防除狼毒后模拟秋季放牧对狼毒型退化草地群落的影响

Effect of simulated autumn grazing on the communityof degraded grassland after control ofStellera chamaejasme

摘要:

防除狼毒是青藏高原狼毒型退化草地恢复的主要措施之一,同时刈割作为放牧的一种人为模拟,对群落物种多样性和生产力有重要影响。以狼毒型退化草地为研究对象,在防除狼毒后进行为期5年的模拟秋季放牧(留茬10 cm)野外控制试验,研究模拟秋季放牧对狼毒密度、草地群落多样性以及地上生物量等的影响,探讨防除狼毒后模拟放牧对狼毒型退化草地群落的影响。结果表明:围封(FE)、刈割(C)和刈割+防除(C+SC)处理的狼毒密度及地上生物量均显著低于正常放牧(CK)(P＜0.05),且随着年份的延长,狼毒密度下降明显;各处理下总物种数都随年份增加而相应减少,C和C+SC的物种数下降幅度较小;FE、C和C+SC的多样性指数、丰富度指数、均匀度指数、优势度指数与CK相比均有所下降,FE、C和C+SC处理的均匀度指数在年份间均呈降低趋势;FE、C和C+SC的地上生物量在处理后第2年均比CK有增加趋势,其中总地上生物量和禾本科的地上生物量在第2年后就显著高于CK(P＜0.05),豆科在第3年后显著高于CK(P＜0.05),同时,C和C+SC处理的总地上生物量、禾本科以及豆科地上生物量随着年份的增加呈显著上升趋势(P＜0.05),而各处理的莎草科和杂类草的地上生物量均在年份间变化不显著(P＞0.05)。

Abstract:

Control of Stellera chamaejasme is one of the main measures to restore the degraded grasslands in the Qinghai-Tibet Plateau.Clipping,used as artificial simulation of grazing,has important effects on species diversity and productivity.After the prevention and control of S.chamaejasme,this study investigated the effects of a five-year simulated autumn grazing(10 cm stubble) on the density of S.chamaejasme,diversity and aboveground biomass of grassland community in a degraded grassland caused by S.chamaejasme.The results showed that the density and aboveground biomass of S.chamaejasme in the FE,C and C+SC treatments were significantly lower than that of CK(P＜0.05),and the density of S.chamaejasme significantly decreased with the extension of years(P＜0.05).While the number of total species decreased with the increase of years under each treatment,the number of species in the C and C+SC treatments only decreased slightly.The Shannon-Wiener index,richness index,Pielou index and Simpson index in the FE,C and C+SC treatments were lower relative to CK,the Pielou index in FE,C and C+SC decreased along the extension of years.The aboveground biomass of FE,C and C+SC in the second year increased relative to CK.Particularly,the total aboveground biomass of Gramineae in the second year and Leguminosae in the third year were significantly higher than CK(both P＜0.05).Meanwhile,the total aboveground biomass,aboveground biomass of Gramineae and Leguminosae of C and C+SC increased significantly with the extension of years(P＜0.05),while the aboveground biomass of Cyperaceae and forbs in each treatment did not change significantly between years(P＞0.05).