Abstract
A sub-tropical foot-hill forest of Uttaranchal (Garhwal) Himalaya flourishing at the slopes along with left bank of river Ganga in District Pauri-Garhwal (opposite Rishikesh) is enriched by 45 species of angiospermic trees. The trees of Bombax ceiba, Erythrina glabrescens, Haldina cordifolia, Holoptelea integrifolia, Mitragyna parvifolia, Shorea robusta and Toona ciliata constitute the upper canopy layer of the forest. Though the general morphology and crown architecture of all the individuals of each species were essentially alike, nevertheless, there were variations in leaf longevity, leaf growth rate, number of leaves and empty nodes per unit length, rate of leaf fall and leaf flux rate in the individuals of the same species growing at different locations/elevations. Among the 13 tree species dominating the area, mean leaf longevity ranged between 105 to 237 days and the leaf duration between 185 to 365 days. During a year, maximum leaf-fall noticed in Mitragyna parvifolia (60.40%) and the minimum (5.17%) in Bombax ceiba. The trees of Bombax ceiba, Casearia elliptica, Cassia fistula, Haldina cordifolia, Holoptelea integrifolia, Mallotus philippensis, Mitragyna parvifolia, Naringi crenulata and Shorea robusta exhibited intermittent leaf shedding. The number of leaves per unit length of 1.5 m varied from 26 (Sapium insigne) to 304 (Holoptelea integrifolia). Leaf senescence was higher in Holoptelea integrifolia (69.69%) as against Sapium insigne (6.80%) which recorded the minimum value. Turnover Rate of Haldina cordifolia, Holoptelea integrifolia, Mitragyna parvifolia and Naringi crenulata were around three, that of Bombax ceiba, Casearia elliptica, Mallotus philippensis, Shorea robusta and Syzygium cumini were around two, and the same of Cassia fistula, Erythrina glabrescens, Sapium insigne and Toona ciliata was around one.
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