Multiyear Drought Strengthens Positive and Negative Functional Diversity Effects on Tree Growth Response

作者：Hernán Serrano‐León, Haben Blondeel, Paula Glenz, Johannes Steurer, Florian Schnabel, Lander Baeten, Joannès Guillemot, Nicolas Martin‐StPaul, Georgios Skiadaresis, Michael Scherer‐Lorenzen, Damien Bonal, Matthieu Boone, Renaud Decarsin, Arsène Druel, Douglas L. Godbold, Jialiang Gong, Peter Hajek, Hervé Jactel, Julia Koricheva, Simone Mereu, Quentin Ponette, Boris Rewald, Hans Sandén, Jan Van den Bulcke, Kris Verheyen, Ramona Werner, Jürgen Bauhus · 发表于：Global Change Biology · 年份：2025 · DOI：10.1111/gcb.70394 · 被引用次数：15 · 研究领域：Plant Water Relations and Carbon Dynamics、Tree-ring climate responses、Hydrology and Drought Analysis

Mixed-species forests are proposed to enhance tree resistance and resilience to drought. However, growing evidence shows that tree species richness does not consistently improve tree growth responses to drought. The underlying mechanisms remain uncertain, especially under unprecedented multiyear droughts. We used a network of planted tree diversity experiments to investigate how neighborhood tree diversity and species' functional traits influence individual tree responses to drought. We analyzed tree cores (948 trees across 16 species) from nine young experiments across Europe featuring tree species richness gradients (1-6 species), which experienced recent severe droughts. Radial growth response to drought was quantified as tree-ring biomass increment using X-ray computed tomography. We applied hydraulic trait-based growth models to analyze single-year drought responses across all sites and site-specific responses during consecutive drought years. Growth responses to a single-year drought were partially explained by the focal species' hydraulic safety margin (representing species' drought tolerance) and drought intensity, but were independent of neighborhood species richness. The effects of neighborhood functional diversity on growth responses shifted from positive to negative with increasing drought duration during a single growing season. Tree diversity effects on growth responses strengthened during consecutive drought years and were site-specific with contrasting directi...