Die horizontale und vertikale Verbreitung der Vegetation im Himalaya

Abstract

The idea of attempting a geographical survey of the vegetation of the Himalayas was conceived when in 1937 Professor C. TROLL was travelling in the north-western and eastern parts of the hills (Nanga Parbat, Sikkim). The character of the vegetation in both these parts of the mountains is - entirely different and demands a transition from W to E (or from E to W). Furthermore it was also clear, both in the NW and in the E, that there is a change in the nature of the vegetation going from S to N as well as a transition in the vertical arrangement of the various belts of vegetation. <br /> TROLL's observations and the general conception of the contrary nature of the plains of India in the S and the Tibetan highlands in the N, the wet tropical rain-forest of Assam in the E and the desert-like regions of Afghanistan in the NW and of the vertical gradation from tropical conditions along the foot-hills to alpine conditions high up in the mountains, represent the basis of this thesis, the object of which has been to check and to fill out this generally known frame-work in a careful regional analysis based on the data contained in the prolific literature and on a number of particulary valuable personal discoveries. <br /> A map has been drawn on a scale of 1 : 1 000 000 showing the regional distribution of the Himalayan vegetation on the basis of the types of vegetation classified during the work on this subject. This map gives a clear idea of the great contrast between the southern slope of the main Himalayan range and the Tibetan highland in the N and it furthermore reveals the gradual transition in the vegetation from W to E (or E to W). Eight c r o s s - s e c t i o n s of important parts of the mountain system help to give a better appreciation of the vertical arrangement of the vegetation. <br /> Regional analysis and d e s c r i p t i o n of the types of vegetation under discussion constitute the main part of this paper which is introduced by general remarks about the material used, the method employed and the bounds of the Himalayan regions under consideration. There is also a brief survey of the history of research in the plant geography of the Himalayas, the beginnings of which can be traced as far back as Alexander the Great's campaign in India. The main part is followed by a concluding chapter which summarises the results of the work undertaken and deals with certain phenomena of particular interest with special reference to the whole Himalayan area, e. g. dry valleys, the influence of aspect, the position of the tree-line and the influence of man on natural vegetation. <br /> This paper on the distribution of vegetation in the Himalayas has, I believe, met the following needs: a compilation of the literature of the plant geography of the area has been made and is, on the whole, complete up to and including 1956; a comprehensive survey of the vegetation of the Himalayas has been carried out; a map (1 : 1 000 000) has been designed and published (1 : 2 000 000). On it the regional distribution of the vegetation is demonstrated. The areas in which our knowledge of the vegetation still has great gaps have been clearly shown up and the way has been paved for advances in the researches concerning these parts.