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Contributed Talk

Session: : Ecosystem Function: Biodiversity 3

COS 147-1 - The Influence of Structural and Species Diversity on Resilience to Drought in US Temperate Forests

Wednesday, August 9, 2023
8:00 AM – 8:15 AM PDT
Location: D139
Abstract: Biodiversity-ecosystem functioning research suggests that diversity may enhance ecosystem resilience, lead to higher productivity, and provide resistance to invasive species. As climate change has led to more frequent and more intense drought events in forests across the USA, understanding the conditions under which diversity confers resilience could help forest managers promote healthy ecosystems. Here, we examine whether species diversity and structural diversity (i.e., the variation in tree heights, stand density, clumping, canopy cover, and/or spatial heterogeneity in vertical arrangement) increase the resistance of ecosystem productivity to, and recovery from, drought events. We used forest inventory data across the USA to calculate species and structural diversity metrics. We applied the Standardised Precipitation-Evapotranspiration Index (SPEI) to identify droughts under several different thresholds and durations (e.g., SPEI values of -1, -1.5, -2, and durations of 6mo, 12mo, 18mo), and used Landsat images to estimate productivity before, during, and after the drought. We found that structural diversity generally showed weak associations with resistance to drought, but that structural diversity mattered more (i.e., showed a stronger relationship with resistance) in more substantial droughts (i.e., at SPEI values of -2 than -1). Structural diversity showed stronger associations with resistance than did species diversity, perhaps because species composition may also influence drought resistance. Relationships between structural diversity and recovery and between species diversity and recovery showed mixed results depending on the metrics of recovery used. These results suggest that incorporating structural and species diversity into management plans could help forests maintain their productivity as temperatures and precipitation continue to become more variable with climate change.