亚高山草甸植物群落对气候变化的响应

Response of Plant Community in Subalpine Meadow to Climate Change

为了研究气温升高、氮素增加和人为干扰对亚高山草甸植物生长和非结构性碳水化合物(NSC)的影响,该研究采用开顶式生长箱(OTC)模拟增温,同时进行施加氮肥和除草处理,对青藏高原东南缘邛崃山脉东坡巴郎山(四川盆地向青藏高原的过渡地带)的亚高山草甸植物的生长和NSC含量进行测定分析。结果显示:(1)各处理土壤全磷(P)和全钾(K)含量与对照均无显著差异,增温加施肥处理的土壤全氮(N)含量与对照无显著差异,但增温处理、施肥处理、除草处理、增温加除草处理、施肥加除草处理和增温加施肥加除草处理的土壤全氮含量较对照均显著降低。(2)增温促进禾本科和杂类草功能群生长,抑制莎草科功能群生长,提高禾本科功能群重要值,降低杂类草功能群重要值,且对莎草科功能群重要值的作用受施氮和除草的影响;施肥促进禾本科和杂类草功能群的高生长,并且促进莎草科功能群生长;除草促进莎草科功能群生长,抑制禾草科和杂类草功能群的生长;而施肥和除草的交互作用有利于禾草科功能群生长,施肥和除草都提高了莎草科功能群的重要值,降低了禾草科功能群的重要值。(3)不同物种NSC含量及分配对于各处理的响应有所不同,紫地榆的NSC含量与物种分盖度相关性显著,珠芽蓼的NSC含量与物种高度相关性显著。研究表明,气候变暖和土壤氮素增加有利于禾本科和莎草科植物的生长,并使植物改变体内非结构性碳水化合物的分配来抵御环境压力。

A field experiment was conducted to understand the response of growth and non-structural carbohydrates（NSC）content of subalpine meadow plants to climate warming,nitrogen addition and human disturbance.We used open-top chamber（OTC）to simulate warming with nitrogen fertilization and weeding treatments,to analyze the growth and non-structural carbohydrates content of subalpine meadow plants in Balang Mountain,east of Qionglai Mountains in southeast margin of Tibetan Plateau（the transitional zone from Sichuan Basin to Tibetan Plateau）The results showed that：（1）the soil total phosphorus（P）and potassium（K）contents of all treatments have shown non-significant difference towards the control.Soil total nitrogen（N）content of warming＋fertilization treatment has shown non-significant difference towards the control,while obviously decline of soil total nitrogen was shown in warming,fertilization,weeding,warming ＋ weeding,fertilization ＋ weeding,and warming ＋fertilization ＋ weeding treatments.（2）Warming promoted the growth of functional group of grasses and forbs but inhibited the growth of functional group of sedges.Warming enhanced the importance value of functional group of grasses but reduced the importance value of functional group of forbs.And the effect of warming on functional group of sedges＇ importance value was influenced by fertilization and weeding.Fertilization promoted the height growth of functional group of grasses and forbs,and promoted the growth of sedges.Weeding promoted the growth of functional group of sedges but weeding inhibited the growth of functional group of grasses and forbs.The interaction of fertilization and weeding was beneficial to functional group of grasses.Both fertilization and weeding enhanced functional group of sedges＇ importance value but reduced functional group of grasses＇ importance value.（3）Content and distribution of non-structural carbohydrates（NSC）of different species responded differently to the treatments.The non-structural carbohydrates content in Geranium strictipes showed significant correlation with species coverage,and non-structural carbohydrates content in Polygonum viviparum showed significant correlation with species height.The result indicates that both climate warming and nitrogen addition promote the growth of functional group of grasses and sedges,and cause the plants NSC changing to defend the environmental stresses.