Dynamics of native tree structure and diversity in coffee agroforest: a case study from Central Western Ghats

Agroforestry systems are the most promising land use practice for achieving both conservation goals and supporting rural livelihoods at landscape level. Coffee agroforests in Western Ghats region of India are sustainably managed under the shade of native trees. Kodagu district located in the Central Western Ghats is the largest shade coffee-growing regions in the country hosting rich biodiversity. In the recent years, the landscape is undergoing transformation in terms density and diversity of shade trees to increase coffee production. With the base line data from Coffee Agro-Forestry Network project during 2008, the present study was carried out during 2017 in four villages under Cauvery watershed, namely Arekad, Hachinad, Yeduru and Byrambada. The important objective of this study was to analyze the changes in tree diversity and structure and the effect of land tenure systems on tree density. We adopted similar sampling procedures for tree enumeration as that of first census conducted during 2008. Results revealed that the Grevillea robusta remained as the dominant tree species with an increased importance value index from 36.05 to 2008 to 53.29 in 2017. Tree density decreased significantly from 2008 (420 +/- 349 number of stems ha(-l)) to 2017 (274 +/- 82 number of stems ha(-l)). Basal area has increased from 2008 (27.62 +/- 11.27 m2ha(-l)) to 2017 (30.31 +/- 11.03 m2ha(-l)). Among the tenure systems, tree density was higher in unredeemed coffee farms compared to redeemed coffee farms. In this study, the sampling was limited to the Cauvery watershed. Therefore, we recommend further studies to address the dynamics of tree diversity and structure covering larger part of the coffee-growing region.