THE IMPERATA GRASSLANDS OF TROPICAL ASIA - AREA, DISTRIBUTION, AND TYPOLOGY

The rehabilitation or intensified use of Imperata grasslands will requ ire a much better understanding of their area, distribution, and chara cteristics. We generated estimates of the area of Imperata grasslands in tropical Asia, and suggested a typology of Imperata grasslands that may be useful to define the pathways toward appropriate land use inte nsification. We conclude that the area of Imperata grasslands in Asia is about 35 million ha. This is about 4% of the total land area. The c ountries with the largest area of Imperata grasslands are Indonesia (8 .5 million ha) and India (8.0 million ha). Those with the largest prop ortion of their surface area covered with Imperata are Sri Lanka (23%) , the Philippines (17%), and Vietnam (9%). Laos, Thailand, Myanmar, an d Bangladesh evidently all have similar proportions of their land area infested with Imperata (about 3 to 4%). Malaysia(< 1%), Cambodia(1%), and the southern part of China (2%) have but a minor proportion of th eir total land area in Imperata. The species was found widely distribu ted on the full range of soil orders. It occupied both fertile (e.g. s ome of the Inceptisols and Andisols) and infertile soils (Ultisols and Oxisols) across a wide range of climates and elevations. Imperata lan ds fall into four mapping scale-related categories: Mega-grasslands, m acro-grasslands, meso-grasslands, and micro-grasslands. The mega-grass lands are often referred to as 'sheet Imperata'. They are the large co ntiguous areas of Imperata that would appear on small-scale maps of sa y 1:1,000,000. We propose that this basic typology be supplemented wit h a number of additional components that have a key influence on inten sification pathways: land quality, market access, and the source of po wer for tillage. The typology was applied in a case study of Indonesia n villages in the vicinity of Imperata grasslands. We propose an inter national initiative to map and derive a more complete and uniform pict ure of the area of the Imperata grasslands, This should include select ed studies to understand conditions at the local level, These are crit ical to build the appreciation of change agents for the indigenous sys tems of resource exploitation, and how they relate to local needs, val ues, and constraints.