The mammalian communities in coffee plantations around a protected area in the Western Ghats, India. A. Balia, A. Kumarb, and J. Krishnaswamy. 2007. Biological Conservation 139: 93-102.
This study looked at the number of mammal species found in 15 coffee plantations around the Bhadra Wildlife Sanctuary in the Western Ghats of India, and any correlation between the number of species and distance from the park or vegetation characteristics.
First, a bit of background. Climate conditions in India — monsoon seasons followed by long dry periods — require coffee to be grown under a protective canopy of shade trees, usually under a three-tier system. Although coffee plantations have replaced much of the mid-elevation moist deciduous and evergreen forests in India, coffee has at least traditionally used native forest tree species for shade, such as Ficus glomerata (Doomar, Gular, or Cluster Fig), Dalbergia latifolia (Rosewood), Sapindus laurifolius (Soapnut), and Artocarpus integrifolia (Jackfruit tree).
More recently, non-native species have been used in Indian coffee plantations. In the lowest layer, nitrogen fixing species such as Erythrina lithosperma (Dadap; native to the Philippines and Java) and Gliricidia maculata/sepium (native to Mexico and Central America) are planted. The middle layer, trees that shed their leaves in the monsoon and maintain a dense canopy during the summer, are often native Ficus species. For the canopy layer of hardwood, many coffee farmers are now planting a fast-growing, sparse shade timber species from Australia, Grevillea robusta, often called silver oak although not related to North American oak species.
Twenty-eight species of mammals were recorded in the plantations; this included a number of large carnivores (e.g., tigers and leopards) and herbivores (e.g., elephants and deer). Not surprisingly, more species were found in plantations nearer to the sanctuary. The authors concluded that coffee estates act as a buffer around the park for large mammals, protecting them from the direct effects of more intensive agriculture and higher-density human settlements.
The study did not find any negative correlation with Grevillea abundance, but the fact that the estates with the highest proportion of Grevillea were the closest to the sanctuary may have diluted the effect. The percentage of Grevillea was about 30%; a high percentage of this species is usually avoided, because they drop their leaves during the monsoon, a situation which can cause rot.
Nonetheless, the authors noted that the non-native timber species provide few or no resources for resident wildlife and cautioned that “Such conversions not only lead to the loss of biodiversity values of these plantations, but also severely affect the integrity of the adjoining protected areas.”