三江平原不同强度干扰下湿地植物群落的物种组成和多样性变化

以三江平原湿地-农田景观中沟渠的密度作为反映干扰强度的指标,研究了不同沟渠密度下湿地斑块植物群落的物种组成和多样性变化.结果表明:(1)在不同的干扰强度下,湿地植物群落的物种组成差异很大, 随干扰强度增大,原有湿生物种减少,而中湿生、中生物种显著增加;(2)湿地植物群落的多样性随干扰强度的增大,整体上呈降低趋势,群落多样性在中等沟渠密度下(0.6～1.2km/km2)达到最大,但不同沟渠密度下群落间多样性差异基本不显著;(3)位点间的干扰强度差异越大,Whittaker指数值越高;(4)不同的干扰强度下,各湿地斑块内部的物种周转速率同样在沟渠密度中等(0.6～1.2km/km2)时最高.

Variation in species composition and diversity of wetland communities under different disturbance intensity in the Sanjiang Plain

In this study, ditch density was chosen as an indicator of disturbance intensity, and four sites with different ditch density were chosen to compare species composition and diversity among them. Four transects and sixty-seven quadrats were sampled along the ditch density gradient. The results showed that there existed a significant negative relationship between disturbance intensity and species parameters, while species diversity did not differ greatly among sites, but species composition varied considerably. With increasing disturbance intensity, the wetlands tended to be reduced in plant species diversity, and an increasing loss of indigenous wetland species was paralleled with an increasing invasion of upland species. The results also show that the rate of species turnover within communities differed among communities under different disturbance intensities. The communities with intermediate ditch density (0.6-1.2 km/km²) had higher rates than the other communities.