The Forest Resistance to Droughts Differentiated by Tree Height in Central Europe

More frequent droughts are altering the dynamics and function of the European forest ecosystem, which is deeply connected to the global carbon cycle. Tree height is an important structural feature of forests; however, how it regulates the response of forests to droughts remains controversial. By comprehensively examining the variations of satellite-based vegetation greenness with drought evolution and the legacy effect of drought indicated by radial growth, we observed apparent height-dependence forests' resistance to drought. Short forests showed lower resistance to drought than taller forests, demonstrating earlier and larger negative vegetation greenness anomalies. Additionally, larger reductions in radial growth after the drought year were also observed for shorter trees, implying an apparent legacy effect of drought on tree growth. The observed resistance differences can be attributed to the differences in the capacity for water absorption and regulation among forests of different heights. Our results provide an integrated explanation of tree-level function that will be critical in understanding the response of forests and vegetation-climate feedbacks in more widespread, prolonged, and extreme drought in the future.

Automated summary

More frequent droughts are changing the European forest ecosystem, impacting the global carbon cycle. Tree height plays a role in forests' resistance to drought, with taller forests showing higher resistance and shorter forests experiencing larger negative effects. The capacity for water absorption and regulation differs between forests of different heights, contributing to these resistance differences. This research provides insight into tree-level function and its implications for future droughts.