Seedling survival and growth of two Rhododendron species viz., Rhododendron kenderickii and Rhododendron grandewere studied along an altitudinal gradient in a temperate forest. Differences in survivality and relative growth responses of the two selected rhododendrons in terms of height, collar diameter and leaf number were monitored seasonally. High seedling mortality was recorded highest in winter season as well as in the higher altitude. Both the species attain maximum growth in terms of height, collar diameter and mean leaf number during rainy season while, minimum in winter season. Moreover, both the Rhododendron species exhibit variation in growth response with altitude and higher total growth was recorded in lower altitude. The result of the present study showed that the survival and growth of seedlings of both the selected Rhododendron species were greatly influenced by altitude as well as season. This variability may be due to the variation in light, temperature, moisture and edaphic factors in various seasons as well as at different altitudes, which results into development of an array of microclimatic conditions for differential growth behavior of different species.

An attempt had been made to study the impact of altitude on population structure and regeneration status of two Rhododendron species as well as its associated species in a temperate forest of Arunachal Pradesh. Population structure was worked out based on the density of seedlings, saplings and adults while, the regeneration status was determined from the population size of seedlings, saplings and adults. The mid altitude site (Hanuman Camp) has highest density (2692 individuals ha-1) comprising of seedlings, saplings and adults of all species followed by lower altitude (Shagong) site (2379 individuals ha-1) and lowest at (Yarlung) higher altitude site (2180 individuals ha-1). However, the relative proportion of seedlings of all woody species was recorded highest in low altitude site, while it was lowest in higher altitude. Conversely, the relative proportion of saplings and adults were highest in higher altitude. The selected Rhododendron species shows reverse J shaped population structure and fair regeneration status in all study stands having higher number of seedlings compared to saplings. However, the number of saplings is less than the adults. It was observed that the seedling populations dominate the overall population of the selected Rhododendron species. Moreover, it was found that although altitude does not affect regeneration status, but affects the population structure of the selected Rhododendrons. The fluctuation in population density of seedlings, saplings and adults along the altitudinal gradient may be linked with the prevailing environmental factors.