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为明晰牦牛和藏羊践踏对阴山扁蓿豆光合特性的分异影响,在天祝高寒草地采用模拟降水和践踏双因子控制试验,研究了阴山扁蓿豆单叶面积、叶绿素含量、叶片气体交换参数变化对短期模拟牦牛、藏羊践踏和降水的响应。结果表明,随着模拟牦牛和藏羊践踏强度的增加、模拟降水量的降低,阴山扁蓿豆单叶面积、叶绿素含量、蒸腾速率(T_r)、叶片气孔导度(G_s)和净光合速率(P_n)均呈下降趋势,胞间CO_2浓度(C_i)呈上升趋势。相同降水量下,藏羊和牦牛轻度践踏强度下阴山扁蓿豆蒸腾速率、叶片气孔导度和净光合速率均高于对照,胞间CO_2浓度低于对照。与对照相比,牦牛重度践踏处理下阴山扁蓿豆单叶面积、叶绿素含量、蒸腾速率、叶片气孔导度和净光合速率的降幅和胞间CO_2浓度的升幅均大于藏羊重度践踏处理。单一的模拟降水或模拟践踏极显著地影响了各测定指标,且两者共同作用对阴山扁蓿豆单叶面积、蒸腾速率、叶片气孔导度、净光合速率和践踏末期叶绿素含量的影响达极显著水平。综合可得,牦牛和藏羊轻度践踏可促进阴山扁蓿豆光合作用,重度践踏严重抑制了阴山扁蓿豆光合作用,且牦牛践踏对阴山扁蓿豆光合能力的抑制作用大于藏羊践踏。
To clarify the differential effects of yak and Tibetan sheep trampling on the photosynthetic characteristics of YMCA alfalfa, single leaf area, chlorophyll content, leaf gas exchange parameters Changes in short-term simulated yak, Tibetan sheep trampling and precipitation response. The results showed that single leaf area, chlorophyll content, transpiration rate (T_r), leaf stomatal conductance (G_s) and net photosynthetic rate (P_n) of YMCA decreased with the increase of trampling intensity of simulated yak and Tibetan sheep, ) Showed a downward trend, the intercellular CO 2 concentration (C_i) showed an upward trend. Under the same precipitation, the transpiration rate, stomatal conductance and net photosynthetic rate of YMCA in Tibetan sheep and yak were higher than those in control, and the intercellular CO 2 concentration was lower than that in control. Compared with the control, single leaf area, chlorophyll content, transpiration rate, stomatal conductance, net photosynthetic rate and increase of intercellular CO 2 concentration of YMCs under severe trampling treatment were higher than those of Tibetan sheep. A single simulated precipitation or simulated trampling significantly affected each of the measured indicators, and the combined effect of both had significant effects on single leaf area, transpiration rate, leaf stomatal conductance, net photosynthetic rate and trampling chlorophyll content of YMCA Level. Synthetically, yak and Tibetan sheep mild trampling can promote the Yam Mountain Medicago sativa photosynthesis, heavy trampling seriously inhibited Yinshan Medicago sativa photosynthesis, and yak trampling on Yam Mountain Medicago sativa photosynthetic capacity greater than the Tibetan sheep trampling.