春季延迟放牧对高寒草甸草地群落特征及生产力的影响

冬春草地由于放牧时间长和返青期采食等原因,是高寒牧区退化较为严重的区域。本研究在高寒草甸选择4个放牧小区,依次延迟10天开展春季延迟放牧试验,并监测每个延迟区草地的产草量、盖度和牧草繁殖情况等,结果表明:在延迟放牧试验开始时,各试验小区之间的植被高度、盖度、生物量以及主要植物种的重要值无显著性差异,在6,7和8月份时,各小区的植被高度、盖度、生物量随着放牧时间的延迟而依次增加,8月份时,第4区达到最高分别为12.83 cm,100%和348.98 g·m^-2;延迟放牧最晚的第4区的开花数显著低于其他3个小区,但结实数以及开花结实总数显著高于其他;4个试验小区早熟禾(Poa sp.)以及垂穗披碱草(Elymus nutans)的重要值有所增加,赖草(Leymus secalinus)、无芒雀麦(Bromus inermis)的重要值有所下降,1,2和3区的阿尔泰狗娃花(Heteropappus altaicus)、扁蓿豆(Medicago ruthenica)的重要值有所增加,而4区呈下降趋势。试验结果证明延迟放牧对提高草地生产力,改善草地植被盖度和增加牧草繁殖机会效果显著。

Effects of Deferred Grazing on Grassland Community Characteristics and Productivity in Alpine Meadow

Winter-spring pasture is severely degraded rangeland because of grazing for long time and in the stage of returning green. The experiments of deferred grazing with 4 paddocks and an interval of 10 days between paddocks were conducted in alpine meadow. The plant height, coverage, biomass as well as the number of flowering and seed setting were measured and recorded. The results showed that there was no significant difference in the plant height, coverage, biomass and the important value of dominant species among four paddocks at the beginning. However, the plant heights, coverage, biomass of all tested paddocks increased with the grazing time deferred. The plant height, coverage and biomass of the most deferred grazing area were 12.07 cm, 97.67%, 348.98 g·m^-2, respectively. The number of flowering in the most deferred grazing paddock was significantly lower than that in other three paddocks(P<0.05), whereas the total number of seed setting was significantly higher than that in others(P<0.05). The important value of Poa sp. and Elymus nutans increased, whereas the important value of Leymus secalinus and Bromus inermis decreased in all tested paddocks. The important value of Heteropappus altaicus and Medicago ruthenica increased in 1st, 2nd and 3rd paddocks, whereas decreased in 4th paddock. These results suggest that the strategy of deferred spring grazing in winter-spring pasture is a good management measure for controlling the rangeland degradation of alpine meadow.