A phytoclimatic approach to the problem of mediterraneity in the Indo-Pakistan sub-continent

Abstract

In the N. W. part of the sub-continent winter-spring rains coupled with low temperature and dry, hot summer create mediterranean conditions. Variants may be recognised in relation to aridity, temperature of the coldest month and intensity of summer dryness based on the contribution of average summer rainfall and rainy days to the annual total, percentage frequency of estival rainfall and rainy days, percentage number of years showing mediterranean regime. The degrees of mediterraneity (pure, moderate, attenuated) recognised according to the above criteria are supported by phytogeographic evidence. Dry evergreen sclerophyllous forests, with one ore more of the typical mediterranean species like Olea cuspidata, Pistacia khinjuk, P. mutica, Quercus baloot, Punica granatum, Cedrus deodara occur under moderate degree of mediterraneity. Some of these and few others of mediterranean stock persist under attenuated degree though the forest physiognomy is not well developed. The floristic elements viz. mediterranean, tropical, arid zone and general, show close correlations with the degrees of mediterraneity, aridity and temperature regimes.