When a severe drought and heat wave hit China’s Yangtze River Basin in 2022, forests in the area faced intense conditions. Researchers used the event to examine how different forest types respond to simultaneous high temperatures and low water availability. The basin contains key forests that limit soil erosion, manage water flow and maintain biodiversity. As the country’s largest river system, the Yangtze supports major water resources and economic activity, making forest health essential. After past deforestation and floods such as the 1998 disaster, China began large tree-planting efforts to restore cover and curb erosion. With climate change increasing combined drought and heat events, scientists sought to compare how planted forests handle these stresses versus natural ones. Compound drought-heat events harm plants through both soil water shortage and higher leaf water loss, threatening forest functions including water storage and runoff control. Results showed a clear trade-off. Natural forests resisted damage better during the event, while planted forests lost more vegetation yet recovered faster afterward. The study, published in Water Resources Research, highlights the balance between resistance during extremes and post-event recovery. Researchers from the University of Chinese Academy of Sciences analyzed satellite data on forest greenness, photosynthesis and carbon production. The 2022 episode ranked among the worst since 1950, with record heat and sharply reduced rainfall and soil moisture across over 90 percent of the region. Natural forests showed stronger short-term resistance, with more than 70 percent of studied areas faring better. Their greater species variety, mixed ages and layered canopies likely helped buffer stress. Planted forests often feature fewer species and similar-aged trees, making them more uniformly vulnerable. After the event, planted forests displayed quicker recovery in 2023, probably due to younger fast-growing trees. Natural forests with larger trees and complex structures recover more slowly but maintain better function during extremes. Lingering drought effects, known as legacy impacts, can delay full recovery of processes such as carbon uptake and soil interactions.
