干扰程度对典型草原植物群落数量特征及物种多样性的影响

Effects of disturbance degree on quantitative characteristics and species diversity in typical steppe plant communities

摘要:

【目的】为明晰不同程度的干扰对典型草原植物群落数量特征及物种多样性的影响 。 【方法】通过野外调查和遥感影像解译数据，在放牧和未放牧交互区选取未干扰、轻度干扰、中度干扰和重度干扰 4 种干扰等级的草地。分别从群落数量特征和物种多样性两个方面，探讨干扰影响下草地群落的变化。【结果】随着干扰程度的加剧：（1）群落优势种数量减少，重要值下降 1. 21 倍。杂类草数量增加，重要值增加 59. 70%。（2）群落的高度、盖度和密度呈显著下降的趋势（P＜0. 05）。其中，群落高度下降 79. 74%，群落盖度下降 70. 99%，群落密度下降 59. 39%。（3）群落地上生物量呈现先降低后增加的趋势，在各干扰程度间差异显著（P＜0. 05）；群落地下生物量和各土层的地下生物量均表现为降低后趋于稳定的趋势，且地下根系主要集中在 0~10 cm 土层中。（4）物种多样性未呈现一致的变化规律。 其中，物种丰富度指数和 Simpson 指数在重度干扰草地时最高，Shannon-Wiener 指数和 Pielou 指数在轻度干扰草地时最高。【结论】研究结果可为山地草原退化治理提供基础数据。

Abstract:

As a typical type of grassland in Xinjiang，mountain grassland is an important pasture in Xinjiang grass- land. In order to understand the effect of different degrees of disturbance on the quantitative characteristics and species diversity in typical steppe plant communities，grassland with four disturbance levels including non-disturbance，mild disturbance，moderate disturbance and severe disturbance were selected in grazing and non-grazing interaction areas through field investigation and remote sensing image interpretation data. The changes of grassland community under disturbance were analyzed from two aspects of community quantity characteristics and species diversity. The results showed that with the intensification of disturbance，（1） the number of dominant species decreased，and the importance value decreased by 1. 21 times. The number of miscellaneous grass increased，and the importance value increased 59. 70%.（2） The community height，coverage and density were significantly decreasedby 79. 74%，70. 99% and 59. 39%，respectively （P＜0. 05）.（3） The aboveground biomass of the community first decreased and then in- creased，and there were significant differences among disturbance degrees （P＜0. 05）. The underground biomass of communities and soil layers tended to be stable after decreasing，and the underground roots mainly concentrated in 0- 10 cm soil layer.（4） Species diversity did not show a consistent change. Species richness index and Simpson index were the highest in severely disturbed grassland. The shannon-Wiener index and Pielou index were the highest in lightly disturbed grassland. The results provided basic data for the degradation control of mountain steppe.