物种多样性及生物量与地下水位的关系——以海流兔河流域为例

摘要

以3条样带上117块植被群落调查样方为基础资料,研究了海流兔河流域植被物种多样性及生物量与地下水位之间的关系.结果表明:1)地下水位高低及地貌类型均会影响草本层植物群落组成及优势种构成.滩地样地中,随地下水位降低,优势草本的更替方向为寸草,芨芨草,马蔺,狗尾草,碱茅;沙坡样地中,优势草本的更替方向为大针茅,沙鞭,沙蓬,沙打旺.2)地下水位为1.5m时是草本植物群落生长发育最适宜区域,物种多样性及丰富度达到最大,而灌木层物种多样性及丰富度随地下水位下降呈现波动变化的特征;当地下水位埋深小于5.0 m时,草本层物种多样性及丰富度明显高于灌木层,在地下水位埋深大于5.0m时,草本层物种多样性指数开始出现低于灌木层的现象.3)草本植物多样性及丰富度和生物量之间关联性不强,滩地样地中,草本层地上生物量及地下生物量在地下水位为1.8m时具有最大值,但植物群落结构较为单一;沙坡样地中,地上生物量最大值出现在地下水位为5.0m的区域内,而地下生物量最大值出现在地下水位为3.5m时.综上,物种多样性、地上及地下生物量与地下水位都不是简单的线性关系,而是有一个最适水位;高于或低于这个最适水位,多样性和生物量都会下降.%Based on the data from 117 sampling plots,the relationships between plant species diversity,biomass,and the groundwater table in the Hailiutu River basin were investigated.The main findings of this study can be summarized as follows:1) The value and species composition of herbs in the plant community are greatly affected by the groundwater table and geomorphic type.In the fiat land of river beds or lake beaches,a decrease in the groundwater table,resulted in a shift in dominant herbaceous plants from Carex duriuscul,Achnatherum splendens,Iris lactea var,Setaira viridis,to Puccinellia tenuiflora in sequence;however,on the slope of the sand-dune,the dominance was shown from Stipa grandis,Psammochloa villosa,Agriophyllum squarrosum to Astragalus adsurgens in sequence.2) The species diversity and richness of the herbaceous plant community had a maximum value when the groundwater table was 1.5 m;therefore,the region with the depth of groundwater table at 1.5 m is the most suitable region for the herbaceous plant community growth and development.The species diversity and richness of the herb layer were significantly higher than those of the shrub layer when the groundwater depth was less than 5.0 m.However,when the groundwater table was greater than 5.0m,the species diversity of the herb layer was lower than that of the shrub layer.3) The correlation among herbaceous plant diversity,richness,and biomass was not significant;in the flat land of river beds or lake beaches,the herb layer aboveground and underground biomass had a maximum value when the groundwater table was 1.8 m with simple plant community structure.However,on the slope of the sand dune,the aboveground biomass reached the highest value when the depth of groundwater table was 5.0 m,but the underground biomass was at a maximum when the groundwater table was 3.5 m.In conclusion,we found that there was no simple linear relationship among plant diversity,plant biomass,and groundwater table.There is an optimal ground water table level for both plant diversity and biomass:values higher or lower than this value will cause a reduction in plant diversity or biomass.