黄土高原退耕刺槐中龄林密度和空间结构对灌草多样性的影响  

Effects of density and spatial structure of middle-aged Robinia preudoacacia plantations on the diversity of shrub and grass in the Loess Plateau

作　　者：王宇[1] 王冬梅[1] 王彦辉[2] 云慧雅 张梦棋 张莹莹[1] WANG Yu;WANG Dongmei;WANG Yanhui;YUN Huiya;ZHANG Mengqi;ZHANG Yingying(School of Soil and Water Conservation,Beijing Forestry University,Forestry Ecological Engineering Research Center of the Ministry of Education,Beijing 100083,China;Key Laboratory of Forest Ecology and Environment,National Forestry and Grassland Administration,Ecology and Nature Conservation Institute,Chinese Academy of Forestry,Beijing 100091,China)

机构地区：[1]北京林业大学水土保持学院,教育部林业生态工程研究中心,北京100083 [2]中国林业科学研究院森林生态环境与自然保护研究所国家林业和草原局森林生态环境重点实验室,北京100091

出　　处：《生态学报》2025年第2期822-836,共15页Acta Ecologica Sinica

基　　金：“十四五”国家重点研发项目课题(2022YFF0801803,2022YFF0801804);国家自然科学基金项目(U20A2085,U21A2005)。

摘　　要：为了在理解林分密度和空间结构参数对林下灌草多样性的影响基础上科学指导黄土高原退耕还林工程早期栽植的刺槐(Robinia pseudoacacia)中龄林经营,于甘肃省泾川县官山林场选择了生长在残塬顶部退耕梯田相似立地上的林龄18—25 a的4个密度梯度的刺槐中龄人工林,建立了样地共12个,调查角尺度、混交度、密集度、开敞度和大小比数等林分空间结构参数,同时调查计算林下灌木、草本层的Simpson指数、Gini多样性指数、Shannon-Wiener指数、Pielou均匀度指数及Patrick指数等林下植物多样性指标,运用Person相关性分析和灰色关联度分析探究刺槐中龄人工林密度和空间结构参数与林下灌木层和草本层植物多样性的关系,并确定主要影响因子。结果表明:(1)林下植物物种总数随林分密度增加呈先增后减的变化,在密度1300—1700株/hm^(2)时,林下植物物种总数和草本层多样性指数均达到最大。(2)林分密度主要影响刺槐林的透光性、分布格局和混交程度,密度<1300株/hm^(2)时林分透光性最好;密度1300—1700株/hm^(2)时,57%的刺槐林木呈随机分布,此时分布格局最接近天然状态;密度>2100株/hm^(2)时,林分的混交程度最高。(3)Person相关性分析表明,开敞度和灌木层Simpson指数、物种丰富度指数呈极显著正相关(P<0.01),混交度和草本层物种丰富度指数、Gini指数呈显著正相关(P<0.05)。灰色关联度分析表明,当林分密度<1300、1300—1700、>1700株/hm^(2)时,影响林下灌草多样性的主要因子分别是混交度、开敞度、胸径大小比数。(4)对在研究立地条件上退耕栽植的刺槐中龄林,可将1300—1700株/hm^(2)作为考虑林下植物多样性的合理经营密度范围。可以基于研究结果,针对性地优化刺槐人工中龄林的林分密度和空间结构,促进林下灌草层发育,提高林下植物多样性和森林的多功能性。In order to scientifically guide the management of middle-aged black locust(Robinia pseudoacacia)plantations established in the early stage of the Grain for Green Program on the Loess Plateau,based on the understanding of the effects of stand density and spatial structure parameters on the diversity of understory shrubs and herbs,a study was conducted in the Guanshan Forest Farm,Jingchuan County,Gansu Province.12 sample plots of middle-aged(18—25 years)black locust plantations with four density gradients were selected,all growing on similar terraced field on the top of residual plateau.Spatial structure parameters,such as neighborhood pattern,mingling,crowding,openness,and dominance,were investigated,along with the diversity indices of understory shrubs and herbs,including Simpson′s index,Gini diversity index,Shannon-Wiener index,Pielou′s evenness index,and Patrick′s index.Person′s correlation analysis and grey relational analysis were employed to explore the relationship between stand density,spatial structure parameters,and the plant diversity of the undergrowth shrub layer and herb layer in middle-aged black locust plantations,and to identify the main influencing factors.The results revealed the followings:(1)The total number of understory plant species firstly increased and then decreased with rising stand density,with the peaks of the total number of understory plant species and the diversity index of the herbaceous layer within the density range of 1300—1700 trees/hm^(2).(2)Stand density mainly affected the light transmittance,distribution pattern,and mixing degree of black locust plantations.When the density was less than 1300 trees/hm^(2),the light transmittance was optimal.Within the density range of 1300—1700 trees/hm^(2),57%of the black locust trees exhibited a random distribution pattern,closest to a natural state.When the density exceeded 2100 trees/hm^(2),the mixing degree reached its highest level.(3)Person′s correlation analysis showed that a very significant positive correlation(P

关 键 词：黄土高原 林分空间结构 林下植被多样性 林分密度 

分 类 号：S718.5[农业科学—林学]