Kapoor, V. (2008). Effects of rainforest fragmentation and shade-coffee plantations on spider communities in the Western Ghats, India. Journal of Insect Conservation, 12(1), 53-68.
Ants and butterflies are often the two most studied arthropods on coffee farms, so it was nice to see a paper looking at spiders. The study took place in Tamil Nadu and Kerala states in areas of mid-elevation tropical wet evergreen rainforest that had tea, coffee, and cardamom plantation surrounded by the Indira Gandhi Wildlife Sanctuary. The authors examined the community structure of spiders in two organic shade coffee farms and ten rainforest fragments of various sizes that were also under varying degrees of degradation.
Most of the study discussed the impact (or lack thereof) of fragment size on spider communities. Results regarding the shade coffee farms were limited. First, both of the coffee farms had similar spider density. The species composition in the two farms were more similar to each other than to other fragment types, but one farm did have higher species richness than the other. The author began by noting that the farm with higher richness had more native shade trees, versus the monoculture of non-native Eucalyptus in the other farm. That would be notable, except that the author went on to say that the first farm adjoined two forest fragments, while the other had poor connectivity. This is likely to have a strong effect on spiders with their relatively limited dispersal ability. Another factor mentioned by the author was that the coffee trees in the first (richer) farm were “much taller” than in the other farm. However, the sampling took place in the herbaceous and shrub layer up to 1.6 m, which is not very tall for a coffee tree, so it is unclear to me how this variable may have influenced the results.
One spider species was noted as being commonly found in undisturbed sites but absent from the coffee farms, while three types of spiders were more common in disturbed sites and the coffee farms. Unfortunately, “disturbance” was not specifically defined. Finally, the author admitted there is virtually no information on the natural history of spiders in the Western Ghats, and said this lack of data hindered using them as indicators of habitat disturbance.
Spiders do have many life-history features that should make them good habitat barometers. Despite some shortcomings, this study was a first step in examining spider communities in forested agrosystems. The results also at least suggested that shade coffee farms in this region are utilized more like “disturbed” than pristine sites by spiders, and that these spider communities may show responses similar to those documented for other organisms to forest connectivity and shade management of coffee farms.
Photo of Nephila pilipes, one of the spiders found in this study, by amateur_photo_bore; thanks for publishing under a Creative Commons license.
V. Kapoor. (2007). Effects of rainforest fragmentation and shade-coffee plantations on spider communities in the Western Ghats, India Journal of Insect Conservation, 12 (1), 53-68 DOI: 10.1007/s10841-006-9062-5