高寒嵩草草甸植物群落数量特征对不同利用强度的短期响应

Plant functional groups numerical characteristics responses to different grazing intensities under different community succession stages of Alpine Kobresia meadow in spring

以时空转换的方法确定典型高寒嵩草草甸演替过程的4个关键阶段,以此为研究对象,探讨冬春放牧对高寒草甸生态系统植物功能群数量特征的影响,及在现有放牧制度下不同退化程度草甸植物群落数量特征对禁牧和减牧的响应。结果表明:当禾本科功能群在群落中的地位大于等于莎草科功能群时,减牧可以提高禾本科和莎草科功能群而降低杂类草功能群在群落中的地位;禁牧可以提高禾本科和杂类草功能群而降低莎草科功能群在群落中的地位。当莎草科功能群在群落中的地位大于禾本科功能群,且莎草科功能群以根茎密丛型植物为优势种时,放牧强度降低可以提升禾本科功能群但降低莎草科功能群在群落中地位;而莎草科功能群以密丛型植物为优势种时,放牧强度降低可增加莎草科功能群在群落中的地位,而禾本科功能群在群落中地位的变化取决于草地中裂缝的性质,一定强度的裂缝可以增加禾本科功能群在群落中的地位。因此,退化高寒嵩草草甸自我恢复方式的选择取决于可食性牧草组分、地表特征及恢复目标。当可食性牧草以禾本科功能群为优势种(或禾本科同莎草科功能群为共优种)时,减牧容易提高草地的牧用价值,而禁牧容易增加草地中杂类草功能群的比例,不利于畜牧业生产;当高寒嵩草草甸可食性牧草以莎草科功能群为优势种时,禁牧较减牧更容易加快其牧用性的恢复。小嵩草草甸草毡表层开裂期为该演替系列的激变期,而由于冻融交替形成的裂缝是草地恢复的新生带,如加以利用可以加速草地恢复。

We used 4 typical community succession stages of Alpine Kobresia meadows where stock animals graze in late autumn, winter and early spring, to explore plant functional groups （PFG） characteristics responses to different grazing intensities. The grazing intensities include freedom grazing （ according to the normal grazing intensity） , reducing stock- grazing intensity 50%, no grazing. The succession stages include Gramineae grass-Kobresia humilis community, Kobresia humilis community, thicken in Kobrecia pygrnaea community and Cracks in Kobrecia pygmaea community. The PFGs include Gramineae, Sedge, Legumes, shrub and Forbs. All the PFGs characteristics collected in the early of June, which is the end of grazing in winter and spring pastures. The data statics were used One Way ANOVA （c~ = 0.05） by SPSS 11.5, the resuhs showed： the status and function of Gramineae and Sedge PFGs could be increased, but Forbs PFG could be decreased under grazing-deducing, if numerical characteristics of Gramineae PFG was greater than or equal to Sedge PFG in plant communities. While the status and function of Gramineae and Forbs PFGs would be increased, but Sedge PFG would be decreased under the grazing-prohibition based on the prerequisite above. If the status and function of Sedge PFG was greater than Gramineae, and dominate species of Sedge PFG was rhizome sparse cluster-type plants, deducing stocks grazing intensity could increase the recovering efficiency of Gramineae PFG, while if the dominate species of Sedge were dense cluster-type plants, deducing stock grazing intensity could increase the recovering efficiency of Sedge PFG, and all recovering efficiency would be promoted when the alpine meadow in grazing-prohibition. So the way to choose degradation alpine Kobresia meadows restoration method should pay more attentions to edible composition structures of forage in the community, land status of pasture and recovery goals. When Gramineae is dominate edible forage in degradation alpine meadows, grazing-reducing is the best recovery method, while if Sedge PFG is dominate edible forage, grazing-prohibition is the best recovery method. And cracks in pasture land on alpine meadows are the new plant growing area, if the intensity of cracks in pasture land is in a proper ranges, it will improve the alpine meadows recovery efficiency