不同高寒生态系统植物光能利用效率及其环境影响

Light use efficiency of plants and the environmental impact factors in different alpine ecosystems

光能利用效率是植物光合作用的重要指标,也是提高生态系统生产力的关键。本研究选择若尔盖高原这一生态敏感区,开展高寒草地和高寒湿地两个典型生态系统植物光能利用效率的观测,并分析环境因素对不同生态系统植物光能利用效率的影响。结果表明:高寒草地优势种植物垂穗披碱草(Elymus nutans)的净光合速率和光能利用效率均高于湿地优势种植物木里苔草(Carex muliensis),但差异不显著;对于两种生态系统共有种蕨麻(Potentilla anserina)来说,高寒湿地蕨麻的净光合速率和光能利用效率均高于草地蕨麻。逐步回归分析表明:两个生态系统的优势种光能利用效率受微气象因素和土壤因素的影响较大,而共有种蕨麻主要受微气象因素的影响;不同高寒生态系统植物的光能利用效率不同,优势种植物受环境影响因素较大,其中空气温度是影响高寒植物光能利用效率的最主要因素。

Light use efficiency is an important indicator of plant photosynthesis, and also is crucial for improving ecosystem productivity. In this study, we selected Zoige Plateau, an ecologically sensitive alpine area, to evaluate the light use efficiency of the dominant plant species in two typical ecosystems, namely alpine meadows and wetlands, and to analyze the impacts of environ- mental factors on light use efficiency in each ecosystem. The net photosynthetic rate and light use efficiency of Elymus nutans dominated in alpine meadows were higher than those of Carex mulien- s/s dominated in alpine wetlands, but the difference was not significant. Regarding Potentilla an- serina, a common species in both ecosystems, the net photosynthetic rate and light use efficiency were higher in alpine wetlands than in alpine meadows. Regression analyses revealed that there were highly significant correlations between the light use efficiency of the two dominant plant spe- cies （E. nutans and C. muliensis） and microclimatic and edaphic factors. In contrast, the light use efficiency of the common plant species P. anserina was mainly affected by microclimatic factors only. This study indicated that the light use efficiency varied with alpine plant species. For the dominant species, the light use efficiency was mainly influenced by microclimatic factors, es- pecially air temperature, which was the most important factor affecting the light use efficiency of alpine plants.