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Aim: Tropical forest succession and associated changes in community composition are driven by species demographic rates, but how demographic strategies shift during succession remains unclear. Our goal was to identify generalities in demographic trade-offs and successional shifts in demographic strategies across Neotropical forests that cover a large rainfall gradient and to test whether the current conceptual model of tropical forest succession applies to wet and dry forests. Location: Mexico and Central America. Time period: 1985–2018. Major taxa studied: Trees. Methods: We used repeated forest inventory data from two wet and two dry forests to quantify demographic rates of 781 tree species. For each forest, we explored the main demographic trade-offs and assigned tree species to five demographic groups by performing a weighted principal components analysis to account for differences in sample size. We aggregated the basal area and abundance across demographic groups to identify successional shifts in demographic strategies over the entire successional gradient from very young (

Conserving the tree species of the world requires syntheses on which tree species are most vulnerable to pressing threats, such as climate change, invasive pests and pathogens, or selective logging. Here, we review the population and forest dynamics models that, when parameterized with data from population studies, forest inventories, or tree rings, have been used for identifying life-history strategies of species and threat-related changes in population demography and dynamics. The available evidence suggests that slow-growing and/or long-lived species are the most vulnerable. However, a lack of comparative, multi-species studies still challenges more precise predictions of the vulnerability of tree species to threats. Improving data coverage for mortality and recruitment, and accounting for interactions among threats, would greatly advance vulnerability assessments for conservation prioritizations of trees worldwide.

Life history variation in trees is a ubiquitous feature of tropical forests that may facilitate the niche partitioning of light. However, many tests have failed to detect light partitioning by saplings in gaps, which may reflect the stochastic nature of understory light penetration and recruitment. We argue that tree size is a critical component of niche partitioning that is more tightly linked to light availability. To account for size, we use a scaling framework to assess patterns of growth, abundance, mortality, and richness across life histories from >114,000 trees in a primary, neotropical forest. Relative abundance, productivity, and richness shift ~1−2 orders of magnitude with tree size: from shade tolerant, slow trees dominating the understory to parity with rapidly growing fast and long-lived pioneer species in the canopy. Life history tradeoffs promote vertical niche partitioning in tropical forests.

Ecological theory aims to understand how and why species differences allow competitors to coexist, but explanations remain inconsistent with data. Tightly constrained parameter tradeoffs needed for coexistence in models contrast with evidence that forests can support high diversity and be invaded repeatedly by species that lack specialized tradeoffs. By translating environmental responses to individual covariance, a universal coexistence hypothesis shows i) that species differences lead to a natural tendency to concentrate competition within the species, the common feature needed to promote coexistence in models, and ii) the fingerprint of this effect is available in covariances between individuals that can be observed in nature. The many ways in which species differ make high diversity almost inevitable. This covariance not only provides the evidence for this mechanism; it further provides a new direction for earth surface models that currently cannot sustain diverse communities despite large numbers of evidence-based parameters.

One goal for the 50-ha plot on Barro Colorado Island since its inception has been to understand demographic variability across the entire community of tree species. Early papers classified demographic response of many species to canopy gaps, culminating over the last decade with improved statistical methods that could quantify the response of growth, survival, and recruitment rates to increasing light for the entire community. We compile results from recent studies to illustrate the demographic trade-off between fast growth in high light and long life in deep shade. Growth and recruitment in high light are significantly correlated with mortality across species, and this trade-off is the primary demographic differentiation in the community. Here we add a new analysis of expected adult lifespan of 31 dominant canopy species spanning the growth-mortality axis. Using analytical solutions to matrices describing the lifetable, we demonstrate that the trade-off between high growth and long lifespan is not equalizing. The expected adult lifespan of a newly-recruited sapling is shorter in fast-growing pioneers than in long-lived shade-tolerant species: elevated growth rates of pioneers is insufficient to overcome their high death rates. If reproductive output were equal across the demographic axis, pioneer species could not persist. This suggests pioneers out-reproduce shade-tolerant species. The next goal is incorporating seed and seedling production into the demographic analysis to test the trade-off using lifetables having reproductive output included.

1. Organisms of all species must balance their allocation to growth, survival and recruitment. Among tree species, evolution has resulted in different life-history strategies for partitioning resources to these key demographic processes. Life-history strategies in tropical forests have often been shown to align along a trade-off between fast growth and high survival, that is, the well-known fast–slow continuum. In addition, an orthogonal trade-off has been proposed between tall stature—resulting from fast growth and high survival—and recruitment success, that is, a stature−recruitment trade-off. However, it is not clear whether these two independent dimensions of life-history variation structure tropical forests worldwide. 2. We used data from 13 large-scale and long-term tropical forest monitoring plots in three continents to explore the principal trade-offs in annual growth, survival and recruitment as well as tree stature. These forests included relatively undisturbed forests as well as typhoon-disturbed forests. Life-history variation in 12 forests was structured by two orthogonal trade-offs, the growth−survival trade-off and the stature−recruitment trade-off. Pairwise Procrustes analysis revealed a high similarity of demographic relationships among forests. The small deviations were related to differences between African and Asian plots. 3. Synthesis. The fast–slow continuum and tree stature are two independent dimensions structuring many, but not all tropical tree communities. Our discovery of the consistency of demographic trade-offs and life-history strategies across different forest types from three continents substantially improves our ability to predict tropical forest dynamics worldwide.

Plant functional traits can predict community assembly and ecosystem functioning and are thus widely used in global models of vegetation dynamics and land–climate feedbacks. Still, we lack a global understanding of how land and climate affect plant traits. A previous global analysis of six traits observed two main axes of variation: (1) size variation at the organ and plant level and (2) leaf economics balancing leaf persistence against plant growth potential. The orthogonality of these two axes suggests they are differently influenced by environmental drivers. We find that these axes persist in a global dataset of 17 traits across more than 20,000 species. We find a dominant joint effect of climate and soil on trait variation. Additional independent climate effects are also observed across most traits, whereas independent soil effects are almost exclusively observed for economics traits. Variation in size traits correlates well with a latitudinal gradient related to water or energy limitation. In contrast, variation in economics traits is better explained by interactions of climate with soil fertility. These findings have the potential to improve our understanding of biodiversity patterns and our predictions of climate change impacts on biogeochemical cycles., Nature Ecology & Evolution, 6 (1), ISSN:2397-334X

All species must balance their allocation to growth, survival and recruitment. Among trees, evolution has resulted in different strategies of partitioning resources to these key demographic processes, i.e. demographic trade-offs. It is unclear whether the same demographic trade-offs structure tropical forests worldwide. Here, we used data from 13 large-scale and long-term tropical forest plots to estimate the principal trade-offs in growth, survival, recruitment, and tree stature at each site. For ten sites, two trade-offs appeared repeatedly. One trade-off showed a negative relationship between growth and survival, i.e. the well-known fast−slow continuum. The second trade-off distinguished between tall-statured species and species with high recruitment rates, i.e. a stature−recruitment trade-off. Thus, the fast-slow continuum and tree stature are two independent dimensions structuring most tropical tree communities. Our discovery of the consistency of demographic trade-offs and strategies across forest types in three continents substantially improves our ability to predict tropical forest dynamics worldwide.

All species must balance their allocation to growth, survival and recruitment. Among trees, evolution has resulted in different strategies of partitioning resources to these key demographic processes, i.e. demographic trade-offs. It is unclear whether the same demographic trade-offs structure tropical forests worldwide. Here, we used data from 13 large-scale and long-term tropical forest plots to estimate the principal trade-offs in growth, survival, recruitment, and tree stature at each site. For ten sites, two trade-offs appeared repeatedly. One trade-off showed a negative relationship between growth and survival, i.e. the well-known fast−slow continuum. The second trade-off distinguished between tall-statured species and species with high recruitment rates, i.e. a stature−recruitment trade-off. Thus, the fast-slow continuum and tree stature are two independent dimensions structuring most tropical tree communities. Our discovery of the consistency of demographic trade-offs and strategies across forest types in three continents substantially improves our ability to predict tropical forest dynamics worldwide.

Community composition is a primary determinant of how biodiversity change influences ecosystem functioning and, therefore, the relationship between biodiversity and ecosystem functioning (BEF). We examine the consequences of community composition across six structurally realistic plant community models. We find that a positive correlation between species’ functioning in monoculture vs. their dominance in mixture with regards to a specific function (the “function-dominance correlation”) generates a positive relationship between realized diversity and ecosystem functioning across species richness treatments. However, because realised diversity declines when few species dominate, a positive function-dominance correlation generates a negative relationship between realized diversity and ecosystem functioning within species richness treatments. Removing seed inflow strengthens the link between the function-dominance correlation and BEF relationships across species richness treatments but weakens it within them. These results suggest that changes in species’ identities in a local species pool may more strongly affect ecosystem functioning than changes in species richness.

Data on plant traits are increasingly used to understand relationships between biodiversity and ecosystem processes. Large trait databases are sparse because they are compiled from many smaller and usually more local databases. This sparsity severely limits the potential for both multivariate and global data analyses, and so "gap-filling" (imputation) approaches are commonly used to predict missing trait data prior to analysis. Data imputation can result in large biases and circularity; yet, no best practice has evolved for the appropriate use of gap-filled data. Here, we use the TRY database, the largest global database of plant traits, in combination with the commonly used gap-filling algorithm, BayesianHierarchical Probabilistic Matrix Factorization (BHPMF), to address opportunities and problems introduced by gap-filling. BHPMF is the gap-filling method of choice for both TRY, and the large and widely used database sPLOT. It predicts missing trait data using the taxonomic hierarchy and observed patterns of trait variance and trait-trait correlations. We use three metrics: root mean square error estimates, coefficient of variation to assess univariate deviation, and silhouette indices to assess multivariate deviation and clustering strength. We show that gap-filling results in deviation of these metrics calculated for groupings at lower taxonomic levels (intra-specific and intra-genera), but less so at higher taxonomic levels (family) and for functional groups. Trait-trait correlations are preserved at all levels. The strength of deviations depends both on the percentage of gaps, and on data characteristics, e.g. intra-taxa variability. Gap-filling with dataset-external trait data generally ameliorates prediction error, but the deviations of intra-taxonomic variation measures depend on the content of the added data. We conclude that BHPMF gap-filling introduces little bias if specifically used for analyses of traits within functional groups, including growth forms and plant functional types (PFTs), as well as trait-trait correlations. However, we generally discourage their use for analyses of taxonomic groupings at or below the family level. In summary, our study supports decisions on when and how to integrate BHPMF gap-filled trait data in future studies. We conclude with selected best practices when using sparse databases.

This repository contains the data and analysis for the manuscript, "The function-dominance correlation drives the direction and strength of biodiversity-ecosystem functioning relationships.", This revision removes hidden files associated with Mac OS.

The competition for light has long been regarded as a key axis of niche partitioning that promotes forest diversity, but available evidence is contradictory. Despite strong tradeoffs between growth and survival with light, field tests suggest neutral forces govern tree composition across forest gaps and resource use across size classes. Here we integrate scaling and niche theory, and use data from >114,000 woody plants in a tropical, old growth forest to test and predict patterns of niche partitioning with size and light. Consistent with predictions, the relative abundance, production, light capture, and richness of species in life histories with fast growth follow a power law relationship, increasing 1–2 orders of magnitude along a solar and size gradient. Competitive neutrality between size classes emerges above the sapling layer, where increasing access to light is counterbalanced by stronger self-shading. Convergent power law patterns of resource partitioning across taxa and spatial scale suggest general life history tradeoffs drive the organization of diverse communities.

Local tree species distributions in tropical forests correlate strongly with soil water availability. However, it is unclear how species distributions are shaped by demographic responses to soil water availability. Specifically, it remains unknown how growth affects species distributions along water availability gradients relative to mortality. 2. We quantified spatial variation in dry season soil water potential (SWP) in the moist tropical forest on Barro Colorado Island, Panama, and used a hierarchical Bayesian approach to evaluate relationships between demographic responses of naturally regenerating seedlings to SWP (RGRs and first‐year mortality) and species distributions along the SWP gradient for 62 species. We also tested whether species that were more abundant at the wet or dry end of the gradient performed better (a) at their “home end” of the gradient (“best at home” hypothesis) and (b) “at home” compared to co‐occurring species (“home advantage” hypothesis). 3. Four and five species responded significantly to SWP in terms of growth or mortality respectively. Growth (but not mortality) responses were positively related to species distributions along the SWP gradient; species with a more positive (negative) growth response to SWP were more abundant at higher (lower) SWP, that is, at wetter (drier) sites. In addition, wet distributed species grew faster on the wet end of the SWP gradient than on the dry end (“best at home”) and grew faster on the wet end than dry distributed species (“home advantage”). Mortality rates declined with seedling size for all species. Thus, seedling growth responses to SWP indirectly shaped local species distributions by influencing seedling size and thereby mortality risk. 4. Synthesis. By demonstrating how growth responses to spatial variation in soil water availability affect species distributions, we identified a demographic process underlying niche differentiation on hydrological gradients in tropical forests. Recognizing the role of these growth responses in shaping species distributions should improve the understanding of tropical forest composition and diversity along rainfall gradients and with climate change.

Advancing phenology is one of the most visible effects of climate change on plant communities, and has been especially pronounced in temperature-limited tundra ecosystems. However, phenological responses have been shown to differ greatly between species, with some species shifting phenology more than others. We analysed a database of 42,689 tundra plant phenological observations to show that warmer temperatures are leading to a contraction of community-level flowering seasons in tundra ecosystems due to a greater advancement in the flowering times of late-flowering species than early-flowering species. Shorter flowering seasons with a changing climate have the potential to alter trophic interactions in tundra ecosystems. Interestingly, these findings differ from those of warmer ecosystems, where early-flowering species have been found to be more sensitive to temperature change, suggesting that community-level phenological responses to warming can vary greatly between biomes.

Life-history theory posits that trade-offs between demographic rates constrain the range of viable life-history strategies. For coexisting tropical tree species, the best established demographic trade-off is the growth-survival trade-off. However, we know surprisingly little about co-variation of growth and survival with measures of reproduction. We analysed demographic rates from seed to adult of 282 co-occurring tropical tree and shrub species, including measures of reproduction and accounting for ontogeny. Besides the well-established fast-slow continuum, we identified a second major dimension of demographic variation: a trade-off between recruitment and seedling performance vs. growth and survival of larger individuals (≥ 1 cm dbh) corresponding to a 'stature-recruitment' axis. The two demographic dimensions were almost perfectly aligned with two independent trait dimensions (shade tolerance and size). Our results complement recent analyses of plant life-history variation at the global scale and reveal that demographic trade-offs along multiple axes act to structure local communities.

The majority of variation in six traits critical to the growth, survival and reproduction of plant species is thought to be organised along just two dimensions, corresponding to strategies of plant size and resource acquisition. However, it is unknown whether global plant trait relationships extend to climatic extremes, and if these interspecific relationships are confounded by trait variation within species. We test whether trait relationships extend to the cold extremes of life on Earth using the largest database of tundra plant traits yet compiled. We show that tundra plants demonstrate remarkably similar resource economic traits, but not size traits, compared to global distributions, and exhibit the same two dimensions of trait variation. Three quarters of trait variation occurs among species, mirroring global estimates of interspecific trait variation. Plant trait relationships are thus generalizable to the edge of global trait-space, informing prediction of plant community change in a warming world., It is unclear whether plant trait relationships found at the global scale extend to climatic extremes. Here the authors analyse six major aboveground traits to show that known plant trait relationships extend to the tundra biomes and exhibit the same two dimensions of variation detected at the global scale.

Seedlings in moist tropical forests must cope with deep shade and seasonal drought. However, the interspecific relationship between seedling performance in shade and drought remains unsettled. We quantified spatiotemporal variation in shade and drought in the seasonal moist tropical forest on Barro Colorado Island (BCI), Panama, and estimated responses of naturally regenerating seedlings as the slope of the relationship between performance and shade or drought intensity. Our performance metrics were relative height growth and first-year survival. We investigated the relationship between shade and drought responses for up to 63 species. There was an interspecific trade-off in species responses to shade versus species responses to dry season intensity; species that performed worse in the shade did not suffer during severe dry seasons and vice versa. This trade-off emerged in part from the absence of species that performed particularly well or poorly in both drought and shade. If drought stress in tropical forests increases with climate change and as solar radiation is higher during droughts, the trade-off may reinforce a shift towards species that resist drought but perform poorly in the shade by releasing them from deep shade.

Assessing vegetation feedbacks with the climate system and planning sustainable management in tropical forests requires efficient, yet accurate, predictions of the joint dynamics of hundreds of tree species. With increasing information on tropical tree life-histories, our predictive understanding is no longer limited by species data, but by the ability of existing models to make use of it. Using a demographic forest model, we show that the basal area and compositional changes during forest succession in a Neotropical forest can be accurately predicted by representing tropical tree diversity (hundreds of species) with only five functional groups spanning two essential tradeoffs – the growth–survival and stature–recruitment tradeoffs. This data-driven modeling framework substantially improves our ability to predict consequences of anthropogenic impacts on tropical forests.

Species range limits are thought to result from a decline in demographic performance at range edges. However, recent studies reporting contradictory patterns in species demographic performance at their edges cast doubt on our ability to predict climate change demographic impacts. To understand these inconsistent demographic responses at the edges, we need to shift the focus from geographic to climatic edges and analyse how species responses vary with climatic constraints at the edge and species’ ecological strategy.Here we parameterised integral projection models with climate and competition effects for 27 tree species using forest inventory data from over 90,000 plots across Europe. Our models estimate size-dependent climatic responses and evaluate their effects on two life trajectory metrics: lifespan and passage time – the time to grow to a large size. Then we predicted growth, survival, lifespan, and passage time at the hot and dry or cold and wet edges and compared them to their values at the species climatic centre to derive indices of demographic response at the edge. Using these indices, we investigated whether differences in species demographic response between hot and cold edges could be explained by their position along the climate gradient and functional traits related to their climate stress tolerance.We found that at cold and wet edges of European tree species, growth and passage time were constrained, whereas at their hot and dry edges, survival and lifespan were constrained. Demographic constraints at the edge were stronger for species occurring in extreme conditions, i.e. in hot edges of hot-distributed species and cold edges of cold-distributed species. Species leaf nitrogen content was strongly linked to their demographic responses at the edge. In contrast, we found only weak links with wood density, leaf size, and xylem vulnerability to embolism.Synthesis. Our study presents a more complicated picture than previously thought with demographic responses that differ between hot and cold edges. Predictions of climate change impacts should be refined to include edge and species characteristics.

In the version of this Article originally published, the following sentence was missing from the Acknowledgements: “This work was supported by the Norwegian Research Council SnoEco project, grant number 230970”. This text has now been added.

Essential Biodiversity Variables (EBVs) allow observation and reporting of global biodiversity change, but a detailed framework for the empirical derivation of specific EBVs has yet to be developed. Here, we re-examine and refine the previous candidate set of species traits EBVs and show how traits related to phenology, morphology, reproduction, physiology and movement can contribute to EBV operationalization. The selected EBVs express intra-specific trait variation and allow monitoring of how organisms respond to global change. We evaluate the societal relevance of species traits EBVs for policy targets and demonstrate how open, interoperable and machine-readable trait data enable the building of EBV data products. We outline collection methods, meta(data) standardization, reproducible workflows, semantic tools and licence requirements for producing species traits EBVs. An operationalization is critical for assessing progress towards biodiversity conservation and sustainable development goals and has wide implications for data-intensive science in ecology, biogeography, conservation and Earth observation., Sí

Altres ajuts europeus: P.A.W. was additionally supported by the European Union Fourth Environment and Climate Framework Programme (Project Number ENV4-CT970586)P.A.W. was additionally supported by the European Union Fourth Environment and Climate Framework Programme (Project Number ENV4-CT970586). The tundra is warming more rapidly than any other biome on Earth, and the potential ramifications are far-reaching because of global feedback effects between vegetation and climate. A better understanding of how environmental factors shape plant structure and function is crucial for predicting the consequences of environmental change for ecosystem functioning. Here we explore the biome-wide relationships between temperature, moisture and seven key plant functional traits both across space and over three decades of warming at 117 tundra locations. Spatial temperature-trait relationships were generally strong but soil moisture had a marked influence on the strength and direction of these relationships, highlighting the potentially important influence of changes in water availability on future trait shifts in tundra plant communities. Community height increased with warming across all sites over the past three decades, but other traits lagged far behind predicted rates of change. Our findings highlight the challenge of using space-for-time substitution to predict the functional consequences of future warming and suggest that functions that are tied closely to plant height will experience the most rapid change. They also reveal the strength with which environmental factors shape biotic communities at the coldest extremes of the planet and will help to improve projections of functional changes in tundra ecosystems with climate warming.

For many tree species, growth patterns derived from tree-ring time series have been shown to be good indicators of tree mortality. Although tree rings of common beech (Fagus sylvatica) have been widely used to answer complex questions of forest ecology, there are only few studies using growth characteristics, such as growth decline or growth variability, as informative predictors of tree mortality in old-growth beech forests. To do this, we used dendrochronological data of living and dead trees from a nature reserve in eastern Germany. Using a logistic regression model, we predicted tree mortality based on growth characteristics (basal area increment; variance, autocorrelation, mean sensitivity of ring widths; growth trends) over different time horizons. Beech mortality could reliably be predicted up to 20 years in advance on the basis of relative basal area growth. Trees that grew slower in relative basal area than 0.95 cm2/cm y on average over a 20-year-period had a much higher mortality risk than faster-growing trees. Other statistical characteristics of the dendrochronological time series, such as the variance or autocorrelation of ring widths, the mean sensitivity or growth trends, did not convey significant additional information and did not lead to better mortality predictions.

Relationships between functional traits and average or potential demographic rates have provided insight into the functional constraints and trade-offs underlying life-history strategies of tropical tree species. We have extended this framework by decomposing growth rates of -130 000 trees of 171 Neotropical tree species into intrinsic growth and the response of growth to light and size. We related these growth characteristics to multiple functional traits (wood density, adult stature, seed mass, leaf traits) in a hierarchical Bayesian model that accounted for measurement error and intraspecific variability of functional traits. Wood density was the most important trait determining all three growth characteristics. Intrinsic growth rates were additionally strongly related to adult stature, while all traits contributed to light response. Our analysis yielded a predictive model that allows estimation of growth characteristics for rare species on the basis of a few easily measurable morphological traits.

Summary 1. Metabolic scaling theory predicts that diameter growth rates of tree species are related to tree diameter by a universal scaling law. This model has been criticised because it ignores the influence of competition for resources such as light on the scaling of demographic rates with size. 2. We here test whether scaling exponents of abundant tropical tree species comply with the prediction of metabolic scaling theory and evaluate whether the scaling of growth with size depends on light availability. Light reaching each individual tree was estimated from yearly vertical censuses of canopy density, and a hierarchical Bayesian approach allowed quantifying confidence intervals for scaling exponents and accounting for different sources of error. 3. We found no universal scaling relationship, and 50–70% of the species had scaling exponents that significantly differed from the predicted value of 1 ⁄ 3. As would be expected if competition for light were important, scaling exponents were >1 ⁄ 3 for the majority of species when all trees were combined. However, the community average of scaling exponents was not significantly different from the predicted value of 1 ⁄ 3 when only considering individuals that grew under highlight conditions. 4. These results support the hypothesis that the prediction of metabolic ecology for the scaling of tree growth with size is only valid when competition for light is unimportant.

Tree mortality is an important process determining forest dynamics. However, in species-rich tropical forests it is largely unknown, how species differ in their response of mortality to resource availability and individual condition. We use a hierarchical Bayesian approach to quantify the impact of light availability, tree size and past growth on mortality of 284 woody species in a 50-ha long-term forest census plot in Barro Colorado Island, Panama. Light reaching each individual tree was estimated from yearly vertical censuses of vegetation density. Across the community, 78% of the species showed increasing mortality with increasing light. Considering species individually, just 29 species showed a significant response to light, all with increasing mortality at high light. Past growth had a significant impact on all but three species, with higher growth leading to lower mortality. For the majority of species, mortality decreased sharply with diameter in saplings, then levelled off or increased slightly towards the maximum diameter of the species. Diameter had the biggest impact on mortality, followed by past growth and finally light availability. Our results challenge many previous reports of higher mortality in shade, and we suggest that it is crucial to control for size effects when assessing the impact of environmental conditions on mortality.

Summary 1. Many hypotheses about species coexistence involve differential resource use and trade-offs in species’ life-history traits. Quantifying resource use across most species in diverse communities, although, has seldom been attempted. 2. We use a hierarchical Bayesian approach to quantify the light dependence of recruitment in 263 woody species in a 50-ha long-term forest census plot in Panama. Data on sapling recruitment were obtained using the 1985–1990 and 1990–1995 census intervals. Available light was estimated for each recruit from yearly censuses of canopy density. 3. We use a power function (linear log–log relationship) to model the light effect on recruitment. Different responses of recruitment to light are expressed by the light effect parameter b. The distribution of b had a central mode at 0.8, suggesting that recruitment of many species responds nearly linearly to increasing light. 4. Nearly every species showed increases in recruitment with increasing light. Just nine species (3%) had recruitment declining with light, while 198 species (75%) showed increasing recruitment in both census intervals. Most of the increases in recruitment were decelerating, i.e. the increase was less at higher light (b < 1). In the remaining species, the response to light varied between census intervals (24 species) or species did not have recruits in both intervals (41 species). 5. Synthesis. Nearly all species regenerate better in higher light, and recruitment responses to light are spread along a continuum ranging from modest increase with light to a rather strict requirement for high light. These results support the hypothesis that spatio-temporal variation in light availability may contribute to the diversity of tropical tree species by providing opportunities for niche differentiation with respect to light requirements for regeneration.

Fuelwood extracted from natural forests serves as a principal energy source in rural regions of many tropical countries. Although fuelwood extraction (even low intensities) might strongly impact the structure and species composition of natural forests, long-term studies remain scarce. Here, we estimate the potential long-term impacts (over several hundred years) of such repeated harvesting of single trees on tropical montane cloud forest in central Veracruz, Mexico, by applying a process-based forest growth model. We simulate a wide range of possible harvesting scenarios differing in wood volume harvested and preferred tree species and sizes, and use a set of indicators to compare their impacts on forest size structure and community composition. Results showed that the overall impact on forest structure and community composition increased linearly with the amount of harvested wood volume. Even at low levels of harvesting, forest size structure became more homogeneous in the long term because large old trees disappeared from the forest, but these changes might take decades or even centuries. Although recruitment of harvested species benefited from harvesting, species composition shifted to tree species that are not used for fuelwood. Our results demonstrate that fuelwood extraction can have marked long-term impacts on tropical montane cloud forests. The results also offer the possibility to support the design of management strategies for the natural species-rich forests that achieve a balance between economic needs and ecological goals of the stakeholders.

Current forestry practices in Chile largely rely on exotic tree plantations, and limited management experiences are available for the species-rich native evergreen rain forests. Yet, conservationists and forest scientists call for sustainable management of native forests as an alternative to plantations so as to maintain important ecosystem services. We parameterised the process-based forest growth model FORMIND for a Valdivian coastal temperate rain forest in Chiloe Island, Chile, to assess the ecological implications of different logging practices including selective logging and strip-cutting. We tested the model by comparing simulation results with field data from the study site and carried out an extensive sensitivity analysis to explore the impacts of parameter values on model results. Simulated logging practices were compared in regard to expected timber harvest and long-term impacts on forest structure and composition. Results showed that highest harvests could be achieved when strip-cutting was applied, because it promoted the regeneration of the relatively light-demanding and fast-growing Eucryphia cordifolia . However, forest structure and composition were severely altered by this practice. In contrast, selective logging, although providing lower harvests, better conserved old-growth forest structure and composition. Canopy gaps created by selective logging were not large enough to ensure regeneration of E. cordifolia , but favoured the shade-tolerant Laureliopsis philippiana . Overall, the similarity of logged stands to undisturbed forest decreased linearly with increasing harvesting intensity. Management strategies that rely on native species and keep an uneven-aged forest structure ensure the maintenance of native biodiversity, protect ecosystems from exotic species invasions, and promote the conservation of biotic interactions essential for tree reproduction.

Earth is home to a remarkable diversity of plant forms and life histories, yet comparatively few essential trait combinationshave proved evolutionarily viable in today?s terrestrial biosphere. By analysing worldwide variation in six major traitscritical to growth, survival and reproduction within the largest sample of vascular plant species ever compiled, we foundthat occupancy of six-dimensional trait space is strongly concentrated, indicating coordination and trade-offs. Threequartersof trait variation is captured in a two-dimensional global spectrum of plant form and function. One majordimension within this plane reflects the size of whole plants and their parts; the other represents the leaf economicsspectrum, which balances leaf construction costs against growth potential. The global plant trait spectrum provides abackdrop for elucidating constraints on evolution, for functionally qualifying species and ecosystems, and for improvingmodels that predict future vegetation based on continuous variation in plant form and function. Fil: Díaz, Sandra Myrna. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Kattge, Jens. Max Planck Institute for Biogeochemistry; Alemania Fil: Cornelissen, Johannes H. C.. Vrije Universiteit; Países Bajos Fil: Wright, Ian J.. Macquarie University; Australia Fil: Lavorel, Sandra. Université Grenoble Alpes; Francia Fil: Dray, Stéphane. Université Lyon; Francia Fil: Reu, Björn. University of Leipzig; Francia Fil: Kleyer, Michael. University of Oldenburg; Alemania Fil: Wirth, Christian. Max Planck Institute for Biogeochemistry; Alemania Fil: Prentice, I. Colin. Macquarie University; Australia Fil: Garnier, Eric. Université Paul-Valéry Montpellier; Francia Fil: Bönisch, Gerhard. Max Planck Institute for Biogeochemistry; Alemania Fil: Westoby, Mark. Macquarie University; Australia Fil: Poorter, Hendrik. Forschungszentrum Jülich GmbH; Alemania Fil: Reich, Peter B.. University of Minnesota; Estados Unidos. University of Western Sydney; Australia Fil: Moles, Angela T.. University of New South Wales; Australia Fil: Dickie, John. The Royal Botanic Gardens Kew; Reino Unido Fil: Gillison, Andrew N.. Center for Biodiversity Management; Australia Fil: Zanne, Amy E.. George Washington University; Estados Unidos. Missouri Botanical Garden; Estados Unidos Fil: Chave, Jérôme. Université Paul Sabatier; Francia Fil: Wright, S. Joseph. Smithsonian Tropical Research Institute; Estados Unidos Fil: Sheremetev, Serge N.. Komarov Botanical Institute; Rusia Fil: Jactel, Hervé. Université de Bordeaux; Francia Fil: Baraloto, Christopher. Florida International University; Estados Unidos. Ecologie des Forêts de Guyane; Guayana Francesa Fil: Cerabolini, Bruno. University of Insubria; Italia Fil: Pierce, Simon. University of Milan; Italia Fil: Shipley, Bill. Université de Sherbrooke; Canadá Fil: Kirkup, Donald. The Royal Botanic Gardens Kew; Reino Unido Fil: Casanoves, Fernando. Centro Agronómico Tropical de Investigación y Enseñanza; Costa Rica Fil: Joswig, Julia S.. Max Planck Institute for Biogeochemistry; Alemania Fil: Günther, Angela. Max Planck Institute for Biogeochemistry; Alemania Fil: Falczuk, Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Rüger, Nadja. German Centre for Integrative Biodiversity Research; Alemania Fil: Mahecha, Miguel D.. Max Planck Institute for Biogeochemistry; Alemania Fil: Gorne, Lucas Damián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina

Simulation models that describe autonomous individual organisms (individual based models, IBM) or agents (agent-based models, ABM) have become a widely used tool, not only in ecology, but also in many other disciplines dealing with complex systems made up of autonomous entities. However, there is no standard protocol for describing such simulation models, which can make them difficult to understand and to duplicate. This paper presents a proposed standard protocol, ODD, for describing IBMs and ABMs, developed and tested by 28 modellers who cover a wide range of fields within ecology. This protocol consists of three blocks (Overview, Design concepts, and Details), which are subdivided into seven elements: Purpose, State variables and scales, Process overview and scheduling, Design concepts, Initialization, Input, and Submodels. We explain which aspects of a model should be described in each element, and we present an example to illustrate the protocol in use. In addition, 19 examples are available in an Online Appendix. We consider ODD as a first step for establishing a more detailed common format of the description of IBMs and ABMs. Once initiated, the protocol will hopefully evolve as it becomes used by a sufficiently large proportion of modellers.

Summary 1 We developed a spatially explicit and individual-based simulation model describing the dynamics of tree populations across treeline ecotones. Our aims were to identify minimal factors and processes able to generate treeline types with abrupt vs. smooth transitions in different variables (tree height, age, density), to investigate the role of positive feedback in pattern generation, and to determine why krummholz appears at some but not all treelines. We hypothesized that a different balance between smooth growth and mortality gradients across the treeline ecotone could account for differences between commonly observed treeline types. 2 The model contained only processes and factors regarded as essential for producing a treeline ecotone and was parameterized with an extensive, individual-based data set from Pinus uncinata treelines in the Spanish Pyrenees. However, parameters expected to influence treeline type were systematically varied. 3 The simple model was able to generate major treeline types differing in abruptness and krummholz abundance. The most important factors determining treeline types were the relative strength of growth and mortality gradients, followed by facilitation strength, whereas demographic parameters accounted for more subtle differences. 4 Only certain combinations of growth inhibition, mortality and facilitation allowed for the emergence of certain treeline types characterized by contrasting abruptness values and the presence or absence of krummholz. High krummholz densities emerged only under positive feedback and strongly increasing growth inhibition across the ecotone. Abruptness in adult tree density was positively correlated with facilitation strength and growth inhibition. By contrast, treelines with abrupt height transitions occurred only where both low growth inhibition and a strongly increasing mortality occurred across the ecotone. 5 Our analysis suggests that treeline features are not arbitrary but that there is a clear signal in the pattern which allows for inference of the underlying processes. Our approach of a systematic comparison of model predictions and various observed patterns can be widely applied for testing hypotheses on the functioning of ecological systems and for deriving specific questions for further investigations in the field.

In the Northern Amudarya delta (Uzbekistan), the regulated hydrological regime is one of the main factors determining the ecological state of riverine ecosystems, such as the characteristic tugai forests. Euphratica poplar (Populus euphratica, syn. ariana) is the dominant tree species of tugai forests in Central Asia. A habitat suitability index for P. euphratica is developed to provide a measure for the evaluation of future water management alternatives as to their effects on the ecological situation in the delta region. The following environmental variables are chosen as determining parameters for habitat suitability: geomorphology, groundwater level and flooding regime (i.e. flooding frequency, timing and duration of the last flooding). Here, flooding frequency is a dynamic variable that reflects the flooding history at a given site. Collected semi-quantitative and qualitative knowledge about the impact of those variables on suitability of a site for P. euphratica is formalised using a fuzzy set approach. The resulting index is implemented in GIS and applied to a test period (1991–1999). The results are compared to the actual distribution of tugai forest in the year 2000 to check their plausibility. By these means a ‘virtual expert’ is created that enables a fast and simple evaluation of the habitat suitability for P. euphratica on a landscape scale. As part of an integrated simulation tool, the HSI shall support the ecological impact assessment of future water management strategies on the Northern Amudarya delta.

Forests are major components of the global carbon cycle, providing substantial feedback to atmospheric greenhouse gas concentrations. Our ability to understand and predict changes in the forest carbon cycle—particularly net primary productivity and carbon storage— increasingly relies on models that represent biological processes across several scales of biological organization, from tree leaves to forest stands. Yet, despite advances in our understanding of productivity at the scales of leaves and stands, no consensus exists about the nature of productivity at the scale of the individual tree, in part because we lack a broad empirical assessment of whether rates of absolute treemass growth (and thus carbon accumulation) decrease, remain constant, or increase as trees increase in size and age. Here we present a global analysis of 403 tropical and temperate tree species, showing that for most species mass growth rate increases continuously with tree size. Thus, large, old trees do not act simply as senescent carbon reservoirs but actively fix large amounts of carbon compared to smaller trees; at the extreme, a single big tree can add the same amount of carbon to the forest within a year as is contained in an entire mid-sized tree. The apparent paradoxes of individual tree growth increasing with tree size despite declining leaf-level and stand-level productivity can be explained, respectively, by increases in a tree’s total leaf area that outpace declines in productivity per unit of leaf area and, among other factors, age-related reductions in population density. Our results resolve conflicting assumptions about the nature of tree growth,inform efforts to undertand and model forest carbon dynamics, and have additional implications for theories of resource allocation and plant senescence. Fil: Blundo, Cecilia Mabel. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Ecología Regional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Grau, Hector Ricardo. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Ecología Regional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Malizia, Agustina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Ecología Regional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Malizia, L. R.. Universidad Nacional de Jujuy. Facultad de Ciencias Agrarias; Argentina

Although sustainable forest management (SFM) has been widely adopted as a policy and management goal, high rates of forest loss and degradation are still occurring in many areas. Human activities such as logging, livestock husbandry, crop cultivation, infrastructural development, and use of fire are causing widespread loss of biodiversity, restricting progress toward SFM. In such situations, there is an urgent need for tools that can provide an integrated assessment of human impacts on forest biodiversity and that can support decision making related to forest use. This paper summarizes the experience gained by an international collaborative research effort spanning more than a decade, focusing on the tropical montane forests of Mexico and the temperate rain forests of southern South America, both of which are global conservation priorities. The lessons learned from this research are identified, specifically in relation to developing an integrated modeling framework for achieving SFM. Experience has highlighted a number of challenges that need to be overcome in such areas, including the lack of information regarding ecological processes and species characteristics and a lack of forest inventory data, which hinders model parameterization. Quantitative models are poorly developed for some ecological phenomena, such as edge effects and genetic diversity, limiting model integration. Establishment of participatory approaches to forest management is difficult, as a supportive institutional and policy environment is often lacking. However, experience to date suggests that the modeling toolkit approach suggested by Sturvetant et al. (2008) could be of value in such areas. Suggestions are made regarding desirable elements of such a toolkit to support participatory-research approaches in domains characterized by high uncertainty, including Bayesian Belief Networks, spatial multi-criteria analysis, and scenario planning., Most of the research described here was undertaken in three projects supported by the European Commission (INCO programme), namely SUCRE (ERBIC18CT970146), BIOCORES (ICA4- CT-2001-10095), and ReForLan (INCO-DEV-3 N° 032132), and three Darwin Initiative (DEFRA, UK Government) grants to the senior author. Additional funding was provided by a variety of sources within the partner countries. All sources of financial support are gratefully acknowledged.

The development of ecologically sound water allocation strategies that account for the needs of riverine ecosystems is a pressing issue, especially in semiarid river basins. In the Aral Sea Basin, a search for strategies to mitigate ecological and socioeconomic deterioration has been in process since the early 1990s. The Geographic Information System–based simulation tool TUGAI has been developed to support the policy determination process by providing a simple, problem-oriented method to assess ecological effects of alternative water management strategies for the Amudarya River. It combines a multiobjective water allocation model with simple, spatially explicit statistical and rule-based models of landscape dynamics. Changes in environmental conditions are evaluated by a fuzzy habitat suitability index for Populus euphratica, which is the dominant species of the characteristic riverine Tugai forests. Water management scenarios can be developed by altering spatiotemporal water distribution in the delta area or the amount of water inflow into the delta. Outcomes of scenario analysis are qualitative comparisons of the ecological effects of different options for a time period of up to 28 years. The given approach utilizes different types of knowledge, from quantitative hydrological data to qualitative local expert knowledge. The main purpose of the tool is to integrate the knowledge in a comprehensive way to make it available for discussions on alternative policies in moderated workshops with stakeholders. In this article, the modules of the tool, their integration, and three hypothetical scenarios are presented. Based on the experience gained when developing the TUGAI tool, we propose that the general framework can be transferred to other areas where tradeoffs in water allocation between the environment and other water users are of major concern. The potential for a simulation tool to structure and inform a complex resource management situation by involving local experts and stakeholders in the development of possible future scenarios will become increasingly valuable for transparent and participatory resource management.