华北农牧交错带人工草地放牧系统植物补偿性生长研究

研究华北农牧交错带不同人工草地在不同放牧强度下的总净生长量及净生长量的变化.结果表明,无芒雀麦-杂花苜蓿草地在任何放牧强度下均表现为超补偿性生长,即净生长量增加;新麦草-杂花苜蓿和杂花苜蓿-新麦草-扁穗冰草草地在轻度放牧下,总净生长量增加,在中度和重度放牧条件下分别表现为等补偿性生长和欠补偿性生长;新麦草草地在轻牧下呈超补偿性生长,在中牧下为等补偿性生长,重牧时表现欠补偿性生长;杂花苜蓿净初级生产力变化同新麦草草地一致;无芒雀麦在所设放牧强度下均表现为超补偿性生长,表明其耐牧性极强.因此,草地放牧强度应根据其组成种群来确定,以保证可持续利用.

Plant Compensatory Growth in the Grazing System of Cultivated Pasture of the Agro-Pastoral Transitional Zone

A study on the influence of different grazing intensities on the net aboveground production of pastures in the agro-pastoral transitional zone showed that different grazing intensities affect the pastures' compensatory growths. The pasture of smooth bromegrass-alfalfa showed over-compensatory growth under any grazing intensities, that is, increase of the total net growth production. The other two mixed pastures dominated by alfalfa, Russian wildrye and crested wheatgrass showed extra-compensatory growth under light grazing intensity, equal-compensatory and under-compensatory growths with medium and heavy grazing intensities respectively. The Russian wildrye pasture witnessed extra-compensatory growth with light grazing, even-compensatory growth with medium grazing, and under-compensatory growth with heavy grazing. Similar situations recurred with the varied alfalfa pasture's primary productioity. However,smooth bromegrass showed over-compensatory growth under all the different grazing intensities in this experiment, indication that smooth bromegrass is a species of high grazing tolerance. Consequently, the grazing intensity of the pasture should be determined according to its plant composition to ensure sustainable service.