海拔对青海湖流域群落水平植物功能性状的影响

海拔变化会引起气压、温度、降水、土壤湿度和风速等环境因子发生急剧变化, 植物功能性状-海拔的相互关系对于预测全球变化背景下山地植物的适应方式具有重要意义。该研究在青海湖流域海拔3 400-4 200 m范围内布设了5个样地(海拔间隔约200 m), 通过植物群落调查, 测定植物功能性状和土壤理化性质, 结合气象数据, 探讨了海拔对青海湖流域群落水平植物功能性状的影响。结果如下: (1)群落加权平均植株高度(H)、叶片干物质含量(LDMC)、叶片碳氮比(C:N)和叶片氮磷比(N:P)随海拔升高显著降低, 比根表面积(SRA)随海拔升高波动下降, 比叶面积(SLA)、叶片氮含量(LNC)和叶片磷含量(LPC)随海拔升高显著升高, 叶片碳含量(LCC)、比根长(SRL)和根组织密度(RTD)随海拔未发生显著变化。(2)所有性状的变异来源以物种组成变化为主, N:P和LPC的种内性状变异与物种组成变化呈现正的协变效应, 其余性状为负的协变效应。(3)降水和0- 10 cm土层土壤养分含量对SLA变化的解释率较高, 温度和10-20 cm土层土壤养分含量对其余性状随海拔变化的解释率较高。以上结果表明青海湖流域植物群落主要通过物种更替来适应随海拔升高而剧烈变化的环境, 且各群落中的非优势种倾向于占据与优势种相反的性状空间来提高资源利用率, 随海拔变化的热量和深层土壤养分含量是群落水平植物功能性状变化的主要影响因子。

Effect of altitude on community-level plant functional traits in the Qinghai Lake Basin,China

Aims Altitude has prominent effects on many environmental factors, such as atmospheric pressure, temperature, precipitation, soil moisture and wind velocity. The relationship between plant functional traits and altitude are critical for predicting the effects of climate change on montane plants. Our objective is to examine the effect of altitude on community-level plant functional traits in the Qinghai Lake Basin, China.Methods Five sites were selected with 200 m increase in altitude (3 400-4 200 m) in the Qinghai Lake Basin, China. Community structure, plant functional traits, soil property and atmospheric factors were surveyed and analyzed in this study. Community-weighted mean functional traits (CWM) was calculated according to the relative abundance of species.Important findings The results showed that: (1) Community-weighted mean plant height (H), leaf dry matter content (LDMC), leaf C:N ratio (C:N) and leaf N:P ratio (N:P) decreased significantly along altitude, while specific root surface area (SRA) fluctuated with altitude. Specific leaf area (SLA), leaf nitrogen content (LNC) and leaf phosphorus content (LPC) increased significantly along altitude, while altitude had no significant effect on leaf carbon content (LCC), root tissue density (RTD) and specific root length (SRL). (2) The variation in CWM along altitude could be explained by species turnover more rather than intraspecific variability. N:P and LPC had a positive covariation, other CWM had a negative covariation. (3) Precipitation and 0-10 cm depth soil nutrients content explained the largest proportion change of SLA. Temperature and 10-20 cm depth soil nutrients content explained the largest proportion change of other CWM along altitude. Overall, these findings suggested that the plant communities in our study adapted to altitude through species turnover, and the non-dominant species tended to occupy opposite trait spaces to the dominant species in the Qinghai Lake Basin, China. Temperature and deeper soil nutrients content had significant effects on CWM along altitude.