中文摘要：

外来物种入侵严重威胁着乡土植物多样性并削弱了生态系统服务功能。本文基于滇西北怒江河谷植被调查的样方数据,从群落水平研究了乡土和入侵植物多样性的空间分布格局,以及地形、气候、人类干扰等因子对两种格局的影响。本研究共记录到外来入侵植物26种,隶属于13科21属;乡土植物1,145种,分属于158科628属。沿着怒江河谷,入侵植物物种丰富度随纬度与海拔的增加而减少;乡土物种丰富度则随纬度增加而增加,并在海拔梯度上呈单峰格局。运用广义线性模型分析公路边缘效应（反映生境干扰）、气候、地形和土壤等环境因素对物种丰富度分布格局的影响。等级方差分离的结果显示,公路两侧的生境干扰对入侵种和乡土种的丰富度格局均具有首要影响。在自然环境因子中,降水量是入侵植物丰富度的主要限制因子,而乡土物种丰富度则主要受到地形因子尤其是坡向的影响。结构方程模型的分析结果也表明,乡土植物和入侵植物丰富度之间的负相关关系反映了二者对环境响应的差异。本文结果支持物种入侵的资源可利用性限制假说,并强调了人类活动对生物多样性的负面影响;乡土植物或已较好地适应了干旱河谷气候,但并没有显示出对外来物种入侵的抵抗作用。

英文摘要：

Biological invasion has attracted widespread attention because invasive species threaten native biodiversity and weaken ecosystem services. Based on field investigation of vegetation in Nujiang River valley, Northwest Yunnan, we analyzed the spatial patterns of native and invasive species richness, and the effects of topography, climate, and roadside habitat disturbance on the invasive versus native plant species richness. We recorded 26 exotic invasive plant species that belong to 13 families and 21 genera, and 1,145 native plant species, belonging to 158 families and 628 genera. Along the Nujiang River valley, species richness of invasive plants decreased with increasing latitude and altitude, while species richness of native plants increased with increasing latitude, and showed a hump-shaped pattern with elevation. A generalized linear model was used to estimate the roles of roadside disturbance, climate, topography and soil nutrients on the distribution of both native and invasive species richness. Results of hierarchical variation partitioning revealed that roadside habitat disturbance had primary impact on the distribution of two groups of species. Precipitation was the climatic determinant of invasive species diversity, and small-scale topographic factors, especially aspect, mainly affected native species diversity. It is likely that native species became drought-resistant in the evolutionary process while invasive species failed to adapt themselves to the local arid environments due to the short colonization time. This research supports the hypothesis that resource availability is the main factor limiting plant invasion, and highlights the negative effects of human activity on biodiversity. In addition, results of structural equation modelling revealed that native communities aren＇t resistant to plant invasion. The negative relationship between invasive and native species richness reflects the different responses of the two group species to environmental factors.