dataset for "Drought-modulated allometric patterns of trees in semi-arid forests"

Tree allometry in semi-arid forests is characterized by short height but large canopy. This pattern may be important to carbon sequestration maintaining but still lacks quantification. Here we use terrestrial laser scanning to quantify allometry variations of Quercus mongolica in semi-arid forests. With tree height (Height) declining, canopy area (CA) decreased with substantial variations. The theoretical CA-Height relationships in dynamic global vegetation models (DGVMs) matched only the 5th percentile of our results because of the CA underestimation and Height overestimation by breast height diameter (DBH). Water supply determined Height variation (P = 0.000) but not CA (P = 0.2 in partial correlation). The decoupled functions of stems, hydraulic conductance and leaf spatial arrangement, might explain the inconsistency, which may further balanced tree water consumption and carbon assimilation, avoiding forest dieback. Works on the tree allometry pattern and determinant would effectively supply tree drought tolerance studying and support future DGVM improvements.

半干旱森林的树木异速生长特征表现为株高偏矮，但冠幅宽大。该格局可能对维持森林碳汇功能具有重要意义，但目前尚未得到定量刻画。本研究采用地面激光扫描技术，对半干旱森林中的蒙古栎（Quercus mongolica）的异速生长变异进行定量分析。随株高（Height）降低，冠幅面积（CA）呈下降趋势，且存在显著变异。动态全球植被模型（DGVMs）中理论上的冠幅面积-株高关系仅与本研究结果的5%分位数相匹配，这是由于通过胸径（DBH）反推的冠幅面积被低估、株高被高估。水分供应显著调控株高变异（P=0.000），但对冠幅面积无显著影响（偏相关分析P=0.2）。茎秆、水力导度与叶片空间配置的解耦功能，或可解释上述不一致性；该解耦机制可进一步平衡树木的水分消耗与碳同化过程，进而避免森林衰退。针对树木异速生长格局及其调控因子的研究，可有效支撑树木耐旱性相关研究，并为未来动态全球植被模型的优化提供科学支撑。