Drought determines the growth stability of different dominant conifer species in Central Asia

Abstract

Accelerated drought-induced tree decline and mortality in Central Asia has threatened forest health and ecological services functions under global climate change. There is also uncertainty about the response mechanisms and ecological adaptation strategies of different tree species. Therefore, we compared differences in the growth-climate sensitivity and ecological adaptations of different tree species using tree-ring width data records from 84 sites of 5 tree species in central Asia. Four main conclusions were drawn: 1) Tree growth patterns represented by basal area increment (BAI) indicated that the radial growth trends of Pieca crassifolia (PC, 0.531 cm2yr−1/10a) was significantly increasing, while those of Sabina przewalskii (SP, 0.267 cm2yr−1/10a) and Pinus sylvestris (PSY, −0.562 cm2yr−1/10a) showed the opposite growth trend and growth variability, and those of Larix sibirica (LS) and Picea schrenkiana (PSC) were insignificant. 2) Correlation analysis of climatic factors limiting radial growth indicated that drought caused by reduced precipitation was the main cause of tree growth limitation, with the strongest limitation on PC, SP, and PSY. All tree species were insensitive to temperature, and PSC, SP, and PSY showed a stable positive response to scPDSI in spring and summer of the current year. 3) Quantile regressions demonstrated that low values of drought did not correspond exactly to low values of tree growth (BAI) and were even significantly correlated with high values of growth of PC, SP and PSY. 4) PSY and SP at higher and lower elevations showed the greatest variation with the lowest resistance, the highest recovery and resilience, and maintained consistent adaptation strategies under the most severe summer drought stress. This work contributes to existing knowledge regarding tree growth-climate response patterns in arid zones under drier climates in the future.