Jayme Augusto Prevedello’s research while affiliated with Rio de Janeiro State University and other places

Habitat loss can lead to biotic homogenization (decrease in β diversity) or differentiation (increase in β diversity) of biological communities. However, it is unclear which of these ecological processes predominates in human-modified landscapes. We used data on vertebrates, invertebrates, and plants to quantify β diversity based on species occurrence and abundance among communities in 1367 landscapes with varying amounts of habitat (<30%, 30−60%, or >60% of forest cover) throughout the Brazilian Atlantic Forest. Decreases in habitat amount below 30% led to increased compositional similarity of vertebrate and invertebrate communities, which may indicate a process of biotic homogenization throughout the Brazilian Atlantic Forest. No pattern was detected in plant communities. We found that habitat loss was associated with a deterministic increase in faunal community similarity, which is consistent with a selected subset of species being capable of thriving in human-modified landscapes. The lack of pattern found in plants was consistent with known variation between taxa in community responses to habitat amount. Brazilian legislation requiring the preservation of 20% of Atlantic Forest native Conservation Biology. 2024;e14419. vegetation may be insufficient to prevent the biotic homogenization of faunal communities. Our results highlight the importance of preserving large amounts of habitat, providing source areas for the recolonization of deforested landscapes, and avoiding large-scale impacts of homogenization of the Brazilian Atlantic Forest.

Habitat loss can lead to biotic homogenization (decrease in β diversity) or differentiation (increase in β diversity) of biological communities. However, it is unclear which of these ecological processes predominates in human‐modified landscapes. We used data on vertebrates, invertebrates, and plants to quantify β diversity based on species occurrence and abundance among communities in 1367 landscapes with varying amounts of habitat (<30%, 30−60%, or >60% of forest cover) throughout the Brazilian Atlantic Forest. Decreases in habitat amount below 30% led to increased compositional similarity of vertebrate and invertebrate communities, which may indicate a process of biotic homogenization throughout the Brazilian Atlantic Forest. No pattern was detected in plant communities. We found that habitat loss was associated with a deterministic increase in faunal community similarity, which is consistent with a selected subset of species being capable of thriving in human‐modified landscapes. The lack of pattern found in plants was consistent with known variation between taxa in community responses to habitat amount. Brazilian legislation requiring the preservation of 20% of Atlantic Forest native vegetation may be insufficient to prevent the biotic homogenization of faunal communities. Our results highlight the importance of preserving large amounts of habitat, providing source areas for the recolonization of deforested landscapes, and avoiding large‐scale impacts of homogenization of the Brazilian Atlantic Forest.

Many conservation guidelines to halt biodiversity loss have been suggested, including the protection of ~40% of the original habitat cover in fragmented landscapes. This guideline relies on the presumed existence of a ~30% threshold value in the responses of biological communities to habitat amount, a generalization still not yet fully tested globally. We conducted an extensive global synthesis based on 108 empirical datasets to test for general patterns in the responses of biological communities to habitat amount at the landscape scale, and to estimate how frequent and at which conditions thresholds would be present in these responses. Our results confirm the overall negative effect of habitat loss on species richness, but also reveal that thresholds in the response to habitat amount are much less frequent than previously assumed. When present, thresholds did indeed occur at ~30% of remaining habitat amount, but with higher variability among communities and landscapes. The probability of detecting thresholds increased with the number of landscapes analyzed in the study, with at least 28 landscapes being necessary for a 50% probability of detecting a threshold. The available evidence indicates that habitat amount thresholds are relatively rare and variable among communities and, therefore, should be used with caution for landscape conservation planning.

Context The species-area relationship (SAR) is one of the main patterns in Ecology, but its underlying causes are still under debate. The random placement hypothesis (RPH) is the simplest one to explain the SAR: larger areas passively sample more individuals and, consequently, more species. However, it is still unclear the degree to which this null hypothesis is supported for different taxa and locations globally. Objectives We performed the first global synthesis on the RPH to investigate which variables mediate variation in the degree of support of this hypothesis across taxa and regions. Methods We conducted a review of the global literature and estimated the degree of support of the RPH. The degree of support (effect size) was inferred through the coefficient of determination of the relationship between observed (empirical) and predicted (according to the RPH) species richness. We analyzed the relationship between this effect size metric and different geographic and ecological factors. Results About 31% of the studies explicitly considered the RPH. From these, only 14% tested the RPH in a total of 52 independent case studies. About 42% of these case studies confirmed the RPH. The degree of support was significantly higher for plants than animals, and increased consistently with latitude for animals. Conclusions Passive sampling is important to determine SARs, especially for animals at higher latitudes and plants. Further tests of the RPH, which is still scarcely explored in the literature, are vital to understanding the stochastic and ecological processes underlying the SAR and to advancing Landscape Ecology.

Context The species-area relationship (SAR) is one of the main patterns in Ecology, but its underlying causes are still under debate. The random placement hypothesis (RPH) is the simplest one to explain the SAR: larger areas are more likely to contain more individuals and, as a consequence, more species. However, it is still unclear the degree to which the RPH is supported for different taxa and regions globally. Objectives We performed the first global synthesis on the RPH to investigate which variables mediate variation in the degree of support of this hypothesis across taxa and regions. Methods We conducted a review of the global SAR literature and created a new integrative metric to estimate the degree of support of the RPH. This metric takes into account the coefficient of determination, the intercept, and the slope of the relationship between observed (empirical) and predicted (according to the RPH) species richness. We analyzed the relationship between this metric and different geographic and ecological factors. Results We found a total of 52 independent tests of the RPH. About 42% of these tests confirmed the RPH. Using the new metric, we found that the degree of support of the RPH was significantly higher for plants than animals, and increased consistently with latitude. Conclusions Simple probabilistic processes are important to determine SARs, especially for sessile organisms and at higher latitudes. Further tests of the RPH, especially using the new metric introduced here, will be vital to understand the processes underlying the SAR and to advance Landscape Ecology.

O estudo avaliou o uso dos estratos da floresta pelas espécies de pequenos mamíferos através de três métodos de amostragem: armadilhas de captura viva, ninhos artificiais e carretel de rastreamento. Nas armadilhas e com esforço total de 69.525 armadilhas-noites (17.550 no dossel), houve 2.759 capturas de 1.172 indivíduos de 15 espécies, sendo oito espécies de marsupiais e sete de roedores. Nos ninhos, com esforço total de 6.018 verificações, foram registrados 71 indivíduos pertencentes a seis espécies. Foram mapeados com carretel de rastreamento aproximadamente 53.000 m de linha em 403 caminhos de 272 indivíduos, de quatro espécies de marsupiais. A amostragem do dossel foi imprescindível para a caracterização adequada da estrutura da comunidade, principalmente quanto às abundâncias relativas das espécies. Os diferentes métodos de amostragem foram complementares em seus resultados, cada um com vantagens e limitações para o estudo da estratificação vertical de pequenos mamíferos. A análise conjunta dos dados revelou que a comunidade de pequenos mamíferos do Garrafão apresenta marcada estratificação vertical, mas o uso dos estratos da floresta por pequenos mamíferos é mais complexo e sofisticado que a simples classificação por estrato utilizado. Algumas espécies usam predominantemente o solo ou dossel, mas apenas estes extremos são detectados pelas armadilhas. Este método por si só não é capaz de detalhar o uso do sub-bosque e mesmo do dossel por espécies predominantemente terrestres ou semi-terrestres.