Indian Institute of Remote Sensing
4- Kalidas Road, Dehradun, Uttarakhand
ABSTRACT
The primary goal of this article was to explore the studies showing the status of forest vegetation and land uses for developing eco-restoration strategy in Garhwal Himalayan region. Remote sensing and Geographical Information System (GIS) were taken as tools and techniques for identification, mapping, monitoring and evaluation of all forest vegetation types and land use/ land cover categories. The digital database layers of concerned bio-physical parameters were integrated, analysed and modeled under GIS domain for developing the eco-restoration strategy. The studies revealed a total change of 28.52 and 27 % among different land use land cover types between1960- 98 and 1960-85 respectively.
The changes themselves indicate eco-restoration strategy under different schemes and the ecologically restored areas, which do not need any ecorestoration. The studies not only indicated the sites for eco-restoration but also the success of plantation and protection based on the fact of minimum adverse change viz., 1.52% between 985-98 in comparison to 1960-85. The land areas found suitable for ecorestoration under Agro-forestry, social forestry, silvi-pasture and afforestation schemes were assessed as 9%, 1.6%, 12.5% and 1.45% respectively. More over the studies reflected agricultural land suitability, forest fire burnt areas, mining and landslide areas for various eco-restoration measures.
INTRODUCTION
Degradation of natural resources has been a global problem. Accelerated conversion of forests with rapid industrialization and urbanization, intensive agriculture, over-exploitation, overgrazing, mining and other human activities have resulted in the degradation of both the land and water resources. Eco-restoration (or ecological restoratio n) which means redevelopment (rehabilitation) of degraded ecosystems, is a key component of a broader subject of Sustainable Development. Forest ecosystems have been increasingly subjected to anthropogenic perturbation (Xiongwen, 2006). The disturbed forest ecosystem requires its eco-restoration and managing them in a sustainable way. Eco-restoration is also required for any kind of degraded land or the land, which has not shown its optimal use. It is a known fact that the reduction of forest cover in India is based on the increasing dependence of human population on them with respect to meet their basic needs of fuel wood, fodder, roof thatching and small timber. This is followed by agricultural development, which tends to reduce the forest to scattered woodlots or other patches with sharp edges, while suburban development reduces the forests to strips and corridors along roads and streams (Odum, 1997) Himalayas are geologically young and the environment is fragile.
There are number of factors, which have been damaging the forests and agro-ecosystem and subsequently degrading the total ecological processes. Exploding population in the past decades, lack of suitable land for agriculture and a search about the economic activities have resulted unplanned and unscientific land use practices in this region. The effect of this degradation among ecological processes is not only confined within the Himalayan region but also all over the country due to the flood and siltation by the major rivers originating from the area and the degradation of forests contributing considerable role in balancing the ecosystem. The concern for the rapidly degrading environment is no more academic but has become real as its consequences are being felt everywhere and the policy and decision makers, the industrialists and the corporate community have recognised the need for action for conservation (Singh et.al. 2006). Satellite remote sensing and GIS has emerged as a vital tool in understanding and monitoring the spatial and structural changes in vegetation and other earth surface features (Pant and Kharkwal, 1997; Pant and Singh, 1992).
The present paper is based on the review of some of the important case studies conducted in the Garhwal Himalaya of Uttarakhand by using satellite remote sensing data, GIS, census reports and annual report of department of environment and space. These sample studies revealed the changes in forest cover and other land use categories, site suitability for optimization cum restoration of a particular land use along with the information about the extent, distribution and prediction of natural disasters. The studies are mostly focusing the identification of sites, which need eco-restoration techniques of afforestation, reforestation, agro-forestry, social forestry, silvi-pasture, protection, conservation etc. On the contrary, the studies are also highlighting the existing potential sites, which do not need any eco-restoration. Such sites are like dense forest vegetation without any reduction in density over the past years, highly suitable land for agriculture, stabilized land without any change etc. The studies also focus the suitability of sites for agriculture so that the inferior land could be used towards its optimization under any eco-restoration scheme.
THE STUDY REGION
The Garhwal Himalayan region of Uttarakhand falls between the geocoordinates 290 30' to 310 30'N and 770 30' to 800 15'E. The region occupies a total area 53,484 km2 with a total population of 70, 50,634. The rainfall pattern is governed by the summer monsoon. The year has warm dry period, warm wet period and cool dry period. The climatic condition tends to increase with increasing elevation. The annual rainfall varies about 1,300mm to 2,5000mm and average annual temperature range has been confined between 230Cat 300m and 130C at 2000m. Snowfall occurs above 1,800m.
The extremes of climate, topography, vegetation and other land use pattern are the common phenomena of the region.
Figure 1. Location map of Study areas
FOREST COVER AND LAND USE CHANGE ASSESSMENT
The study was carried out in the Mussoorie sub-division of Dehradun district, Garhwal Himalaya (Pant, 2002). Aerial photographs and IRS 1C LISS – III data for the years 1960 and 1998 respectively were interpreted for preparation of respective maps. The spatial database of these two maps was generated in PC -based ILWIS 3.0 software. The operation 'map cross' was performed to find out the spatial changes in the resultant change map. The study revealed a total change of 28.52 % out of a total area of 64.00 km 2 between1960 and 1998. Oak forest has been subjected to maximum change through reduction in density after heavy biotic influence. The habitation has mostly been expanded in Oak forests.
The Oak forest has also been converted into agriculture to an extent greater than other forest types. Mining activities were mostly carried out amidst degraded and scrub forest. Pant et al. (2000) studied the same area for identifying the changes between 1960 and 1985 using aerial photographs and Landsat TM false colour composite image (spectral bands 2, 3 & 4 ) of the respective years. The study revealed a total change of 27% consisting of changes/conversion from one cover type/land use pattern to another one out of the total area (Figure 2 and Table1). Comparing the above two studies it is significant to note that between the periods of 1985 to 1998, the only adverse or negative change of 1.52% was assessed. The most important aspect of those two studies is based on the fact that there had been a very high degree of differences between yearly changes of 1.08% and 0.12% during 1960-85 and 1985-98 respectively. It reflects many positive changes due to plantation, success of plantation, protection measures (by eco-task force), ban in mining activities etc. during the year 1985-98.
Such positive changes highlight the results of effective eco-restoration measures of degraded sites. On the contrary the sites showing negative changes viz., reduction of forest cover, increasing the areas of degraded and scrub/shrubby vegetation need the strategy for ecorestoration. Considering the status, extent and trend of changes among forest cover and land use in three different periods of 1960, 1985 and 1998 and verifying their actual topographical and other concerned features in the field a plan could have been or can be prepared for eco-developmental strategy. But the actual restoration of those sites is only possible after finding their suitability for different land use/ land utilization types as mentioned below:
EVALUATION OF DEGRADED SITES
The study was carried out in Jaunpur block of district Tehri Garhwal. One of the objectives of this study was evaluating the degraded /unutilised/under utilized lands for ecorestoration.
Forest cover and land use map of the period 2004 was generated through visual interpretation technique of Indian Remote Sensing satellite-1C (IRS-1C) LISS III image. The slope map was generated from the existing topographical map on 1:50,000 scale by employing Wentworth technique of slope analysis. The soil types were taken from the existing soil map. The data pertaining to all those maps were integrated, analysed, manipulated and retrieved by using PC based Arc/View 3.2a GIS software. The resultant map (Figure 4) was generated for developing the following kinds of eco-restoration measures:
- Reforestation/Enrichment plantation/improvement forestry: The open and degraded forests (density 10 to 40%) occurring on 55% slope category were identified for reforestation/enrichment plantation as they need effective management for restocking.
- Agro-forestry: Agricultural lands falling between the slope category 35-55% and soil depth category of shallow to moderately deep (10-50cm.) were selected for this scheme. Ground evidences revealed that these lands are mostly un-irrigated and are having low productivity in comparison to lower slopes and valley lands. The total area under this category of land was estimated as 37% of total agricultural area (138 km2). or 9% of the total
Figure 2. Forest cover and land use change/conversion of Mussorie between 1960-85 geographical area of the study (564km2).The tree species suggested under the scheme were based on their indigenous availability, people's requirement and the specific property related to least influence on the underneath crop. Grewia optiva (Bhimal), Grewia elastica (Dhaman), Bauhinea variegate (Kachnar), and Celtis australis (Kharik) are some of the examples.
- Social Forestry: Social forestry sites were selected nearby and within the village common land, which had been badly degraded and as such lying waste. The soil was moderately deep to very deep (25cm) and slope category estimated as 35%. The tree
Figure 3. Digital map of Mussoorie showing sites for eco-restoration and Ecologically Developed areas having no change.
Table 1. Forest vegetation and land use/land cover change
- species recommended for plantation were like Quercus leocotrichophora, Eucalyptus hybrid, Grevillea robusta etc. The total area had been estimated under this category as 1.6% of total geographical area.
- Silvi-pasture: Silvi-pastural techniques were suggested on the existing degraded natural grassland falling between slope category of 35%-55% and soil depth range of shallow to moderately deep (10-50cm.). These grasslands were either in pure form or associated with tree density 10% and or shrubs 50%. The soils of the area were generally dry, shallow, skeletal with higher percentage of stone and were having pH value 7. The tree species were suggested as the seedlings of Acacia catechu, populus ciliate, celtis australis, Robinia pseudoacacia, Albizzia lebbek, Albizzia procera etc. The total area had been estimated as 12.5% of the total geographical area.
- Afforestation: The study area was having minor agricultural patches in steep sloppy areas having > 55% slope in higher mountain zone. Peas and potato were the main vegetable grown in these areas. The loose soil working of such areas is prone to severe soil erosion and land slides, particularly on the slopes, where the natural vegetation is either scanty or absent. There is no alternative but to adopt eco-restoration processes based on both engineering and vegetative techniques. Based on the land use requirement of land utilization types, the tree species proposed for eco-restoration were Robinnia pseudoacacia, Quercus leucotrichophora, Cedrus deodara, Pinus wallichiana along with temperate grasses. The area under this category was estimated as 1.45% of total geographical area.
- Areas for protection: Barren rock out crops with or without the patchy formation of vegetation in between the rocks/ boulders, very -very steep/ precipitous slopes were included under this category. These areas can not be restored /reclaimed by human beings because of inaccessibility and negligible potential for plantation or any other non vegetative measure. Therefore the only way of eco-restoration of such areas is protection against human influence for allowing natural regeneration and stabilization of areas. The sites identified for eco-restoration strategy need their evaluation for the purpose of its suitability not only for forestry point of view but also for agricultural crops. Therefore the study had also been focused on agricultural land suitability classification of study area based on its technical, social and economic parameters (Table 3).
FOREST FIRE MAPPING
Both remote sensing and GIS based techniques were found very useful for forest fire mapping, monitoring and predictions of occurrence of forest fires. The fire prediction and damaged areas in conjunction with locality factors themselves indicate a preliminary plan and estimate for taking up eco-restoration measures. A study entitled "Digital mapping of forest fire in Garhwal Himalaya using Indian Remo te Sensing satellite" was carried out in Tehri Garhwal district (Pant at. al., 1996).
Figure 4. Digital map of Jaunpur block, district Tehri -Garhwal showing sites for adopting different eco-restoration techniques
Table 2. Area under different eco-restoration techniques
Table 3. Area estimates for eco-restoration under different degree of agricultural land suitability, Jaunpur block, district Tehri Garhwal
LANDSLIDE MAPPING
Remote sensing studies with selective ground data have helped in identifying various mass wasting process, which are operative in the area of study as seen in the variety of forms. These had been broadly categorised as active, old and potential landslide zones (Lakhera, 1991). It had been quoted that the main cause of landslides is instability of slope or slope failure. These slope failures are found to be more frequent in lime stone and slate units of Pipalkoti formation (Garhwal group) and rocks of central crystalline. The type and causes of landslides facilitates the type of eco-restoration strategy.
IMPACT OF MINING ACTIVITIES ON ENVIRONMENT
In order to find out the environmental problems related with mining activities in Mussoorie hill area, multispectral satellite data of 1972, 1985 and 1988 have been studied and prepared the map of respective periods (Garg, at.ai, 1990). The study highlighted that forest area has been decreased by 2.8km during the period 1972 to 1988. Significantly, there is not much change during 1985 to 1988. Density of sal forest in some areas has reduced. Active and abandoned mines occupied an area of 0.6 km2 and 1.4 km2. At places, due to shallowing of the river beds by the debris of mines and landslides, streams and rivers have change their courses or widened. All Such kinds of information provide the strategy for restoration of degraded sites.
CONCLUSION
The advantage of using multi date remote sensing data interpretation and GIS is based on the fact of identification, mapping, monitoring and evaluation of the type of land subjected by different intensity of damage/ degradation; success or failure of eco-restoration schemes and suitability of sites for different kinds of eco-restoration processes. Identification of all such areas in different ecological units facilitate an affective planning for execution of eco-restoration schemes viz., simple protection for self regeneration, type of species to be planted under the processes of afforestation/reforestation, social forestry, agro-forestry, silvi-pasture etc. and or adopting any engineering measures. Mapping of existing potential sites, which do not need any eco-restoration, also play a key role in planning process.
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