(1) The biomass, productivity and litterfall patterns during a 20-year fallow, subsequent to shifting agriculture were studied in north-eastern India. 2)The early colonizers varied depending upon the type of vegetation before farming and the seed and rhizome sources in the soil, and these depended largely on the agricultural practices. Initially, weeds predominated, but a bamboo (Dendrocalamus hamiltonii) was an important component of 10-20 year old fallow; later this was replaced by shade-intolerant trees. 3)The succession was accompanied by increased species diversity, reduced dominance, and increased above-ground net primary productivity which reached 1.8kg m-2year-1 in a 20 year old fallow. 4)The above-ground biomass increased linearly with age up to 15kg m-2 in a 20 year old fallow. The rate of accumulation of biomass increased for 15 years, when it was 0.9 kg m-2 year-1; it then declined slightly. 5)Litterfall increased with the age of the fallow up to 1.0 kg m-2 year -1 in a 20 year old fallow. © Blackwell Science Ltd. Abstract reproduced by permission.