Across South and Southeast Asia, farmlands are a dominant form of land use. Over the past twenty years, there has been rising demand for tropical crops such as rubber (Hevea brasiliensis) and coffee (Coffea spp.), which have increasingly supplanted native forests. In India's highly biodiverse Western Ghats, one poorly studied land use transition is conversion from shade-grown Coffea arabica to Coffea canephora (robusta). Previous research on climate impacts and farmer preferences indicate that robusta planted area will continue to expand in the Ghats. We explored the responses of habitat specialist birds alongside the financial returns and growing practices associated with each crop in Karnataka, India. Our findings had direct implications for farmer livelihoods and certification measures that are currently undergoing rapid expansion in tropical Asia.
Rubber production is a major form of smallholder agriculture in tropical Asia. In many regions, rubber is planted in intensive monocultures, precipitating ecosystem function decline. We performed an inter-country comparison between rubber farms in India and China that evaluated institutional differences in policies affecting smallholder farmers. We linked differences in growing practices as well as landscape-level features with biodiversity impacts.
Results/Conclusions
For coffee production in the Ghats, we found that arabica agroforests were more speciose and more profitable. However, robusta farms supported surprisingly high population abundance, driven by dense overstories and limited pesticide use. Additionally, distance to protected area did not exhibit a clear effect on habitat specialist avian species, highlighting the value of coffee agroforests in supplementing highly fragmented native forests. Our results--particularly our finding on the conservation value of robusta farms in the Ghats--emphasizes that certification efforts should prioritize maintaining native canopy shade trees and forest cover, which has been neglected in regionally popular certification schemes.
On the other hand, rubber production lands in tropical China did not support speciose or functionally diverse avian assemblages. To retain sensitive avian species, conserving natural forest patches at landscape scales was far more critical than farm-level measures. Similarly, Karanth et al. (2016) found that rubber supported the lowest densities of avian populations in a comparison against other agroforestry crops, and observed that distance to protected area was a crucial determinant of avian richness. Policy measures to support smallholder farmers differ markedly between the two countries, with implications for production practices and perceptions of human-wildlife conflict.