首页|The physiological constraints of alpine treeline in Qilian Mountains
The physiological constraints of alpine treeline in Qilian Mountains
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NSTL
Elsevier
The dynamics of the alpine forest boundary and the mechanisms behind have long been the ecological research hotspots. Growing season temperature (T-gs) decreases along with altitude gradients limiting alpine treeline has become the widely accepted mechanism among various theories. However, the physiological process amid T-gs limitation of the alpine treeline is still not well understood. Here, we measured leaf hydraulic conductance (K-l), stem hydraulic conductance (K-s), leaf and stem anatomic structures, and leaf saturated photosynthetic rate (A(sat)) of 11 tree and shrub species naturally distributed along the altitude gradients towards the typical alpine treeline in the north face of Qilian Mountains. We found, irrespective of interspecies or intraspecies, K-l and K-s both significantly decreased along the altitude gradients, and the species distributed in the high altitude with rather low K-l and K-s. The decrease of leaf midvein and stem xylem vessel diameter were the anatomical cause of the decreases of K-l and K-s. Further analysis proved that the decreased T-gs, not growing season precipitation (P-gs), was closely coordinated with the decrease of K-l and K-s along altitude gradients. The path analysis showed that the decreased T-gs, K-l, and K-s along the altitude gradients negatively influenced A(sat), and thereby limits the species survival in high altitudes. The findings proposed the physiological constraints of the alpine forest treeline and provided the physiological insights for alpine forest management and conservation.
Alpine treelineHydraulicPhysiologicalAltitudePlant distribution
Feng, Xiangyan、Lin, Pengfei、Zhao, Wenzhi
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Chinese Acad Sci, Northwest Inst Ecoenvironm & Resources, Lanzhou 730000, Peoples R China
NSTL
Elsevier
