Intensifying aridity induces tradeoffs among biodiversity and ecosystem services supported by trees

Abstract

Aim: Changes in climate are likely to have major impacts on benefits (i.e., biodiversity and ecosystem services) supported by trees. Here we explore the extent to which trees can support multiple benefits, and the potential tradeoffs among them, under increasing dryness. Location: Eastern Australia. Time period: 2018–2019. Major taxa studied: Trees. Methods: We evaluated changes in biodiversity and services supported by trees and the nature of potential tradeoffs in response to increasing aridity, our proxy of drying regional climates. We assessed six benefits (biodiversity and five ecosystem services) supported by trees at 126 sites across a gradient from Australia's mesic coast to the arid interior. Results: The value of average benefits did not vary with aridity, with winners and losers in biodiversity and ecosystem services as aridity intensified. Tradeoffs between biodiversity and soil stability declined with increasing aridity, but only in mesic environments, whereas tradeoffs between wood production potential and carbon storage intensified under greater aridity levels, but only in mesic environments. Aridity and tree structure were the major regulators of these tradeoffs, particularly under dry environments. Increasing aridity affected tradeoffs directly or indirectly by either suppressing the positive effect of tree height or exacerbating the negative effect of tree canopy size. Main conclusions: Our results indicate that biodiversity and most ecosystem services supported by trees are likely to decline under future climate change scenarios and demonstrate the importance of targeting afforestation programs to specific services in particular climatic areas rather than attempting to improve multiple services.