牧草种群生长对家畜践踏的短期响应

通过模拟试验研究了牧草种群生长对家畜践踏的短期响应,试验于2004年6月下旬在甘肃环县温带典型草原区进行.践踏强度分别为:0,40,80,120 次/m2,4次重复.践踏后1个月,观测试验各小区主要牧草种的株高、株基直径、盖度和实生苗密度,并建立了综合响应指数,分析了植物对践踏的敏感性.结果表明,植物对践踏的响应存在明显的种间差异.长芒草、达乌里胡枝子和沙打旺的随践踏强度呈凸抛物线变化;苜蓿、阿尔泰狗娃花和二裂委陵菜随践踏增强而下降;茵陈蒿的综合响应指数随践踏呈现无规律变化.同时,根据植物生长对践踏的响应模式,可以将7种植物分为纵向敏感型,沙打旺和达乌里胡枝子;横向敏感型,长芒草和阿尔泰狗娃花;横向-纵向敏感型,苜蓿和茵陈蒿.因此,适度践踏促进一些植物的生长、繁殖,有利于种群更新.

Short stage response of population growth to livestock trampling

This simulation experiment was based on the short stage response of population growth of seven plant species to trampling by livestock. It was conducted on the warm typical steppe area of Huaxian, Gansu Province, in late June 2002. The trampling intensity treatments used were 0, 40, 80 and 120 pass/m~2, replicated 4 times. After one month of trampling the plant height, shoot base diameter, coverage, and seeding density of Stipa bungean, Lespedeza davurica, Medicago sativa, Artemisia capillaries, Astragalus adsurgens, Heteropappus altaicus and Potentilla bifurca were observed. A comprehensive response index of these seven species to trampling was constructed, and the sensitivity of these species to trampling was analyzed. Observation of the plant characteristics measured indicated that the species exhibited obvious differences in responses to trampling. As trampling intensities increased the comprehensive index of S. bungean, L.davurica and A.adsurgens showed a protruding parabola pattern, and the comprehensive index of M.sativa, H.altaicus and P.bifurca decreased. However, the comprehensive index of A.capillaries remained consistent. Based on the sensitivity of the seven plants to trampling intensity, the species were divided into one of either ordinate sensitivity pattern (A.adsurgens and L.davurica), transverse sensitivity pattern (S.bungean and H.altaicus) or transverse - ordinate sensitivity pattern (M.sativa and A.capillaris). Based on results it is reasonable to suggest that trampling can encourage some species to grow and reproduce, and can therefore be beneficial for population regeneration.