Posts Tagged ‘map’
Preliminary Analysis of Land Cover in the Sinharaja Adiviya using Planet Dove Imagery
Figure 1: Sinharaja Adiviya (or greater Sinharaja area) mapped with Planet Dove imagery. Reduced in size to fit this post.
In March this year I attended a fascinating talk entitled “Sinharaja: From a Timber Reserve to a Biological Treasure Trove. What next?” by Nimal and Savitri Gunatillike at the BMICH in Colombo. The lecture was sponsored by the WNPS in their monthly lecture series. There were several aspects of the talk reflecting back on their decades of research in Sri Lanka’s preeminent forest. Initially, Savitri did botanical studies documenting the diversity of plants in Sinharaja in the period before mechanical logging started (1960s-77). They were witness to period of commercial logging and recovery to a world renowned UNESCO-designated world heritage site. The Gunatilleke’s experiments with rainforest restoration were of particular interest to me, given the lessons that these examples hold for similar non-native plantation areas across the Western Ghats/Sri Lankan biodiversity hotspot. In the lecture, both spoke of the broader Sinharaja area of forest fragments and large patches that are connected or satellites to the core area-something they identified as the Sinharaja Adiviya.
At the same time, I was interested in mapping land cover and forest types in study areas that I take students to for field work. Up to this stage, our DP Geography studies in Sinharaja have utilized Survey Department 1:50,000 and 1:10,000 land use data. It comes as a shape file with the data that I have purchased from their map sales office. This data is satisfactory but we have found significant omissions and inaccuracies in the Kudawa area where OSC students conduct field work (much of the data is based on surveys conducted in the early 1980s).
Forest types and land cover are a key part of the Sinharaja story. Literature about the area’s successful conservation refer to primary and secondary forest as well as Pinus caribaea plantations (along the border). Yet, I couldn’t locate GIS-ready shapefiles of boundaries of these forest types! The Forest Department has files based on its 2010 forest cover map but these are, thus far, not in the public sphere. I had mapped the area using a Landsat tile from 2005 (published in my blog in 2012) but this was before I had learnt how to conduct a supervised classification of a raster image.
Home garden landscape on the border with Sinharaja rainforest (north west side). (September 2019)
Pinus caribaea plantation in the Sinharaja buffer zone undergoing ecological succession as part of an ecological restoration effort. This area was once dominated by a monoculture community. The intervention of conservationists in thinning pine trees and planting appropriate native species is helping to return it to the climax lowland rainforest community. See linked articles by Professors Mark Ashton, Nimal Gunatillike and others for details of these efforts. (September 2019)
Primary/ridge forest below Moulawella Peak in the Sinharaja core zone. This area did not experience any logging in the period of commercial exploitation in the 1960s-70s. (September 2019)
A Brief Literature Review
A review of land cover analysis in Sinharaja shows that only a few studies have been published to date. The most significant, publicly available study looking at land cover change in Sinharaja was conducted by Buddhika Madurapperuma and Janak Kuruppuarchchi in 2014 (see link). Their analysis used Landsat ETM data between 1993 and 2005 in an area slightly larger than the Sinharaja boundary provided by the Forest Department. They used a Normalized Difference Vegetation Index (NDVI) and Burn Index (BI) to assess changes in three years (2001, 1993 and 2005). The study is thorough but the data that they use is coarse and it is difficult to get a sense of the land cover patterns at a large scale. They conclude with an acknowledgment that ground surveys need to be conducted to better understand the change. Thanura Madusanka Silva published a study entitled “Land Cover Changes of a Tropical Forest Buffer Zone” in 2018 that used Sri Lanka Survey Department data to assess changes in land use in the Kudawa area (see link). This study is based on secondary data and not satellite imagery and it concludes that major change has occurred in home garden areas. There may be other studies that I have missed but the field of land cover change in Sinharaja, as seen in satellite imagery, is ripe for further study.
Figure 2: Supervised classification of land cover based on Planet Dove imagery. Because the images were not collected on the same flight, there are some unavoidable gaps and seams, that are visible on close inspection.
Planet Dove Methodology and Results
Two years ago I became familiar with Planet Dove imagery and saw that it might provide a solution in my attempts to classify land cover in the Sinharaja area. Planet Dove’s constellation of 120+ satellites, which revisit the same areas every day, offers a new opportunity to visualize and analyze any area of the earth. At the beginning of 2019 I successfully applied to Planet’s Education and Research program and was able to download a host of tiles of study areas. I found a series of cloud-free scenes from December 2018 and downloaded them. These are from around December 18 but some were collected at slightly different dates. Using ArcGIS, I mosaiced these various tiles so that I had most of the area Sinharaja Adiviya covered. Because the images were not collected on the same flight there is some unavoidable gaps and visible seams, that are visible on close inspection. The improved spatial resolution of 3-5m means that it is easier to distinguish between different land cover types (lowland rainforest, vs, Pinus caribaea plantation, for example). Initially I worked on a map using the non-visible near infrared (NIR 780-860 nm) layer to highlight vegetation (see figure 1).
In the second part of my efforts I conducted a supervised classification using tools in ArcGIS’s Spatial Analyst extension toolbar. For land cover type, I collected between 5 and 10 training samples and merged each of them into their own distinct land cover type. The classified image (Figure 2) clearly highlights the dense lowland rainforest pockets in a landscape dominated by home garden and tea agriculture. The effort to categorize the Pinus caribaea plantation was partially successful. However, there are errors with some of the classification. For example, plantation in the midst of dense (primary) forest near Moulawella peak.
Conclusion/Future
In the next attempt I plan to collect more training samples in the hopes of getting a more accurate picture of the land cover patterns. A focused study on the pine forest in the buffer area near Kudawa deserves attention. Some of these areas are being successfully restored to their original lowland rainforest vegetation type and time a change study would be illuminating. There are areas of the landscape that I am very familiar with (the Kudawa tourist and village zone) while I have far less personal experience in other areas like western Sinharaja and the various forest fragments. Further studies of landcover need to be verified with ground truthing in the field.
Figure 3: The Kudawa area of Sinharaja with classification of land cover based on Planet Dove imagery. In this image I have highlighted the popular tourist area around the settlement of Kudawa. The lower part of the map experienced mechanical logging 40+ years ago (some of it is encircled in red). The stream running down to the Sinharaja ticket gate is not depicted on this map and is missing from Survey Department 1:10,000 sheets that were used for the hydro/stream layer.
SELECTED REFERENCES (Land Cover Focus)
Ashton, Mark et al. “Restoration pathways for rain forest in southwest Sri Lanka: A review of concepts and models.” Forest Ecology and Management 154(3):409-430. December 2001. Web.
Ashton, Mark et al. “Restoration of rain forest beneath pine plantations: A relay floristic model with special application to tropical South Asia.” Forest Ecology and Management 329:351–359. October 2014. Web.
Gunatilleke, Nimal, C.V.S. Gunatilleke and M.A.A. Dilhan. “Plant Biogeography and Conservation of the South Western Hill Forests of Sri Lanka.” The Raffles Bulletin of Zoology, 2005. No. 12 9-22. Web.
Gunatilleke, C.V.S, et al. Ecology of Sinharaja Rain Forest and the Forest Dynamics Plot in Sri Lanka’s Natural World Heritage Site. Colombo: WHT Publications, 2004. Print.
Lockwood, Ian. “Into the Wet: Field Notes From Sri Lanka’s Wet Zone.” Sanctuary Asia. August/September 2007. 3-11. Print. PDF.
Madurapperuma Buddhika and Kuruppuarachchi Janaka.“Detecting Land-cover Change using Mappable Vegetation Related Indices: A Case Study from the Sinharaja Man and the Biosphere Reserve.” Journal of Tropical Forestry and Environment Vol.4, No 01 (2014) 50-58. May 2014. Web.
Madusanka, Thanura. “Land Cover Changes of Tropical Forest Buffer zone A case study of Kudawa Village, Sinharaja forest buffer zone; Sri Lanka.” International Journal of Scientific and Research Publications. October 2018. Web.
Ministry of Mahaweli Development and Environment. Proceedings of the Stakeholder Workshop on Landscape Planning & Management. 29 September 2017. Web. See page 10 for Sinharaja map.
Planet Team. Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. 2017. Web.
Sri Lanka Survey Department. District Land Use Maps. 1983. Print/Web.
UN-REDD Programme. Sri Lanka’s Forest Reference Level submission to the UNFCCC. January 2017. Web.
Wijesooriya W. A. D. A. and, C. V. S. Gunatilleke. “Buffer Zone of the Sinharaja Biosphere Reserve in Sri Lanka and Its Management Strategies.” Journal of the National Science Foundation of Sri Lanka. 31(1–2), 57. June 2003. Web.
Landscape & Ecology in the Nilgiri Hills: A Spatial Exploration
View form Mettupalayam train station looking north to the slopes of the Nilgiri Hills. The famous Nilgiri Mountain railway steam engine is warming up for the morning ride up to Conoor. Thirty minutes later it took Lenny, Merrick and me up the hill. (Composite digital image taken in July 2009).
The Nilgiri Hills are an important range in the Western Ghats range. The broader Nilgiris area, located at the tri-junction of Tamil Nadu, Kerala and Karnataka, contains a variety of contrasting ecosystems and have the largest elevated plateau area in the Western Ghats. The Nilgiri Hills have been designated a “biosphere reserve” and include key protected areas including Silent Valley, Mukkurthy, Mudumalai and Bandipur National Parks (see the Keystone Foundations’ page for details). The Nagarhole, Wayanad and Satyamangalam forests adjoin the Nilgiris and thus it represses a vast protected area. Several important groups of people have lived in the hilly area prior to colonization by the British in the early 19th Century. The town of Ooty (Udhagamandalam) became the summer capital of the Madras Presidency and was the largest, most cosmopolitan hill station in southern imperial India. Many of the early scientific investigations of Western Ghats flora and fauna were conducted in the Nilgiris and adjoining areas. In fact, according to Paul Hocking, the leading authority on the area, the Nilgiris are said to be one of the most studied areas in Asia (see his interview in One Earth Foundation).
I’ve had a chance to visit the Nilgiris on several occasions since my first trip in the early 1990s. Initially I went on behalf the PHCC to make contact with individuals and groups working on conservation issues. On the first visit I had the opportunity to interact with Richard Radcliffe, a key figure in the post independence conservation movement in the Nilgiris. Later I returned on my own to work on recording landscapes as part of my ongoing Western Ghats documentation project. Most of the landscapes in this post are from those visits. On a recent trip to Silent Valley and Ooty (see previous blog post) I was immersed in the area’s ecology and landscapes and decided to work with some of the spatial data that I have gathered from various web portals.
My interest in the cartography of the Nilgiri Hills was sparked by an exquisite early 20th Century wall map in the Nilgiri Library. Roughly two meters wide it depicted relief, land use, hydrology, settlements, transport and other key elements. It was most likely a Survey of India product reflecting the high-end cartography that they made available to the public in an age before digital mapping and map restrictions related to security. There are few maps (and almost none that are publically available of the Western Ghats ranges) that come close to the science and art in those early SOI maps. I looked for it on this trip but the wall map has apparently been put away and is not publicly displayed anymore.
Two of the attached maps below utilize the 30 m SRTM Digital Elevation Model released by NASA/USGS in 2014 (Bhuvan also has DEMs available but they have voids and gaps that make it difficult to get a seamless base layer)(see announcement). The attached maps also highlight land cover data from the Western Ghats Biodiversity portal courtesy of my friend Prabhakar and his colleague J.P. Pascal (French Institute Pondicherry). The two NASA Landsat images look at the same area in 1973 and 2014. This provides a visual overview of changes similar to what I did in my “Land Cover Changes in the Palani Hills: A Preliminary Visual Assessment” blog post from April 2014. The issue of land cover changes, as evidenced in satellite imagery and terrestrial photos, continues to be an issue that I am interested in investigating using GIS and photo documentation.
Nilgiri Hills relief & elevation map (click twice on image for larger 150 DPI A3 version).
Cairn Hills Shola in the Nilgiri Hills (left side of image) with adjoining eucalyptus plantations and former grasslands converted to agricultural plots. (Digital image, June 2006)
Emerald Reservoir, one of several large hydroelectric projects in the upper Nilgiri Hills. Tea is grown in the foreground, whereas further back there are large non-native timber (eucalyptus) plantations. The monsoon mist hides the protected grasslands and sholas of Mukkurthy National park. (Digital image, June 2006).
Toda home near Avalanche in the south-western Nilgiri Hills. Note the large shola in the background. The grasslands here have been converted into vegetable plots. (Digital image, June 2006).
Looking south, south-west from the Western Catchment area in Mukkurthy National Park towards Bangittapal. This part of the Nilgiris -known as the Kundhas- has some of the most dramatic scenery in the entire Western Ghats. As is evident in the picture, Mukkurthy supports significant areas of montane grasslands interspersed with shola pockets and lone Rhododendron trees. After hydroelectric dams were built here in the 1960s the Western Catchment area became a popular site for Hindi and Tamil film makers. It is now off limits to movie makers and the general public and is protected for its biodiversity (notably Nilgiri tahr as well as large predators such as tigers). It took me significant time and effort to obtain the permissions to visit and make these few photographs (taken during a very short ½ day visit in January 1995).(120 film image scanned)
Devil’s Gap at Western Catchment. Here granite cliffs drop precipitously into the Nilambur Valley in Kerala. A chasm is hidden along the line of shola vegetation parallel to the cliff. With the montane grasslands, Rhododendron trees and cliffs in the background, Devil’s Gap makes for a most unusual Western Ghats landscape. I find similarities between this site and Devil’s Kitchen in the Palani Hills. At Devil’s Kitchen the encroaching plantations have obliterated the feel of the grasslands surrounding wind-sculpted sholas growing around the deep, hidden gorges. Taken on T-max 100 film using a Fujica 6×9 120 fixed lens camera. (January 1995).
Looking north to Devil’s Gap from the escarpment at Western Catchment in Mukkurthy National Park. Note the undulating hills supporting montane grasslands free of non-native timber plantations. As seen in the maps below, there are few areas left in the Nilgiri Hills where this once dominant vegetation still exists. Significant work is now being conducted by the Tamil Nadu Forest Department and NGOs to protect and restore montane grasslands in the Nilgiris. (Taken on Kodak T-max 100 film using a Fujica 120 6×9 fixed lens camera in January 1995).
Looking south from Masinagudi to the Nilgiri Plateau. (Digital image, June 2006)
Nilgiri Hills Vegetation & Land Cover Map (click twice on image for larger 150 DPI A3 version)
1973 Landsat image of Nilgiri Hills (click twice on image for larger 150 DPI A3 image)
2014 Landsat Nilgiri Hills map (click twice on image for larger 150 DPI A3 image)
REFERENCES
Chhabra, Tarun. The Toda Landscape: Explorations in Cultural Ecology. New Delhi: Oriental Black Swan/Harvard, 2015. Print.
Hockings, Paul. Encyclopedia of the Nilgiri Hills: Parts 1 & 2. New Delhi: Manohar, 2012. Print.
Lakshumanan, C. et al. “Landuse/Land cover dynamics study in Nilgiris district part of Western Ghats, Tamil Nadu.” International Journal of Geomatics and Geosciences. Volume 2, No. 3 2012. Web.
Lockwood, Ian. “Into the Blue Mountains on Steam Power.” Ian Lockwood Blog. 7 September 2009. Web.
Lockwood, Ian. “Land Cover Changes in the Palani Hills: A Preliminary Visual Assessment.” Ian Lockwood Blog. 4 April 2014. Web.
Lockwood, Ian. “Landscape and ecology in India’s Western Ghats: A Personal Odyssey.” Asian Geographic. July 2008. Print & Web.
Nalina, P. et al. “Land Use Land Cover Dynamics of Nilgiris District, India Inferred From Satellite Imageries.” American Journal of Applied Sciences. 11 (3) 455-461, 2014. Web.
Satish, K.V. et al. “Geospatial assessment and monitoring of historical forest cover changes (1920–2012) in Nilgiri Biosphere Reserve, Western Ghats, India.” Environmental Monitoring Assessment. 12 August 2014. Web.
Walker, Anthony R. The Toda of South India: A New Look. Delhi: Hindustan Publishing Corporation, 1986. Print.
Varma, Kalyan. “Revisiting Nilgiris’ Peaks and Passes.” Kalyan Varma Website. 7 August 2009. Web.
Hypsometric Tinting of the Southern Western Ghats Landscapes
Over the last year I have continued to work with various methods of presenting elevation for the study areas that I am interested in, both for school (here in Sri Lanka) and for personal work (in India’s Western Ghats). The two maps here are the result of experiments with hypsometric tints. This method uses contours lines derived from SRTM Digital Elevation Models (DEMs) and assigned colors bands to present variation in the topography of the land. As my ongoing photographic documentation and writing of the Western Ghats illustrates, I have a multi nodal interest in the landscapes, ecosystems and cultures of the region. These experiments with maps are part of my ongoing efforts to better understand, document and share information on this stunning yet threatened South Asian landscape.
Southern Western Ghats without administration layers
Southern Western Ghats with administration (from ArcGIS Online)
For further information on cartography using GIS see the excellent site Cartotalk. The Cartography and Geographic Information Society promotes a wide range of geographic skills with plenty of GIS links. ESRI promotes the art and science of map making using its propriety and online software through its mapping center. There are also several books out that are helpful , although with the rapid change in technological development some of these books quickly go out of date. One book that I got several years ago is Gretchen N. Peterson’s GIS Cartography (CRC Press, 2009) and as mentioned on a previous post Map Use. 6th Edition (John Kemerling et al. 2010, ESRI Press) is a must have resource for understanding maps.
