Significance of phenologically asynchronous populations of the central Himalayan oaks in drought adaptation

摘要

In this paper we describe asynchrony in leaf production of the two major central Himalayan oaks (Quercus floribunda and Q. leucotrichophora) with major focus on their adaptational significance to an unusually severe drought of 1999. In each oak, early and late leafing populations were differentiable and individuals of such types could occur adjacently. However, by and large, they tend to occupy different microsites, early leafing concentrating on moist microsites and late leafing on drier ones. Analysis of association between the two populations within each oak indicated that there was no significant association in distribution. The study provides some direct evidence of adaptational significance of having asynchronous populations. The capacity of the late leafing population of Q. floribunda to employ high osmotic adjustment during the drought, and protecting buds even when leaves were dry and dead enabled them to survive the severe drought of 1999. [References: 19]