<p>Tree growth is influenced by both the external climate and an internal vegetation growth carryover (VGC) effect from prior conditions. However, the underlying mechanisms by which climatic factors and VGC jointly regulate drought resilience remain unclear. Linear mixed-effects and structural equation modeling were applied to tree-ring data from 21 Qinghai spruce (<i>Picea crassifolia</i> Kom.) sites to quantify the regulation of growth loss and recovery by VGC, different droughts, and background climatic factors. Our findings indicate that radial growth is strongly influenced by VGC and the standardized precipitation evapotranspiration index (SPEI). Both exert a stronger influence on radial growth compared to precipitation, vapor pressure deficit (VPD), and average temperature. Compared with single drought events, compound droughts led to a greater decline in radial growth, while increasing the growth loss rate and reducing the recovery rate. Model results show that growth loss was negatively correlated with VGC and SPEI but positively with VPD and drought sensitivity (corrSPEI), with VGC and corrSPEI contributing substantially to growth loss. In contrast, growth recovery was negatively correlated with growth loss but positively with VGC, post-drought moisture (postSPEI), and corrSPEI, among which growth loss and VGC were the most prominent factors governing the recovery process. Our results suggest that VGC serves as an important internal regulator of drought resilience in Qinghai spruce, particularly under compound drought stress.</p>

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Vegetation growth carryover is a key driver of drought resilience in Qinghai spruce of the northeastern Qinghai-Tibet Plateau

  • Peng Zhang,
  • Liang Jiao,
  • Jie Wang,
  • Xuge Wang,
  • Zhengdong Guo,
  • Le Zhang,
  • Yarong Qin,
  • Kuan Zhang,
  • Weiyin Shi

摘要

Tree growth is influenced by both the external climate and an internal vegetation growth carryover (VGC) effect from prior conditions. However, the underlying mechanisms by which climatic factors and VGC jointly regulate drought resilience remain unclear. Linear mixed-effects and structural equation modeling were applied to tree-ring data from 21 Qinghai spruce (Picea crassifolia Kom.) sites to quantify the regulation of growth loss and recovery by VGC, different droughts, and background climatic factors. Our findings indicate that radial growth is strongly influenced by VGC and the standardized precipitation evapotranspiration index (SPEI). Both exert a stronger influence on radial growth compared to precipitation, vapor pressure deficit (VPD), and average temperature. Compared with single drought events, compound droughts led to a greater decline in radial growth, while increasing the growth loss rate and reducing the recovery rate. Model results show that growth loss was negatively correlated with VGC and SPEI but positively with VPD and drought sensitivity (corrSPEI), with VGC and corrSPEI contributing substantially to growth loss. In contrast, growth recovery was negatively correlated with growth loss but positively with VGC, post-drought moisture (postSPEI), and corrSPEI, among which growth loss and VGC were the most prominent factors governing the recovery process. Our results suggest that VGC serves as an important internal regulator of drought resilience in Qinghai spruce, particularly under compound drought stress.