ALBERT

Description: Partitioning of diversity: the "within communities" component Web Ecology, 14, 51-60, 2014 Author(s): H.-R. Gregorius It is routinely understood that the total diversity within a metacommunity (γ-diversity) can be partitioned into one component summarizing the diversity within communities (α-diversity) and a second component representing the contribution of diversity (or differences) between communities (β-diversity). The underlying thought is that merging differentiated communities should raise the total diversity above the average level of diversity within the communities. The crucial point in this partitioning criterion is set by the notion of "diversity within communities" (DWC) and its relation to the total diversity. The common approach to summarizing DWC is in terms of averages. Yet there are many different ways to average diversity, and not all of these averages stay below the total diversity for every measure of diversity, corrupting the partitioning criterion. This raises the question of whether conceptual properties of diversity measures exist, the fulfillment of which implies that all measures of DWC obey the partitioning criterion. It is shown that the straightforward generalization of the plain counting of types (richness) leads to a generic diversity measure that has the desired properties and, together with its effective numbers, fulfills the partitioning criterion for virtually all of the relevant diversity measures in use. It turns out that the classical focus on DWC (α) and its complement (β as derived from α and γ) in the partitioning of total diversity captures only the apportionment perspective of the distribution of trait diversity over communities (which implies monomorphism within communities at the extreme). The other perspective, differentiation, cannot be assessed appropriately unless an additional level of diversity is introduced that accounts for differences between communities (such as the joint "type-community diversity"). Indices of apportionment I A (among which is G ST and specially normalized versions of β) and differentiation I D are inferred, and it is demonstrated that conclusions derived from I A depend considerably on the measure of diversity to which it is applied, and that in most cases an assessment of the distribution of diversity over communities requires additional computation of I D .

Description: Editorial Note – Notice of triplicate publication: "Fish community structure and ecological degradation in tropical rivers of India" published in Web Ecol., 6, 27–36, 2006 Web Ecology, 14, 11-11, 2014 Author(s): D. Montesinos No abstract available.

Description: The effect of mixtures on colonisation of leaf litter decomposing in a stream and at its riparian zone Web Ecology, 14, 13-22, 2014 Author(s): M. Abelho The effect of mixing litter on decomposition and colonisation has been the focus of many studies carried independently in terrestrial and aquatic ecosystems. Those studies are carried out in different regions, use different experimental protocols and methodologies for the assessment of additive or non-additive effects, and the conclusions on the effect of mixtures vary accordingly. In this study I tested the hypothesis, via a short-term decomposition experiment, that, when using the same experimental protocol, mixtures have similar additive effects on decomposition and associated biota in a stream and at its riparian zone. The effect of mixing litter was assessed by comparing values in mixtures with the average of single species, alder and poplar (method 1); comparing the value of a species in mixture with the value of that species alone (method 2); and by a graphical analysis of the average difference between observed and expected values and the 95% confidence intervals (method 3). Method 1 was the most conservative, detecting non-additive effects on macroinvertebrate abundance only; method 2 detected non-additive effects on both dry mass remaining and ergosterol, with differential responses of the leaf species and the habitat; and method 3 detected non-additive effects on all variables except ergosterol and percentage detritivore abundance and also identified different responses of the leaves exposed in the terrestrial and the aquatic habitats. These results show that (i) the methodology used to detect the effects of mixtures deeply influences the results obtained, and may partially explain the diversity of responses available in literature; and (ii) the effect of mixtures may differ in the stream and at the riparian area. However, the findings of the present work should be assessed in a larger-scale experiment in order to generalise the effects of mixing litter on terrestrial and aquatic habitats.

Description: Plant–plant spatial association networks in gypsophilous communities: the influence of aridity and grazing and the role of gypsophytes in its structure Web Ecology, 14, 39-49, 2014 Author(s): H. Saiz, C. L. Alados, and Y. Pueyo In stressful environments many plant species are only able to survive if they benefit from the facilitative effect of "nurse" species. Typically, these nurses are species adapted to the stressful environmental conditions that favor the formation of vegetation patches, where other, less-adapted species can be established. However, ecological interactions can be influenced by abiotic and biotic factors. In this study we quantified the effect of grazing and aridity on the patch structure of gypsophilous plant communities and the role that gypsophytes, species adapted to gypsum soils, play in structuring these communities. Specifically, we created signed networks (networks with positive and negative links) at grazed and ungrazed sites in two areas in the middle Ebro Valley, Spain, that differed in aridity. We built networks connecting plant species with positive and negative links derived from the spatial associations between species. Then, we divided networks in partitions which represented the different vegetation patches present in the community. We found that vegetation patches were more specific (same species always were associated in the same patch type) in high aridity and grazed sites, where environmental conditions were the most stressful and many species persisted by associating with nurse species. Gypsophytes were more important aggregating species than nongypsophytes in grazed high aridity sites. Independently of study sites, gypsophyte shrubs acted as nurses, but small gypsophytes segregated from other species and formed monospecific patches. In conclusion, grazing and aridity influenced the patch structure of gypsophilous plant communities. Gypsophytes played an important role structuring the patch community, but this importance depended on environmental conditions and the identity of gypsophyte.

Description: Meta-analyses and the "editorial love of controversy" Web Ecology, 14, 23-25, 2014 Author(s): R. H. Heleno Meta-analyses are a most valuable tool to overcome the experimental constraints and often idiosyncratic responses typical in ecology. Nevertheless, competition for space in scientific journals increases editorial scrutiny, with editors frequently rejecting papers without outstanding novel results that challenge established paradigms. Whilst legitimate and generally healthy for the advance of science, this intrinsic "love of controversy" violates the independent accumulation of evidence required for conclusive meta-analyses, likely increasing the probability of false negatives and hindering our capacity to identify general rules in ecology.

Description: Ecological boundaries: a derivative of ecological entities Web Ecology, 14, 27-37, 2014 Author(s): J. Kolasa Defining ecological boundary as an outer envelope of an ecological entity such as an individual, colony, population, community, an ecosystem, or any other discernible unit provides methodological benefits and should thus enhance existing perspectives and research protocols. I argue that, because boundaries are features of entities, the first step in investigation of boundary structure and properties should involve identification of the entity the presumed boundary of interest belongs to. I use a general perspective where ecological systems are parts of a larger system and themselves are made of subsystems (or entities). Such a general hierarchy of ecological objects offers guidance as to how boundaries can be found for specific systems, and how their investigations might lead to reliable and generalizable insights. In particular, it may help in (a) categorizing types of boundaries based on mechanisms leading to formation of entities; (b) deciding what is and what is not a boundary by clarifying the nature of discontinuities seen in nature (e.g., sharp habitat transitions or weak separation of entities); (c) assisting in selecting fruitful resolution at which boundaries are examined; (d) approaching boundaries in complex, nested systems; and (e) deciding what criteria to use in answering questions about a particular boundary type. To facilitate the above I provide general criteria one may use for identifying ecological entities. Such criteria should assist in focusing on boundaries appropriate for a given research question. Finally, where advancing the theoretical framework for ecological boundaries is concerned, the diversity of boundary types will be better served when reorganized in relation to the concept of entity as discussed below.

Description: Comment on "Opinion paper: Forest management and biodiversity": the role of protected areas is greater than the sum of its number of species Web Ecology, 14, 61-64, 2014 Author(s): M. Mikoláš, M. Svoboda, V. Pouska, R. C. Morrissey, D. C. Donato, W. S. Keeton, T. A. Nagel, V. D. Popescu, J. Müller, C. Bässler, J. Knorn, L. Rozylowicz, C. M. Enescu, V. Trotsiuk, P. Janda, H. Mrhalová, Z. Michalová, F. Krumm, and D. Kraus No abstract available.

Description: It is routinely understood that the total diversity within a metacommunity (γ-diversity) can be partitioned into one component summarizing the diversity within communities (α-diversity) and a second component representing the contribution of diversity (or differences) between communities (β-diversity). The underlying thought is that merging differentiated communities should raise the total diversity above the average level of diversity within the communities. The crucial point in this partitioning criterion is set by the notion of "diversity within communities" (DWC) and its relation to the total diversity. The common approach to summarizing DWC is in terms of averages. Yet there are many different ways to average diversity, and not all of these averages stay below the total diversity for every measure of diversity, corrupting the partitioning criterion. This raises the question of whether conceptual properties of diversity measures exist, the fulfillment of which implies that all measures of DWC obey the partitioning criterion. It is shown that the straightforward generalization of the plain counting of types (richness) leads to a generic diversity measure that has the desired properties and, together with its effective numbers, fulfills the partitioning criterion for virtually all of the relevant diversity measures in use. It turns out that the classical focus on DWC (α) and its complement (β as derived from α and γ) in the partitioning of total diversity captures only the apportionment perspective of the distribution of trait diversity over communities (which implies monomorphism within communities at the extreme). The other perspective, differentiation, cannot be assessed appropriately unless an additional level of diversity is introduced that accounts for differences between communities (such as the joint "type-community diversity"). Indices of apportionment IA (among which is GST and specially normalized versions of β) and differentiation ID are inferred, and it is demonstrated that conclusions derived from IA depend considerably on the measure of diversity to which it is applied, and that in most cases an assessment of the distribution of diversity over communities requires additional computation of ID.

Description: The paper seeks to provide an introduction to, and review of, the history of concepts of the plant community. Eighteenth-century naturalists recognised that vegetation was distributed geographically and that different species of plants and animals were interconnected in what would later be called ecological relationships. It was not, however, until the early nineteenth century that the study of vegetation became a distinctive and autonomous form of scientific inquiry. Humboldt was the first to call communities of plants "associations". His programme for the empirical study of plant communities was extended by many European and North American botanists, throughout the nineteenth and into the twentieth century. There developed an almost complete consensus among ecologists that vegetation was made up of natural communities, discrete entities with real boundaries. However, there was little agreement about the nature of the putative unit or how it should be classified. Gleason advanced the alternative view that vegetation was an assemblage of individual plants, with each species being distributed according to its own physiological requirements and competitive interactions. This debate was never wholly resolved and the divergent opinions can be discerned within early ecosystem theory.

Description: In this opinion paper we investigate the effects of forest management on animal and plant biodiversity by comparing protected areas with intensively and extensively managed forests in Germany and in Romania. We want to know the extent to which differences in diversity of Romanian compared to German forests are based on management. The number of tree species was not different in protected and managed forests ranging between 1.8 and 2.6 species per plot in Germany and 1.3 and 4.0 in Romania. Also herbaceous species were independent of management, ranging between 13 species per plot in protected forests of Romania and 38 species per plot in German coniferous forest. Coarse woody debris was generally low, also in protected forests (14 to 39 m3 ha−1). The main difference between Romania and Germany was the volume of standing dead trees (9 to 28 m3 ha−1 for Romania), which resulted in larger numbers of forest relict saproxylic beetles independent of management. Large predators (wolves, bears and lynxes) are only found in regions with low human intervention. Thus, we identified a "cut and leave" type of management in Romania, in which clear-felling of forest are followed by long periods of no human intervention. Forests managed in the "cut and leave" mode contained the highest diversity, due to a natural succession of plant species and due to habitat continuity for animals. In Germany intensive management eliminates poorly formed tree individual and species of low market value during stand development. Forest protection does not ensure the maintenance of more light demanding key species of earlier stages of succession unless competition by shade-tolerant competitors is reduced through disturbances. We compare the economics of intensive and extensive management. The "cut and leave" mode delivers less wood to the wood market, but saves expenses of tending, thinning and administration. Thus the net income could be quite similar to intensive management at a higher level of biodiversity. Our analysis suggests that forest protection per se does not yet ensure the maintenance of species. Clear-felling followed by natural succession may even be superior to the protection of old growth forests, regarding biodiversity. Further research is needed to substantiate this hypothesis.

Description: Although the conflict between conservation efforts and economic growth is a major topic of conservation science, the conflicts between different conservation projects are much less documented and represented in the literature. We provide an overview of some case studies where these conflicts arise and discuss how to manage and solve them. We argue that conflicts are unavoidable, and that we can find optimal and efficient solutions only by studying the holistic, macroscopic properties of whole socio-ecological systems. Novel computational solutions offer simple and efficient simulation toolkits providing indicators that can support strategic and integrative decisions from a systems perspective.

Description: Ecosystem boundaries are important structures in defining ecosystems. To date, ecologists have not extensively considered which boundaries are important in explaining ecological phenomena in order to simplify ecological theories. The four-color theorem in mathematics maintains that only four colors are required to color a set of regions so that no two adjacent regions have the same color. Before being proven in 1976, the theorem was considered the "four-color issue", which proposed that a small number of colors were required to separate regional boundaries. Applying the principle of "four-color issue" to the ecological field, we can also examine reducing the number of ecosystem boundaries considered. That is, we can ask ourselves the following question: "how many boundaries of an ecosystem should be considered for ecology"? Here, I suggest a principle of ecosystem boundaries as the "four-color issue of ecology", and propose that this will be an important step toward advancing knowledge in ecology and conservation biology. In addition, I introduce graph theory, developed from the four-color theorem, which can be useful for estimating ecosystem boundaries.

Description: The effect of mixing litter on decomposition and colonisation has been the focus of many studies carried independently in terrestrial and aquatic ecosystems. Those studies are carried out in different regions, use different experimental protocols and methodologies for the assessment of additive or non-additive effects, and the conclusions on the effect of mixtures vary accordingly. In this study I tested the hypothesis, via a short-term decomposition experiment, that, when using the same experimental protocol, mixtures have similar additive effects on decomposition and associated biota in a stream and at its riparian zone. The effect of mixing litter was assessed by comparing values in mixtures with the average of single species, alder and poplar (method 1); comparing the value of a species in mixture with the value of that species alone (method 2); and by a graphical analysis of the average difference between observed and expected values and the 95% confidence intervals (method 3). Method 1 was the most conservative, detecting non-additive effects on macroinvertebrate abundance only; method 2 detected non-additive effects on both dry mass remaining and ergosterol, with differential responses of the leaf species and the habitat; and method 3 detected non-additive effects on all variables except ergosterol and percentage detritivore abundance and also identified different responses of the leaves exposed in the terrestrial and the aquatic habitats. These results show that (i) the methodology used to detect the effects of mixtures deeply influences the results obtained, and may partially explain the diversity of responses available in literature; and (ii) the effect of mixtures may differ in the stream and at the riparian area. However, the findings of the present work should be assessed in a larger-scale experiment in order to generalise the effects of mixing litter on terrestrial and aquatic habitats.

Description: Meta-analyses are a most valuable tool to overcome the experimental constraints and often idiosyncratic responses typical in ecology. Nevertheless, competition for space in scientific journals increases editorial scrutiny, with editors frequently rejecting papers without outstanding novel results that challenge established paradigms. Whilst legitimate and generally healthy for the advance of science, this intrinsic "love of controversy" violates the independent accumulation of evidence required for conclusive meta-analyses, likely increasing the probability of false negatives and hindering our capacity to identify general rules in ecology.

Description: African manatees (Trichechus senegalensis) and crocodiles are threatened species in parts of their range. In West Africa, crocodiles may constitute the main predators for manatees apart from humans. Here, we explore the macro-habitat selection of manatees and two species of crocodiles (West African crocodiles Crocodylus suchus and dwarf crocodile Osteolaemus tetraspis) in the Niger Delta (Nigeria), testing the hypotheses that (i) manatees may avoid crocodiles in order to minimize risks of predation, and (ii) the two crocodile species do compete. The study was carried out between 1994 and 2010 with a suite of different field techniques. We observed that the main macro-habitat types were freshwater rivers and coastal lagoons for manatees, mangroves for West African crocodiles, and rivers and creeks for dwarf crocodiles, with (i) the three species differing significantly in terms of their macro-habitat type selection, and (ii) significant seasonal influence on habitat selection of each species. Null models for niche overlap showed a significantly lower overlap in macro-habitat type use between manatee and crocodiles, whereas the two crocodiles were relatively similar. Null model analyses did not indicate any competitive interactions between crocodiles. On the other hand, manatees avoided macro-habitats where crocodiles, and especially West African crocodiles, are abundant.

Description: Urbanization generally leads to a complex environmental gradient, ranging from almost undisturbed natural areas to highly modified urban landscapes. Here we analyse the effects of a rural–urban gradient on breeding bird communities and functional species groups in remnant natural and semi-natural areas of Rome. A total of 69 breeding bird species were found in the study area. Species richness decreased with increasing urbanization at two spatial scales: the point count station and the landscape scales. Evenness showed a negative trend from periphery to city centre, whereas for dominant species the opposite was true. Functional species groups responded to the urbanization gradient with functional group-specific patterns. Those groups linked to open habitats (nesting and habitat functional groups) decreased in abundance along the rural–urban gradient, whereas those associated with forests exhibited a mixed trend. Generalist species' occurrence increased with urbanization. As for predators and granivorous species, we found a negative relationship with urbanization whereas for omnivorous species the opposite trend was true. The distribution of old villas (large-sized remnant green areas) in the inner city areas influenced species composition along the studied gradient, usually showing higher species richness than surrounding fragments. Agricultural areas hosted richer and better balanced bird assemblages in respect to those found in urban and forested areas. Our findings proved that an urban gradient plays a major role in structuring bird communities, although the extent and distribution of land use categories was another factor that influenced avian assemblages. The presence of historical villas also influenced bird assemblages, making it possible to preserve high bird diversity even in inner city-areas.

Description: Within-tree variation in abiotic conditions can create a mosaic of fitness gradients for herbivorous insects. To explore these effects, we quantified the patterns of mortality of the solitary oak leafminer, Cameraria hamadryadella (Lepidoptera: Gracillariidae), which lives within leaves of white oak, Quercus alba. We found differential patterns of survival and larval feeding rate within the tree and in association with several abiotic factors: light levels, leaf nitrogen content, and canopy height. We suggest that the leaf scale microhabitat conditions are fundamental to plant-herbivore-enemy interactions because of the differential fitness effects on herbivores. Such effects would be missed by studies that average effects by whole plants. Our study population of C. hamadryadella is located within the Orland E. White State Arboretum of Virginia in Boyce, Virginia, USA.

Description: Since the early 1940s, the ecosystem approach has been developed in a variety of forms by North American ecologists. Lindeman established its foundation, with his focus on functional components and energy transfers between trophic levels; this view was developed further by several ecologists, including G. Evelyn Hutchinson, and H. T. and E. P. Odum. Ecosystem ecology eventually became closely associated with powerful American institutions, such as the Atomic Energy Commission, receiving ample support; in association with the International Biological Program it became known as "big ecology''. More recently, ecosystem ecology has exhibited strengthened interest in spatial patterns, the role of species in ecosystems, and global change. This history has encompassed various ontological, methodological, ethical and political claims regarding the place of this approach in the discipline of ecology and in environmental governance.

Description: All organisms have to cope with spatial and temporal heterogeneity of the environment. At short temporal and small spatial scales, organisms may respond by behavioural or physiological mechanisms. To test for physiological adjustments to variation in host quality among tree individuals within a host species, we performed a transfer experiment in a climate chamber using larvae of the polyphagous gypsy moth (Lymantria dispar). We reared larvae for two weeks on leaves of one of three Quercus robur individuals. We found differences in the growth rate of larvae across the host individuals, which indicate that the oak individuals differed in their quality. Furthermore, families of larvae varied in their growth rate and there was variation among the families of gypsy moth larvae in response to leaves from the different oak individuals. After two weeks we offered larvae either leaves of the same or a different individual of the three oaks. We found no effect of transferring larvae to a different tree individual. The results thus do not support the idea of physiological adjustment of a generalist insect herbivore to variation in leaf quality among host individuals.

Description: The metapopulation framework presumes the habitat of a local population to be continuous and homogenous, and patch area is often used as a proxy for population size. Many populations of pond-breeding amphibians are assumed to follow metapopulation dynamics, and connectivity is mostly measured between breeding ponds. However, the habitat of pond-breeding amphibians is not only defined by the pond but, typically, consists of a breeding pond surrounded by clusters of disjoint summer-habitat patches interspersed with an agricultural/semi-urban matrix. We hypothesise that the internal structure of a habitat patch may change connectivity in two ways: (i) by affecting animal movements and thereby emigration and immigration probabilities; and (ii) by affecting habitat quality and population size. To test our hypotheses, we apply a spatially explicit individual-based model of Moor frog dispersal. We find that the realised connectivity depends on internal structure of both the target and the source patch as well as on how habitat quality is affected by patch structure. Although fragmentation is generally thought to have negative effects on connectivity, our results suggest that, depending on patch structure and habitat quality, positive effects on connectivity may occur.

Description: Compared to monocultures, diverse ecosystems are often expected to show more comprehensive resource use. However, with respect to diversity–soil-water-use relationships in forests, very little information is available. We analysed soil water uptake in 100 tree clusters differing in tree species diversity and species composition in the Hainich forest in central Germany. The clusters contained all possible combinations of five broadleaved tree species in one-, two- and three-species clusters (three diversity levels), replicated fourfold (20 one-species, 40 two-species and 40 three-species clusters). We estimated soil water uptake during a summer dry period in 0–0.3 m soil depth, based on throughfall and soil moisture measurements with a simple budgeting approach. Throughout the whole vegetation period in 2009, soil water uptake was additionally determined at a higher temporal resolution and also for a greater part of the soil profile (0–0.7 m) on a subset of 16 intensive clusters. During the dry spell, mean soil water uptake was 1.9 ± 0.1 mm day−1 in 0–0.3 m (100 clusters) and 3.0 ± 0.5 mm day−1 in 0–0.7 m soil depth (16 clusters), respectively. Besides a slightly higher water use of Fraxinus clusters, we could not detect any effects of species identity or diversity on cluster water use. We discuss that water use may indeed be a conservative process, that differences in tree-species-specific traits may be compensated for by other factors such as herb layer coverage and tree spatial arrangement, and that diversity-driven differences in water use may arise only at a larger scale. We further conclude that with respect to stand water use "tree diversity'' alone is not an appropriate simplification of the complex network of interactions between species traits, stand properties and environmental conditions that have varying influence on stand water use, both in space and time.

Description: For species distribution models, species frequency is termed prevalence and prevalence in samples should be similar to natural species prevalence, for unbiased samples. However, modelers commonly adjust sampling prevalence, producing a modeling prevalence that has a different frequency of occurrences than sampling prevalence. The separate effects of (1) use of sampling prevalence compared to adjusted modeling prevalence and (2) modifications necessary in thresholds, which convert continuous probabilities to discrete presence or absence predictions, to account for prevalence, are unresolved issues. We examined effects of prevalence and thresholds and two types of pseudoabsences on model accuracy. Use of sampling prevalence produced similar models compared to use of adjusted modeling prevalences. Mean correlation between predicted probabilities of the least (0.33) and greatest modeling prevalence (0.83) was 0.86. Mean predicted probability values increased with increasing prevalence; therefore, unlike constant thresholds, varying threshold to match prevalence values was effective in holding true positive rate, true negative rate, and species prediction areas relatively constant for every modeling prevalence. The area under the curve (AUC) values appeared to be as informative as sensitivity and specificity, when using surveyed pseudoabsences as absent cases, but when the entire study area was coded, AUC values reflected the area of predicted presence as absent. Less frequent species had greater AUC values when pseudoabsences represented the study background. Modeling prevalence had a mild impact on species distribution models and accuracy assessment metrics when threshold varied with prevalence. Misinterpretation of AUC values is possible when AUC values are based on background absences, which correlate with frequency of species.

Description: In Amphibians, both positive and negative correlations between activity and full moon phase have been observed. In this study, we present data for two anuran species (Hyla intermedia and Rana dalmatina) studied in a hilly Mediterranean area of central Italy. We analysed, in a two-year survey, the relationships between the number of egg clutches laid each night and the moon phases by means of circular statistics. Moreover, the studied species exhibited clear oviposition site selection behaviour influenced, at least in H. intermedia, by moon phases. We observed the occurrence of an avoidance effect by amphibians for oviposition and specific egg-laying behaviour during moon phases around the full moon. This apparent lunar phobia was evident in both species when yearly data were pooled. On the other hand, while this pattern continued to be also evident in H. intermedia when single years were considered, in R. dalmatina it stood just in one year of study. Nonetheless, during cloudy nights, when moonlight arriving on the ground was low, the frogs' behaviour was similar to that observed in new moon phases. We interpreted the observed pattern as an anti-predatory strategy. Overall, comparisons between our own study and previous research suggest that there was insufficient evidence to establish any unequivocal patterns and that further research in this regard is needed.

Description: We identified high-value biodiversity areas (HVBAs) of terrestrial vertebrates according to a combined index of biodiversity (CBI) for each major taxon and a standardized biodiversity index (SBI) for all taxa in 2195 cells of 50 × 50 km in Western Europe to evaluate whether these areas are included in the current protected area networks. The World Database on Protected Areas (WDPA) and NATURA 2000 protected area network were used to assess the protected area cover in HVBAs. WDPA and NATURA 2000 were geographically quite complementary as WDPA is more densely represented in Central and Northern Europe and NATURA 2000 in the Mediterranean basin. A total of 729 cells were identified as HVBAs. From the total of these HVBA areas, NATURA 2000 network was present in more cells (660) than the WDPA network (584 cells). The sum of protected land percentages across all the HVBA cells was 28.8%. The identified HVBA cells according to the SBI included 603 or 78.2% of all vertebrate species in the study region, whereas the identified HVBA cells according to the SBI for individual taxa included 47 (90.4%) species of amphibians, 79 (74.5%) of reptiles, 417 (88.5%) of birds, and 130 (91.5%) of mammals. However, neither network was present in 7 or 3% of the identified HVBA cells. Thus, we recommend expanding protected areas in Europe to fill this gap and improve coverage of vertebrate species to strengthen biodiversity conservation.

Description: Developmental and growth rates are known to vary in response to genetic, developmental, physiological and environmental factors. However, developmental variations that exist within a cohort under any constant rearing condition are not so well investigated. A few such prominent polymorphisms have been studied, but not the subtle ones. The current study investigates the presence of such varying rates of development, slow and fast, in a cohort reared under constant conditions in two ladybirds, Cheilomenes sexmaculata and Propylea dissecta. Our results reveal slow and fast developers in the cohorts of each species and the ratio of slow and fast developers was similar. Slow developers showed a female biased sex ratio. The two developmental variants differed significantly in juvenile duration only in the first instar and the pupal stage, though variations in developmental time were observed in all stages. Fecundity was higher in slow developers, but developmental rates did not affect egg viability. The similar ratio in both ladybirds indicates it to be a result of either presence of a constant ratio across species or an effect of the similar rearing environment.

Description: Seed dispersal is a key process for the invasion of new areas by exotic species. Introduced plants often take advantage of native generalist dispersers. Australian acacias are primarily dispersed by ants in their native range and produce seeds bearing a protein and lipid rich reward for ant mutualists (elaiosome). Nevertheless, the role of myrmecochory in the expansion of Australian acacias in European invaded areas is still not clear. We selected one European population of Acacia dealbata and another of A. longifolia and offered elaiosome-bearing and elaiosome-removed seeds to local ant communities. For each species, seeds were offered both in high-density acacia stands and in low-density invasion edges. For both acacia species, seed removal was significantly higher at the low-density edges. For A. longifolia, manual elimination of elaiosomes reduced the chance of seed removal by 80% in the low-density edges, whereas it made no difference on the high-density stands. For A. dealbata, the absence of elaiosome reduced seed removal rate by 52%, independently of the acacia density. Our data suggests that invasive acacias have found effective ant seed dispersers in Europe and that the importance of such dispersers is higher at the invasion edges.

Description: The time between introduction of an alien species and escape from cultivation shows considerable variation among species. One hypothesis to explain this variation of the time lag invokes the evolution of genotypes adapted to the conditions of the new environment. Here, we analyse the variation in time lags among 53 alien woody plant species in Germany. Accounting for the effects of time since introduction, growth form (trees versus shrubs), biogeography and taxonomic isolation (presence or absence of a native congener in the adventive area) we found that the time lag decreases with increasing polyploidization. By contrast, the haploid chromosome number was not significantly related to the time lag. These results provide evidence for the hypothesis that recent genome duplication events are important for a fast escape from cultivation of an alien woody plant species. We suggest that a large number of duplicated chromosomes increase the partitioning of the genome and hence the average rate of recombination between loci facilitating the formation of adaptive genotypes.

Description: Successional processes are an important element of commercial-forest ecosystems. They can be followed by studying the species composition of various animal groups, e.g. millipedes. Over the vegetation periods 2009 and 2010, we pitfall-trapped millipedes and centipedes (Myriapoda: Diplopoda, Chilopoda) on 21 Western German (North Rhine-Westphalian) deciduous and coniferous forest as well as fallow-ground sites of increasing age (1–165 yr) and determined them to the species and sex. Diplopoda (2009: 1659/2010: 3417 individuals) outnumbered the trapped Chilopoda (2009: 37/2010: 111 individuals) by far while the general catching results approximately doubled from 2009 to 2010. Indirect gradient analysis (CA) revealed that the influence of the habitat type on the formation of diplopod assemblages exceeded the influence of the successional stage. Although no clear trend in individual-count development over time occurred in most species detected, Julus scandinavius (Latzel, 1884) significantly increased in numbers with ageing of the deciduous (beech) forests. In conclusion, J. scandinavius may be a suitable bioindicator of deciduous-forest succession. More data are necessary to transfer our results into a mathematical function describing the course of increasing J. scandinavius abundance.

Description: Despite efforts to discern the role of plant size in resource competition, the circumstances under which size-dependent plant-plant interactions occur are still unclear. The traditional assumption is that competition intensifies with increasing neighbour size. However, recent studies suggest that the size (biomass) dependence of competitive interactions is strongest at very low biomass levels and becomes negligible after a certain threshold neighbour biomass has been reached. We searched for the generality of such patterns for three common annual plant species in Israel. We monitored target and neighbour biomass along their entire lifecycle using an even-aged, intraspecific and intrapopulation competition screenhouse experiment under water-limited conditions. For all focal species, neighbour presence had a net negative effect on vegetative biomass at harvest. However, this was not explained by increasing neighbour biomass over time, as a consistent pattern of size-dependent facilitative, rather than competitive, interactions was observed at all life stages. We explain these observations in terms of co-occurring aboveground facilitation and dominant belowground competition for water. Since our findings are the first of their kind and contradict theoretical predictions of biomass dependence of net negative interactions, we advocate further experiments addressing size dependence in interactions among plants. In particular, theoretical models addressing size dependence of positive interactions must be developed.

Description: Mining is one of the main causes of environmental pollution by heavy metals and (re)vegetation of mine spoils is the most effective method of preventing wind and water erosion and the consequent spread of contaminants to surrounding areas. However, plant establishment and growth are conditioned by some limiting factors of mine soils, such as low pH, low fertility, high heavy metal concentration, and a small seed bank to initiate plant establishment. Improving soil physical and chemical properties is required in many cases for successful (re)vegetation programs. In the copper mine of Touro, Galicia, Spain there is a large-scale project of soil amendment underway using technosols, a mixture of several organic residuals, to improve the conditions of mine soils. We evaluated the seed bank of several types of technosols, mine soil and soil from a control area outside the mine by studying seedling emergence in these soils. In a second experiment we evaluated the impact of increasing pH with liming and the admixing of nutrient-rich soil on the growth of two grasses (Lolium perenne and Dactylis glomerata) and two legumes (Medicago sativa and Trifolium subterrraneum) both sown individually and in mixtures. Seedling emergence and species richness were highest in the technosols. Soil amendments promoted plant growth, with the addition of high-nutrient soil being the best amendment for the four plant species tested. Plant growth was impaired in the mine soil. Lolium perenne was the only plant species that germinated and grew in this soil. We found that soil amendments, either through the addition of technosols, pH buffering or nutrient enrichment, are essential for promoting the revegetation of mine areas.

Description: Primary succession is an ecological process of fundamental importance referring to the development of vegetation on areas not previously occupied by a plant community. The bulk of knowledge on primary succession comes from areas affected by relatively recent volcanic eruptions, and highlights the importance of symbiosis between host plants and fungi for the initial stages of succession. Arbuscular mycorrhizas (AM) are of particular interest as they are often present from the very beginning of primary succession and because they show different relationships with pioneer and late-successional species, which suggests they may be involved in important, yet unknown, ecological mechanisms of succession. We review existing knowledge based on case studies from the volcanic desert of Mount Fuji, Japan, where primary succession was examined intensively and which represents one of the best-known cases on the role of AM in primary succession. We also assess the potential of sand dunes and semi-arid, erosion-prone systems for addressing the role of mycorrhizas in primary succession. Analyzing primary succession under different ecological systems is critical to understand the role of AM in this basic process. While volcanoes and glaciers are restricted to particular mountainous areas, naturally eroded areas and sand dunes are more common and easily accessible, making them attractive models to study primary succession.

Description: The interactive-versus-isolationist hypothesis predicts that parasite communities should be depauperated and weakly structured by interspecific competition in amphibians. A parasitological survey was carried out to test this hypothesis using three anuran species from Nigeria, tropical Africa (one Bufonidae; two Ranidae). High values of parasite infection parameters were found in all three species, which were infected by nematodes, cestodes and trematodes. Nonetheless, the parasite communities of the three anurans were very depauperated in terms of number of species (4 to 6). Interspecific competition was irrelevant in all species, as revealed by null models and Monte Carlo permutations. Cluster analyses revealed that, in terms of parasite community composition, the two Ranidae were similar, whereas the Bufonidae was more different. However, when prevalence, intensity, and abundance of parasites are combined into a multivariate analysis, each anuran species was clearly spaced apart from the others, thus revealing considerable species-specific differences in terms of their parasite communities. All anurans were generalists and probably opportunistic in terms of dietary habits, and showed no evidence of interspecific competition for food. Overall, our data are widely consistent with expectations driven from the interactive-versus-isolationist parasite communities hypothesis.

Description: We investigated the variability in resin yield of Aleppo pines in Evia (Greece) with the aim to exploit this natural resource in a sustainable way. Ten experimental plots were established in natural pine stands for monitoring. Our results revealed significant differences among stands, with high variation among individual trees in each plot. Maximum resin production was achieved in the Livadakia site whereas the minimum was obtained in Kokinomilia. All trees were classified according to their resin production into five classes ranging from not economically profitable (I) to highly profitable (V). From a total of 2483 trees, 1043 (42%) were in class I whereas the remaining 58% was classified into economically acceptable classes (II–V). A weak correlation (R2 = 0.315) between resin production and tree size was found suggesting that taller trees produced more resin than smaller trees.

Description: We analyzed the structure and growth of naturally regenerated stands of Pinus brutia that mixed with planted broad-leaved and conifer species, 12 years after wildfire and examined the degree of species mix. Field data on stand structure of P. brutia forest were taken in spring 2009 on northern and southern aspects differing in regeneration conditions. Sixteen sample plots were selected and all individuals and their attributes measured. The results showed that in northern aspects the forest is composed of P. brutia in the over-storey and Quercus pubescens and Cupressus sempervirens in the under-storey, while in southern aspects the forest was mainly composed by P. brutia (81%). Stem diameter distribution of P. brutia in both aspects followed almost a normal pattern. All P. brutia individuals were characterized by vigorous growth and good to normal stem quality. Aspect did not statistically affect structural characteristics of P. brutia trees and saplings. However, on the northern aspect stem diameter, height, crown length and basal area of P. brutia were greater than in the southern aspect. Aspect significantly affected structural characteristics of Q. pubescens.

Description: Cushion-forming plant species are found in alpine and polar environments around the world. They modify the microclimate, thereby facilitating other plant species. Similar to the effectiveness of shrubs as a means to study facilitation in arid and semi-arid environments, we explore the potential for cushion plant species to expand the generality of research on this contemporary ecological interaction. A systematic review was conducted to determine the number of publications and citation frequency on relevant ecological topics whilst using shrub literature as a baseline to assess relative importance of cushions as a focal point for future ecological research. Although there are forty times more shrub articles, mean citations per paper is comparable between cushion and shrub literature. Furthermore, the scope of ecological research topics studied using cushions is broad including facilitation, competition, environmental gradients, life history, genetics, reproduction, community, ecosystem and evolution. The preliminary ecological evidence to date also strongly suggests that cushion plants can be keystone species in their ecosystems. Hence, ecological research on net interactions including facilitation and patterns of diversity can be successfully examined using cushion plants, and this is particularly timely given expectations associated with a changing climate in these regions.

Description: The effects of management after fire in Pinus halepensis forests were assessed in northern Greece. Seeding, logging and building of log barriers were applied in burned sites and compared to a control site. Two years after treatment application, 70–80% of the ground in all sites was covered with vegetation. Seeding with herbaceous plants did not increase plant cover. Logging and building of log barriers negatively affected herbaceous species but increased woody species. During the first spring after fire, the highest numbers of P. halepensis seedlings were observed in the control site and the lowest number in the logged site. Logging and log barrier building had a negative effect on pine regeneration compared to control and seeding treatments. Woody plant composition was similar in control and seeding sites, with dominance of P. halepensis and Cistus species. A different pattern was observed in the logging and log-barrier sites with a low number of seeders and a high number of resprouter species.

Description: Amaranthus retroflexus, Echinochloa crus-galli and Datura stramonium are the most important weed species in Kosovo. They cause severe yield depression, contaminate fodder and negatively affect growth and reproduction of other weed species. To counteract these problems, specific strategies need to be developed. Such strategies should consider information on species germination traits. In this context, our study provides information on temperature requirements for germination. Seeds of A. retroflexus, E. crus-galli and D. stramonium were harvested in two sub-regions of Kosovo (western and eastern parts) differing in climate and land use. They were set for germination experiments in growth chambers at temperatures ranging from 3 to 35 °C and under field conditions. In both experiments, the germination rate differed between species and provenances. In the growth chamber experiment, germination of all three species was negligible below 15 °C and reached the highest rates between 24 and 30 °C. Seeds originating from the western part of Kosovo had higher germination rates and required a lower temperature for germination than seeds originating from the eastern part. In the field experiment, the time-dependent germination behaviour of D. stramonium differed between provenances. In general, germination started when soil temperature was above 18 °C and continued as long as the soil was moist. The results are discussed in the context of the need to develop weed management strategies against these weeds in Kosovo.

Description: Understanding dune ecosystem responses to multi-scale environmental changes can provide the framework for reliable forecasts and cost-efficient protocols for detecting shifts in prevailing coastal dynamics. Based on the hypothesis that stress and disturbance interact as primary community controls in coastal dunes, we studied the fine-scale floristic assembly of foredune vegetation, in its relation to topography, along regional and local environmental gradients in the 200 km long coastline of northern Portugal, encompassing a major biogeographic transition in western Europe. Thirty topographic profiles perpendicular to the shoreline were recorded at ten sites along the regional climate gradient, and vegetation was sampled by recording the frequency of plant species along those profiles. Quantitative topographic attributes of vegetated dune profiles (e.g. length or height) exhibited wide variations relatable to differences in prevailing coastal dynamics. Metrics of taxonomic diversity (e.g. total species richness and its additive beta component) and of the functional composition of vegetation were highly correlated to attributes of dune topography. Under transgressive dynamics, vegetation profiles have fewer species, increased dominance, lower turnover rates, and lower total vegetation cover. These changes may drive a decrease in structural and functional diversity, with important consequences for resistance, resilience and other ecosystem properties. Moreover, differences in both vegetation assembly (in meta-stable dunes) and response to increased disturbance (in eroding dunes) between distinct biogeographic contexts highlight a possible decline in facilitation efficiency under extreme physical stress (i.e. under Mediterranean climate) and support the significance of functional approaches in the study of local ecosystem responses to disturbance along regional gradients. Our results strongly suggest that assessing fine-scale community assembly can provide insights on the relation between dune vegetation, environmental filters and ecosystem processes. A combination of cost-efficient indicators from dune topography and vegetation is thus suggested as a promising approach to survey, forecast and monitor changes in coastal dune ecosystems.

Description: Defining ecological boundary as an outer envelope of an ecological entity such as an individual, colony, population, community, an ecosystem, or any other discernible unit provides methodological benefits and should thus enhance existing perspectives and research protocols. I argue that, because boundaries are features of entities, the first step in investigation of boundary structure and properties should involve identification of the entity the presumed boundary of interest belongs to. I use a general perspective where ecological systems are parts of a larger system and themselves are made of subsystems (or entities). Such a general hierarchy of ecological objects offers guidance as to how boundaries can be found for specific systems, and how their investigations might lead to reliable and generalizable insights. In particular, it may help in (a) categorizing types of boundaries based on mechanisms leading to formation of entities; (b) deciding what is and what is not a boundary by clarifying the nature of discontinuities seen in nature (e.g., sharp habitat transitions or weak separation of entities); (c) assisting in selecting fruitful resolution at which boundaries are examined; (d) approaching boundaries in complex, nested systems; and (e) deciding what criteria to use in answering questions about a particular boundary type. To facilitate the above I provide general criteria one may use for identifying ecological entities. Such criteria should assist in focusing on boundaries appropriate for a given research question. Finally, where advancing the theoretical framework for ecological boundaries is concerned, the diversity of boundary types will be better served when reorganized in relation to the concept of entity as discussed below.

Description: In stressful environments many plant species are only able to survive if they benefit from the facilitative effect of "nurse" species. Typically, these nurses are species adapted to the stressful environmental conditions that favor the formation of vegetation patches, where other, less-adapted species can be established. However, ecological interactions can be influenced by abiotic and biotic factors. In this study we quantified the effect of grazing and aridity on the patch structure of gypsophilous plant communities and the role that gypsophytes, species adapted to gypsum soils, play in structuring these communities. Specifically, we created signed networks (networks with positive and negative links) at grazed and ungrazed sites in two areas in the middle Ebro Valley, Spain, that differed in aridity. We built networks connecting plant species with positive and negative links derived from the spatial associations between species. Then, we divided networks in partitions which represented the different vegetation patches present in the community. We found that vegetation patches were more specific (same species always were associated in the same patch type) in high aridity and grazed sites, where environmental conditions were the most stressful and many species persisted by associating with nurse species. Gypsophytes were more important aggregating species than nongypsophytes in grazed high aridity sites. Independently of study sites, gypsophyte shrubs acted as nurses, but small gypsophytes segregated from other species and formed monospecific patches. In conclusion, grazing and aridity influenced the patch structure of gypsophilous plant communities. Gypsophytes played an important role structuring the patch community, but this importance depended on environmental conditions and the identity of gypsophyte.

Description: We characterized and compared the use of nitrate (N-NO3−), in three recognized pioneer and secondary tropical species, analyzing their relationships with the availability of inorganic nitrogen in the soil of a riparian forest. We tested the hypothesis that pioneer species of the ecological succession (Cecropia glaziovi – Cgl) would be more responsive to N-NO3− available and would have high nitrate reductase activity (NRA) in leaves while secondary species (Inga marginata – Ima and Hymenaea courbaril – Hco) would have less responsiveness and would have lower levels of this enzyme on its leaves. We evaluated, tested and compared the NRA and N-NO3− content in leaves and xylem sap of each species. We measured N-NO3− and N-NH4+ content in the soil. The results for Cgl showed an N-NO3− content of xylem sap that met the demand of NRA and were correlated with inorganic soil nitrogen, showing the responsiveness of species to N-NO3−. Hco was verified as less responsive to assimilation and high N-NO3− content in leaves. The species Ima showed an intermediate behaviour, which suggests the possibility of use of other nitrogen forms. The ecophysiological behaviours of the plants were related to the seasonal variation and indicate that these plants use strategies with different responsiveness to the use of soil N-NO3−. In this sense and considering that these species are typically used in ecological restoration projects in Brazil, the knowledge of a strategy for nitrogen use specific to each of them can assist in choosing the species appropriate to the edaphic conditions of the environment.

Description: Patterns and mechanisms of species occurrence in space and time are outstanding questions in community and conservation ecology. Much of the current debate focuses on randomness or non-randomness in the structuring process of ecological communities, and the extent to which local/deterministic or regional/stochastic processes may drive their composition. However, a categorical subdivision could be misleading, as community composition may be driven by a continuum between neutral- and niche-based processes. For instance, in spatially structured systems local processes may surpass regional processes over time or across space to derive non-random metacommunity structure, suggesting the filtering role of the environment in mediating the pattern of species occurrence. In this work we study the temporal composition of detritus-based communities, which are an essential component in many aquatic and terrestrial ecosystems. We used data about macroinvertebrate colonization of leaf detritus in different sites of a patchy-connected system, to measure the co-occurrence of species on the detrital resource and evaluate the role of the spatial configuration and the environmental variability in determining the community’s composition. Our results show the importance of considering the joint role of regional and local processes in mediating stochastic and deterministic mechanisms in species assemblage, with important outcomes from a conservation point of view.