滩地杨树林下草本植物层片物种数量特征及多样性与林龄关系的研究

The relationship between the species number and diversity of undergrowth herbaceous plants layer and the age of poplar plantation in the beach area

为研究湖区滩地杨树造林后对生态环境的影响,从1997至2004年为监测杨树林下草本植物层片演替,每年定时、定点作草本植物样方调查。结果显示:在1.5 m高差范围内,各高程草本层植物种类及结构虽有所不同,但没有实质性差异,同质性高于异质性。随林龄增加、郁闭度降低,光梯度的演变虽出现某些阳生植物为荫生植物所替代,但它们往往都不是群落的优势种或建群种。在连续8年监测中,始终出现的植物物种为9个,每年其相对重要值之和为71.23%~84.39%,同质性高。Shannon-Wiener多样性指数H′,在不经历外界强力干扰破坏情况下,亦没有显著变化,造林后期与造林前期相比较,生物多样性得以完好保存。

In order to study the influence of poplar afforestation on the ecological environment in the beach area of the Dongting Lake,the monitoring experiment of the herbaceous plant layer succession under the poplar forest was carried out in the same time and same place from 1997 to 2004.The results show that in the range of 1.5 m height difference,although the species and structure of herbaceous plants layer are different,but there is no substantial difference,and the homogeneity is higher than the heterogeneity.With the increase of forest age and the decrease of canopy density,although the evolution of light gradient makes some sunny plants replaced by shade plants,they are often not the dominant or constructive species of community.In 8 years of continuous monitoring,there are 9 plant species always appearance in the beach area,the sum of their relative importance value is 71.23%~84.39%with high homogeneity.The Shannon Wiener diversity index H′is no significant change under the condition of no external strong interference and damage.Compared with the early stage of afforestation,the biodiversity is well preserved in the late stage of afforestation.