Quantifying Radial Growth Response of Pinus Yunnanensis to Climate Change and Drought Event at Different Altitudes and Ages in the Jinsha River Basin
Abstract Background The relative influence of climate change and drought events on tree growth at different altitude and tree ages remains insufficiently understood in the Jinsha River Basin, southwest China, limiting prediction of forest adaptability to high-frequency droughts and climate change. We conducted a dendroecological study to explore and quantify the dominant climate factors that determining radial growth of Pinus yunnanensis trees of different ages and at different altitudes, to evaluate their resilience to drought events. Results Radial growth of P. yunnanensis at high elevations is typically limited by low temperatures, the explanatory rate of temperature factors on growth increased from 23.6–59.7% with altitude. Tree growth at low elevations is more sensitive to moisture factors, the explanatory rate of moisture factors on growth decreased from 76.4–40.3% with altitude. The young and mature trees are more prone to moisture factors than middle-age and near-mature trees, the young and near-mature trees are more prone to temperature factors than middle-age and mature trees. The older trees usually showed less drought resistance and recovery than the young and middle-age trees. The resistance and recovery of P. yunnanensis weakened with the increased frequency of drought events. Tree resistance and resilience was highly dependent on the average pre-drought growth, whereas the recovery showed weak or no significant relationships with average pre-drought growth. Conclusion Our study demonstrates that radial growth of P. yunnanensis trees showed age- and altitude-specific demand for energy and moisture. P. yunnanensis trees at different altitudes and ages are differentially adapted to varying levels of climate stress and display different strategies to withstand the effects of drought with altitude and ages.