162 FORMATIONS AND GUILDS [Part I 



2. THE CLIMATIC FORMATIONS. 

 i. CLASSIFICATION. 



Climatic formations may be traced back to three chief types — woodland, 

 grassland, and desert. 



Woodland is constituted essentially of woody plants, and is termed 

 forest if trees grow in a closed condition ; bushwood, when shrubs are so 

 abundant as to keep the crowns of the trees from touching one another ; 

 sJiritbivood, where shrubs constitute the chief feature. Herbaceous plants 

 are always present on woodlands, but as accessory components only ; 

 they are completely dominated in their oecology by woody plants. 



Grassland consists essentially of perennial grasses growing in tufts. 

 Other herbaceous plants, even if they should be just as numerous as 

 the grasses, are merely companions of the grasses, for the existence of 

 the formation depends in the first place on its grassy covering. Grass- 

 land, when hygrophilous or tropophilous, is termed meadow ; when xero- 

 philous, steppe ; and xerophilous grassland containing isolated trees is 

 savannah. 



Woodland and grassland stand opposed to one another like two equally 

 powerful but hostile nations, which in the course of time have repeatedly 

 fought against one another for the dominion over the soil. The climates 

 that now prevail have limited the domains of each of the opponents, 

 but merely slight changes of climate would suffice to revive the contest. 

 In districts which, in a sense to be explained further on, possess neither 

 a decided woodland climate nor a decided grassland climate, the action 

 of mankind suffices to start the struggle. Thus at the present time, 

 owing to the clearance of forests in Eastern Java and a few other localities 

 in the Malayan Archipelago, districts formerly occupied by woodland 

 are being invaded by grass. Although I have personally witnessed this 

 contest, yet I will give an account of it in the words of Junghuhn, the 

 veteran authority on Malayan vegetation, for it is hardly possible to 

 equal his clearness. 



When the soil remains uncultivated after clearing the forest, 'as 

 a rule the social and dense-growing alang-grass (Imperata Koenigii, 

 Beauv.) first replaces the vanished forests, then areas extending for miles, 

 even indeed for whole days' journeys, are transformed into a uniform 

 wilderness of dense grass three to five feet high, while on mountain- 

 slopes the same grass extends far beyond its original zone, and spreading 

 over everything it ranges up to altitudes of 6,000-7.000 feet, being almost 

 insensible to differences of temperature. 



' Its silken-haired seeds, light as the tenderest down, are wafted away 



