不同去叶强度对羊草群落特征影响的研究

Effect of the Degree of Defoliation on Characteristic of Leynus chinensis Community

通过３０％、５０％、６０％、８０％去叶强度的试验研究，表明：７月份，不同去叶强度下群落的地上部生物量没有明显差异．８月份，３０％、５０％、６０％的去叶处理，也没有明显差异，但８０％处理的生物量却明显减少．９月份，各处理间地上部生物量差异很大，６０％和８０％的处理，生物量均低于３０％和５０％的处理．７～９月份，随着去叶强度的增大，群落去叶的总收获量增加，枯落物的积累量逐渐减少．１０月份，５０％、６０％、８０％的处理，枯落物的积累量分别比３０％的处理减少了一倍多．随着去叶强度的增大，各处理间当年的总生产量没有明显差异，枯落物积累的总量逐渐减少，群落盖度减小，优势种羊草的平均高度和密度下降，而糙隐子草和狗尾草却有所升高．

The experimental results of different degrees of defoliation (30%,50%,60%,80%) indicated that the aboveground biomass showed unnoticeable difference in July, neither did it under 30%,50%,60% degrees of defoliation in August, however, aboveground biomass for 80% degree increasingly decreased. Biomass for 60% and 80% degrees were both lower than that for 30% and 50% degree in September. From July to September, total removals of community increased with the increase of defoliation degrees, while litter accumulation decreased. In October, litter accumulation for 30% degree is more than 2 times that for 50%, 60%, 80% degrees respectively. With the increase of defoliation degree, total biomass of different degrees of defoliation didn't show evident difference, while total litter accumulation and the cover of community decreased, the average height and density of dominant Leymus chinensis reduced, that of Cleistogenes squarrosa and Setaria viridis increased.