- Kodagu district in Karnataka, which was battered by the recent rains, is the starting point of Kaveri river and home to most of India’s coffee production.
- The native coffee-growing ecosystem has comparable tree diversity as the rainforest in which it is grown. It is also good for the climate, since it has similar carbon storage.
- There is a decline in both biodiversity and carbon storage as the coffee ecosystem moves from Coffea arabica to C. robusta, and as exotic silver oak trees replace the native shade trees.
- Coffee farmers need policy support to conserve native trees. Silver oaks are financially more profitable because they can be cut and sold in the market.
New research findings caution against the ongoing introduction of exotic silver oak tree species into coffee farm systems in the Indian Western Ghats. Scientists say this could become a threat to both climate change mitigation and tree diversity conservation. The study has relevance in the context of the destruction that the recent heavy rains caused in Kodagu, a district in the state of Karnataka on the Western Ghats.
The multi-country research team that includes scientists from Brazil, France and India studied two widely-grown coffee varieties – Coffea arabica and C. robusta – under contrasted management systems with native and exotic shade trees of silver oak (Grevillera robusta). They measured carbon storage and shade tree diversity in native forests and the two coffee agro-forestry systems at 67 plots along a slope that receives 3500 mm of rain in the Kaveri watershed in southern India.
The scientists conclude that native coffee agroforestry systems and forests have comparable carbon stocks and tree diversity as the original forests. But introducing exotic shade trees such as silver oak reduces these carbon stocks and tree diversity.
Silver oak negatively affects carbon storage and tree diversity
The scientists also found that switching from Coffea arabica to C. robusta agroforestry systems affects carbon storage. The current trend towards introduction of G. robusta in coffee farms of the study area negatively affects carbon storage and tree diversity, especially in robusta coffee systems. The findings from the study are reported in Agriculture, Ecosystems and Environment.
The research is part of a larger “Connecting, enhancing and sustaining environmental services and market values of coffee agroforestry in Central America, East Africa and India (CAFNET)” study across seven countries, including India, from 2007 to 2011, which aimed to improve the livelihoods of coffee farmers and conserve natural resources in three major coffee regions located in the world hotspots for biodiversity.
The latest findings add to previous concerns raised over the wisdom of introducing silver oak in coffee plantations, brought out by the CAFNET study. The India arm of the project was conducted in 38 villages in Kodagu district in southern India, the largest coffee-producing region, which contributes to 35 percent of the production under shade-grown systems. The southern Indian river Kaveri too originates in the Kodagu region, with the coffee plantations covering a large area of this watershed.
With India opening to the international coffee market and intensifying its coffee production, coffee farmers are opening the tree shade to produce more coffee. This has resulted in reduction in density and diversity of shade trees and associated biodiversity, the CAFNET study noted.
For example, the CAFNET project found that the exotic silver oaks dominate the estimated 250 types of trees in the coffee plantations; and it is the native species that are important for birds and small mammals, water dynamics and coffee quality in coffee holdings.
Harvest and sale not possible for native trees
Cheppudira G. Kushalappa, dean at the Forestry College , Ponnampet, and one of the authors of the CAFNET study, told Mongabay-India that some farmers’ preference for the fast-growing silver oak is mainly due to free harvest and sale which is not possible for other native trees. The CAFNET study also found that in cases where farmers were interested in planting native trees, non-availability of saplings of native species was a major constraint.
“Given that there are native trees in India that grow fast too and offer other benefits such as ecosystem services, there is a need to dissuade farmers from growing silver oak and provide them to grow native trees, such as giving them tree rights and payment of ecosystem services for water, biodiversity and carbon,” Kushalappa said. “Even providing specific labels such as elephant- and bird-friendly coffee can also be explored.”
Under certification schemes, farmers can also ensure that if silver oaks exceed 30 percent of the trees in an estate, then it may not qualify for certification, said Kushalappa. This is in line with one of the recommendations from the CAFNET study, that silver oaks should be limited to a threshold of 30 percent within coffee blocks; and that this threshold could be taken up as a biodiversity indicator by certifying agencies.
“Currently, most of the coffee sale is happening at the farm gate where there is no incentive for the quality of coffee,” said Kushalappa. Hence there is a need to educate farmers to form farmer producer companies and get their product tested for quality, and provide incentives based on the quality of the bean which is better when grown under the shade of naturally-occurring trees of Kodagu.”
More value added services with native ecosystem
The fact that native trees support the overall sustainability of agroforestry systems was also confirmed in another study published in the International Journal of Biodiversity Science, Ecosystem Services & Management. Agroforestry systems with native trees provide a range of ecosystems services that are both “simultaneously exploited” and “least recognized”, it says.
The joint study by researchers from the Forestry College at Ponnampet in Kodagu; Institute of Wood Science and Technology, Bengaluru; and Ashoka Trust for Research in Ecology and the Environment, Bengaluru; compared the potential of native trees and introduced trees in optimising different ecosystem services, in two traditional agroforestry systems. The two systems were coffee-based shaded perennial systems in Kodagu district of the tropical humid zone; and dryland agro-ecosystems with Ficus trees in Mandya district of the semi-arid zone.
Field data and farmers’ perceptions showed that “compared with exotic species, native trees provide more direct and indirect benefits, irrespective of differences in type, location, scope, and management of these systems.”
“Native tree cover helps in getting sustainable coffee yields compared to coffee grown under shade of exotic trees like silver oak, as evidenced by our research data,” said B.N. Sathish, assistant professor and head of the department of forest products and utilisation at the College of Forestry, Ponnampet.
Better quality coffee
The quality of coffee is also influenced by the tree cover, native and exotic and within native trees, it varies with different tree species, he added.
Shade coffee has shown great promise in providing crucial habitats for biodiversity outside formal protected areas, reports another recent study in PLoS One, based on research on insectivorous , an understudied species in coffee plantations, despite their pest control services.
A joint team from Bangalore-based National Centre for Biological Sciences (NCBS), Wildlife Conservation Society of India and Duke University, studied the influence of local and landscape-level features of coffee farms on air-borne insectivorous bats – their richness and activities in response to changes in tree density – in Chikmagalur district in the Western Ghats, one of India’s biodiversity hotspot.
The researchers conclude that that the coffee farms in their study area “offer an important commuting space for insectivorous bats across a gradient of shade management”
“For India in particular, coffee farms are a significant landscape feature in the Western Ghats but we know very little about how the structure of these plantations affects insectivorous bats,” explained Shashank Ongole, who is with WCS-India and NCBS. “We show that across a range of shade tree densities, the farms are crucial in helping bats navigate agricultural areas outside natural forests” Ongole said.
He pointed out that “apart from the mere presence of native or exotic shade trees, the overall three-dimensional structure of the farm (for example tree density, canopy cover, presence of large or fruiting trees) matters for taxa such as bats and birds.”
“A larger presence of native trees will also make the farm functionally similar to the nearby forest, i.e. it can retain the various ecosystem functions such as nutrient cycling, maintenance of soil quality that native trees perform in their natural habitat,” Ongole added.
The larger surroundings in which these farms are embedded matter because animals and plants move large distances. For example, large expanses of farms with only exotic shade trees/fewer shade trees could be detrimental to biodiversity to a greater extent than isolated exotic shade farms mixed up with a lot of thick native vegetation or natural forest areas in the surroundings.
Policy support needed to balance biodiversity and farmers’ income
“Since exotic shade trees are primarily planted to supplement farmer income through timber, a key priority is to balance the such farmer needs with the maintenance of sufficient native shade trees and forest areas in the landscape,” Ongole noted. “We cannot be immune to the economic considerations of the farmers, who plant a fast-growing species like silver oak to gain additional income from timber when coffee production is low or the market is down.”
Shashank pointed out there is research which shows that some native species could potentially grow as fast as silver oak. “But there are also policies in India that make it extremely difficult for farmers to harvest, transport and sell native trees. Therefore, it is very important to find a middle ground where the needs of farmers are balanced with those of biodiversity.”
- Guillemot J., Maire G.L., Munishamappa M., Charbonnier F., and Vaast P. (2018). Native coffee agroforestry in the Western Ghats of India maintains higher carbon storage and tree diversity compared to exotic agroforestry. Agriculture, Ecosystems and Environment, Vol. 265, 461-469. https://doi.org/10.1016/j.agee.2018.06.002
- Kushalappa C.G., Vaast P., Raghuramulu Y., Garcia C.A., and Sinclair F.L. (2014). CAFNET – First effort in India to value ecosystem services from coffee based agroforestry systems. In : Abstracts of the 3rd World Congress of Agroforestry ‘Trees for life: accelerating the impact of agroforestry’. Nairobi. ISBN 92-9059-372-5.
- Dhanya B., Sathish B.N., Viswanath S. and Purushothaman(2014).Ecosystem services of native trees: Experiences from two traditional agroforestry systems in Karnataka, Southern India. International Journal of Biodiversity Science, Ecosystem Services & Management, 10:2, 101-111. https://doi.org/10.1080/21513732.2014.918057.
- Ongole S, Sankaran M, Karanth KK. (2018). Responses of aerial insectivorous bats to local and landscape-level features of coffee agroforestry systems in Western Ghats, India. PLoS ONE 13(8): e0201648. https://doi.org/10.1371/journal.pone.0201648.