希拉穆仁草原两种主要植物光合特征对草地退化的响应

Effects of Grassland Degradation on Photosynthetic Characteristics of Main Plant Species in Xilamuren Grassland

用LI-6400便携式光合作用测定系统对希拉穆仁草原短花针茅和糙隐子草的各项光合指标进行了测定,结果显示:随着草地退化程度加重,短花针茅和糙隐子草的净光合速率、蒸腾速率、胞间CO_2浓度及气孔导度均表现为轻度退化>中度退化>重度退化,短花针茅和糙隐子草的光合速率、蒸腾速率随草地退化的加剧而降低,短花针茅的各项光合指标降低幅度比糙隐子草相应指标降幅大。短花针茅的水分利用效率低于糙隐子草而光合速率高于糙隐子草,表明其对环境特别是干旱的耐受能力低于糙隐子草。土壤全氮、全磷和含水量是影响不同退化程度草原短花针茅光合特性的主要因素,而不同退化程度草原糙隐子草光合特性主要受土壤含水量影响。

In order to study the photosynthetic characteristics of plants under different degradation degrees of grassland, the photosynthetic indexes of Stipa breviflora and Cleistogenes squarrosa were measured with LI-6400 portable photosynthesis system.The results showed that:(1) With the deteriorating degree of grassland degradation, the net photosynthetic rate (Pn), transpiration rate (Tr), intercellular CO 2 concentration (Ci) and stomatal conductance (Gs) of Stipa breviflora and Cleistogenes squarrosa were all as follows: light deteriorate (LD)>moderate deteriorate (MD)>heavy deteriorate (HD), The photosythesis and transpiration of Stipa breviflora and Cleistogenes squarrosa decreased with increasing grassland degradation.(2) The photosynthetic indices of Stipa breviflora decreased more than those of Cleistogenes squarrosa, and the water use efficiency of Stipa breviflora was lower than that of Cleistogenes squarrosa, indicating that the photosynthetic capacity of Stipa breviflora was stronger than that of Cleistogenes squarrosa, but the environmental tolerance of Stipa breviflora was lower than that of Cleistogenes squarrosa.(3) Total nitrogen (TN), total phosphorus (TP) and soil water content (Sw) were the main factors affecting the photosynthetic characteristics of Stipa breviflora under different degraded grasslands, while the photosynthetic characteristics of Cleistogenes squarrosa in different degraded grasslands were mainly affected by Sw.