Date Published: April 11, 2019
Publisher: Public Library of Science
Author(s): Leonardo S. Miranda, Vera L. Imperatriz-Fonseca, Tereza C. Giannini, François Rigal.
Although the impacts of climate change on biodiversity are increasing worldwide, few studies have attempted to forecast these impacts on Amazon Tropical Forest. In this study, we estimated the impact of climate change on Amazonian avian assemblages considering range shifts, species loss, vulnerability of ecosystem functioning, future effectiveness of current protected areas and potential climatically stable areas for conservation actions. Species distribution modelling based on two algorithms and three different scenarios of climate change was used to forecast 501 avian species, organized on main ecosystem functions (frugivores, insectivores and nectarivores) for years 2050 and 2070. Considering the entire study area, we estimated that between 4 and 19% of the species will find no suitable habitat. Inside the currently established protected areas, species loss could be over 70%. Our results suggest that frugivores are the most sensitive guild, which could bring consequences on seed dispersal functions and on natural regeneration. Moreover, we identified the western and northern parts of the study area as climatically stable. Climate change will potentially affect avian assemblages in southeastern Amazonia with detrimental consequences to their ecosystem functions. Information provided here is essential to conservation practitioners and decision makers to help on planning their actions.
The average global surface temperature has increased by approximately 0.8°C during the last century and is expected to continue increasing . Species have always reacted to climatic changes throughout their evolutionary history [2–4]; however, currently, the main concern is the unprecedented rapidity of the observed changes . Although, until now, habitat loss and fragmentation have represented the highest threat to biodiversity [5,6], some studies have suggested that climate change is likely to outweigh habitat loss as a global threat in the coming decades . In fact, even though climate change constitutes its own set of risks, it may interact with habitat loss and increase shifts in species distributions, extinctions, and hence compositional changes in communities . This potential distribution reshuffling of biodiversity may affect the structure, dynamics and functioning of ecosystems and the contributions they provide .
The quality of the models, according to TSS (0.68 ± 0.11) and ROC (0.90 ± 0.05; all values above 0.80), had a high levels of accuracy (S1 Table), indicating good model fit. Temperature Seasonality (BIO4, for 80% of the species), Annual Mean Temperature (BIO1, for 67%) and Mean Temperature of Warmest Quarter (BIO10, for 46%) were important drivers (mean importance > 30%) for many species distributions; and all species (except for Myiozetetes cayanensis) have at least one predictor variable with importance greater than 30% (S1 Table). The sum of squares obtained to each cell showed distinct contributions to variation around the SR maps (S1 Fig). Algorithms are responsible for the greatest proportion of variation (FT median [min-max] = 79% [5–100%]; and OAV median [min-max] = 87%, [1–100%]), widely spread in the study area. The proportion of variation attributable to future scenarios was lower than the former (FT median [min-max] = 62% [1–100%]; and OAV median [min-max] = 41%, [1–100%]).
Climate change will impact the biodiversity across the globe  and it is important to forecast the effects not only on range shifts but also on the functionalities . Through our SDMs we show that avian assemblage from SE Amazonia will be potentially strongly affected by climate change in the near future, even under the most optimistic scenario. As expected, species occupying different habitats will respond differently, but invariably frugivores will be more negatively affected. Considering only FT species, currently, the centre and western portion of SE Amazonia are potentially the richest areas, and future projections suggest a northern shift with an expressive depletion in SR. The OAV species have a disjunct distribution, where the occurrence core is in the “dry diagonal” (out of the scope of this work) and isolated patches of the Amazonia . As our study system includes a transition zone encompassing both environments (FT and OAV), the OAV species occur naturally at low numbers (<30% in almost all areas) but potentially could reach 46% east of Marajó Island and 59% in patches at the central and northwestern portion of the focal area based on our current projections. Under the future scenarios, potential SR was predicted to increase due to a northward shift (from the core region, not shown) that becomes uniform along all of the focal area, maintaining its maximum value (~55%) at the northwestern portion. Throughout our habitat suitability models, we show that (1) birds in SE Amazonia will be affected by climate change even under the most optimistic scenario; (2) frugivores are the most sensitive group facing climate change in coming decades which could bring consequences on seed dispersion and plant recruitment; and (3) the current set of protected areas has the potential to protect half of current projected biodiversity, and that 55% of climatically stable areas identified in this study overlapped with PAs. In the context of decision-making, our models are important in suggesting insightful conservation strategies that involve not only improving currently established PAs but also demonstrating which areas to maintain and which to restore to optimize the potential for natural processes, such as dispersal and adaptation. Source: http://doi.org/10.1371/journal.pone.0215229