放牧对牧草光合作用、呼吸作用和氮、碳吸收与转运的影响

研究放牧对草地植物生理活动的影响，对于揭未草地放牧演替的生理机制有重要意义，大量研究表明，家畜放牧对牧草光合作用、呼吸作用以及C和N吸收与转运的影响，可以分为生理伤害和生理恢复2个阶段，放牧通过改变草地冠层结构影响牧草光合作用，净光合作用速率短期内迅速下降，随着叶面积指数增加又逐渐上升，呼吸作用有相似的变化趋势，牧草放牧后再生长所需的C和N最初主要来自根系和留茬中的贮藏物质，此后随着牧草生长恢复逐渐由同化作用供给，C代谢与土壤N水平负相关，放牧后牧草生理活动变化与牧草遗传特性、种间竞争、家畜放牧特征、非生物环境等因素密切相关。

Effect of grazing on photosynthesis and respiration of herbage and on its absorption and transporation of nitrogen and carbon.

The research on the effect of grazing on physiological action of herbage plays an important role in probe into the physiological mechanism of succession in grazing grassland.Many results showed that the effect of grazing on photosynthesis respiration,absorption and transportation of nitrogen and carbon in herbage could be significantly divided into two stages,including physiological injury and regularization.The changed structure of canopy by grazing resulted in a variation of canopy photosynthesis.The net photosynthetic rate was sharply decreased in short period,and then gradually getting back with the increase of leaf area.The response of respiration to grazing was similar to that of photosynthesis.Nitrogen and carbon used in the revegetation chiefly came from the stored matter in root and stubble at the first period after grazing.Then,the assimilation met the need of revegetation to use nitrogen and carbon with the recovery of physiological action.The absorption and transportation of carbon after grazing was negative relationship with the nitrogen level in soils.The effect of grazing on the physiological processes of herbage had a close relationship with the genetic characteristics of herbage,inter-specific competition,grazing characteristics of livestock,and environmentally abiotic factors such as light,heat,water and soil.