放牧强度对黑麦草/白三叶混播草地种群牧草量构成与年生产力的影响  

Effect of grazing intensity on the annual productivity and composition of mixed Lolium perenne and Trifolium repens pasture

作　　者：徐震[1] 于应文[1] 常生华[1] 

机构地区：[1]兰州大学草地农业科技学院甘肃草原生态研究所,甘肃兰州730020

出　　处：《草业学报》2003年第5期31-37,共7页Acta Prataculturae Sinica

基　　金：国家重点基础研究发展规划项目(G2000018602);国家"九五"科技攻关项目(96-016-02-01)资助。

摘　　要：研究了不同放牧强度下(轻牧、适牧、重牧、过牧),黑麦草/白三叶混播草地的牧草现存量,种群牧草量构成及年产量变化。随放牧强度增大,草地牧草现存量呈下降,牧草利用率呈增加趋势。放牧强度对黑麦草茎、叶生长具明显影响,对白三叶影响则较小;黑麦草绿色茎叶比随放牧强度增大而降低,白三叶茎、叶植物量分配主要受季节影响。适牧的黑麦草和白三叶种群牧草量呈线形函数变化,而轻牧、重牧和过牧则呈幂函数变化,各放牧强度黑麦草现存量均随白三叶牧草量的增大而增多。黑麦草种群和群落产量均为:适牧>重牧>过牧>轻牧;白三叶种群产量为:适牧>过牧>重牧>轻牧。随放牧强度增大,黑麦草组分相近,白三叶组分呈增加,杂草和死物质组分呈降低趋势。因此,放牧能提高白三叶组分,抑制杂草植物生长,降低混播草地凋落、枯死损失,增强黑麦草和白三叶种群生长的正效应作用;适度放牧利于混播草地中黑麦草、白三叶组分比的稳定,维持混播草地高生产力。合理的草地利用率是保持高产、优质草地的关键。The pasture cover, composition and changes in annual productivity for a mixed Lolium perenne and Trifolium repens pasture were studied under four different grazing intensities (lax, moderate, heavy and overgrazing: postgrazing pasture covers were 1 200～1 300 kg/hm2, 900～1 000 kg/hm2, 600 kg/hm2 and 300 kg/hm2 respectively). The results showed that pasture cover decreased with increase in grazing intensity, but pasture utilization rate increased. The growth of stems and leaves of L.perenne showed an obvious response to grazing intensity, but the growth of stems and leaves of T.repens showed very little response. The stem to leaf ratio of L.perenne decreased with increase in grazing intensity, whereas different seasons played the key role affecting the stem to leaf ratio of T.repens. Under moderate grazing, pasture cover of L.perenne increased as a linear function with the pasture cover increase of T.repens. Under lax grazing, heavy grazing and overgrazing, the pasture cover of L.perenne increased as a power function with the pasture cover increase of T.repens. Total pasture yield and forage yield of L.perenne showed the following pattern: moderate grazing>heavy grazing>overgrazing>lax grazing, and for T.repens was: moderate grazing>over grazing>heavy grazing>lax grazing. From lax grazing to overgrazing, the proportion of L.perenne remained similar (about 74%), the proportion of T.repens increased, and the proportion of weeds and dead matter decreased. Therefore, grazing can increase the proportion of T.repens, restrain weed growth, reduce dead matter loss, and enhance the positive relationship between L.perenne and T.repens resulting in increased growth of both species. Moderate grazing is beneficial in maintaining stable proportions of L.perenne and T.repens in the mixed pasture sward, and in maintaining high pasture productivity. Reasonable pasture ut

关 键 词：放牧强度 混播草地 黑麦草 白三叶 牧草量构成 生产力 

分 类 号：S812[农业科学—草业科学]