Archive for April 2014
I continue to be interested in themes of change in the southern Western Ghats (and Sri Lanka) and am now working to better measure and detect land cover change using Geographic Information Systems (GIS) and temporal satellite data gathered by the USGS/NASA Landsat satellites. My interest in the area has grown out of a deeply personal engagement with the landscape over the last few decades. It started on childhood walks with my parents, was excited by explorations with friends in school and then developed in more systematic photo-documentation trips as an adult. In recent years teaching and family commitments have kept me from visiting the field as much as I would like. My interest in using GIS as a tool for teaching and learning has brought me back in touch with the Western Ghats, but this time through the lenses and sensors of distant earth observing satellites. In the last year I have been working with the latest Landsat 8 imagery and am thoroughly impressed with the quality of the imagery that is now publically available. This has led me to look back through NASA’S archives to find old imagery to conduct change detection with. This post highlights preliminary comparison of Landsat mages from 1973 and 2014.
The maps included in this post look at the block of the southern Western Ghats just below the Palghat gap where significant features illustrate momentous changes in the landscape over the last forty years. Both sets of images were collected in February, a time of the year when it is dry and there are cloud free days in the southern Western Ghats. The first image, however, was taken 42 years before the 2nd and thus offers a unique opportunity to compare the land cover changes in these hill areas. My particular interest here is the western plateau of the Palani Hills. This is an area that many generations of KIS students know well from the hiking program that took us to places like Vembadi Peak, Berijam Lake, Vandarvu and the Ibex Cliff area. Starting in the 1960s and 70s these areas experienced intensive silviculture based on the earlier designation of montane grasslands being “wastelands.” Few KIS students and faculty members appreciated that they were witness to a radical ecological reworking of the landscape. The net result has been a significant change in the ecology and landscape of the area. Vast areas of the shola/grasslands systems in the Vembadi-Berijam-Vandaravu area have experienced significant changes.
It is a complicated mosaic of vegetation, ecosystems and issues that is now in place on the upper plateau of the Palani Hills. As the 2014 Landsat 8 image illustrates, most of the Vembadi-Berijam-Vandaravu area is covered by non-native tree plantations but there are important sholas that thrive between them. Several invasive species are spreading beyond plantation boundaries and threaten the remnant grasslands. In some areas shola species are regenerating in and amongst non-native plantation species. Some feel that this will eventually give way to mixed forests of shola species and dying plantations. Logging of planation species has been largely curtailed though there is a move afoot in the Forest Department to remove exotic species. Much of the upper plateau area is of limits because of forestry rules that have sought to limit the impact of tourists and agricultural communities in the reserve forest (RS) zone. A Kodaikanal National Park is in the pipeline and its notification and boundary lines are expected in the near future. Nevertheless, human communities are pushing into outer areas as the township of Kodaikanal and its satellite communities expand. Gaur (Bos gaurus) populations are on the rise, felt mostly in urban areas rather than remote areas!
One feature that has remained relatively constant has been the shola/grasslands mosaic that makes up Kerala’s Eravikulam National Park and Tamil Nadu’s Grasshills (part of the Anaimalais Tiger Reserve). Comparing both the 1973 and 2014 maps shows that these areas of montane grasslands, interspersed with sholas, have stayed roughly the same. This perhaps is no accident since Eravikulam and Grasshills have both enjoyed protection in the midst of the flurry of tree planting in the adjoining ranges. The grasslands show up particularly well and contrast with the neighboring shola vegetation. This is most likely the result of winter frost that has dried out much of the exposed grass (and thus is not photosynthesizing).
Eravikulam will feature in a series of upcoming posts tentatively entitled the High Range Diaries but I have included a few images from my visits and explorations of the area in the 1990s.
Be sure to read Farshid Ahrestani’s article “To cut or not to cut” published by Conservation India last month. It looks at the dilemma of what to do with the huge amount of non-native tree plantation biomass in the Palanis and other Western Ghats ranges. We visited Eravikulam together, through the good offices of KN Chengappa and Tata Tea, in 1993 and continue to share a passion for conservation issues in the Palanis and neighboring ranges. One of ours tasks is to collect historical imagery of the hill ranges and use these to cross reference with contemporary imagery to illustrate change at a terrestrial level (as is done in his article).
For information about interpreting false color satellite imagery, see Hollis Riebeek’s excellent article on the Earth Observatory website.
SCHOLARLY (and TECHNICAL) ARTICLES
Amaranth, Giriraj et. al. “Diagnostic analysis of conservation zones using remote sensing and GIS techniques in wet evergreen forests of the Western Ghats – An ecological hotspot, Tamil Nadu, India.” Biodiversity and Conservation. 12. 2331-1359, 2003. Print.
Joshi, Kumar P.K. “Vegetation cover mapping in India using multi-temporal IRS Wide Field Sensor (WiFS) data.” Remote Sensing of Environment. Volume 103 Issue 2. 30 July 2006. Web.2 April 2014.
Menon, Shally and Kamal Bawa. “Applications of Geographic Information Systems, Remote-Sensing, and a Landscape Ecology Approach to Biodiversity Conservation in the Western Ghats. Current Science. 73.2 (1997): 134-145. Web. 30 March 2014.
Nagendra, Harini and Ghate Utkarsh. “ Landscape ecological planning through a multi-scale characterization of patterns: Studies in the Western Ghats, South India. Environmental Monitoring and Assessment. 2003. Web. 30 March 2014.
Nagi, Rajinder. “Using the Landsat image services to study land cover change over time.” ARCGIS Resources. 13 May 2011. Web.
Prakasam, C. “Land use and land cover change detection through remote sensing approach: A case study of Kodaikanal taluk, Tamil Nadu.” International Journal of Geomatics and Geosciences. Vol 1, No 2, 2010. Web. 30 March 2014.