Loss of species and functions in a deforested megadiverse tropical forest.

Tropical species richness is threatened by habitat degradation associated with land-use conversion, yet the consequences for functional diversity remain little understood. Progress has been hindered by difficulties in obtaining comprehensive species-level trait information to characterize entire assemblages and insufficient appreciation that increasing land-cover heterogeneity potentially compensates for species loss. We examined the impacts of tropical deforestation associated with land-use heterogeneity on bird species richness, functional redundancy, functional diversity, and associated components (i.e., alpha diversity, species dissimilarity, and interaction strength of the relationship between abundance and functional dissimilarity). We analyzed over 200 georeferenced bird assemblages in the Atlantic Forest of Brazil. We characterized the functional role of the species of each assemblage and modeled biodiversity metrics as a function of forest cover and land-cover heterogeneity. Replacement of native Atlantic Forest with a mosaic of land uses (e.g., agriculture, pastures, and urbanization) reduced bird species richness in a nonrandom way. Core forest species, or species considered sensitive to edges, tended to be absent in communities in heterogenous environments. Overall, functional diversity and functional redundancy of bird species were not affected by forest loss. However, birds in highly heterogenous habitats were functionally distinct from birds in forest, suggesting a shift in community composition toward mosaic-exclusive species led by land-cover heterogeneity. Threatened species of the Atlantic Forest did not seem to tolerate degraded and heterogeneous environments; they remained primarily in areas with large forest tracts. Our results shed light on the complex effects of native forest transformation to mosaics of anthropogenic landscapes and emphasize the importance of considering the effects of deforestation and land-use heterogeneity when assessing deforestation effects on Neotropical biodiversity.

Pérdida de especies y funciones en un bosque tropical megadiverso deforestado Resumen La riqueza de especies tropicales está amenazada por la degradación asociada con la conversión del uso de suelo, y aun así entendemos muy poco de las consecuencias que esto tiene para la diversidad funcional. El progreso está obstaculizado por las dificultades para obtener información completa de los rasgos a nivel de especie para caracterizar ensamblajes completos y la apreciación insuficiente de que la heterogeneidad creciente de la cobertura del suelo tiene el potencial para compensar la pérdida de especies. Analizamos el impacto que tiene la deforestación tropical asociada con la heterogeneidad del uso de suelo sobre la riqueza de especies de aves, la redundancia funcional, la diversidad funcional y sus componentes asociados (es decir, diversidad alfa, disimilitud de especies y fuerza de interacción de la relación entre la abundancia y la disimilitud funcional). Analizamos más de 200 ensamblajes georreferenciados de aves en el Bosque Atlántico de Brasil. Caracterizamos el papel funcional de las especies de cada ensamblaje y modelamos las medidas de biodiversidad como función de la cobertura forestal y de la heterogeneidad del uso de suelo. La sustitución del Bosque Atlántico nativo con un mosaico de usos de suelo (p. ej.: agricultura, pastura y urbanización) redujo la riqueza de especies de una manera no aleatoria. Las especies nucleares del bosque, o las especies consideradas como sensibles a los bordes, tendieron a estar ausentes en las comunidades de los ambientes heterogéneas. En general, la diversidad y la redundancia funcionales de las especies de aves no se vieron afectadas por la pérdida del bosque. Sin embargo, las aves en los hábitats con alta heterogeneidad eran funcionalmente distintas a las aves de los bosques, lo que sugiere un cambio en la composición x de la comunidad hacia especies exclusivas de mosaicos llevadas por la heterogeneidad de la cobertura del suelo. Las especies amenazadas del Bosque Atlántico no parecieron tolerar el ambiente degradado y heterogéneo pues permanecieron principalmente en las áreas con grandes extensiones de bosque. Nuestros resultados arrojan luz sobre los efectos complejos de la transformación de los bosques nativos en mosaicos de paisajes antropogénicos y recalcan la importancia de considerar los efectos de la deforestación y la heterogeneidad del uso de suelo cuando se evalúan los efectos de la deforestación sobre la biodiversidad neotropical.

Global maps and factors driving forest foliar elemental composition: the importance of evolutionary history.

Consistent information on the current elemental composition of vegetation at global scale and the variables that determine it is lacking. To fill this gap, we gathered a total of 30 912 georeferenced records on woody plants foliar concentrations of nitrogen (N), phosphorus (P) and potassium (K) from published databases, and produced global maps of foliar N, P and K concentrations for woody plants using neural networks at a resolution of 1 km2 . We used data for climate, atmospheric deposition, soil and morphoclimatic groups to train the neural networks. Foliar N, P and K do not follow clear global latitudinal patterns but are consistent with the hypothesis of soil substrate age. We additionally built generalized linear mixed models to investigate the evolutionary history effect together with the effects of environmental effects. In this comparison, evolutionary history effects explained most of the variability in all cases (mostly > 60%). These results emphasize the determinant role of evolutionary history in foliar elemental composition, which should be incorporated in upcoming dynamic global vegetation models.

The effect of global change on soil phosphatase activity.

Soil phosphatase enzymes are produced by plant roots and microorganisms and play a key role in the cycling of phosphorus (P), an often-limiting element in terrestrial ecosystems. The production of these enzymes in soil is the most important biological strategy for acquiring phosphate ions from organic molecules. Previous works showed how soil potential phosphatase activity is mainly driven by climatic conditions and soil nitrogen (N) and carbon. Nonetheless, future trends of the activity of these enzymes under global change remain little known. We investigated the influence of some of the main drivers of change on soil phosphatase activity using a meta-analysis of results from 97 published studies. Our database included a compilation of N and P fertilization experiments, manipulation experiments with increased atmospheric CO2 concentration, warming, and drought, and studies comparing invaded and non-invaded ecosystems. Our results indicate that N fertilization leads to higher phosphatase activity, whereas P fertilization has the opposite effect. The rise of atmospheric CO2 levels or the arrival of invasive species also exhibits positive response ratios on the activity of soil phosphatases. However, the occurrence of recurrent drought episodes decreases the activity of soil phosphatases. Our analysis did not reveal statistically significant effects of warming on soil phosphatase activity. In general, soil enzymatic changes in the reviewed experiments depended on the initial nutrient and water status of the ecosystems. The observed patterns evidence that future soil phosphatase activity will not only depend on present-day soil conditions but also on potential compensations or amplifications among the different drivers of global change. The responses of soil phosphatases to the global change drivers reported in this study and the consideration of cost-benefit approaches based on the connection of the P and N cycle will be useful for a better estimation of phosphatase production in carbon (C)-N-P models.

Metabolome-Wide, Phylogenetically Controlled Comparison Indicates Higher Phenolic Diversity in Tropical Tree Species.

Tropical plants are expected to have a higher variety of defensive traits, such as a more diverse array of secondary metabolic compounds in response to greater pressures of antagonistic interactions, than their temperate counterparts. We test this hypothesis using advanced metabolomics linked to a novel stoichiometric compound classification to analyze the complete foliar metabolomes of four tropical and four temperate tree species, which were selected so that each subset contained the same amount of phylogenetic diversity and evenness. We then built Bayesian phylogenetic multilevel models to test for tropical-temperate differences in metabolite diversity for the entire metabolome and for four major families of secondary compounds. We found strong evidence supporting that the leaves of tropical tree species have a higher phenolic diversity. The functionally closer group of polyphenolics also showed moderate evidence of higher diversity in tropical species, but there were no differences either for the entire metabolome or for the other major families of compounds analyzed. This supports the interpretation that this tropical-temperate contrast must be related to the functional role of phenolics and polyphenolics.

Increasing atmospheric CO2 concentrations correlate with declining nutritional status of European forests.

The drivers of global change, including increases in atmospheric CO2 concentrations, N and S deposition, and climate change, likely affect the nutritional status of forests. Here we show forest foliar concentrations of N, P, K, S and Mg decreased significantly in Europe by 5%, 11%, 8%, 6% and 7%, respectively during the last three decades. The decrease in nutritional status was especially large in Mediterranean and temperate forests. Increasing atmospheric CO2 concentration was well correlated with the decreases in N, P, K, Mg, S concentrations and the increase of N:P ratio. Regional analyses indicated that increases in some foliar nutrient concentrations such as N, S and Ca in northern Europe occurred associated with increasingly favourable conditions of mean annual precipitation and temperature. Crucial changes in forest health, structure, functioning and services, including negative feedbacks on C capture can be expected if these trends are not reversed.

Behaviour, life history and persistence in novel environments.

Understanding what affects population growth in novel environments is fundamental to forecast organisms' responses to global change, including biological invasions and land use intensification. Novel environments are challenging because they can cause maladaptation, increasing the risk of extinction by negative population growth. Animals can avoid extinction by improving the phenotype-environment match through behavioural responses, notably matching habitat choice and learning. However, the demographic consequences of these responses remain insufficiently understood in part because they have not been analysed within a life-history context. By means of an individual-based model, we show here that matching habitat choice and learning interact with life history to influence persistence in novel environments. In maladaptive contexts, the likelihood of persisting is higher for life-history strategies that increase the value of adults over the value of offspring, even at the cost of decreasing reproduction. Such a strategy facilitates persistence in novel environments by reducing the costs of a reproductive failure while increasing the benefits of behavioural responses. Our results reinforce the view that a more predictive theory for extinction risk under rapid environmental changes requires considering behavioural responses and life history as part of a common adaptive strategy to cope with environmental changes. This article is part of the theme issue 'Linking behaviour to dynamics of populations and communities: application of novel approaches in behavioural ecology to conservation'.

Fast attrition of springtail communities by experimental drought and richness-decomposition relationships across Europe.

Soil fauna play a fundamental role on key ecosystem functions like organic matter decomposition, although how local assemblages are responding to climate change and whether these changes may have consequences to ecosystem functioning is less clear. Previous studies have revealed that a continued environmental stress may result in poorer communities by filtering out the most sensitive species. However, these experiments have rarely been applied to climate change factors combining multiyear and multisite standardized field treatments across climatically contrasting regions, which has limited drawing general conclusions. Moreover, other facets of biodiversity, such as functional and phylogenetic diversity, potentially more closely linked to ecosystem functioning, have been largely neglected. Here, we report that the abundance, species richness, phylogenetic diversity, and functional richness of springtails (Subclass Collembola), a major group of fungivores and detritivores, decreased within 4 years of experimental drought across six European shrublands. The loss of phylogenetic and functional richness was higher than expected by the loss of species richness, leading to communities of phylogenetically similar species sharing evolutionary conserved traits. Additionally, despite the great climatic differences among study sites, we found that taxonomic, phylogenetic, and functional richness of springtail communities alone were able to explain up to 30% of the variation in annual decomposition rates. Altogether, our results suggest that the forecasted reductions in precipitation associated with climate change may erode springtail communities and likely other drought-sensitive soil invertebrates, thereby retarding litter decomposition and nutrient cycling in ecosystems.

Predictable evolution towards larger brains in birds colonizing oceanic islands.

Theory and evidence suggest that some selective pressures are more common on islands than in adjacent mainland habitats, leading evolution to follow predictable trends. The existence of predictable evolutionary trends has nonetheless been difficult to demonstrate, mainly because of the challenge of separating in situ evolution from sorting processes derived from colonization events. Here we use brain size measurements of >1900 avian species to reveal the existence of one such trend: increased brain size in island dwellers. Based on sister-taxa comparisons and phylogenetic ancestral trait estimations, we show that species living on islands have relatively larger brains than their mainland relatives and that these differences mainly reflect in situ evolution rather than varying colonization success. Our findings reinforce the view that in some instances evolution may be predictable, and yield insight into why some animals evolve larger brains despite substantial energetic and developmental costs.

Environmental variation and the evolution of large brains in birds.

Environmental variability has long been postulated as a major selective force in the evolution of large brains. However, assembling evidence for this hypothesis has proved difficult. Here, by combining brain size information for over 1,200 bird species with remote-sensing analyses to estimate temporal variation in ecosystem productivity, we show that larger brains (relative to body size) are more likely to occur in species exposed to larger environmental variation throughout their geographic range. Our reconstructions of evolutionary trajectories are consistent with the hypothesis that larger brains (relative to body size) evolved when the species invaded more seasonal regions. However, the alternative-that the species already possessed larger brains when they invaded more seasonal regions-cannot be completely ruled out. Regardless of the exact mechanism, our findings provide strong empirical support for the association between large brains and environmental variability.

Urbanisation tolerance and the loss of avian diversity.

Urbanisation is considered an important driver of current biodiversity loss, but the underlying causes are not fully understood. It is generally assumed that this loss reflects the fact that most organisms do not tolerate well the environmental alterations associated with urbanisation. Nevertheless, current evidence is inconclusive and the alternative that the biodiversity loss is the result of random mechanisms has never been evaluated. Analysing changes in abundance between urbanised environments and their non-urbanised surroundings of > 800 avian species from five continents, we show here that although random processes account for part of the species loss associated with urbanisation, much of the loss is associated with a lack of appropriate adaptations of most species for exploiting resources and avoiding risks of the urban environments. These findings have important conservation implications because the extinction of species with particular features should have higher impact on biodiversity and ecosystem function than a random loss.

Unraveling the life history of successful invaders.

Despite considerable current interest in biological invasions, the common life-history characteristics of successful invaders remain elusive. The widely held hypothesis that successful invaders have high reproductive rates has received little empirical support; however, alternative possibilities are seldom considered. Combining a global comparative analysis of avian introductions (>2700 events) with demographic models and phylogenetic comparative methods, we show that although rapid population growth may be advantageous during invasions under certain circumstances, more generally successful invaders are characterized by life-history strategies in which they give priority to future rather than current reproduction. High future breeding expectations reduce the costs of reproductive failure under uncertain conditions and increase opportunities to explore the environment and respond to novel ecological pressures.