Forest resilience to drought varies across biomes

Area of Science:

• Ecology
• Forest Science
• Climate Change Adaptation

Background:

• Increasing drought frequency and severity threaten global forest productivity.
• Species-specific functional traits influence forest responses to arid conditions.

Purpose of the Study:

• To analyze forest resilience to drought across different biomes and species in Spain.
• To compare the sensitivity of tree-ring width indices (TRWi) and Normalized Difference Vegetation Index (NDVI) as drought resilience metrics.

Main Methods:

• Utilized an extensive network of tree-ring width data and satellite imagery for 11 tree species and 502 forests.
• Calculated four components of forest resilience to drought using TRWi and NDVI data before, during, and after four major drought events.
• Compared drought resilience metrics between Mediterranean, temperate, and continental biomes.

Main Results:

• Tree-ring width indices (TRWi) proved more sensitive to drought impacts than NDVI.
• Evergreen gymnosperms in semi-arid Mediterranean forests exhibited lower drought resistance but higher recovery rates compared to deciduous angiosperms in temperate forests.
• Semi-arid gymnosperm forests showed a declining trend in drought resistance over time, unlike those in continental and temperate biomes.

Conclusions:

• Forest composition and drought severity significantly impact resilience.
• While Mediterranean gymnosperms recover faster, their resilience may be compromised by increasing drought frequency.
• Temperate and continental species may face recovery challenges after severe droughts despite their resistance.