Leaf and bud demography and shoot growth in evergreen and deciduous trees of central Himalaya, India

Leaf and bud demography and shoot growth were studied in 10 evergreen (ES) and 15 deciduous (DS) tree species occurring between 600 and 2200 m elevation in the central Himalayan mountains in India. Results were analyzed to help explain why ES prevail in the vegetation of this region, even though the number of ES is no greater than for DS. Although each species had its own pattern with regard to leaf and bud demography and seasonality of shoot extension and radial growth, it was possible to group the species on the basis of shoot growth phenology. In most species, leaves emerged during March-April, at the onset of warm and dry summer season. The ES recruit leaves in shoots more rapidly than the DS. Across all species, peak number of leaves per shoot (5.8–20.7), peak leaf area per shoot (116.2–1559.2 cm2), peak number of vegetative buds per shoot (1.9–14.5), bud survival per shoot (23–84%), shoot extension growth (6.4–40.8 cm) and shoot extension period (13–30 weeks) varied considerably. The peak leaf area per shoot (587.7 vs. 246.7 cm2) and shoot extension growth (19.3 vs. 11.2 cm) were significantly greater for DS than for ES, and these two functional groups of species were clearly separable with regard to shoot growth characteristics.