Higher forest biodiversity (specifically plant functional diversity related to water, or hydraulic, transport) engenders greater ecosystem resilience to drought. This is because different species respond differently to water stress – some species slow down their release of water (and heat) through transpiration sooner than others do. Plants’ response to water availability in turn affects the local climate.
Water, carbon and energy exchanges from the land surface strongly influence the atmosphere and climate; these exchanges are dominated by plants in most ecosystems. Plant physiological responses to water stress influence these fluxes, and the resulting land-surface feedback effects influence local weather as well as the regional atmospheric circulation. Furthermore, changes in vegetation physiology and cover can drive shifts in sensible and latent heat fluxes that intensify droughts [Anderegg 2018: 538].
We have documented a fundamental effect of trait variation on ecosystem stability that directly influences the atmosphere and climate system. Temperate and boreal forest ecosystems with higher hydraulic diversity are more buffered to changing drought conditions [Anderegg 2018: 540].
Anderegg, William R.L., et al., 2018, Hydraulic diversity of forests regulates ecosystem resilience during drought, Nature 561, https://www.nature.com/articles/s41586-018-0539-7.