CHINA - VEGETATION It is very difficult to reconstruct the primitive vegetation for the face of nature has been greatly changed by long and intensive cultivation, and woods particularly have been destroyed. From the evidence of what remains, the natural vegetation of by far the greater part of China must have been woodland of peculiar richness and variety. The climate favours profusion of growth and the complex topography, especially of the south China high lands, where temperate and sub-tropical forms "dovetail" into each other, induces great variety of species. China has some 9,000 flowering plants, about half endemic, mainly in the valleys of the south-west. The Chinese flora, in fact, represents the overlap of the Indo-Malayan, the Palaearctic of the north European and Siberian plains and the Himalayan. The flora so compounded escaped any extensive impoverishment during the Ice age. In both North America and China plant-forms could migrate south wards more freely before the ice-sheets than in Europe, where they were crushed between the Scandinavian and Alpine ice and destroyed. The genera Magnolia, Liriodendron, Menispermum and Nyssa survive in both China and North America, though represented by different species, but they have been exterminated altogether in Europe.
The marked climatic rhythm of north China, which induces luxuriance of growth in summer but eliminates all but the hardier plants in winter, produces the supreme expression of the cool temperate, broad-leaved deciduous forest. The dominant trees, however, are not oaks and beeches, but more southern forms as the paulownia, catalpa and broussonetia, the paper-tree. But in north China the woodland covering must always have been scantier and less continuous than in any other region: in the loess lands only the better-watered ranges can have been forested and the north China plain probably consisted as much of heath and marsh as of forest. In the Yangtze valley the milder and rainier winter imposes no such check on plant-life and broad-leaved ever greens replace deciduous trees. But deciduous and coniferous woods, though of a southern type, persist on the higher ranges and sub-tropical trees like camphor-wood, the tea-tree and the bamboo creep up the river valleys. The bamboo, which serves an enormous number of purposes, is, unlike any other, a culti vated tree, grown in groves throughout China south of the Tsin ling. The variety of plant-life, typical of China as a whole, reaches its highest development in the Yangtze valley and the south. Certain tropical forms, e.g., the tall palm and banana, are typical only of the lowlands of Kwangtung and Hainan, while others, e.g., the banyan tree, do not penetrate beyond the northern waterparting of the Si-kiang. The tropical forest of the valleys gives way on the lofty plateau of south-west China to grasses and shrubs, including many rhododendrons and trees and herbs of common European genera.
Even in the south China highlands de-forestation, though not so complete as in north China, has restricted the forests to the less accessible mountain slopes, long the refuge of pre-Chinese tribes; the more extensive are along the eastern edges of the Kweichow plateau and the axial ranges of the Fukien-Kiangsi border. They are made up of both deciduous (oak and chestnut) and coniferous trees (cunninghamia fir and sub-tropical pines). These woods supply timber to south China and the Yangtze valley, while north China is dependent on the forests of the east Manchurian highlands. Throughout China there is urgent need for re-afforestation.