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

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, treering 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 timescale) 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 timescales, 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. drought impacts | NDVI | drought adaptation | Standardized Precipitation Evapotranspiration Index | drought index

An improved species distribution model for Scots pine and downy oak under future climate change in the NW Italian Alps

“…Widespread tree mortality can occur under extreme dry spells, but it is uncertain whether one or two extreme years are sufficient to trigger major shifts in forest composition (e.g., Vicente-Serrano et al 2013). The effect of extreme years on the realized niche of Scots pine will likely depend on the frequency and severity of droughts, rather than on decadal climate means such as the ones we used in our projections.…”

Stock Volume Dependency of Forest Drought Responses in Yunnan, China

“…[30][31][32], each with its own advantage. However, SPEI incorporates the advantages of PDSI that are sensitive to the evaporative demand, and that of SPI with multiple time scales [32,55,56], so the SPEI reflected the cumulative effects of water deficit and surplus over multiple time scales in the research. In calculating the water balance, SPEI was calculated as follows [32,55]: (1) potential evapotranspiration (PET) was obtained by the Thornthwaite and the Penman-Monteith models; (2) different time scales of the cumulative effects of water deficit and surplus were calculated; (3) the three-parameter log-logistic probability density function was adopted to fit the established cumulative series; and (4) the cumulative series was converted by the standard normal distribution.…”

Reduction in Water Stress for Tree Saplings Using Hydrogels in Soil

“…Physiological processes in plants are highly constrained by water deficits [33], as illustrated by the positive correlation between NDVI and watering frequency both for Siberian elm (r = 0.37, p < 0.01) and for silver maple (r = 0.16, p < 0.05).…”