踩踏对城市森林林下草本层植被物种组成和多样性及土壤理化性质的影响

The Impact of Trampling on the Species Composition and Diversity of Understory Herbaceous Layer Vegetation in Urban Forests and on Soil Physicochemical Properties

为探究踩踏对城市森林生态系统林下草本层植被物种组成和多样性及土壤理化性质的影响,以南京市紫金山城市森林公园为研究对象,对草本层植被、土壤样品进行调查和分析。应用方差分析、相关性分析法,对5种不同踩踏强度(无踩踏对照、轻度踩踏、中度踩踏、重度踩踏、极端踩踏),林下草本层植被的平均高度、群落α多样性指数以及林下表层土壤各项理化指标进行了探讨。结果表明:(1)极端踩踏与其他踩踏强度的草本层群落相似性最低,相似性系数小于0.3;(2)群落均匀度指数和丰富度指数均为中度踩踏显著高于无踩踏对照(P<0.05),无踩踏对照显著高于极端踩踏(P<0.05);(3)严重、极端踩踏时,土壤密度显著高于无踩踏对照区(P<0.05);(4)轻度踩踏时,土壤持水量显著高于极端踩踏区(P<0.05),但土壤总孔隙度变化不显著;(5)植被覆盖度与土壤密度呈显著负相关(P<0.01),与土壤铵态氮、硝态氮质量分数呈显著正相关(P<0.05)。适度踩踏对草本层植被的多样性和丰富度有积极作用,过度踩踏导致草本层植物生长受限,从而导致地表裸露,不利于森林生态系统的稳定发展。

To investigate the effects of trampling on the species composition and diversity of understory herbaceous layer vegetation in urban forest ecosystems,as well as on soil physicochemical properties,a study was conducted at the Zijing Mountain Urban Forest Park in Nanjing.Surveys and analyses were performed on herbaceous layer vegetation and soil samples.Variance analysis and correlation analysis were employed to examine five different levels of trampling intensity(no trampling control,light trampling,moderate trampling,heavy trampling,and extreme trampling)in relation to the average height of herbaceous layer vegetation,communityαdiversity index,and various physicochemical indicators of the surface soil.The results showed that:(1)The similarity of herbaceous communities was the lowest between extreme trampling and other trampling intensities,and the similarity index was less than 0.3.(2)The community evenness index and richness index were significantly higher under moderate trampling compared to the no-trampling control(P<0.05),while the no-trampling control was significantly higher than the extreme trampling(P<0.05).(3)Soil density during severe and extreme trampling was significantly higher than in the no-trampling control area(P<0.05).(4)Soil water holding capacity during light trampling was significantly higher than in the extreme trampling area(P<0.05),while changes in total soil porosity were not significant.(5)Vegetation cover showed a significant negative correlation with soil density(P<0.01)and a significant positive correlation with the mass fractions of ammonium nitrogen and nitrate nitrogen in the soil(P<0.05).Moderate trampling positively influenced the diversity and richness of herbaceous layer vegetation,while excessive trampling restricted the growth of herbaceous plants,leading to surface exposure that is detrimental to the stable development of forest ecosystems.