SUCCESSIONS OF THE SAT TAL VALLEY. 255
Ulmaceae Verbenaceae
Celtis australis L. Caryopteris WallichiaDa Sohau.
Urticaceae Vit&ceae
Boehmeria raaorophylla Don. Vit is lanata Roxb.
Debregeasia hypoleuca Wedd. ,, lanata glabra.
Gerardinia beterophylla .Dene ,, semicordata Wall.
Laportea crenulata Gaud. ,, lanceolaria Wall.
Summary.
1. In the region between 4,000 and 5,000 ft. in altitude in the part of Kumaon studied there are three forest types, the'monsoon, dominatod by Bauhinia variegata, B. rettisa and B. VaJilii, the Finns longifolia, and the Quercus incana. This altitude is the upper limit of the Bauhinia and the lower of the pine and oak formations.
2. The Bauhinia is a distinctively monsoon type almost leafless at the beginning of the rains. It is adapted to great extremes of humidity.
3. The pine forest has sparse foliage and occupies well drained slopes, crests and ridges. It is adapted to relatively low humidity and high insolation.
4. The oak forest is of the broad-leaved sclerophyllous type of Schimper. It is adapted to places with no very great extremes of temperature or humidity.
5. The pine and the Bauhinia are, at this altitude, pioneer forms which tend to be ultimately succeeded by the oak. At a lower altitude the Bauhinia is the climax type.
6. Xerophytic and hydrophytic successions include numerous pioneer grassy or shrubby stages but the whole tendency is toward the oak.
7. The influence of man is constantly causing a retrogression of the plant population toward the xerophytic, the climax forest being reapproached by a secondary succession.
8. The valley abounds in lianas, epiphytes, strangling forms and parasites.
Grateful acknowledgment is due to Dr. Winfield Dudgeon for loaning a number of the photographs used as well as for giving valu- able hints in this study.
