卧龙自然保护区华西箭竹（Fargesia nitida）生态学特征随海拔梯度的变化

海拔梯度由于包含了温度、水分、光照等环境因子的剧烈变化而成为研究植物的环境适应性及其对全球气候变化响应的理想区域。在卧龙自然保护区沿海拔梯度研究了华西箭竹（Fargesia nitida（Mitford）T.P.Yi）分株的丛结构,比叶面积（SLA）、基径、株高、枝下高、单株地上部生物量及各器官生物量的分配。结果表明：华西箭竹丛结构表现为平均单丛面积和丛密度随着海拔升高呈先增大后降低的趋势,而单丛分株数先减少后增大;华西箭竹分株生长特征除SLA和枝下高线性降低,其他各调查变量随着海拔升高,总体呈先增大后减小的单峰变化趋势,高峰值在2 800 m附近。反映了环境因子随海拔升高的非线性变化。分析认为,高海拔地区的华西箭竹对温度较为敏感,气候变暖将有利于它的生长,因此其分布上限可能会提高。本研究结果拓展和丰富了海拔梯度上植物对异质性环境的适应和响应的规律研究,也可对地震后保护区植被的恢复与重建提供科学参考。

Ecological responses of Fargesia nitida to altitude in the Wolong Nature Reserve

Global warming has been predicted to occur most rapidly at high altitude.We investigated the clump structure and growth traits of F.nitida across its altitudinal gradients from the lowest distribution boundaries（higher temperature） to the uppermost elevational limits（lower temperature） in the Wolong Nature Reserve.The present study aimed to answer the questions：（1） Do plants with or without secondary growth respond to global climate change similarly？（2） What factors mainly determine the ecological characteristics of F.nitida to elevation？（3） What is the future fate of these bamboos and the Giant Panda under global climate change in the reserve？ The field investigation was carried out in April,2008.The growth are temporally stable before the growing season and thus are most suitable for altitudinal comparisons.According to nearly-equal interval of elevation,three plots at every elevation（10 m × 10 m each） were established and the gap is above 50 m among them.Number of F.nitida clumps in each plot was recorded to estimate the clump density.Three clumps in each plot were randomly selected to investigate ramet number per clump,basal diameter,height and the clear length of each ramet were measured.The clumps were then harvested,and the leaf,shoot,and stem biomass were measured separately after oven-drying to a constant weight.Fresh leaf area was scanned and analyzed using the ImageJ software and dried to a constant weight.One-way analysis of variances were used for all variables to test the differences among plots at different elevations,and multiple comparisons were conducted by Tukey＇s HSD test.Statistical analyses and modeling were done with SPSS 12.0 statistical software packages,and figures were done with SigmaPlot 10.0 software.The results showed that changes in the mean clump area and clump density of F.nitida populations with increasing elevation showed a convex curve,but change in the number of ramets per clump was a concave curve,both with a turning point at about 2800 m a.s.l.Except for a decreased trend of SLA and clear length,changes in other morphological traits（diameter,height,internode number） and biomass（leaf,shoot,stem and aboveground biomass） of F.nitida with increasing elevation were not linear,but formed a convex curve peaked at about 2800 m a.s.l.The high-altitude species（F.nitida） may benefit from global warming and its uppermost limit will shift upwards with further global warming.These results can also contribute to protecting the long-term survival of the Giant Panda in the reserve.