PRODUCTION, NUTRIENT DYNAMICS AND BREAKDOWN OF LEAF LITTER IN SEX FOREST PLANTATIONS RAISED ON GRAVELLY FLOOD PLAINS IN THE LOWER WESTERN HIMALAYAS

Abstract

Leaf litter production, nutrient returns, retranslocation patterns and breakdown of confined litter were determined in plantations of six tree species that have been raised on gravelly flood plains in the Doon Valley (Uttaranchal, India). Leaf litter production values (t ha^-1) followed the order of bamboo (Dendrocalamus and Bambusa sp.) (4.25) > Eucalyptus (2.97) > Bauhinia purpurea (2.86) > Grewia optiva (2.63) > Melia azedarach (2.61) > Morus alba (2.35). Retranslocation of nutrients varied between evergreens and deciduous species. Maximum N was retranslocated in M. alba (84%) and least in bamboo (16%). The half-life of confined leaf litter ranged between 0.561 and 1.128, with breakdown being fairly rapid in deciduous species. Fractional annual turnover rate varied between elements and species, with N having the highest values (68-92%) and Mg
the least (13-62%). The impact of these plantations on soil physico-chemical properties were not significant in the top surface layers (0-7.5 cm).