Stand structure, phenology and fruit yield of Illicium griffithii in western Arunachal Pradesh, North-East India

Abstract

Illicium griffthii is an important medicinal tree species of the temperate broad-leaved forests of Northeast India. The species has high demands for its fruits. In view of scanty information on the species in natural stands, this investigation explores three forest stands under different management regimes in Western Arunachal Pradesh with particular reference to study stand structure, fruit production and phonological behaviour of I. griffthii. The study revealed that I. griffthii was an important species in the middle storey and it grew frequently with other top canopy species. The tree species richness, stand density and total basal cover of three stands varied between 27 to 40 species, 482 to 568 tree ha-1, and 18.08 to 59.28 m2 ha-1, respectively. The data showed that high biotic pressure resulted decline in tree species richness, stand density and total basal area while moderate level of pressure was beneficial. The contribution of I. griffthii to total stand density and basal cover was high at all three forests. It was interesting to note that these forests supported 72-81% tree species used for fuel, fodder, timber, edible fruits and other useful products, thus provided diverse opportunities to communities to visit these stands. The dominance-diversity curve showed that the resource allocation were homogenous to shared by a few species at different stands. Tree girth class structure showed that all forest stands are still evolving. The phenological progression of I. griffithii showed no marked leaf fall event, the flowering phase prevailed between February to April and mature fruits in October. The fruit yield for I. griffithii varied from 0.015 kg to 23.28 kg per tree for 11 to 180 cm girth class individuals. The study concluded that in view of high demand of fruits of I. griffithii, these forests may face higher pressure in near future, therefore information on stand structure, phenology and fruit productivity would help the management planners. It is suggested that if local communities could be educated about the potential of I. griffithii and promoted in agroforestry systems, the income of local farmers could be increased substantially, at the same time the species could be conserved in natural stands.