Not seeing the grass for the trees: Timber plantations and agriculture shrink tropical montane grassland by two-thirds over four decades in the Palani Hills, a Western Ghats Sky Island

• Published in: PloS one Vol. 13; no. 1; p. e0190003
• Main Authors: Arasumani, M, Khan, Danish, Das, Arundhati, Lockwood, Ian, Stewart, Robert, Kiran, Ravi A, Muthukumar, M, Bunyan, Milind, Robin, V V
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 10.01.2018; Public Library of Science (PLoS)
• Subjects: Acacia mearnsii; Agricultural industry; Agricultural management; Agriculture; Agriculture - trends; Analysis; Area Under Curve; Biodiversity; Biology and Life Sciences; Climate change; Conservation; Conservation of Natural Resources; Descaling; Earth Sciences; Ecology; Ecology and Environmental Sciences; Ecosystem; Ecosystem services; Endangered & extinct species; Environmental changes; Environmental restoration; Forestry - trends; Forests; Generalized linear models; Grassland; Grassland management; Grasslands; Habitats; Harbor facilities; Hills; Host plants; Human Activities; Introduced species; Invasive species; Lakes; Land cover; Land use; Models, Theoretical; Plantations; Protection and preservation; Remote sensing; Restoration; ROC Curve; Satellite Imagery; Science education; Sri Lanka; Timber; Trees; Urban heat islands; India; Western Ghats
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0190003

Tropical montane habitats, grasslands, in particular, merit urgent conservation attention owing to the disproportionate levels of endemic biodiversity they harbour, the ecosystem services they provide, and the fact that they are among the most threatened habitats globally. The Shola Sky Islands in the Western Ghats host a matrix of native forest-grassland matrix that has been planted over the last century, with exotic timber plantations. The popular discourse on the landscape change is that mainly forests have been lost to the timber plantations and recent court directives are to restore Shola forest trees. In this study, we examine spatiotemporal patterns of landscape change over the last 40 years in the Palani Hills, a significant part of the montane habitat in the Western Ghats. Using satellite imagery and field surveys, we find that 66% of native grasslands and 31% of native forests have been lost over the last 40 years. Grasslands have gone from being the dominant, most contiguous land cover to one of the rarest and most fragmented. They have been replaced by timber plantations and, to a lesser extent, expanding agriculture. We find that the spatial pattern of grassland loss to plantations differs from the loss to agriculture, likely driven by the invasion of plantation species into grasslands. We identify remnant grasslands that should be prioritised for conservation and make specific recommendations for conservation and restoration of grasslands in light of current management policy in the Palani Hills, which favours large-scale removal of plantations and emphasises the restoration of native forests.