Department of Botany, University of Kashmir, Jammu and Kashmir, India.
Environ Res. 2011 Oct;111(7):967-77. doi: 10.1016/j.envres.2011.05.006. Epub 2011 Jul 23.
Many studies have shown that alien species richness pattern follows that of native species richness patterns along environmental gradients, without taking the specific composition of the two groups into account.
To compare species richness patterns of native and alien woody plants along an altitudinal gradient in Kashmir Himalaya, India, and to analyse the specific composition, e.g. proportion of life forms.
Analysis of secondary data from published floristic inventories. The gradient (500-4800m asl) was split into 100m bands and presence/absence data for each species were obtained, for each band.
Species richness of both native and alien species followed a hump-shaped distribution. Alien species richness dropped faster above 2000masl than the native did. The ratio of trees to shrubs decreased monotonically along the gradient in native species, but showed a peak at c. 2500masl in alien species. Alien species flowered in average earlier than native species.
The change of species richness of native and alien species along altitude is similar, but the proportion of life forms is not. Most likely both climatic and socio-economic factors affect alien species richness and its specific composition in the Kashmir Himalaya.
许多研究表明，在环境梯度上，外来物种的丰富度模式与本地物种的丰富度模式一致，而没有考虑到这两组物种的具体组成。
在印度克什米尔喜马拉雅山的一个海拔梯度上，比较本地和外来木本植物的物种丰富度模式，并分析其具体组成，例如生活型的比例。
分析已发表的植物区系名录中的二手数据。梯度（500-4800m 海拔）分为 100m 带，对于每个带，获取每个物种的存在/不存在数据。
本地和外来物种的物种丰富度都呈现出驼峰形分布。在海拔 2000m 以上，外来物种的丰富度下降速度比本地物种快。在本地物种中，乔木与灌木的比例沿梯度单调下降，但在 2500m 左右的外来物种中出现峰值。外来物种的开花时间平均比本地物种早。
本地和外来物种的物种丰富度沿海拔的变化相似，但生活型的比例不同。很可能气候和社会经济因素都影响了克什米尔喜马拉雅山的外来物种丰富度及其特定组成。
