Forest Ecology and Management

Forest disturbance and pollination of a keystone species in the rainforest of Kalakad-Mundanthurai Tiger Reserve, India.

Investigators: Soubadra Devy and T.Ganesh

Location: KMTR

Duration: 2 years

Plant-animal interactions in tropical forests maintain local diversity of trees. The loss of these pollinators due to human disturbance could affect the pollination success of these trees and consequently their regeneration and survival. If these trees are keystone species then it could affect the entire community. This project will determine the effect of a depauperate mammal pollinator assemblage on the reproductive efficacy of an important keystone tree species, Cullenia exarillata, a dominant member of the evergreen forests of the southern Western Ghats. Visitation rates and mammal activity on the trees and fruit set will be recorded at a disturbed and undisturbed site to evaluate the relative pollination success of the trees. The result of this study could help in restoring lost mammals in degraded ecosystems.

Progress

Results obtained so far indicate that 6 arboreal mammal species, 1 bat species, 16 bird species, 2 species of butterflies, one social bee, and several species of smaller insects visited the flowers of Cullenia exarillata. Wild boar (Sus scrofa) ate flowers fallen in the ground below the trees. Cullenia exarillata is out-crossed and requires pollinators for fruit production. The frequency of visitors to the flowers is more from diurnal flower visitors than by nocturnal visitors. However, nocturnal visitors were responsible for greater fruit set than diurnal visitors. This was consistent across years. The trees received very few visits from the lion- tailed macaque in disturbed sites compared to in the undisturbed sites. Giant squirrels visited the flowers more often in disturbed sites. Lion-tailed macaques were lower in relative abundance in disturbed sites. Nilgiri langurs and giant squirrels were disproportionately higher in the disturbed sites. Mammal abundance in different sites was dependent on Cullenia flowering. Occurrence of lion-tailed macaque is dependent on the flowering of Cullenia exarillata in the forest. Fruit bats play an important role in promoting pollination of Cullenia in disturbed sites. Fruit set in disturbed sites was less compared to undisturbed sites.

Output

Under preparation.


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