Ecosystem reconstruction through 'Taungya' plantations following commercial logging of a dry, mixed deciduous forest in Darjeeling Himalaya

Abstract

In Darjeeling Himalaya, after commercial logging, natural forest is converted into 'taungya' plantations. Under the 'taungya' system, choice species of high timber value are planted following slash-burning on clear-cut forest lands. Agricultural crops are raised in the interplanting space for the first two consecutive years. Regeneration is allowed along with the growth of planted species after abandoning the crop cultivation. This study examines ecosystem recovery 35 yr after the conversion of a dry, mixed deciduous forest into 'taungya' plantation. Only 28 out of 87 species in natural forest regenerated in the ≥10-cm cbh class of individuals. The loss of species was independent of abundance in the community; not only rare, but also common, species of natural forest were lost in 'taungya' plantation. Mature forest specialists suffered the greatest loss, and open-habitat specialists increased. An introduced species, Tectona grandis, dominated in terms of abundance, use of vertical space, and total ground coverage. Shorea robusta was codominant due to its coppicing ability. Prospects for recovery of the lost species are bleak because juvenile populations in the regeneration layer (comprising individuals <10-cm cbh and >30-cm height) are either absent or very small. The study concludes that conversion of natural forest into 'taungya' plantations dramatically alters the landscape, interrupts recovering ecosystem structure and causes considerable loss of species.