Altitudinal distribution patterns of the native and alien woody flora in Kashmir Himalaya, India

BackgroundMany 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.ObjectivesTo 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.MethodsAnalysis of secondary data from published floristic inventories. The gradient (500–4800 m asl) was split into 100 m bands and presence/absence data for each species were obtained, for each band.ResultsSpecies richness of both native and alien species followed a hump-shaped distribution. Alien species richness dropped faster above 2000 m asl than the native did. The ratio of trees to shrubs decreased monotonically along the gradient in native species, but showed a peak at c. 2500 m asl in alien species. Alien species flowered in average earlier than native species.ConclusionsThe 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.