Vegetation growth carryover and lagged climatic effect at different scales: from tree rings to the early growth season of xylem

Vegetation growth is influenced not only by current climatic conditions but also by the growth-enhancing signals and preceding climate factors. In order to explore the effects of Vegetation growth carryover (VGC) and lagged climatic effect (LCE) on tree-rings and the early growth season of xylem at two different scales. Taking the dominant species Juniperus seravschanica in Tajikistan as the research subject, this study combines tree-ring width data with early of growth season of xylem data (from the start of xylem growth to the first day of the NDVI peak month) simulated using the Vaganov-Shashkin (V-S) model, a process-based tree-ring growth model. A vector autoregression (VAR) model was employed to analyze the response intensity and duration of vegetation growth carryover effect (VGC) and lagged climatic effect (LCE) to climate. The results show that the VGC response intensity in the early of growth season of xylem phase is higher than that of tree-ring width. The LCE duration for both early of growth season of xylem and tree-ring width ranges from 0 to 11 (year or season), with peak LCE response intensity observed at lag 2–3(year or season). The persistence of climate’s lag effect on vegetation growth has been underestimated, supporting the use of lag 0–3(year or season) to study the long-term impacts of climate. The influence of VGC on vegetation growth is significantly stronger than that of LCE；Ultimately, indicating that Juniperus seravschanica adapts to harsh environments by modulating its growth strategy through VGC and LCE. Investigating the VGC and LCE of multi-scale xylem growth indicators enhances our understanding of forest ecosystem dynamics.