载畜率对荒漠草原群落及植物功能群生物量的影响

Effects of Stocking Rates on the Biomass of Desert Steppe Community and Plant Functional Group

以内蒙古短花针茅（Stipa breviflora）草原为研究对象,设置4 个载畜率水平的随机区组实验,根据生活型和不同光合途径划分植物功能群,探讨载畜率对群落地上地下生物量和不同功能群生物量的影响.结果表明：群落地上生物量随载畜率的增大而显著降低（P〈0.05）,且二者呈负相关关系,回归方程Y=281.54-53.47X;地下生物量呈“T”字型分布,约80%生物量集中分布在0-20 cm 土层中,载畜率对地下生物量及分布无显著影响（P〉0.05）;群落根冠比在7-12 之间,随载畜率的增大而显著增大（P〈0.05）.载畜率对C4 植物地上生物量无显著影响（P〉0.05）,但其相对生物量随载畜率的增大而增大,C3 植物地上生物量与相对生物量均随载畜率的增大而降低（P〈0.05）.多年生丛生禾草地上生物量相对稳定,受载畜率的影响差异不显著（P〉0.05）;其相对生物量在群落中最高,且均随载畜率的增大而增大（P〈0.05）;灌木、半灌木和小半灌木的地上生物量随载畜率的增大而减小（P〈0.05）,但其相对生物量除重度放牧显著最低（P〈0.05）外,其他处理之间无显著差异（P〉0.05）;多年生杂类草、多年生根茎禾草和一、二年生植物地上生物量与相对生物量均随载畜率的增大而显著降低（P〈0.05）,多年生根茎禾草在轻度放牧下就几乎消失,而一、二年生植物在重度放牧下消失.

Desert steppe of Stipa breviflora in Inner Mongolia was taken as the object, and randomized block experiment was set based on 4 stocking rates, as well as plant functional groups were divided according to different life forms and photosynthetic pathways to study the effects of different stocking rates on above-and-underground biomass of community and the biomass of different functional groups. The results indicated that with stocking rates raised, aboveground biomass of community was dropping(P<0.05), and they were negative correlated as well, the regression equation was Y=281.54-53.47 X. Belowground biomass distributed like 'T', and about 80 percent of it concentrated on 0~20 cm soil, meanwhile, it was not effected significantly by stocking rates(P>0.05). However, the root shoot ratio which between 7 and 12 was increasing with the stocking rates added. Aboveground biomass of C4 was also not influenced remarkably, whereas its relative biomass was upgrading and both of aboveground and relative biomass of C3 were reducing markedly by stocking rates increased(P<0.05). Aboveground biomass of perennial bunchgrass was not impacted(P>0.05) but its relative biomass, the highest one in community, was advancing with stocking rates ascended(P<0.05). On the contrary, the aboveground biomass of shrub, subshrub and semishrub was declining(P<0.05), whereas its relative biomass was stable except it was the lowest in heavy grazing(P>0.05). Both aboveground and relative biomass of perennial forbs, perennial rhizome grasses, annuals and biennials were decreasing respectively by stocking rates enlarged(P<0.05), and even perennial rhizome grasses practically disappeared under light grazing as well as annuals and biennials vanished under heavy grazing.