Differential responses of pinaceae and cupressaceae tree radial growth to drought in Central Asia

Abstract

Global climate change is increasing the intensity and frequency of compound hot-drought events, with many negative impacts on forest ecosystems. The dynamics of tree growth recovery after compound hot-drought events and the factors influencing it are unclear. Therefore, we collected data on a total of 101 tree ring widths of eight tree species in Central Asia, which were categorized into two main groups, Pinaceae and Cupressaceae. We first quantified tree growth loss during drought and growth recovery after drought, and then linear mixed models assessed factors affecting tree growth recovery. The results showed that after a compound hot-drought event, Pinaceae radial growth declined more and took longer to recover, while Cupressaceae radial growth declined less and recovered quickly. There was a significant downward trend in growth loss during drought as tree pre-drought growth levels increased. Tree growth recovery tended to increase as both pre-drought growth levels and post-drought wetness increased, and higher pre-drought growth levels were required for Pinaceae to return to normal growth levels after a compound hot-drought event. Linear mixed modeling results showed greater contribution of pre-drought growth levels and growth loss to growth recovery. Thus, Cupressaceae was able to better adapt to compound heat-drought events, while higher pre-drought growth levels and post-drought wetness were key to increased growth recovery.