Effect of Plantation on Plant Diversity and Soil Status of Tropical Forest Ecosystems in Meghalaya, Northeast India

Abstract

The present study was conducted in three planted and primary forest stands in Nongkhyllem Wildlife sanctuary and its adjoining reserve forests to investigate the impact of plantation on soil properties, plant diversity, vegetation structure and regeneration status. Soil status measured in terms of soil organic carbon, total Kjeldahl nitrogen, available phosphorus and potassium were significantly low in the plantation as compared to primary forests. A total of 5184 individuals belonging to 127 woody species (> 5 cm dbh) and 53 families were identified in the study area. The species richness was high (51-94) in the primary forests as compared to plantation (31 - 67). The basal area was high in Sal plantation (94 m² ha^-1) than the other forest stands (38 - 84 m² ha^-1). In terms of density, Dipterocarpaceae, Verbenaceae, Lauraceae and Theaceae were the dominant families. Species richness and density decreased with increasing diameter classes in all the stands. The overall age structure based on the density of seedling, sapling and adult individuals showed a growing and healthy population in all the stands. However, the density of seedling and sapling was low in plantation as compared to primary forest. Results revealed that the plantation of monoculture tree species decreases species richness, alters vegetation composition and regeneration status and leads to low soil fertility.