Phenological events along the elevation gradient and effect of climate change on Rhododendron arboreum Sm. in Kumaun Himalaya

摘要

Phenological events of rhododendron (Rhododendron arboreum Sm.) were monitored along elevation gradients in distinct ecological settings. The observations were carried out between 1500 and 2500 m elevation in Central Himalaya. The phenological events, i.e. bud formation, bud bursting, leafing, flowering, fruit formation and seed formation were recorded. Phenological duration and synchrony of all these phenophases were determined within site and along the elevation gradient in each study site. Our observations showed high synchrony throughout the elevation gradient, especially for peak flowering. Temperature, rainfall, age of the observed trees and site characteristics were related to initial and peak flowering dates. The circumference varied from 35.0 +/- 2.73 to 140.0 +/- 2.88 cm; similarly, height varied from 5.0 +/- 1.02 to 16.5 +/- 1.41 m. All the phenological events began early at low elevation and were delayed at higher elevation. R. arboreum had a sharp flowering peak from January to March. Wet season flowering was rare, and seed formation occurred in summer. The climatic conditions affected the phenological characters of R. arboreum.