不同方法研究太白山不同海拔梯度林下主要草本植物群落的种间关联

种间关联能反映区域尺度群落内和群落之间植物物种的共存格局，是研究植物种间关系的主要手段。以陕西太白山不同海拔梯度主要林下草本植物为研究对象，通过种间联结系数(AC)、Jaccard指数(JI)、Ochai指数(OI)，结合χ²检验和Spearman相关系数检验，对研究区主要林下草本植物物种的种间联结性进行了分析，以揭示太白山较大海拔范围内林下草本植物的分布特征。结果表明:1)穿龙薯蓣(Dioscorea nipponica)、繁缕(Stellaria media)、大戟(Euphorbia pekinensis)等与其他物种的关联比较密切，与之关联的物种较多，说明这些物种是该区域，尤其是中低海拔地区常见的广布种；东北羊角芹(Aegopodium alpestre)、川赤芍(Paeonia veitchii)、鄂西香茶菜(Rabdosia henryi)、碎米荠(Cardamine hirsuta)、短毛独活(Heracleum moellendorffii)和点叶薹草(Carex hancockiana)之间存在紧密的联系，且均出现在中海拔(1 800~2 750 m)地区，是中海拔区域常见的共生种；狭叶红景天(Rhodiola kirilowii)和紫苞风毛菊(Saussurea purpurascens)之间有强烈相关关系，但与其他物种无关，且只出现在高海拔(>3 100 m)区域，也与生境选择和过滤有关。2)基于物种之间不同的关联性，将太白山海拔梯度上的主要草本植物划分成3个生态种组，不同生态种组之间存在适生海拔上的差异，表明海拔作为复合环境因子决定了群落内的植物物种组合。3)通过不同方法研究种间联结关系，可以反映出主要林下草本植物的分布特征，并对该地域的植被管理和恢复提供理论依据。

Interspecific Associations of the Main Understory Herbaceous Communities across Altitudinal Gradients on the Taibai Mountain by Different Approaches

Interspecific association reflects the coexistence pattern of plant species within and among communities on a regional scale,is a main way to study interspecific relationships among plant species.Based on the interspecific association coefficient (AC),Jaccard index (JI),Ochai index (OI),χ²-test and the Spearman index,the interspecific association of the main understory herbaceous plants across altitudinal gradient on the Taibai Mountain were analyzed to reveal the distribution characteristics of main understory herbaceous plants.The results indicated that 1) Dioscorea nipponica,Stellaria media,Euphorbia pekinensis were closely related to other species,meanwhile many species were associated with them,indicating that these species were the widespread species in this region,especially in the middle and low altitude areas; Aegopodium alpestre,Paeonia veitchii,Rabdosia henryi,Cardamine hirsuta,Heracleum moellendorffii and Carex hancockiana were closely related with each other and occurred in the middle-altitude areas (1 800-2 750 m),which was the common symbiotic species in the middle-altitude regions; there was strong correlation between Rhodiola kirilowii and Saussurea purpurascens but not related to other species,which only occurred at very high altitudes (>3 100 m),suggesting that these species would be filtered from harsh habitat.2) Based on the different associations between species,the main understory herbaceous species across different altitudinal gradients of the Taibai Mountain were divided into three ecological species groups.Different species groups may have different ecological strategies based on their suitable elevation,indicating that as a comprehensive environmental factor,altitude determined the combination of plant species in the community.3) The results of interspecific associations that were obtained by different methods could reveal the actual distribution patterns of the understory herbaceous species,and provide a theoretical basis for vegetation management and restoration in this region.