The fate of páramo plant assemblages in the sky islands of the northern Andes

Abstract

Aims Assessing climate change impacts on biodiversity is a main scientific challenge, especially in the tropics. We predicted the future of plant species and communities on the unique páramo sky islands by implementing the Spatial Explicit Species Assemblage Modelling framework. Specifically we: (a) calculated species’ maximum dispersal distance; (b) modelled species’ present and future distributions up to 2100; and (c) assembled models into plant communities. The final vulnerability assessment was based on a multi‐dimensional evaluation that considered the species, local plant community and sky island levels. Location Ecuadorian super‐páramo (>4,200 m). Methods Using species trait data, the maximum dispersal distance of 435 species was calculated. Species distribution models (SDM) were fitted to obtain current and future distribution predictions based on dispersal and bioclimatic factors. The final current assemblages and those for 2100 were achieved by stacking all probabilistic SDMs and applying the probability ranking rule. The vulnerability of each sky island was evaluated by quantifying richness and composition changes. Results Maximum dispersal distances ranged between 0.008 m/year and 6,027 m/year, and across all scenarios, 70% of models showed a net loss in species distribution, while 9% of all species were predicted to undergo extinction in Ecuador by 2100. Local richness was estimated to decrease by 56.63% on average, and compositional changes in each sky island suggested a mean loss of 64.74% of their original species pool against a 12.97% gain. Finally, 5% of the sky island floras reconverted from high‐elevation to low‐elevation species. These numbers were usually more important for high‐elevation species and the mountains Pichincha, Ilinizas and Antisana. Conclusions This methodological pioneer study provides novel insight into the future of páramo biodiversity. Significant losses in species distribution and changes in community richness and composition suggest drastic impacts and call for further research considering additional factors, such as land use. Finally, we recommend focusing monitoring and conservation strategies on the northern Ecuadorian sky islands as a priority.

Climate Vulnerability Assessment of the Espeletia Complex on Páramo Sky Islands in the Northern Andes

“…Widespread range losses in the distribution of Espeletia are expected by 2050, a pessimistic prediction in line with previous modeling efforts (Buytaert et al, 2011;Crandall et al, 2013;Mavárez et al, 2018;Helmer et al, 2019;Peyre et al, 2020;Young and Duchicela, 2020). This tendency is broadly defined as thermophilization, a progressive decline of cold mountain habitats and their biota (Gottfried et al, 2012).…”

“…were not considered as part of this study because of the difficulties in compiling and comparing data from different national repositories, specifically for some of the variables that compose the adaptive capacity score (i.e., agriculture and mining pressures). Yet, considering analogous approaches in the Ecuadorian Páramo (Crandall et al, 2013;Helmer et al, 2019;Peyre et al, 2020) is essential to gather a more comprehensive understating on the consequences of climate change at high Andean ecosystems north of the Huancabamba depression, a major biogeographical barrier for high-elevation plant taxa (Weigend, 2002).…”

Toward reliable habitat suitability and accessibility models in an era of multiple environmental stressors

“…Obtaining this information could be particularly challenging for species that are hard to monitor or for plant species that depend on vectors for seed dispersal. For plants, dispersal syndrome (wind, animal, ant, and ballistic or no syndrome) and growth form (tree, shrub, and herb) provide reasonable predictions of maximum dispersal distance (MacLean & Beissinger, 2017; Tamme et al., 2014; Thomson, Letten, Tamme, Edwards, & Moles, 2018), allowing integration of dispersal into SDM through simple field observations (e.g., Midgley, Hughes, Thuiller, & Rebelo, 2006; Peyre et al., 2020). For animals, movement ability, longevity, and habitat breadth are important predictors of dispersal distance and climate change‐induced range shifts (MacLean & Beissinger, 2017; Stevens et al, 2013).…”

The importance of dispersal and species establishment in vegetation dynamics and resilience

“…Moving involves dispersal, but, again, many studies of species and vegetation responses to climate change do not consider dispersal, or treat it very simplistically, often contrasting ubiquitous with no dispersal (Holloway et al, 2016). Peyre et al (2020, this issue) show how important it is to consider dispersal ability in terms of actual distances different species can disperse. By doing so, they derive more meaningful predictions of how the plant communities of the unique páramo sky islands in Ecuador might be affected by climate change.…”

“…But there is a great deal of interspecific variation in dispersal abilities within syndromes, due to the exact vector and its behaviour, plant characteristics such as height, and seed traits such as mass (Tamme et al, 2014; Bullock et al, 2017). Using information on these properties derived from global databases, it is possible to calculate a maximum dispersal distance for a species (Tamme et al, 2014), which Peyre et al (2020, this issue) use to good effect. But many species have multiple dispersal vectors and even exhibit different dispersal modes (Bullock et al, 2006).…”