不同刈割强度下草地群落、层片及物种的补偿性生长

The compensatory growth of plant community,synusia and species under different clipping intensity

群落中不同层片物种对刈割的响应有所不同,探讨不同刈割强度下群落各层片物种的补偿性生长对提高群落生产力具有重要意义。本试验以水热条件较好的南方草地——重庆云阳岐山草场为研究样地,采用梯度刈割方式(不刈割、留茬10 cm、留茬6 cm),进而研究不同刈割强度下,草地植物群落、层片以及物种补偿性生长的响应。结果发现,1)中度刈割(MC)下群落生物量恢复最快,而重度刈割下群落地上相对生长速率最大;2)生长季末时,中度和重度刈割下地上部分均实现了超补偿生长;3)顶层物种在中度刈割下地上相对生长速率(relative growth rate,RGR)最大,而中层物种在重度下最大;4)中度刈割下,群落的顶层物种生物量与群落生物量显著正相关,重度刈割下,顶层和中层物种生物量与群落整体生物量正相关,底层物种生物量与群落总生物量在两种刈割强度下均不相关;5)物种水平上芭茅、鸭茅和白三叶生物量变化与群落地上生物量变化基本一致。研究结果表明,在草地群落中,不同层片物种对刈割的响应存在差异,中度刈割更利于顶层物种的超补偿生长,重度刈割则有利于中层物种的超补偿生长。因此根据不同层片物种所占群落的比重确定草地刈割强度能更有效发挥草地的增产潜力。

The species of different layers in community have various responses to clipping,which crucially affect the compensation ability of the whole community and its productivity.Thus,this study aims to investigate the compensatory effects of grassland community and different layer of species,and three clipping intensities were conducted in Qishan pasture of Chongqing in the growing season.The study found that,1 )community aboveground biomass recovered more quickly at moderate clipping rate than that at high clipping rate,while the aboveground relative growth rate (RGR)reached the highest at the high clipping rate;2)at the end of growing season,RGR of the top layer reached maximum at moderate clipping intensity,and the middle layer of RGR was reached maximum at high clipping intensity;3)the moderate clipping intensity appropriated the over-com-pensatory growth for the tall plants,however,the high clipping intensity was suitable for the middle species;4)at the moderate clipping rate,the total community biomass was positively correlated with biomass of top lay-er species,however,there were positive correlations between biomass of top and middle layer species and com-munity biomass at high clipping rate,but no significant relationship was found between community biomass and the lower layer species biomass at the moderate and high clipping rate;5 )for the dominant species, Miscanthus floridulus ,Dactylis glomerata and Trifolium repens presented the similar biomass change patterns with those at synusia level.The results demonstrate that the plants at different synusia level shave species-spe-cific responses to clipping removal with different intensity.Moderate clipping intensity was appropriate for the over-compensatory growth of the tall pants,while the high clipping intensity was suitable for middle species. In conclusion,clipping intensity should be adopted according to the fragments of layers’characteristics and that can be advantageous for grassland productive potential.