Factors Affecting Recruitment of a Critically-Endangered Dipterocarp Species, Vateria indica in the Western Ghats, India

Abstract

Vateria indica is a critically-endangered and economically-important tree endemic to the Western Ghats, a biodiversity hotspot in India. Due to extreme local endemism and anthropogenic destructive harvesting of resin, the species is categorized as critically endangered. The present study investigated the biotic limiting factors of recruitment of V. inidica in its natural populations, and studied the pattern of anthropogenic harvest of nuts of V. indica in the recent past. Seed predation and seedling herbivory particularly by insects were assessed. The sustainability of the nut harvest was assessed by conducting pre- and post-harvest censuses of nuts on forest floors. Over 90 % of the fruits of V. indica were infested by the insects, but, only about 10 % of the infested fruits were seed-predated. Seedling herbivores included a leaf miner, ants of two species, and larvae of a lymantrid moth. Seedling mortality due to herbivores was moderate (45.5 %). Pre- and post-harvest censuses showed that only 3.81 % of the fruits that were naturally-fallen on the forest floor were spared after the harvest had taken place. Sringeri has exported 820 metric tons of nuts in the study year, which was an all-time high estimate. The study concludes that the anthropogenic nut collection can hamper the population structure of V. indica locally. Since V. indica has an alternate-year major flowering cycle, the seed loss as seen in the present study is critical. Raising plantations of V. indica as an afforestation program can contribute to the conservation of the species and the development of local communities.