Spatio-temporally explicit reconstruction of upper range limit of trees since the LGM over the Tibetan Plateau.

Paleo-changes in upper range limit of trees provide a valuable analogue for understanding how high-elevational-trees may respond to future climate. Here, we presented a high-resolution (1 km) reconstruction of paleo-changes in the upper range limits of trees across the Tibetan Plateau, at 100-year intervals since the Last Glacial Maximum (~22 kyr BP). This reconstruction was developed by integrating multi-satellite-derived high-resolution map, in situ dendrochronological observation and paleoclimate dataset into a novel climate-driven predictive model. The model accounts for climate change effects, such as growing season temperatures and local climatic stressors, as well as migration time-lags. Validation demonstrated that the reconstructed paleo-shifts in the upper range limit of trees show strong consistency with dendrochronological reconstructions at the century timescale, corresponding with fossil pollen records from lake sediments during the Holocene period, and supported by phylogeographic evidence. This spatial-temporal explicit database enables the estimation of how paleo-changes in the upper range limit of trees have influenced regional biodiversity, offering critical insights into future changes in high-elevational-trees and their broader regional impacts.