矮嵩草草甸植物群落的光合特性研究

 矮嵩草草甸植物群落的光合、暗呼吸和土壤呼吸的研究表明：光合作用的日变化在6月份接近平坦型，7、8月份呈午间降低型。矮嵩草草甸植物群落的光合作用受较低的光合面积指数及冠层叶片的受光势态的影响，存在着明显的光饱和现象，光补偿点及光饱和点相对于全日照光合有效辐射均较低，接近于单叶的光响应特性。裸露地面的土壤呼吸和植物与土壤体系的暗呼吸不仅与温度有关，而且与土壤水分状况和降雨量也有密切联系。影响草甸群落光合特性的主要因素有：高原地区强烈的太阳辐射，较低的光合面积指数和植物根系与土壤紧密结合所形成的草结皮层结构。

THE PHOTOSYNTHESIS OF PLANT COMMUNITY IN KOBRESIA HUMILIS MEADOW

The photosynthesis, dark respiration and soil resplratlon of plant community in Kobresia humilis meadow were studied from 1990 to 1992 at the Haibei Research Station of Alpine Meadow Ecosystem, Menyuan Lounty, Qinghal province.The characteristics of photosynthesis were measured using Infrared Gasanalyzer(IRGA). The results show that the diurnal variation of net photosynthesis was not obvious in June,but the midday depression appeared in July and August.the photosynthesis of plant community in K.humills meadow was affected by rather low photosynthetic area index and by the light received by canopy leaves. It had obvious light saturation. The light compensation point and the light saturation point were lower, relative to the photosynthetic activity radlanon (PAR)of full sun, which assembles the light response of the single leaves.The soil respiration of uncovered ground and the dark respiration of plant-soil system were not only influenced by temperature,but also related to soil water content and preclpltanon.The main factors of influencing the photosynthesis character of meadow community were:the strong radiation in plateau region, the lower photosynthetic area index and the turf structure due to the tight combination between plant roots and soil of K. humilis meadow.