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  • 1
    Electronic Resource
    Electronic Resource
    PATTERNS AND MECHANISMS OF THE FOREST CARBON CYCLE1 (2003)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Environment and Resources 28 (2003), S. 169-204 
    Details
    ISSN: 1543-5938
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Forests are an important source for fiber and fuel for humans and contain the majority of the total terrestrial carbon (C). The amount of C stored in the vegetation and soil are strongly influenced by environmental constraints on annual C uptake and decomposition and time since disturbance. Increasing concentrations of atmospheric carbon dioxide (CO2), nitrogen deposition, and climate warming induced by greater greenhouse gas (GHG) concentrations in the atmosphere influence C accumulation rates of forests, but their effects will likely differ in direction and magnitude among forest ecosystems. The net interactive effect of global change on the forest C cycle is poorly understood. The growing demand for wood fiber and fuel by humans and the ongoing anthropogenic perturbations of the climate have changed the natural disturbance regimes (i.e., frequency and intensity); these changes influence the net exchange of CO2 between forests and the atmosphere. To date, the role of forest products in the global C cycle have largely been ignored, and important emissions associated with the production, transport, and utilization of the forest products have been excluded, leading to erroneous conclusions about net C storage in forest products.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.energy.28.050302.105515
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  • 2
    Electronic Resource
    Electronic Resource
    Carbon distribution of a well- and poorly-drained black spruce fire chronosequence (2003)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 9 (2003), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: The objective of this study was to quantify carbon (C) distribution for boreal black spruce (Picea mariana (Mill.) BSP) stands comprising a fire chronosequence in northern Manitoba, Canada. The experimental design included seven well-drained (dry) and seven poorly-drained (wet) stands that burned between 1998 and 1850. Vegetation C pools (above-ground + below-ground) steadily increased from 1.3 to 83.3 t C ha−1 for the dry chronosequence, and from 0.6 to 37.4 t C ha−1 for the wet chronosequence. The detritus C pools (woody debris + forest floor) varied from 10.3 to 96.0 t C ha−1 and from 12.6 to 77.4 t C ha−1 for the dry and wet chronosequence, respectively. Overstorey biomass, mean annual biomass increment (MAI), woody debris mass, and litterfall were significantly greater (α = 0.05) for the dry stands than for the wet stands, but the bryophyte, understorey, and forest floor C pools were significantly less for the dry than for the wet stands. The root mass ratio decreased with stand age until 37 years after fire, was fairly constant thereafter, and was not significantly affected by soil drainage. The C pools of the overstorey and bryophyte tended to increase with stand age. Foliage biomass, litterfall, and MAI (for the dry stands) peaked at 71 years after fire and declined in the oldest stands. The results from this study illustrate that the effects of disturbance and edaphic conditions must be accounted for in boreal forest C inventories and C models. The appropriateness of using chronosequences to examine effects of wildfire on ecosystem C distribution is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2486.2003.00645.x
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  • 3
    Electronic Resource
    Electronic Resource
    The influence of fire on carbon distribution and net primary production of boreal Larix gmelinii forests in north-eastern China (2001)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 7 (2001), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: The boreal larch forest of Eurasia is a widespread forest ecosystem and plays an important role in the carbon budget of boreal forests. However, few carbon budgets exist for these forests, and the effects of wildfire, the dominant natural disturbance in this region, on carbon budgets are poorly understood. The objective of this study was to quantify the effects of wildfire on carbon distribution and net primary production (NPP) for three major Dahurian larch (Larix gmelinii Rupr.) forest ecosystems in Tahe, Daxing'anling, north-eastern China: Larix gmelinii–Ledum palustre, Larix gmelinii–grass and Larix gmelinii–Rhododendron dahurica forests. The experimental design included mature forests (unburned), and lightly and heavily burned forests from the 1.3-million-ha 1987 wildfire. We measured carbon distribution and above-ground NPP, and estimated fine root production from literature values.Total ecosystem carbon content for the mature forests was greatest for Larix–Ledum forests (251.4 t C ha−1) and smallest for Larix–grass forests (123.8 t C ha−1). Larix–Ledum forests contained the smallest vegetation carbon (13.5%), while Larix–Rhododendron contained the largest vegetation carbon (63.1%). Fires tended to transfer carbon from vegetation to detritus and soil. Total NPP did not differ significantly between the lightly burned and unburned stands, and averaged 1.58, 1.29 and 1.01 t C ha−1 year−1 for Larix–grass, Larix–Rhododendron and Larix–Ledum lightly burned stands, respectively. Above-ground net primary production (ANPP) of heavily burned stands was 92–95% less than unburned and lightly burned stands. The estimated carbon loss during the 1987 fire showed substantial variability among forest types and fire severity levels. Depending upon the assumptions made about the fraction of the landscape occupied by the three larch forest types, the 1987 conflagration in north-east China released 2.5 × 107−4.9 × 107 t C to the atmosphere. This study illustrates the need to distinguish between the different larch forests for developing general carbon budgets.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1354-1013.2001.00441.x
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  • 4
    Electronic Resource
    Electronic Resource
    Carbon pools in a boreal mixedwood logging chronosequence (2005)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 11 (2005), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Mixedwood forests are an ecologically and economically important forest type in central Canada, but the ecology of these forests is not as well studied as that of single-species dominated stands in the boreal forest. Northern boreal mixedwood forests have only recently been harvested and the effects of harvesting on carbon content in these stands are unknown. We quantified the carbon content and aboveground net primary production (NPP) for four different-aged mixedwood boreal forest stands in northern Manitoba, Canada. The stands included 11-, 18-, and 30-year-old stands that originated from harvesting and a 65-year-old fire-originated stand that typifies the origin of all northern boreal mixed-wood forests that are coming under management. Trees included black spruce (Picea mariana (Mill.) B.S.P.), jack pine (Pinus banksiana Lamb.), balsam poplar (Populus balsamifera L.), and quaking aspen (Populus tremuloides Michx.). Overstory biomass was estimated using species-specific allometric models that generally explained greater than 95% of the observed variation in biomass. Carbon content of the overstory vegetation was greatest in the 65-year-old stand and was 74% larger than the 11-year-old stand and showed a positive relationship with stand age (F1, 2=122.62, P=0.0081 R2=0.99). The slope of mineral soil carbon did not differ significantly among stands (F1, 2=0.39, P=0.5956, R2=0.16). Coarse woody debris carbon content followed a U-shaped pattern among stands. Aboveground NPP differed by 24% between the youngest and oldest stand. Mean annual carbon accumulation and aboveground NPP rates of the mixedwood forests were on average two times greater than nearby relatively pure stands studied during the BOREAS (BOReal Ecosystem Atmospheric Study) project. The trends in the results, along with other field studies, suggest that harvesting does not significantly affect the total soil carbon content. The results of this study suggest that scientists should be cautious about extrapolating results from BOREAS stands to a broader region until more data on other forest types and regions are available.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2486.2005.01019.x
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  • 5
    Electronic Resource
    Electronic Resource
    A cross-biome comparison of daily light use efficiency for gross primary production (2003)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 9 (2003), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Vegetation light use efficiency is a key physiological parameter at the canopy scale, and at the daily time step is a component of remote sensing algorithms for scaling gross primary production (GPP) and net primary production (NPP) over regional to global domains. For the purposes of calibrating and validating the light use efficiency (εg) algorithms, the components of εg– absorbed photosynthetically active radiation (APAR) and ecosystem GPP – must be measured in a variety of environments. Micrometeorological and mass flux measurements at eddy covariance flux towers can be used to estimate APAR and GPP, and the emerging network of flux tower sites offers the opportunity to investigate spatial and temporal patterns in εg at the daily time step. In this study, we examined the relationship of daily GPP to APAR, and relationships of εg to climatic variables, at four micrometeorological flux tower sites – an agricultural field, a tallgrass prairie, a deciduous forest, and a boreal forest. The relationship of GPP to APAR was close to linear at the tallgrass prairie site but more nearly hyperbolic at the other sites. The sites differed in the mean and range of daily εg, with higher values associated with the agricultural field than the boreal forest. εg decreased with increasing APAR at all sites, a function of mid-day saturation of GPP and higher εg under overcast conditions. εg was generally not well correlated with vapor pressure deficit or maximum daily temperature. At the agricultural site, a εg decline towards the end of the growing season was associated with a decrease in foliar nitrogen concentration. At the tallgrass prairie site, a decline in εg in August was associated with soil drought. These results support inclusion of parameters for cloudiness and the phenological status of the vegetation, as well as use of biome-specific parameterization, in operational εg algorithms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2486.2003.00573.x
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  • 6
    Electronic Resource
    Electronic Resource
    Site-level evaluation of satellite-based global terrestrial gross primary production and net primary production monitoring (2005)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 11 (2005), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Operational monitoring of global terrestrial gross primary production (GPP) and net primary production (NPP) is now underway using imagery from the satellite-borne Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. Evaluation of MODIS GPP and NPP products will require site-level studies across a range of biomes, with close attention to numerous scaling issues that must be addressed to link ground measurements to the satellite-based carbon flux estimates. Here, we report results of a study aimed at evaluating MODIS NPP/GPP products at six sites varying widely in climate, land use, and vegetation physiognomy. Comparisons were made for twenty-five 1 km2 cells at each site, with 8-day averages for GPP and an annual value for NPP. The validation data layers were made with a combination of ground measurements, relatively high resolution satellite data (Landsat Enhanced Thematic Mapper Plus at ∼30 m resolution), and process-based modeling. There was strong seasonality in the MODIS GPP at all sites, and mean NPP ranged from 80 g C m−2 yr−1 at an arctic tundra site to 550 g C m−2 yr−1 at a temperate deciduous forest site. There was not a consistent over- or underprediction of NPP across sites relative to the validation estimates. The closest agreements in NPP and GPP were at the temperate deciduous forest, arctic tundra, and boreal forest sites. There was moderate underestimation in the MODIS products at the agricultural field site, and strong overestimation at the desert grassland and at the dry coniferous forest sites. Analyses of specific inputs to the MODIS NPP/GPP algorithm – notably the fraction of photosynthetically active radiation absorbed by the vegetation canopy, the maximum light use efficiency (LUE), and the climate data – revealed the causes of the over- and underestimates. Suggestions for algorithm improvement include selectively altering values for maximum LUE (based on observations at eddy covariance flux towers) and parameters regulating autotrophic respiration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2486.2005.00936.x
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  • 7
    Electronic Resource
    Electronic Resource
    Effects of logging on carbon dynamics of a jack pine forest in Saskatchewan, Canada (2004)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 10 (2004), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: We calculated carbon budgets for a chronosequence of harvested jack pine (Pinus banksiana Lamb.) stands (0-, 5-, 10-, and∼29-year-old) and a∼79-year-old stand that originated after wildfire. We measured total ecosystem C content (TEC), above-, and belowground net primary productivity (NPP) for each stand. All values are reported in order for the 0-, 5-, 10-, 29-, and 79-year-old stands, respectively, for May 1999 through April 2000. Total annual NPP (NPPT) for the stands (Mg C ha−1 yr−1±1 SD) was 0.9±0.3, 1.3±0.1, 2.7±0.6, 3.5±0.3, and 1.7±0.4. We correlated periodic soil surface CO2 fluxes (RS) with soil temperature to model annual RS for the stands (Mg C ha−1 yr−1±1 SD) as 4.4±0.1, 2.4±0.0, 3.3±0.1, 5.7±0.3, and 3.2±0.2. We estimated net ecosystem productivity (NEP) as NPPT minus RH (where RH was calculated using a Monte Carlo approach as coarse woody debris respiration plus 30–70% of total annual RS). Excluding C losses during wood processing, NEP (Mg C ha−1 yr−1±1 SD) for the stands was estimated to be −1.9±0.7, −0.4±0.6, 0.4±0.9, 0.4±1.0, and −0.2±0.7 (negative values indicate net sources to the atmosphere.) We also calculated NEP values from the changes in TEC among stands. Only the 0-year-old stand showed significantly different NEP between the two methods, suggesting a possible mismatch for the chronosequence. The spatial and methodological uncertainties allow us to say little for certain except that the stand becomes a source of C to the atmosphere following logging.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1529-8817.2003.00804.x
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  • 8
    Electronic Resource
    Electronic Resource
    A global relationship between the heterotrophic and autotrophic components of soil respiration? (2004)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 10 (2004), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Soil surface CO2 flux (RS) is overwhelmingly the product of respiration by roots (autotrophic respiration, RA) and soil organisms (heterotrophic respiration, RH). Many studies have attempted to partition RS into these two components, with highly variable results. This study analyzes published data encompassing 54 forest sites and shows that RA and RH are each strongly (R2〉0.8) correlated to annual RS across a wide range of forest ecosystems. Monte Carlo simulation showed that these correlations were significantly stronger than any correlation introduced as an artefact of measurement method. Biome type, measurement method, mean annual temperature, soil drainage, and leaf habit were not significant. For sites with available data, there was a significant (R2=0.56) correlation between total detritus input and RH, while RA was unrelated to net primary production. We discuss why RA and RH might be related to each other on large scales, as both ultimately depend on forest carbon balance and photosynthate supply. Limited data suggest that these or similar relationships have broad applicability in other ecosystem types. Site-specific measurements are always more desirable than the application of inferred broad relationships, but belowground measurements are difficult and expensive, while measuring RS is straightforward and commonly done. Thus the relationships presented here provide a useful method that can help constrain estimates of terrestrial carbon budgets.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2486.2004.00816.x
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  • 9
    Electronic Resource
    Electronic Resource
    Net primary production and net ecosystem production of a boreal black spruce wildfire chronosequence (2004)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 10 (2004), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Net primary production (NPP) was measured in seven black spruce (Picea mariana (Mill.) BSP)-dominated sites comprising a boreal forest chronosequence near Thompson, Man., Canada. The sites burned between 1998 and 1850, and each contained separate well- and poorly drained stands. All components of NPP were measured, most for 3 consecutive years. Total NPP was low (50–100 g C m−2 yr−1) immediately after fire, highest 12–20 years after fire (332 and 521 g C m−2 yr−1 in the dry and wet stands, respectively) but 50% lower than this in the oldest stands. Tree NPP was highest 37 years after fire but 16–39% lower in older stands, and was dominated by deciduous seedlings in the young stands and by black spruce trees (〉85%) in the older stands. The chronosequence was unreplicated but these results were consistent with 14 secondary sites sampled across the landscape. Bryophytes comprised a large percentage of aboveground NPP in the poorly drained stands, while belowground NPP was 0–40% of total NPP. Interannual NPP variability was greater in the youngest stands, the poorly drained stands, and for understory and detritus production. Net ecosystem production (NEP), calculated using heterotrophic soil and woody debris respiration data from previous studies in this chronosequence, implied that the youngest stands were moderate C sources (roughly, 100 g C m−2 yr−1), the middle-aged stands relatively strong sinks (100–300 g C m−2 yr−1), and the oldest stands about neutral with respect to the atmosphere. The ecosystem approach employed in this study provided realistic estimates of chronosequence NPP and NEP, demonstrated the profound impact of wildfire on forest–atmosphere C exchange, and emphasized the need to account for soil drainage, bryophyte production, and species succession when modeling boreal forest C fluxes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1529-8817.2003.0742.x
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  • 10
    Electronic Resource
    Electronic Resource
    Foliar carbon isotope discrimination in Larix species and sympatric evergreen conifers: a global comparison (1998)
    Springer
    Oecologia 114 (1998), S. 153-159 
    Details
    ISSN: 1432-1939
    Keywords: Key words Foliar nitrogen ; Needle age ; Specific leaf area ; Water use efficiency ; δ13 Carbon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Larches (Larix spp.), deciduous conifers, occur in the northern hemisphere in cold-temperate and boreal climates – an environment normally thought to favor evergreen tree species. We compare foliar carbon isotope discrimination (Δ), instantaneous water use efficiency, total foliar nitrogen concentration, and specific leaf area (for a subset of sites) between Larix spp. and co-occurring evergreen conifers at 20 sites throughout the natural range of larches. Except for Larix occidentalis in the xeric Intermountain West, USA, Δ is significantly (P 〈 0.05) greater for larches than co-occurring evergreen conifers at 77% of the sites, suggesting that larches use water less efficiently. At elevations greater than 3000 m, the Δ of Larix spp. and co-occurring conifers converge, suggesting that water is not the limiting resource. Foliar nitrogen concentration and specific leaf area are two ecophysiological characteristics that are positively correlated with high photosynthetic capacity. Foliar nitrogen concentration is significantly greater for larches than evergreen conifers at 88% of the sites and specific leaf area is approximately three times greater for larches than co-occurring conifers. Future studies should examine the potential effect that global warming may have on the distribution of larch forests because the water use efficiency of larches is commonly less than co-occurring evergreen conifers and the boreal and high-latitude environments are likely to experience the greatest climate warming.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050431
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