VEGETATIONAL AND EDAPHIC CHANGES DURING SECONDARY SUCCESSION IN SUBTROPICAL PINE AND BROADLEAVED FORESTS OF NORTHEAST INDIA

Community composition and soil properties were studied in regenerating pine and broadleaved forest ecosystems in north-east India. Pinus kes iya was the only tree species in the pine forest. In the broadleaved f orest, number and diversity of tree species increased with the age of the stand. Grasses and early stages of succession. In the pine forest, seedling density (22 000-694 000 ha(-1)) showed an increasing trend w ith stand age, while in the broadleaved forest, it was maximum in the 7-year old regrowth (66 000 ha(-1)), then it declined with the progres sion of vegetation recovery. The rate of secondary succession was fast er until 13 years in the broadleaved forest, while, the pine forest re generated at a constant rate at least up to 16 years. Soil pH decrease d with the increase of organic matter content in soil during the progr ession of vegetation recovery in both pine and broadleaved forests. So il organic matter, N and P concentrations were lower in the pine fores t, as compared to those in the broadleaved forest. Thus, it may be hyp othesised that the recovery of soil fertility in the disturbed forest communities is closely associated with the vegetation development and its type vis-a-vis detrital input and accumulation.