Projected impacts of climate change on functional diversity of frugivorous birds along a tropical elevational gradient

Abstract

Climate change forces many species to move their ranges to higher latitudes or elevations. Resulting immigration or emigration of species might lead to functional changes, e.g., in the trait distribution and composition of ecological assemblages. Here, we combined approaches from biogeography (species distribution models; SDMs) and community ecology (functional diversity) to investigate potential effects of climate-driven range changes on frugivorous bird assemblages along a 3000 m elevational gradient in the tropical Andes. We used SDMs to model current and projected future occurrence probabilities of frugivorous bird species from the lowlands to the tree line. SDM-derived probabilities of occurrence were combined with traits relevant for seed dispersal of fleshy-fruited plants to calculate functional dispersion (FDis; a measure of functional diversity) for current and future bird assemblages. Comparisons of FDis between current and projected future assemblages showed consistent results across four dispersal scenarios, five climate models and two representative concentration pathways. Projections indicated a decrease of FDis in the lowlands, an increase of FDis at lower mid-elevations and little changes at high elevations. This suggests that functional dispersion responds differently to global warming at different elevational levels, likely modifying avian seed dispersal functions and plant regeneration in forest ecosystems along tropical mountains.

Global distribution and conservation status of ecologically rare mammal and bird species

“…5), driving some of them towards global extinction. This concerns particularly ecologically rare birds species due to their over-representation in tropical mountains 66 . These ecosystems are classified as highly vulnerable to climate change impacts 67 , mainly due to the narrow spatial distribution and environmental niche of many taxa but also to the morphological and physiological adaptations to live in such specific environments.…”

Climate change, coastal tourism, and impact chains – a literature review

“…Concerning the impacts of CC on land environments biodiversity, a wide range of studies suggest that CC can induce species migration (Bender et al, 2019), but also lead to loss of habitats therefore increasing risk of extinction (Da Silva et al, 2019;Wan et al, 2019). As regards socio-economic impacts, this IC is one of the least investigated and, to the best of our knowledge, only two papers published in the last twenty years study the impact of changes in land environment on tourist satisfaction in coastal areas (Hakim et al, 2005;Seekamp et al, 2019), while no papers investigate the supply-side.…”

Mountain Ecosystems as Natural Laboratories for Climate Change Experiments

“…Similar to the elevational variation of plant species richness, the diversity of herbivores (Hodkinson, 2005;Metcalfe et al, 2014;Rasmann et al, 2014; but see Galmán et al, 2018), frugivorous birds (Dehling et al, 2014;Bender et al, 2019), seed predators (Hargreaves et al, 2019), and soil bacteria and fungi (Nottingham et al, 2018) also decreases with elevation. In the case of geometrid moths (Beck et al, 2017), salamanders (McCain and Sanders, 2010), tropical ferns (Kessler et al, 2011) and non-volant small mammals (McCain, 2005), mid-elevational peaks in species richness are reported, but with sharp declines in richness at higher elevations.…”