Predicted alteration of vertebrate communities in response to climate‐induced elevational shifts

Abstract

Aim: Climate change is driving species to migrate to novel areas as current environments become unsuitable. As a result, species distributions have shifted uphill in montane ecosystems globally. Heterogeneous dispersal rates among shifting species could result in complex changes to community assemblages. For example, interspecific differences in dispersal ability could lead to the disruption, or creation, of species interactions and processes within communities, likely amplifying the impact of climate change on ecosystems. Here, we studied the dispersal success of vertebrate species in a tropical montane ecosystem under a climate-induced uphill shift and assessed the derived impacts on community structures. Location:The Australian Wet Tropics bioregion. Method:We simulated the uphill shift of 7613 community assemblages across the elevational gradient using thermal resistance layers for movement analyses. Dispersal success was calculated as the probability of shifting given species' dispersal ability and landscape composition. We then used dissimilarity indices to measure the potential changes in community structures resulting from the heterogeneous dispersal success among migrating species. Results: Dispersal success was strongly influenced by species' dispersal ability, landscape composition and climate change. The heterogeneous dispersal success among migrating species induced marked temporal changes between community assemblages along the elevational gradient. The local extinction rate (i.e. the proportion of species unable to shift) was especially remarkable at high elevations, suggesting potential mass local extinctions of upland species. Furthermore, the increasing local extinction rate with elevation resulted in substantial declines in species co-occurrence in high-altitude ecosystems. Main conclusions: Our study highlights the escalating impact of climate change on community assemblages in response to climate-induced elevational shifts, providing a classic example of the "escalator to extinction." Future predictions of the impacts of climate change on ecosystems will benefit from improvements in understanding | 1181 DE LA FUENTE ET al.

Climate change threatens the future of rain forest ringtail possums by 2050

“…These projections are subject to the consistency of the observed climatic trends, although limiting warming in the following decades might now be beyond reach (Hoegh‐Guldberg et al, 2018). The observed trajectory of ringtail possum populations means the realization of the predictions about climate change impacts on montane ecosystems (McDonald & Brown, 1992), with an early extirpation of marginal populations likely escalating to the extinction of entire upland tropical species (de la Fuente et al, 2022; Urban, 2018). However, as indicated by the effect of climatic exposure on populations across the elevational gradient, we could expect delays in population responses at elevations above 1200 m, where the current exposure to extreme heatwaves is low compared with lower elevations.…”

“…However, as indicated by the effect of climatic exposure on populations across the elevational gradient, we could expect delays in population responses at elevations above 1200 m, where the current exposure to extreme heatwaves is low compared with lower elevations. Nevertheless, despite the potential slower degradation of populations in the mountaintops, rain forest habitat extending above 1200 m represents small areas (<2%; 136 km 2 ; de la Fuente et al, 2022) with high isolation (i.e., “mountain islands”; Brown, 1978). Thus, the idea of remnant high‐altitude rain forest areas as the sole long‐term stronghold for ringtail possum populations might be limited.…”

“…The Australian Wet Tropics bioregion is composed of approximately 7000 km 2 of mixed tropical rain forest (de la Fuente et al, 2022). The region is dominated by mountain ranges, where elevation is the predominant gradient shaping the biodiversity and ecological processes (Williams et al, 1995).…”

“…The Australian Wet Tropics bioregion is composed of approximately 7000 km 2 of mixed tropical rain forest (de la Fuente et al, 2022).…”

The climatic drivers of long‐term population changes in rainforest montane birds

“…Interestingly, our results highlight the contrasting effects of long‐term and short‐term temperature changes on rainforest bird communities. On the one hand, lowland species could benefit from long‐term warming due to an upward habitat expansion (de la Fuente et al, 2022). On the other hand, extreme heatwaves could cause direct population declines, affecting the year‐to‐year population fluctuation.…”