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

BACKGROUND

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.

OBJECTIVES

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.