Response of vegetation to drought time-scales across global land biomes

TLDR

Plant species in arid regions possess mechanisms that enable rapid adaptation to changing water availability. The study aims to identify the dominant drought time‑scales that influence vegetation to better assess resistance, resilience, and vulnerability to climate change. The authors correlated a drought index with satellite vegetation indices, tree‑ring growth, and ANPP records to assess biome responses. Arid and humid biomes react rapidly to drought, while semiarid and subhumid biomes respond only after prolonged deficits, indicating that vegetation sensitivity depends on biome‑specific drought time‑scales.

Abstract

We evaluated the response of the Earth land biomes to drought by correlating a drought index with three global indicators of vegetation activity and growth: vegetation indices from satellite imagery, tree-ring growth series, and Aboveground Net Primary Production (ANPP) records. Arid and humid biomes are both affected by drought, and we suggest that the persistence of the water deficit (i.e., the drought time-scale) could be playing a key role in determining the sensitivity of land biomes to drought. We found that arid biomes respond to drought at short time-scales; that is, there is a rapid vegetation reaction as soon as water deficits below normal conditions occur. This may be due to the fact that plant species of arid regions have mechanisms allowing them to rapidly adapt to changing water availability. Humid biomes also respond to drought at short time-scales, but in this case the physiological mechanisms likely differ from those operating in arid biomes, as plants usually have a poor adaptability to water shortage. On the contrary, semiarid and subhumid biomes respond to drought at long time-scales, probably because plants are able to withstand water deficits, but they lack the rapid response of arid biomes to drought. These results are consistent among three vegetation parameters analyzed and across different land biomes, showing that the response of vegetation to drought depends on characteristic drought time-scales for each biome. Understanding the dominant time-scales at which drought most influences vegetation might help assessing the resistance and resilience of vegetation and improving our knowledge of vegetation vulnerability to climate change.