, a gradual return of rainfall has been observed throughout the Sahel region. In this new environmental context, understanding the development of woody plants is important for effective conservation and management. We analyzed the dynamics of woody plant cover over the 30 years following the end of the 1970s–1980s droughts by using Landsat images from 1986, 1999, and 2015 with 30 m spatial resolution and taking into account changes in rainfall and land use. The change in the enhanced vegetation index 1 (EVI1) at the beginning of the dry season was used as a proxy for the change in photosynthetic activity of woody plants. Results showed an improvement in EVI1 on 98% of the study area, with a mean increase of 0.20 from 1986 to 2015. This improvement was accompanied by an increase in agroforestry and was weakly correlated with rainfall. The improvement in EVI1 was unstable, however, with a decline from 1999 to 2015 in the areas undergoing regreening.

Description: The aboveground biomass of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) and annual production over 7 years was studied in relation to thinning and nitrogen fertilization. Biomass yield of both treatments increased during the first 3–4 years then decreased for fertilization but not with thinning. Treatments doubled biomass production of individual trees over the study period when applied separately and quadrupled it when combined. Annual biomass production per unit of foliage (E) increased during the first 3–4 years, but was at or below control level after 7 years. The increased E accounted for 20, 37, and 27% of the stemwood dry matter response to thinning, fertilization and the combined treatments, respectively; the remainder was attributed to an increase in foliage biomass. Thinning, but not fertilization, influenced distribution of radial growth along the stem, increasing growth only below the top one-third of the stem. This pattern was related to crown development.

Description: In order to test the hypothesis that the deterioration of trembling aspen (Populustremuloides Michx.) is related to variations in climate, soil properties, and genotype, 59 trembling aspen clones were sampled in Michigan, Wisconsin, Minnesota, and Ontario. A longevity index (LI) was calculated by taking the difference between predicted basal area from normal yield tables and measured basal area for each clone. Correlations of environmental variables with LI indicate that aspen longevity decreases with increasing mean annual temperature. Under similar temperature regimes, aspen growing on xeric sites and on sites low in exchangeable Ca are most susceptible to early breakup. Since there were negligible differences in soil properties between nine pairs of adjacent deteriorating and relatively well stocked clones, we hypothesize that, under similar environmental conditions, variation in the timing of deterioration may be due to genotypic differences between clones.

Description: Carbohydrate reserves and root growth potential (RGP) of 2 + 0 Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seedlings were monitored through a lifting season and during dark, cold storage. Concentrations of total nonstructural carbohydrate and extractable sugars in root and stem tissues remained relatively constant through winter, while foliar sugars showed a sharp midwinter peak at about 195 mg•g−1 dry weight. RGP was lowest in November and March and peaked in January. During storage at +2 and −1 °C, carbohydrates were depleted in all tissues through respiratory consumption. In contrast, RGP increased during the first 6 months in storage and then fell rapidly. The results do not support the view that changes in RGP are driven by changes in carbohydrate concentrations. Storage may affect frost hardiness and drought resistance through its effect on sugar concentrations.

Description: A nonlinear analytical model is developed to describe the relationship between average plant size (weight or volume) and stand density in single-aged, monospecific plant populations. The model gives estimates of the slope and intercept of the −3/2 power rule asymptote, the nature of the size–density trajectory, and such features as relative density at crown closure and the effects of soil type or site index. The model is tested by growing red alder (Alnusrubra Bong.) seedlings under greenhouse and lath house conditions at three initial spacings (8 × 8, 4 × 4, and 2 × 2 cm) and two soil types (river loam and alder forest soil) for 525 growth days. There are seven harvests, starting at crown closure. All size–density trajectories tend consistently towards the same single asymptote irrespective of initial spacing, soil type, or age. The asymptote slope and intercept are 1.46 and ca. 94 kg tree−1•m−2. The crown closure line is parallel to the asymptote at a relative density of 4.6 × 10−3. The model also adequately describes the size–density trajectories for 20–50-year-old red pines (Pinusresinosa Ait.) growing at six initial spacings. The asymptote slope and intercept are 1.6 and ca. 87 × 103 m3•tree−1•ha−1, respectively.

Description: The pipe model theory presents the idea that a unit weight of tree foliage is serviced by a specific cross-sectional area of conducting sapwood in the crown. Below the crown, a large fraction of the tree bole may be nonconducting tissue, so the sapwood area would have to be known to estimate foliage. We applied the pipe model theory to the analysis of several western coniferous species to learn whether the distribution of canopy leaf area could be accurately estimated from knowledge of the sapwood cross-sectional area at various heights, including breast height (1.37 m). Results are excellent, but taper in the conducting area must be considered when sapwood area is measured below the crown.

Description: The effect of the radial force applied by a ring debarker tip to frozen balsam fir (Abies balsamea (L.) Mill.) logs, obtained at three positions on the stem, was studied. A one-armed ring debarker prototype was built, which controlled the radial force, the rake angle, and cutting and feed speeds. Balsam fir logs at −19 °C were debarked at three levels of radial force. The rake angle, tip overlap, tip edge radius, and cutting and feed speeds were kept constant. Debarking quality was evaluated by two criteria: the proportion of bark remaining on log surfaces and the amount of wood fibres in bark residues. Log characteristics (dimensions, eccentricity, bark thickness, and knot features), bark–wood shear strength, and the basic densities of sapwood and bark were also measured. Results showed that the radial force had a significant effect on debarking quality. The proportion of bark remaining on log surfaces increased while the amount of wood fibres in bark residues decreased as radial force decreased. A radial force of 18.5 N·mm−1 is suggested for an optimal debarking quality. In contrast, log position on the stem did not affect the debarking quality indicators. Results also showed that the proportion of bark remaining on log surfaces increases as bark–wood shear strength and the proportion of knot surface increase, while the amount of wood fibres in bark residues increases as bark–wood shear strength decreases and logs are more eccentric. The results give useful information to improve the debarking process within the studied range of log diameters and debarking parameters.

Description: In this study, the performance of a selected microbial consortium (Scutellospora calospora + Azotobacter chroococcum + Bacillus coagulans + Trichoderma harzianum) on Acacia auriculiformis A. Cunn. ex Benth. was evaluated through large-scale nursery trials at three locations in the Mandya district of Karnataka state, India. At each location, 500 inoculated and 500 uninoculated seedlings were cultivated. The increase in plant dry biomass of inoculated plants was 31% (mean of three locations) compared with uninoculated plants. The seedlings inoculated with microbial consortium under large-scale nursery trials were planted in wasteland at three locations, and their growth was monitored for nearly 6 years. At the end of the study, field growth of inoculated trees, measured as the biovolume index, was 52% higher than that of uninoculated trees. This study shows that the selected microbial consortium enhances nursery quality and midterm field growth of Acacia auriculiformis plantations on dry wasteland.

Description: Shade-tolerant mesophytic tree species tend to dominate the understories of present-day oak–hickory and mixed-hardwood forests in the eastern United States. We quantified the sapling density associations with abiotic and biotic variables for three important mesophytic species: red maple (Acer rubrum L.), sugar maple (Acer saccharum Marsh.), and American beech (Fagus grandifolia Ehrh.) in southeastern Ohio. In this study, we sampled 165 permanent plots in oak-dominated, topographically diverse, mature (〉90 years old), second-growth forests following a time span of 21–25 years (1993–1995 and 2016–2018) between samples on the Athens and Marietta units of the Wayne National Forest. Our models showed that sugar maple was strongly associated with high pH soils and red maple was strongly associated with low pH soils. Additionally, red maple was associated with upper slope positions and older stands, while American beech was associated with lower slopes, northeasterly aspects, and northeast-facing upper slopes. Basal area of competing species, solum depth, and management unit were not significantly related to sapling density for our focal species. American beech sapling density doubled between the two sampling periods, while densities of both maple species declined by half. Our results will help scientists and managers by providing insight into potential future composition of currently oak-dominated forests in areas without active management intervention.

Description: There has been limited study of songbird communities in different habitats of the lowland boreal forests of southern Yukon, including the mature forest valued for timber harvest. Our goal was to describe the songbird community during the breeding season in a mature (≥80 years since wildfire) forest dominated by white spruce (Picea glauca (Moench) Voss) adjacent to streams (n = 23) and wetlands (n = 15) compared with a nearby upland forest. Based on point count surveys, songbird communities were unique in the mature forest in the riparian forest edge position, including greater species richness and four significant riparian indicator species. Songbird communities were also unique in the forest adjacent to streams versus wetlands. We mapped species observations along 300 m transects from riparian to upland forests and identified nine species with greater abundance closer to the riparian forest edge. Many of these species are typically associated with riparian and wetland habitats for breeding. Most of the variability in the songbird community was explained by study site, likely related to high variability in forest type and amount of wetland and open water but also to unmeasured habitat characteristics. Our results increase the knowledge of songbird communities in this unique boreal region and suggest that riparian reserve zones in forest management may be useful for protecting songbird habitat.

Description: Softwood logs comprise a large portion of forest product exports from the United States. Most of these exports have occurred between the Pacific Northwest region of the United States and several Asian countries. In this study, the extent and degree of market integration of softwood log exports from 1996 to 2018 are examined by co-integration analyses and permanent–transitory decomposition. Softwood log exports to Japan and South Korea appear to be in the same economic market and show a high degree of integration, while trade between the United States and China has evolved more independently. A detailed analysis is conducted on five prices related to Japan and South Korea with full-time coverage, and one common integrating factor is found and estimated. The price of export from the Columbia-Snake Customs District to Japan is identified as the driving force. Price responses to market shocks usually occur within four months. These findings have implications for government agencies and participants in the market of softwood log trade.

Description: In southeast Alaska, United States, multiple-use forest management objectives include both timber production and wildlife habitat. Following stand-replacing disturbances such as clear-cutting, Sitka spruce (Picea sitchensis (Bong.) Carrière) and western hemlock (Tsuga heterophylla (Raf.) Sarg.) naturally regenerate and competitively dominate resources, excluding understory biomass and biodiversity. Thinning may mitigate the effects of canopy closure and permit understory development, but evidence of the effect on understories 8–10 years after thinning is lacking. We report results 4–5 and 8–10 years after thinning experiments on the Tongass National Forest to demonstrate the effects of precommercial thinning (thinned versus control), stand age (15–25, 25–35, and 35–50 years), and weather on understory dynamics and Sitka black-tailed deer (Odocoileus hemionus sitkensis Merriam, 1898) forage availability. Stand density negatively affected understory biomass, whereas temperature and precipitation positively interacted to increase biomass. Thinning had an enduring effect on understories, with biomass at least twice as great in thinned versus unthinned stands through year 10. We identified compositional differences from thinning as stand age class increased. Deer forage responded similarly to biomass, but thinning-induced differences faded with increased winter snowfall scenarios, especially in older stands. This study aids the understanding of stand overstory and understory development following silvicultural treatments in the coastal temperate rain forest of Alaska and suggests management implications and applications for balancing objectives throughout the forest type.

Description: The objective of our research is to extend current conservation applications of modern portfolio theory (MPT) to develop a framework for the cost-efficient budget distribution for a forest carbon payment program that optimizes risk–reward trade-offs in the presence of economic growth uncertainty over time. We consider correlation across space and time of the fluctuating opportunity costs of restoring forestland under changing future economic conditions using a case study of eight states in the central and southern Appalachian region of the United States. The findings suggest that optimal budget allocation decisions that ignore the covariance component of the spatial variance–covariance structure of forest carbon returns fail to minimize the true risk of conservation investment for any level of expected return. The importance of incorporating the spatial covariance in targeting conservation payments is made explicit through alternative approaches using multi-objective (mean–variance) optimization and an ex post analysis with and without the covariance component of the spatial variance–covariance structure of forest carbon return on investment (ROI). A comparison of these approaches against our MPT-based approach revealed misleading risk–return expectations if the ROI covariance is ignored in the spatial targeting of forest carbon payments under uncertainty.

Description: Wood density, an important parameter for evaluating forest biomass productivity and wood product quality control, is influenced by a complex combination of variables of forest plantations, including environmental conditions and the management practices adopted. In this paper, we demonstrate that three site variables (annual rainfall, temperature, and soil texture) and 10 plantation variables (e.g., age and genetic material) are associated with basic wood density (evaluated in two situations: with and without bark) in 936 trees of different species of Eucalyptus L’Hér across five distinct edaphoclimatic regions in Brazil. A canonical correlation analysis was used to identify the most contributory variables affecting wood density. The variables globally associated with high basic wood densities were, in order of importance, the genetic material and area per tree (both under direct control of plantation managers), as well as mean annual temperature and soil texture of the site. These results confirmed the advantage of using clonal material (instead of seedling origin material) planted in larger spacings in sites with higher mean annual temperatures and clayey soils to obtain higher basic wood densities. Conversely, low basic wood densities were associated with high-productivity sites, higher rainfall, and plantations with a higher basal area per stem in second rotation.

Description: Trends in land cover and the demand for ecosystem services suggest that plantation forests will be expected to provide a larger quantity and diversity of ecosystem services. We identified three measures indicative of diverse ecosystem services (aboveground biomass, understory biodiversity, and crown length) and compared their relationships to tree species composition in intensively managed forest plantations of the Coast Range mountains of the Pacific Northwest, United States. This study was conducted in stands of western hemlock (Tsuga heterophylla (Raf.) Sarg.), Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), and red alder (Alnus rubra Bong.), as well as in mixtures of the three species that were 35–39 years old. In this operational setting, we did not observe the positive relationship between species diversity and productivity observed in other studies, which we attributed to management practices that minimize interspecific interaction during most of the rotation. Crown length and understory species diversity were greater in mixtures of tree species than in (monospecific) monocultures. When multiple ecosystem components were considered simultaneously, mixtures of tree species outperformed monocultures. The observed relationships of the three responses to tree species composition and diversity are likely explained by differences in tree phenology, shade tolerance, disease susceptibility, and management interventions. Based on the results, management that is solely fixated on wood production homogeneously throughout the plantation may miss opportunities to provide other ecosystem services.

Description: We compared early seral development between stands subject to single and repeated high-severity wildfire in low-elevation, mixed conifer – hardwood forests in the Klamath Mountains, California, USA. We used a before–after, control–impact (BACI) approach to assess changes in the density of conifer regeneration and the cover of multiple components of vegetation structure (conifers, hardwoods, shrubs, forbs, and graminoids) and compare pathways of seral development between plots that burned once and plots that burned twice. Fifty-three field plots were established 6 years following a high-severity fire in 2004. Nineteen of these plots experienced a second high-severity wildfire 11 years later (2015), and all plots were remeasured in 2016–2017. Conifer regeneration was abundant following the first fire but was greatly reduced by the second fire. Plots that did not reburn increased in conifer, hardwood, and shrub cover, whereas plots that reburned increased in forb cover and decreased in shrub, hardwood, and conifer cover. Despite conifer loss, we found little evidence of shifts to nonforested states following repeated fire due to resilience of resprouting hardwoods. Our results indicate that repeated high-severity fire has the potential to protract early seral development and catalyze transitions from mixed conifer – hardwood forest to hardwood-dominated early seral conditions.

Description: Imaging spectroscopy is currently the best approach for continuously mapping forest canopy traits, which is important for ecosystem and biodiversity assessments. Ideally, models are trained with trait data from fully sunlit leaves from the top of the canopy. However, sampling leaves at the top of the canopy is often difficult, and sunlit foliage from the crown periphery is collected instead, assuming minimal within-crown trait variation among sunlit leaves. We tested the degree to which crown position affects foliar traits and spectra using mixed-effects models comparing sun leaves from the crown centre of mature sugar maple (Acer saccharum Marsh.) trees collected with DeLeaves, a novel twig-sampling unmanned aerial system device, with sun leaves from the crown periphery collected with a pole pruner. Sun leaves from the crown centre differed from sun leaves from the crown periphery in absorption, reflectance, transmittance, and a series of foliar traits, including leaf thickness, leaf mass, and leaf nitrogen content per unit area, demonstrating differences in resource allocation depending on sun exposure. Our study highlights the importance of accurately matching the location of foliar samples and spectral data and of sampling across gradients of intra-individual variation for the accurate prediction of foliar trait distributions across and within canopies using imaging spectroscopy.

Description: Pterocarya fraxinifolia (Poir.) Spach (Juglandaceae) is a model relict tree species native to South Caucasus and is a typical element of threatened riparian forests. Intensive land transformations, which are common in Transcaucasia, have resulted in loss of natural habitat and population decline of the species. One of the methods of ex situ conservation is seed banking. Cryopreservation in liquid nitrogen (−196 °C) is of particular interest, as it allows safe preservation of valuable plant genetic resources. However, the feasibility of seed cryopreservation is related to the desiccation tolerance and intrinsic composition of the seeds. In this study, we examined the physiological traits of Pterocarya fraxinifolia seeds, for which desiccation tolerance is unknown or controversial, and their feasibility for cryopreservation. Additionally, we tested stratification methods for dormancy assessment. Results showed that seeds survived desiccation to a moisture content of 2.8% with a germination rate of 64%. Stratification at a temperature of 3 °C for 8 weeks proved to be both fast and effective. Seed moisture content ranging from 2.8% to 18.1% was determined to be safe for cryopreservation. There was no difference in seedling emergence in seeds stored for 1 year regardless of the storage temperature (−3, −18, or −196 °C). Based on our results, Pterocarya fraxinifolia seeds can be classified as orthodox. This study demonstrates for the first time the feasibility of cryopreserving Pterocarya fraxinifolia seeds.

Description: Blue stain is a type of discoloration that considerably lowers the aesthetic qualities of wood. During harvesting, fungal inoculum finds its way into the wood through places of cutting, delimbing, and damage to the tree stem. The development of peripheral blue stain in the logs of Scots pine (Pinus sylvestris L.) due to damage by a harvester head was investigated, using logs felled and delimbed with a chainsaw as reference. The development of blue stain was related to the age class of the stand, the date of felling, and the microclimatic conditions of the wood storage place. The mean surface area of blue stain in logs produced with the harvester was almost 35 cm2, approximately 30% larger than that of the reference logs. In stands of the fourth age class (diameter at breast height 32 cm), the surface of blue stain was more than two times larger than that of stands of the third age class (diameter at breast height 24 cm). The mean area of blue stain in wood stored after spring felling (19.3 cm2) was about 50% of that after summer felling (38.2 cm2). In particular, the development of blue stain in logs obtained with a harvester was visible between weeks 6 and 9 after spring felling and between weeks 3 and 6 after summer felling. For both felling dates, the range of blue stain depended less on air temperature around the wood stack and depended more on the duration of storage.

Description: Tree height is one of the most important variables for quantitative assessment of forest stocks but is difficult to directly measure. However, such allometric relationships of trees can vary between geographical regions, mainly due to climatic, edaphic, and floristic gradients. Based on the hypothesis that different forest types influence the generic modeling of tree height–diameter relationships on geographical scales, this study aimed to 1) fit equations to estimate tree height in Atlantic Forest types in the state of Rio de Janeiro, Brazil; 2) compare efficiency and precision between generic and specific equations for forest types; and 3) test the effect of different forest types and species on the height–diameter relationship. Four allometric models were tested for all forests (generic) and three main forest types (specific). Effects of tree size, forest types and species on tree height estimation were analyzed using multiple linear models and mixed effect linear models. A significant effect of forest type and species on tree height was seen, showing the need to apply local specific equations to minimize the effects that are not captured by generic equations. Differences in tree allometry between forest types were associated with temperature, rainfall, soil and forest structure. These results confirm the effect of the local environment on the height–diameter relationship of trees as found for large scales in tropical forests.

Description: Herbivores impact soil biogeochemical processes, often increasing nutrient cycling rates under high nutrient availability and decreasing nutrient cycling rates under low nutrient availability. These patterns are far from universal, and interactions between habitat fertility and herbivore effects are under continuing investigation. By sampling inside and outside a network of deer exclosures, we determined deer browsing effects on temperate forest soil nitrogen (N) and carbon (C) cycling along a gradient of soil and litter C–N ratios across our network of sites. Deer browsing increased net N mineralization rates in high nutrient environments and decreased N mineralization rates in low nutrient environments, whereas browsing decreased CO2 respiration rates in high nutrient environments and increased CO2 respiration rates in low nutrient environments. Differences in deer browsing effects on soil processes could be explained by plant responses to herbivory across gradients of resource availability. To our knowledge, our study is one of the first to show that deer browsing can have significant effects on net N mineralization and C respiration in temperate forest soils and that the direction and magnitude of deer browsing effects on soil N and C cycling vary across fertility gradients.

Description: We consider the problem of tactical forest management over a 5-year horizon with yearly periods. The main decisions made consider which harvest areas to cut in each period, the flow of timber from an area to each wood-processing mill to satisfy its annual demand, and which roads to build to access a harvest area not connected to the existing road network. The goal is to minimize the total transportation and road-building costs subject to budget limitations. To explore the benefits of economies of scale (EOS) in road construction, we incorporated this notion in the proposed model. Then, the efficiency of the obtained solution is compared with the model without EOS. The proposed model is a mixed-integer linear program, including several timber assortments and multiple periods. We validated the model for a realistic case in the context of the province of Quebec. The results demonstrate that consideration of EOS significantly reduces the total cost by about 5.3%. In the EOS solution, the road segments that are built every year are very concentrated in specific parts of the region, allowing a road-building company to take advantage of EOS. Moreover, this solution provides a much more efficient timber transportation plan.

Description: Postfire salvage logging is used to reduce economic losses; however, burned trees are rapidly colonized by wood-boring insects, which reduce the merchantable value of the wood. This study aims to predict wood borer (Monochamus Megerle in Dejean, 1821) attacks after wildfire as a function of rapidly available variables such as tree basal area, stem diameter, and burn severity using the differenced normalized burn ratio (dNBR). In 2011, we sampled 60 black spruce (Picea mariana (Mill.) Britton, Sterns & Poggenb.) or jack pine (Pinus banksiana Lamb.) plots in five burns from 2010 in the Haute-Mauricie region of Quebec, Canada. A 50 cm bole section was debarked on seven trees in each plot to estimate wood borer attack density. Wood borer attacks were more abundant in black spruce than in jack pine. As a continuous variable, dNBR unveiled a quadratic effect of burn severity on attack density in black spruce, which was higher at moderate burn severity. In jack pine, the highest levels of attack density were found at high burn severity. Models produced in this article will help forest managers to better prioritize areas for salvage logging and thus reduce economic losses due to wood borer activity.

Description: Les forêts protégées ivoiriennes fournissent des services écosystémiques aux gestionnaires ainsi qu’aux populations riveraines. Cependant, leur gestion connaît de nombreuses difficultés du fait de leur infiltration illégale pour l’agriculture. Ces différentes conversions des classes d’occupation du sol ont modifié les différents services d’approvisionnement des forêts domaniales en général et des forêts classées en particulier. Cette étude a pour objectif d’évaluer les services d’approvisionnement fournis par les plantes de la forêt classée du Haut-Sassandra (FCHS) dans le Centre-Ouest ivoirien, en comparant les bénéfices issus de la FCHS en 2019 à ceux tirés de cet espace en 2000. Les dynamiques spatiotemporelles des formations végétales ont été analysées et ont mis en exergue la progression des exploitations cacaoyères (951,51 % de progression) au détriment des forêts (92,08 % de régression) entre 2000 et 2019. Les enquêtes socioéconomiques ont révélé que cette augmentation des surfaces cacaoyères a entrainé des pertes de 98,11, 93,18 et 78,67 % d’espèces respectivement utilisées pour l’artisanat, la construction et la pharmacopée traditionnelle et une augmentation des services d’alimentation liés aux espèces agricoles. Cependant, ces bénéfices ne profitent pas à l’ensemble des communautés présentes dans la zone d’étude.

Description: Attributes of deadwood in forests, including quantity, landscape position, and state of decay, influence numerous ecosystem processes such as wildfire behavior, tree regeneration, and nutrient cycling. Attributes of deadwood that vary over subdiurnal time steps, including moisture, have not been routinely measured despite the profound effects they have on ecosystem processes. To improve our understanding of forest deadwood subdiurnal moisture dynamics, we installed an intensive time-domain reflectometry (TDR) sensor network in a log and surrounding soil within a northern hardwood forest in New England, United States. Intensive monitoring during a partial growing season indicated that deadwood moisture was dynamic but similar to that of surrounding soils at 15-min intervals, especially during wetting and drying events. Field results and bench analysis of the sample log revealed numerous challenges when attempting to monitor deadwood moisture with TDR such as heterogeneous and (or) advanced decay confounding TDR moisture measurements in logs. An efficient, high-frequency TDR sensor network was demonstrated to record deadwood and soil moisture fluctuations, which provides an opportunity to refine our understanding of deadwood dynamics in the context of global change such as changing precipitation regimes.

Description: Weibull distributions have been widely used to describe tree stem diameter distributions. However, there is a scarcity of studies that suggest the best Weibull formulation. The parameters of the Weibull distribution are usually predicted by either the parameter prediction method (PPM) or the parameter recovery method (PRM), although other methods have been proposed. Thus, this study aimed to evaluate the performance of eight Weibull formulations and compare methods of parameter prediction to describe diameter distributions of clonal eucalypt stands in Brazil. Data originated from remeasurements of 56 plots at ages 3, 5, and 6 years. Weibull distributions were fitted using the maximum likelihood method and evaluated in a goodness-of-fit indicators ranking. The right-truncated two-parameter formulation showed the best results and was used to evaluate the methods of parameter prediction. Stand attributes showed a strong relationship with shape and scale parameters. Regression models were developed and resulted in accurate estimates using PPM. PRM used a growth and yield system to estimate the stand attributes, followed by the moment-based method. The modified cumulative distribution function regression (CDFR) approach was also evaluated, and it presented the poorest results. Although the PPM showed excellent results, PRM is recommended in older stands with inventory because it implicitly promotes compatibility among stand attributes.

Description: The size structure of tree populations making up a forest stand provides a scientific basis for evaluating the forest resources and scheduling future silviculture treatments. We evaluated the efficiency of the skewed Student’s t (ST) model to predict the distributions of various complex diameter at breast height (DBH) data. The ST model was compared with finite mixtures of selected functions (gamma, log-normal, and Weibull). Additionally, two scenarios were employed to determine the number of components: (1) the use of the Bayesian information criterion and (2) visual analysis of the histogram of the DBH relative frequencies. The ST model demonstrated the highest degree of flexibility for fitting the DBH distributions. It outperformed other competitors in modeling the DBH variables in terms of all implemented scenarios. It possesses a high degree of flexibility. This model should be used to fit the DBH distributions of multigeneration forest patches with diverse size structures.

Description: Widespread, rapid aspen (Populus tremuloides Michx.) mortality since the beginning of the 21st century, sometimes called sudden aspen decline (SAD), has been documented in many locations across North America, but it has been particularly pronounced in the southwestern United States. We investigated the relationship among aspen growth, mortality, and climate across three forest types in northern Arizona using cross-dated tree-ring samples from 126 live and 132 dead aspens. Aspen growth was negatively correlated with warm temperatures and positively associated with higher precipitation. Using survival analysis techniques to investigate the links between aspen mortality, tree traits, and climatic conditions, we found that tree traits played a larger role in mortality risk than climate factors. Trees with larger diameters, older trees, and trees with faster growth rates over the past 50 years had a reduced risk of mortality. Management actions aimed at maintaining the most vigorous, fastest growing aspen in the region could help mitigate the impacts of a warmer, drier future.

Description: Ice storms cause widespread damage to forests in many temperate regions, leaving behind many live trees with severe crown damage. Following a severe ice storm in 2014 that damaged forests across Slovenia, we examined how tree-level attributes influenced survival and crown rebuilding three growing seasons after the storm. Field sampling was carried out in four mature stands dominated by native broadleaf species. Of the 763 sampled trees, the annual mortality rate following the storm was 2.2%, and nearly all trees that died experienced 〉75% crown removal. Oak (Quercus petraea (Matt.) Liebl.) and chestnut (Castanea sativa Mill.) had higher rates of mortality than beech (Fagus sylvatica L.) and maple (Acer pseudoplatanus L.). Mixed models revealed that survival significantly increased with tree diameter and decreased with increasing crown damage. Although we observed sprouting across all the dominant species, maple, oak, and chestnut showed a more vigorous response than beech, and maple had the fastest sprout growth. Model results showed that sprout density and length increased with level of crown damage. The results indicate that these broadleaf forests are resilient to severe ice damage. Consequently, hasty salvage cutting of trees with canopy damage should be avoided, as many individuals with 〉75% crown damage are likely to survive and recover.

Description: The use of thermally modified timber (TMT) in outdoor applications is well established, but its performance against the stresses of outdoor conditions is not comprehensively understood. This study investigates the changes in density, surface chemical composition, color, equilibrium moisture content (EMC), checking, hardness, and cupping of thermally modified boards of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst.), and European ash (Fraxinus excelsior L.) during a two-year weather exposure test in Eastern Finland. Unmodified pine, spruce, and ash and copper salt impregnated pine boards were used as controls. The results show that a two-year weather exposure period causes degradation of hydrophobic lignin, and the leaching of the degraded compounds changed the color, increased the EMC, and decreased the hardness of specimens. Although the EMC of TMT specimens was lower compared with unmodified and impregnated ones during weathering, the changes were more obvious in TMT than in the controls. More checks occurred in the TMT specimens than in unmodified ones after the exposure. On the other hand, the TMT specimens had a lower degree of cupping. These findings also indicate that an increase in modification temperature induces more checks but improves the durability of all studied species by reducing the chemical degradation, color change, cupping, and hygroscopicity during weather exposure.

Description: Warming global temperatures are expected to strongly influence plant communities, yet there is limited knowledge of how these changes will interact with stressors such as the invasion of exotic earthworms. We conducted a small-scale microcosm experiment to assess the individual and interactive effects of warming and exotic anecic earthworms (Lumbricus terrestris L.) on the growth of sugar maple (Acer saccharum Marsh.) seedlings. After 50 days, the elevated-temperature chamber created warmer and drier soil conditions and increased several measures of plant growth, including stem width, ratio of stem width to stem height, stem biomass, and fine-root biomass. Earthworms did not have any clear impacts on plant growth on their own nor in interactions with the temperature chambers. However, earthworms both reduced surface leaf litter cover and exposed soils, which could exacerbate evaporative losses and moisture stress in field soils resulting from a warming climate under different growing conditions. Future studies should consider the long-term effects of earthworm–temperature interactions on sugar maple growth, as well as diurnal and seasonal changes in temperature.

Description: The history of spruce budworm (Choristoneurafumiferana (Clem.)) outbreaks for the past 200 to 300 years, for nine regions in eastern Canada, indicates that outbreaks have occurred more frequently in the 20th century than previously. Regionally, 21 outbreaks took place in the past 80 years compared with 9 in the preceding 100 years. Earlier infestations were restricted to specific regions, but in the 20th century they have coalesced and increased in size, the outbreaks of 1910, 1940, and 1970 having covered 10, 25, and 55 million ha respectively. Reasons for the increase in frequency, extent, and severity of outbreaks appear mostly attributable to changes caused by man, in the forest ecosystem. Clear-cutting of pulpwood stands, fire protection, and use of pesticides against budworm favor fir–spruce stands, rendering the forest more prone to budworm attack. The manner and degree to which each of these practices has altered forest composition is discussed. In the future, most of these practices are expected to continue and their effects could intensify, especially in regions of recent application. Other practices, including large-scale planting of white spruce, could further increase the susceptibility of forest stands. Forest management, aimed at reducing the occurrence of extensive fir–spruce stands, has been advocated as a long-term solution to the budworm problem. The implementation of this measure at a time when man's actions result in the proliferation of fir presents a most serious challenge to forest managers.

Description: At 10 locations in Oregon and Washington, tree mortality resulted in dry-matter transfer of 1.5–4.5 Mg•ha−1•year−1 of boles and branches to the forest floor and 0.3–1.3 Mg•ha−1•year−1 of large-diameter roots directly to the mineral soil. The first value is about the same as that reported for leaf fall in similar stands; the second value generally is smaller than that reported for fine root turnover. Results are based on measurements by the U.S. Forest Service spanning 16–46 years and areas as large as 42 ha. Values based on intervals

Description: Flooding of soil for 45 days severely inhibited growth of 115-day-old Pinusbanksiana Lamb, and P. resinosa Ait. seedlings, with significant effects apparent within 15 days after initiation of flooding. Both species adapted poorly to flooding of soil but P. banksiana was more adversely affected than P. resinosa as shown by earlier and more drastic reduction of growth in the former species. In both species flooding decreased the rate of height growth, production of secondary needles, dry weight increment, and relative growth rates of various plant parts. Root growth of both species was reduced more than shoot growth. The reduction in dry weight increment of root systems of both species reflected arrested branching and elongation of roots as well as decay of roots, mainly the very small nonwoody roots. Flooding slightly stimulated ethylene production by submerged stems.

Description: Using data from the National Council of Real Estate Investment Fiduciaries (NCREIF), we examine market integration of commercial real estate and timberland–farmland assets via the Fama–MacBeth two-step approach under the intertemporal capital asset pricing framework. In addition, we study the information transition dynamics between those markets via the vector error correction model (VECM). We find evidence of market segregation and one-way information flow from the timberland–farmland market to the commercial real estate market. We conclude that commercial real estate and timberland–farmland assets are driven by different market fundamentals and that lagged timberland–farmland returns can help predict current commercial real estate returns. The only exception is during market downturns when commercial real estate and timberland–farmland markets are somewhat integrated and driven by some factors that are not specified in this study.

Description: The presence of ectomycorrhizal and vesicular–arbuscular (VA) mycorrhizal fungi in soils from five sites in a mixed conifer zone in southwest Oregon, each consisting of a 1- to 1.5-year-old clear-cut adjacent to an undisturbed forest stand, was determined by bioassay with Pseudotsugamenziesii (Mirb.) Franco, Pinusponderosa Dougl. ex P. Laws & C. Laws, and Trifoliumsubterraneum L. 'Mt. Barker' as hosts grown at root zone temperatures ranging from 7.5 to 35 °C. Maximum formation of both ectomycorrhizae and VA mycorrhizae occurred at 18.5–24 °C in soils from all sites, and there were no significant qualitative or quantitative differences between disturbed (clear-cut) or undisturbed (forest) soils. Mycorrhiza formation was moderate even at the lowest temperature tested (7.5 °C) but was greatly reduced or prevented at or above 29.5 °C. Treatment of soil at 35 °C for 1 week did not appear to adversely affect viability of ectomycorrhizal fungus propagules, but young mycorrhizae subjected to the same treatment appeared to be severely injured. Thus the ability of native mycorrhizal fungi to grow at low soil temperatures is especially important as they may contribute to the survival of seedlings outplanted into climatic zones characterized by warm, dry summers following cool, wet winters and springs.

Description: Reduced levels of root activity were associated with winter injury to shoots of 1-year-old black spruce (Piceamariana (Mill.) B.S.P.) container seedlings.

Description: Techniques are described for field and laboratory extraction of small quantities of sugar maple (Acersaccharum Marsh.) xylem sap when pressure in the xylem is less than atmospheric. Accurate estimates of sap sugar concentration can be made with a hand refractometer most of the year. There is, however, appreciable within-tree variation in sap sugar concentration at any given time and within short periods of time.

Description: Progenies belonging to 49 open-pollinated families of paper birch (Betulapapyrifera Marsh.) representing 13 provenances were evaluated sequentially for rate of root elongation in solutions containing only calcium nitrate and solutions containing calcium nitrate + 120 ppm aluminum. Provenances, but not families within provenances, differed significantly in both rate of root elongation and apparent response to Al. Provenance mean tolerance indices (root growth in Al solutions/root growth in non-Al solutions) varied from 0.10 to 0.37. Exposure to 120 ppm Al caused decreased concentrations of Ca and Cu in the foliage, decreased or nearly unchanged concentrations of P and Mg, and increased concentrations of Al, B, and Mn. Compared with the more tolerant provenances, intolerant provenances exhibited generally greater increases in foliar Al concentration after exposure to Al. Differential tolerance to Al will be useful in improving the performance of planted trees on Al-toxic sites.

Description: Three methods were compared for total sulphur analysis of tree foliage: magnesium nitrate ashing followed by turbidimetry, sodium hypobromite (NaOBr) oxidation followed by colorimetry, and an instrumental method using the Fisher S analyser, model 475. The latter method was found to be substantially better than the other methods with respect to accuracy and speed of analysis, and of satisfactory precision (average coefficient of variation (CV) was 2.5%). Dry ashing resulted in good precision (CV = 1.9%) but only recovered 76% of the reported total S in the United States National Bureau of Standards (NBS) orchard leaf standard. The NaOBr method recovered 88% of reported S from the NBS standard but showed poorer precision (CV = 4.5%). The Fisher analyser had the lowest operating cost per sample, largely owing to lower labour costs.

Description: Seasonal patterns of change in lipids, sugars, starch, labile (ethanol soluble) constituents, holocellulose, and lignin were studied in six forest-grown white oak (Quercusalba L.) trees. Contents of metabolically active constituents in leaves, twigs, branches, boles (upper and lower), and roots (support and small lateral) were used to construct whole-tree budgets of energy allocation. [14C]Sucrose was also concurrently supplied to the study trees to follow the fate and efficiency of utilization of food reserves. Results showed that white oak rapidly mobilized and replaced food reserves during the critical period of canopy generation in the spring. Starch was more important as a reserve food than lipids or sugar. Large fluctuations in starch in roots in spring and fall suggested a bimodal belowground growth pattern. Labile constituents showed the most pronounced seasonal changes and dominated the calculated whole-tree energy flux patterns. Rapid decline in labile compounds in early spring and a parallel increase in holocellulose suggested a possible pattern of mobilization and resupply of stored reserves associated with in cell wells. This possibility was supported by a concurrent shift of labile 14C to nonlabile 14C in tissues. Canopy generation was calculated to have cost ≤17.7 kg of glucose (1.6 g glucose/g of canopy) of which 13 kg appeared to have come from within the canopy.

Description: Total biomass of an aspen – mixed hardwood – spodosol ecosystem in northern Wisconsin, U.S.A., was 197 t/ha and net primary production was 11.5 t/ha per year. Populustremuloides Michx. accounted for 60% of the total biomass and 56% of the annual production and Acersaccharum Marsh, accounted for 25% of the biomass and 28% of the annual production. For all species combined, bole wood was 63% of the total biomass and bole bark was 12%. Bole wood was 33% and bole bark was 7% of the total production. Although crowns accounted for only 15% of the total biomass, they were responsible for 49% of net annual production. Using allometric equations from the literature, root biomass and production were calculated as being approximately 10% of the total biomass and of the annual production. The average rate of total production per unit leaf tissue was 5.7 g production/g leaf tissue for P. tremuloides and 3.7 g/g for A. saccharum.

Description: Water chemistry profiles of an 18-year-old forest ecosystem are compared with those of a 70- to 90-year-old forest ecosystem for a 9-month period. The younger ecosystem was dominated by Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and red alder (Alnusrubra Bong.) whereas western hemlock (Tsugaheterophylla (Raf.) Sarg.), Douglas-fir, and western red cedar (Thujaplicata Donn.) dominated the older ecosystem. Concentrations of nutrients and other chemicals were measured in throughfall, forest floor and mineral soil lecachates, saturated-zone water, and stream water. Concentrations of dissolved chemicals were much greater in the younger ecosystem than in the older ecosystem at intermediate stages in the profiles. However, stream water concentrations differed less between the two ecosystems for most of the chemicals investigated. Nitrate and silica were exceptional; stream water nitrate concentrations in the younger ecosystem averaged 16 times greater than those in the older ecosystem. This was probably a result of biological nitrogen fixation by red alder in the younger ecosystem, a process which would more than compensate for the higher nitrate losses. Silica concentrations in the younger ecosystem consistently exceeded levels in the older ecosystem by 40 to 100%. suggesting a possibility of a greater rate of mineral weathering in the younger ecosystem.Although nutrient concentrations were higher in the soil leachates of the younger ecosystem, these higher levels failed to persist through the saturated-zone water and stream water stages of the water chemistry profile. Consequently, the younger ecosystem appeared relatively more efficient at retaining dissolved nutrients than the older ecosystem. Stream water chemistry was relatively insensitive to the magnitudes of the differences in biogeochemical process rates of the two ecosystems.

Description: Seedlings of five half-sibs (seedlings that share a commom maternal parent) of Pinustaeda L. exposed to a bidirectional mechanical perturbation for 6 months exhibited a reduced rate of stem elongation and a reduction in the length of both juvenile leaves and needles. Of the five half-sibs tested, two different anatomical mechanisms of radial enlargement could be identified. Two half-sibs exhibited increased radial growth in the xylem parallel to the direction of the perturbation and no change in the axis perpendicular to the perturbation. Two exhibited a reduction in growth perpendicular to the perturbation with no change in the axis parallel to the perturbation. One half-sib appears to be intermediate between the two other pairs of half-sibs.An overall increase in extractable compounds was observed in the organic solvent fraction of mechanically perturbed seedlings. The amount of lignin appeared to remain fairly constant, and there was no change in the amounts of holocellulose or water extractable compounds.

Description: Above- and below-ground net primary production was estimated for 40-year-old Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stands growing on sites with apparently large differences in productivity potential. Aboveground net production was estimated from direct measurements of tree growth; belowground productivity was derived from data obtained by sorting live and dead roots from soil cores used in combination with measurements of root growth on observation windows.Aboveground net production was 13.7 t•ha−1 on the high productivity site and 7.3 t•ha−1 on the low productivity site. Belowground dry matter production on the high productivity site was 4.1 t•ha−1 compared with 8.1 t•ha−1 for the poorer site. On the more productive site, 8% of total stand dry matter production was in fine roots in contrast to over 36% on the poorer site. The difference in total net production (aboveground plus belowground) between the two sites was small (2.4 t•ha−1). Apparent differences in aboveground productivity may, to a large extent, result from the need for a greater investment in the fine roots on harsher sites.

Description: Low addition levels of high enrichment isotope (〉1% of the total nitrogen pool with 99 at.% excess 15N) were used to follow nitrogen movement through selected forest floor components of permafrost-free and permafrost-dominated black spruce ecosystems in subarctic Alaska. The nitrogen pool examined in this study was the total nitrogen pool. 15N was retained most effectively by the feather moss layer (Pleuroziumschreberi (BSG.) Mitt. and Hylocomiumsplendens (Hedw.) BSG.) on both black spruce sites. Twenty-eight months after isotope application the feather moss layer still contained over 90% of the 15N that could be recovered. The limited movement of 15N between feather moss layers and underlying forest floor horizons appeared to be slightly affected by climatological events. Differences in 15N movement patterns between permafrost-free and permafrost-dominated black spruce sites are discussed in terms of precipitation, soil temperature, and biological controls.

Description: A data screening algorithm (SCREEN) identified stand age, average stand diameter, timber type, soil type, aspect, habitat type, and elevation as forest stand or site characteristics strongly associated with root-disease occurrence in northern Idaho forests. The logistic regression model was used to predict root disease center occurrence. A second algorithm (RISK) was used to compute the estimates for the coefficients and to test different prediction equations. On wet aspects, highest probability of root disease centers was found on soils with lowest year-round moisture availability. The reverse was true on dry aspects. Increased slope was associated with increased root disease. Root disease center frequency was inversely related to elevation and directly related to occurrence of Pseudotsugamenziesii (Mirb.) Franco and Abiesgrandis (Dougl.) Lindl. Expression of disease centers was maximum at 60–100 years of stand age on all habitat types. A habitat-type–age interaction was observed in oldest aged stands.

Description: The main purpose of this study was to study spatial and competition effects on estimates of genetic parameters, as well as on selection options for growth traits, including height (H), diameter at breast height (DBH), and volume (V), in a progeny test of Japanese larch at age 20. We compared performances among the individual tree additive genetic base model (B) with design factors only, the spatial effect model (AR1), competition model (C), and combined spatial and competition model (CS). Spatial heterogeneity had significant effects on growth traits; plot variance decreased by more than 80% in the AR1 model relative to base model. Competition had significant effects on DBH and V, but a smaller effect on H. In the C model, direct additive genetic variances for DBH and V increased by 205% and 93%, respectively, whereas residual variances decreased by 8% and 6%. In the CS model, the correlations between direct and competitive genetic effects were 0.83, −0.97 and −0.98 for H, DBH and V. Competition significantly affected the forward selection. The proportions of selected elite trees were only 39% and 25% common between the B and CS models for DBH and V when selection intensity was 5%. For breeding selection, depending on thinning regimes planned, trees of high additive breeding values, but low competitive breeding values are preferable for plantation.

Description: Tree and stand volume estimates are relevant for forest inventories, forest sales, and carbon stock evaluations. Forest practice commonly uses generalized stem-wood volume functions; however, such generalized approaches neglect the stem form in detail. Hence, trees of a given species with the same diameter at breast height (d1.3) and height (h) are always assumed to have the same form factor and thus the same volume. This case study focused on stem form variation of Norway spruce (Picea abies (L.) Karst.) due to competition effects. Using terrestrial laser scanning (TLS), we measured the stem shape of 868 trees from a long-term spacing and thinning experiment in Germany. The plots covered a broad density range. We analysed the effect of competition and compared the TLS-determined stem volume estimates with those determined conventionally. TLS-based volume estimations showed that the lower the competition was, the lower the tree volume was with a given d1.3 and h. Commonly used functions underestimated the volume stock overall by 4.2%, disregarding any levels. At plot level, underestimation varied from 0.7% to 7.0%. At tree level, the volume was under- and over-estimated by −10% to +10%, respectively. The more precise the examination was, the more suitable the application of TLS was for enhancing volume estimation.

Description: Models for prediction of site index (SI) typically include only abiotic causal variables (e.g., soil) and lack biotic response variables (e.g., vegetation), which could exhibit greater sensitivity to important environmental factors affecting tree height growth. Our study objective was to evaluate Whittaker’s moisture condition index (MCI) (R.H. Whittaker. 1956. Ecol. Monogr. 26: 1–80) as a potential biotic variable for inclusion with conventional abiotic variables in oak (Quercus L.) SI prediction models. The MCI is the sum of relative abundances of inventoried plot tree species weighted by their moisture affinity classification. We compared regression parameters of conventional base models including only abiotic variables with exploratory models configured with abiotic variables and MCI for explaining variation of SI. The best abiotic model included only aspect. When MCI was included in the abiotic model, aspect became insignificant, resulting in a single-variable biotic model that accounted for increased SI variation. The MCI biotic model remained significant when tested with independent data from a distant location. The MCI is easily calculated using plot inventory data, and with further evaluation, it may be confirmed as a useful biotic variable in combination with abiotic soil and topographic variables for prediction of oak SI.

Description: The Kispiox Timber Supply Area, a 1.3 million ha region in northwestern British Columbia, Canada, supports a significant assemblage of temperate rainforest (oceanic) lichens that depend on old forests. Given their known sensitivity to edge effects, we ask whether or not the current configuration of Kispiox Old-Growth Management Area (OGMA) reserves will provide viable future habitat for oceanic lichens as surrounding landscapes are progressively logged in coming decades. Landscape indicators were calculated from provincial map data sets. Old Interior Cedar–Hemlock biogeoclimatic zone forests, the primary habitat for Kispiox oceanic lichens, had a landscape shape index of 6.4 in OGMAs, indicative of elongate shapes susceptible to edge effects. Mean patch size in OGMAs was 43 ha, with the largest patch size being 1 378 ha. In contrast, the landscape shape index for pre-industrial old cedar–hemlock forests was 1.3, with a mean patch size of 1 293 ha and largest patch size of 23 357 ha. When modelled edge effects were extended to 120 m, only 25% of cedar–hemlock forests in Kispiox OGMAs remained interior habitat (7 754 ha total). Adoption of silvicultural practices that maintain buffer zones around existing OGMAs, and the designation of additional OGMAs, especially in watersheds with intact old cedar–hemlock forests, is recommended to conserve oceanic lichen communities in the Kispiox region.

Description: Unmanned aerial vehicles (UAVs) have gained attention for forestry applications in recent years. These technologies provide ultrahigh-resolution spatial data for detailed mapping of forest structure, among other forestry applications. UAVs have mainly been tested in high-value timber stands, but little is known about their performance in other woody ecosystems such as shrublands that also provide key ecosystem services. Field measurements in shrublands are time-consuming, so UAVs could be used instead to provide data for shrubland management and conservation. We tested whether UAVs could map common structural attributes in shrublands of northern Patagonia. We specifically evaluated the capability of UAV point clouds for mapping (i) canopy height, (ii) stand density, (iii) basal area, and (iv) volume. The agreement with the field measurements was satisfactory (R2 was up to 0.95 and relative root mean square error (rRMSE) ranged between 12% and 39%) and comparable with those found for coniferous forests in similar studies. This study is a first attempt to characterize the structure of Patagonian shrublands using UAV data. Despite the challenges and methodological aspects that need to be solved, our results encourage the use of UAVs in these types of ecosystems.

Description: Spatially explicit, tactical forest planning is a necessary but challenging task in the management of plantation forests. It involves harvest scheduling and planning for road access and log transportation over time and space. This combinatorial problem can be formulated into the fixed-charge transportation problem (FCTP), in which the sum of fixed and variable costs is minimized while meeting harvest volume requirements and allowing necessary road maintenance and log hauling activities. The problem can be solved using general optimization methods such as mixed-integer linear programming (MILP), but the computational efficiency of the MILP-based approach quickly drops as the size and complexity of the problem increases. We developed a new optimization procedure that partitions the large planning problem into smaller subproblems. We applied a hybrid optimization approach using both MILP and heuristic rules to efficiently solve the large FCTP that otherwise may not be solvable using traditional methods. We applied our approach to an industrial plantation forest in Brazil. Our applications demonstrate the performance of the new optimization procedure and the benefit of solving large forest planning problems that integrate harvest scheduling with road access and transportation.

Description: Although several studies have evaluated fisher (Pekania pennanti (Erxleben, 1777)) selection of den structures across their natural range, the role of other nearby trees with suitable cavities that can be used by female fishers for subsequent maternal dens has not been explored. We used conditional logistic regression to describe selection of natal and maternal dens by female fishers in northern Minnesota, United States, and to determine if the density of other cavity trees surrounding a specific tree influences this selection. Our results indicate that cavity density was an important predictor of whether a tree was used as a den site by female fishers. The apparent condition (i.e., live, declining, or dead) and diameter at breast height of the cavity tree itself were also important for selection. These results affirm the need to retain large-diameter cavity trees, illustrate the potential benefits of retaining them in high-density patches, and caution against creating a landscape with highly dispersed denning options.

Description: Taper models are used to estimate the diameter at any height along the bole of a tree. Individual tree volume can then be calculated based on these diameters and corresponding heights. As tree diameters are affected by stand density, inside- and outside-bark taper models that incorporate stand density information were developed for trees in red pine (Pinus resinosa Aiton) plantations. Data used in this study came from stem analysis on 150 red pine trees sampled from 30 even-aged, monospecific plantations across Ontario, Canada. A nonlinear mixed-effects approach was applied in fitting these taper models. Several forms of stand density were evaluated for both inside- and outside-bark diameters. A combination of stand densities expressed as [Formula: see text] (BA, basal area; TPH, trees per hectare) explained the most variation in stem taper of trees grown in red pine plantations in Ontario. This variable was highly significant in the regression and improved the predictive accuracies of both inside- and outside-bark taper models. The taper models presented here are dimensionally compatible. Therefore, these models are applicable for data using any system of units without adjusting parameter values.

Description: The mechanical and physiological support of a tree's crown is the principal function of its bole. A simple model for Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) of different crown classes explains much of the observed differences in stem form development. Sapwood cross-sectional area at any height on the bole of the tree was found to be related linearly to the amount of foliage above that point; however, in large trees the sapwood area needed to supply transpiring foliage with water is insufficient to provide mechanical support. The combination of sapwood and heartwood was found to provide the stem form that would be expected to ensure uniform resistance to bending by the wind.

Description: Masting behavior — variable and synchronized reproduction by a population of plants — has long been recognized as correlating with weather. How and why weather conditions influence seed production is, however, poorly understood. We investigated the relationships between acorn production and both local weather and long-term climate in 10 populations across the geographic range of the valley oak (Quercus lobata Née), a California endemic that matures acorns in a single season. Acorn production was larger following a cold spring in the prior year and dry conditions in the winter and spring immediately preceding acorn maturation; similar patterns were also found, with minor differences, at all 10 individual sites. The strength of the relationships varied geographically in the case of the correlation between winter rainfall and annual acorn production, which was stronger (more negative) at wetter sites. Thus, in contrast to a recent study in Quercus petraea (Matt.) Liebl., weather had generally similar effects on acorn production throughout the range of Q. lobata. Similar to Q. petraea, however, the strength of the relationship between site-level annual acorn production and one of the weather factors affecting acorn production (winter rainfall in the case of Q. lobata) varied geographically in ways that may be related to differences among sites in the degree of pollen limitation. Understanding the mechanisms by which weather affects seed production is challenging but critical if we are to understand how climate change will affect masting behavior in the future.

Description: Increasing the production of wood fibre from conifer species such as white spruce (Picea glauca (Moench) Voss) is one of many challenges in the management of boreal mixedwood forests. The effects of various competition measures on relative growth and relative growth rate variables were calculated for individual white spruce subject trees. Correlation analysis was used to explore relationships with competitor structural features, including the ratio of competitor basal area to subject tree basal area (CBAS), the ratio of competitor height to subject tree height (AHCS), and the proportion of softwood (FSW). Regression analysis was used to explore relationships with three distance-dependent competition indices. The ratio of subject tree height to diameter at breast height (DBH) (HDR), crown ratio (CR), and crown relative increment rate (CRIR) were significantly correlated with CBAS and AHCS. HDR, CR, CRIR, and DBH relative growth rate were all statistically significantly related to the competition indices. Results indicated that (i) relative growth and relative growth rate measures successfully captured a range of competition, (ii) crowns of trees with larger diameters used their horizontal growing space more efficiently to produce stemwood, and (iii) the proportion of softwood contributing to competition did not appear to influence subject tree production efficiency. Growth efficiency variables have the potential to improve our understanding of boreal mixedwood dynamics.

Description: In many regions, forestry practices are shifting to partial harvesting approaches that seek to maintain species and structural diversity in managed forests. We monitored windthrow for 21 years following partial cutting treatments with 0%, 30%, and 60% removal in a large, replicated experiment located in mixed-species mature and old-growth forests of fire origin. There was no evidence that wind damage to merchantable trees (≥17.5 cm) varied among the three removal treatments. We found no evidence of a short-term spike in susceptibility to windthrow after partial cutting during the initial years following treatment. Over 21 years, a total basal area of 2.4 m2·ha–1 was damaged, which was 5.9% of the original standing basal area at the start of the experiment. We found clear differences in susceptibility to windthrow among the different tree species. The percentage of original standing trees that were windthrown varied from 0% to 23.7%. Eight of nine species had ≤10% damage over the monitoring period. Foresters should be aware of differences among tree species in risk of wind damage but should not use a general concern about susceptibility to windthrow as a reason to avoid partial cutting systems (that can achieve a diversity of management objectives) in structurally diverse, multispecies forests.

Description: We used a common garden study to investigate genetic variation in spring budburst phenology, growth, and structural traits of ponderosa pine (Pinus ponderosa Lawson & C. Lawson var. scopulorum Engelm.) seedlings from 10 provenances of different elevations in Arizona and New Mexico, United States. Seedlings were grown with ample resources for two growing seasons in a greenhouse in northern Arizona. Budburst date was measured at the onset of the second growing season; seedling growth, biomass, biomass ratios (shoot:root ratio, root mass ratio, stem mass ratio, and leaf mass ratio), and specific leaf area were measured at the end of the second season. Low-elevation provenances (2500 m) provenances. Height, leaf length, biomass, and biomass ratios were similar for elevational groups. Total biomass was positively correlated (r = 0.824) with provenance mean annual precipitation. Shoot:root ratio was positively correlated (r = 0.652) with longitude. Results suggest adaptation of low-elevation provenances to warm spring temperatures (early budburst) and aridity (low specific leaf area), inherently faster growth of provenances from wet locations, and greater allocation to shoots in eastern provenances. Such information about geographic patterns of genetic variation may be useful for selecting seed sources for planting in a changing climate.

Description: Understanding interactions between competition and climate in relation to their effects on individual tree growth is crucial to the development of climate-sensitive growth models required for modelling boreal forest succession in a changing climate. We used data from permanent growth and yield sample plots in western Canada and Alaska to investigate the impact of competition within a regional gradient of climatic conditions for lodgepole pine (Pinus contorta Douglas ex Loudon), jack pine (Pinus banksiana Lamb.), trembling aspen (Populus tremuloides Michx.), balsam poplar (Populus balsamifera L.), white spruce (Picea glauca (Moench) Voss), and black spruce (Picea mariana (Mill.) Britton, Sterns & Poggenb.). We characterized the effects of competition (basal area of spruce–fir, deciduous, and pine trees larger than the focal tree) and climate (mean annual temperature and precipitation) and their interactions on basal area growth of individual trees using linear mixed-effects models. Our results indicated that intraspecific competition had stronger effects on growth than interspecific competition and climate. Moreover, significant interactions between intraspecific competition and climate suggest that an increase in intraspecific competition will lead to a reduction in tree growth for warmer regions (lodgepole pine, trembling aspen, balsam poplar, and white spruce) and wetter regions (jack pine). The manner in which interspecific competition altered tree growth responses to climate was variable, depending on tree species and competition type. These results indicate that the relationships between growth and climate may differ according to the degree of competition and the structure of the stand.

Description: The objective of this paper was to estimate the effect of either missing or dominated plants (those that developed poorly) in experiments evaluating progenies or clones of Eucalyptus. Additionally, it was to investigate whether the use of the area available per plant is a suitable strategy to mitigate the effect of missing plants. Lastly, it was to evaluate whether missing or dominated plants in the experiments affected the association between plant performance in a progeny trial (PT) and their respective clones in a clonal trial (CT). Five 5-year-old PTs and four 3-year-old CTs were used. The recorded trait was diameter at breast height (DBH). The area available per plant was used to carry out the adjustment, taking into consideration the absence of neighboring plants as well as dominated plants. It was found that with the level of missing plants below 20% in experiments, the adjustment using the area available per plant did not improve the efficiency of the selection of either PTs or CTs. The strategy of considering not only missing plants but also dominated plants is not beneficial for the adjustment.

Description: Plants can develop differentially because of their ability of self/nonself discrimination and the degree of kinship among them. Here, we evaluate the ability of self/nonself discrimination of Eucalyptus urophylla S.T. Blake roots in plant groups with different levels of relatedness. We used three plant groups: clonal, half-siblings, and population. Split-root plants were grown in pots containing either two roots of the same plant (SD) or of two different plants (NSD). The growth of root and leaves of the half-siblings and population plants was decreased in NSD in relation to SD, whereas this response was not observed in the clonal group. The multivariate analysis indicated that there was a progressive increase in plant responses likely caused by competitive interaction of roots, as the level of relatedness between individuals was lower. Our results suggest that the group of clonal plants minimized the competitive interaction among them, indicating low ability to discriminate from each other. However, half-sibling and populational plants reduced growth as a result of root competition, showing high capacity of self discrimination. Thus, a minimum degree of genetic variation between plants seems necessary for kin recognition to be expressed.

Description: Preserving streamside forest habitats or buffer strips is considered to reduce forestry-related biodiversity loss in commercial forest landscapes. However, it is still unclear what type of management in and near streamside forests can be undertaken without compromising their biodiversity and natural change through succession. Using a before–after, control–impact study design, we tested the impacts of forested buffer strips (15 or 30 m wide, with or without selective logging), preserved after clear-cutting, on the changes of polypore communities in streamside boreal forests in Finland. Manipulations in 28 sites produced four treatment classes, the community compositions of which were compared with seven unmanaged controls before and 12 years after the manipulations. The polypore community composition in 15 m wide buffer strips changed differently than that in controls and resembled the community composition typically found in production forests. Moreover, selective logging tended to homogenize polypore communities. These responses of polypore communities indicate that the natural biodiversity and succession of streamside forests was disturbed in both 15 m wide and selectively logged buffer strips. Streamside forests in nonlogged 30 m wide buffer strips seemed to retain the natural polypore community composition and succession, at least during the 12-year period.

Description: Procurement for forest companies with pulp and paper mills aims to ensure that a sufficient volume of wood supply enters the production process. Numerous suppliers and contract types are available; however, their selection is a complex decision for procurement managers. In addition, managers typically dedicate a portion of their wood fiber demand to each group of suppliers, which is referred to as a portfolio strategy. Despite the available literature in contract selection, the consideration of contract types and their characteristics have not been addressed for the complex procurement process. In this study, a mixed-integer optimization model is proposed to best select contracts for pulp and paper procurement. The challenge was to plan deliveries in each time period to satisfy the demand of raw material at the mills. The potential of this model is demonstrated with a case study based on characteristics from a forest company in Quebec, Canada. A comparison between traditional fixed and flexible contracts is presented. Different portfolio strategies are also evaluated for groups of suppliers to investigate potential improvements.