of the smaller gallica. Further on, as the stratum of moisture is more remote from the surface, Prosopis spicigera and Salvadora persica enter into the composition of the forest. Capparis aphylla soon after appears; gradually the forest gets more open, the Salvadora and Capparis more bush-like, and, when even the long roots of these desert trees cannot reach down to the water-level, the last representatives of forest vegetation disappear on the borders of the desert. The swamp forests in Burma are situated on the banks of the rivers, which at a considerable distance from the sea form numerous branches, and especially during the rains are entirely free of brackishness, and they are also found on the shores of backwaters and lakes. The soil in these forests is more or less muddy throughout the greater part of the year; during the rains they are inundated, frequently to a considerable depth. The vegetation forms, as in the evergreen forests, three to four distinct strata; the upper canopy consists of trees, such as Anogeissus acuminata, Mangifera longipes, Xanthophyllum glaucum, which, however, is only 70 to 80 feet high. The second stratum is formed by smaller trees and contains several species of Eugenia, Elæocarpus (with a fruit which is pickled like an olive) and Symplocos. Cassia Fistula and numerous other species of interest to the botanist represent the third stratum. Amongst the shrubs are found Grewia sinuata, a species of Combretum and of Gardenia and many others. The herbage is very scanty and of no special importance; but climbers are plentiful, and in places render the forest almost impenetrable. The most common species are Jasminum scandens, Gmelina villosa, Acacia pennata, etc. F. THE TIDAL FOREST ZONE The tidal forest zone, as its designation implies, comprises the forests situated on the alluvial lands on the sea coast and its neighbourhood and those growing on the deltas of the larger rivers and up their banks as far as the tide flows. The species existing in these forests are dependent for their growth on the salt water reaching them. Along the sea face are the mangrove forests, consisting principally of Rhizophorea, such as Rhizophora mucronata and conjugata; Ceriops Roxburghiana, Kandelia Rheedii, Bruguiera parviflora, Sonneratia apetala, acida and Griffithii, Ægiceras majus and Carapa moluccensis. Further inland, where the land is inundated only during the spring tides, the mangrove forests pass into tidal forests, in which the above-named species become more subordinate; while Sonneratia apetala and Avicennia officinalis prevail, associated with Hibiscus tiliaceus, Thespesia populnea, Heritiera littoralis and minor; Pongamia glabra, Excæcaria Agallocha, Phoenix paludosa and several other less conspicuous trees. Heritiera minor (the sundri tree of the Sundarbans) is the most common and most valuable tree in these forests. Shrubs, such as the following, are much developed: Acanthus ilicifolius, Clerodendron inerme, Pluchea indica, Glochidion multiloculare and Ægialitis rotundifolia mixed with climbers, such as Derris scandens, uliginosa and sinuata, Acanthus and others. Nipa fruticans and Pandanus fœtidus locally form dense thickets. G. ZONE WITHOUT FORESTS This zone is not characteristic of one particular region of India, but, from quite different causes, occurs in various parts of the country. It comprises the mountains above the line of vegetation or tree level, rocky areas devoid of soil and thus incapable of carrying tree growth, areas subject to prolonged inundation and for that reason treeless, and the truly desert regions which comprise plains, plateaux and hills. The areas which are treeless on account of their elevation are situated in the Himalaya, but those which are barren on account of their declivity are distributed over all the mountain ranges of the empire. The tracts on which no forest grows on account of prolonged inundation are chiefly found in Assam, Bengal and Burma; they are covered with tall grasses, wild plantains and other herbaceous growth, here and there overshadowed by a tall Cotton (Bombax) tree. The desert areas of the Empire are chiefly confined to the drainage area of the Indus, south of the twenty-ninth degree; but even in these deserts the courses of perennial rivers are, as already stated, fringed with tree vegetation, and though the hills in these zones are barren, small trees and bushes are found in valleys and ravines and in the vicinity of springs. It has been already mentioned that the boundaries of these zones of the forest growth of India are nowhere sharp and distinct. There is a gradual transition of one zone into the other; but not infrequently one zone is prolonged, with undisturbed characteristics, far into a neighbouring one of quite dissimilar character; or, again, a disconnected area of a particular zone, definitely belonging to that zone, may be found quite outside the general limits of its own zone and surrounded by forest pertaining to a different one. The shading off of one zone into another is, of course, influenced by aspect and also by elevation. But the influence of aspect is not always constant, owing to the large area of the Continent and the great differences in climate. For instance, the scorching produced by the hot-weather sun and dry blistering winds is inimical to tree growth. as also is a cold northern exposure. And to these must be added in varying degrees the physical qualities, the chemical composition of the soil and sub-soil and the distance below the surface of the permanent moisture. Although, therefore, it is possible to broadly group the forests into the zones and regions above delineated and to hold that these zones, for the purposes of the Forester, are sufficiently definite, it is not contemplated that such a treatment of the matter would fulfil strictly botanical requirements. |