Increasing temperatures due to climate change will reshuffle ecological communities. Species range shifts in tropical mountains can therefore result in functional mismatches between interacting plants and birds, says a new study in the scientific journal Diversity and Distributions, published by an international research team including Daniel Kissling from the Institute for Biodiversity and Ecosystem Dynamics at the University of Amsterdam.
Future climate change will force many plant and animal species to change their geographical distributions. In mountains, global warming is most likely to result in a shift of elevational distributions of plants and animals upslope. However, interacting and interdependent taxa from different trophic levels (such as fleshy-fruited plants and their animal seed dispersers) might not shift their distributions at the same pace. Therefore the research team investigated how ecological communities in tropical mountains are reshuffled due to climate change, and how this affects the presence and distribution of functional traits that are relevant for species interactions.
To investigated how climate change will change bird and plant distributions along a tropical mountain, the research team studied communities of fleshy‐fruited plants and frugivorous birds at seven elevations in the Manú National Park in south‐east Peru. Researcher W. Daniel Kissling, co-leader of the study, explains: ‘To quantify functional diversity, we measured morphological traits of 392 plant species and 217 frugivorous bird species, either in the field or on museum specimens. We focused on traits that are relevant for interactions between plants and frugivores, specifically those that influence fruit removal and seed dispersal by birds: fruit width, fruit length, crop mass and height of plants, and bill width, bill length, body mass and wing shape of birds.’
To model the upward shifts in species distributions of all plants and animals, the researchers combined the functional trait data with projected temperature increases from future climate projections. For the future communities, they then calculated functional diversity and identity and assessed to what extent functional mismatches between plant and bird communities could occur in the future.
‘Our results show that the future correspondence between plant and bird functional diversity as well as functional identity is weakest if species distributions are shrinking due to climate change. Future functional diversity and functional identity will most likely decrease at low elevations in the tropics, as we expect that the number of lowland species emigrating or going extinct from low elevations will exceed the number of persisting, warm‐adapted species,’ says Kissling.
The study provides a new framework for integrating functional diversity and future projection models of climate and biodiversity change in mountains, especially of interacting species groups in relation to how climate change will affect the functional composition of ecological communities. Kissling: ‘It was interesting to see that our future projections suggest an unexpected increase in functional diversity of both plants and animals at mid‐ and high elevations, although this assumes that species are able to move as fast as climate changes and that forest areas remain protected.’
Larissa Nowak, W. Daniel Kissling, Irene M.A. Bender, D. Matthias Dehling, Till Töpfer, Katrin Böhning-Gaese, Matthias Schleuning (2019). Projecting consequences of global warming for the functional diversity of fleshy‐fruited plants and frugivorous birds along a tropical elevational gradient. Diversity and Distributions. DOI: 10.1111/ddi.12946
Biogeography & Macroecology (BIOMAC) lab