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Remote Sensing Techniques for Land Use Mapping of Arjuna Basin, Tamil Nadu
Forest
Forest, which comprises of thick and dense canopy of tall trees, which predominantly remain green throughout the year. These lands are discerned by their red to dark red tone and varying in sizes. They show irregular shape and smooth texture. These forest areas are found on west, northwest and northern tracts. It is found on the hill slope of Thaniparai, Perumalswami Uchi, Rajamparai, Valangai Mottai, Thaniparai Medu, Muriamppanjam Mottai, Karikkadan Kombu and Kamba Ittu Malai. Based on the tonal and textural variations, the forests of the study area were divided into three categories as dense, open and degraded.
In the study area, the various forest classes, their distribution and their characteristics are described in the following sections.
- Dense forest
Dense forests are those areas, which have crown cover of 40 per cent and over. These forests have a characteristic dark red tone, smooth texture and are irregular in shape. In the study area, such dense forest areas are found in the west and northwestern areas. It includes, Kamba Ittu Malai, Thungan Kadavu, Kukka Muttu Malai, Perumal Swami Uchchi and Ser Malai. These forests are found confined to the higher and medium altitudinal areas. Approximately such dense forests cover and area of about 62.67 sq. km. (3.71%)
- Open forest
In this forest category, the crown cover varies from 10 to 40 percent and the concentration of trees is less. This forest category can be identified from its dark red to medium red tone, irregular shape and medium texture. In the study area, such open forests are found in western and northwestern areas and are associated with the areas nearer the dense forests. Such forests are found in medium and low altitude areas. Approximately these forests cover an area of about 65.6 sq. km. (3.88%)
- Degraded forest
The forests of this category have limited crown cover (about 10 per cent) and occupy an area of (2.31%) nearly covering by 38.95 sq.km. The relative concentration of scrubs, bushes and smaller trees are predominant. Taller trees are limited. In remotely sensed data, such forests were identified by yellow tone and their proximity to the other mentioned forest areas. These forests are found in lower altitudes of the hill areas and found associated with other forests.
Waste lands
Land, which in its present state does not or only possess limited ability to support vegetation, is called wasteland. Eroded soil, ravine, rock, sand dunes and active depositional features are included in this category. These may result form inherent / imposed constraints such as location, environment, chemical and physical properties of the soil. In the study area, there are three categories of wastelands, which could be easily identifiable from the satellite image.
- Land with scrub
These include the uplands or high grounds with scrub. These lands are subjected to degradation or erosion and consist mainly of thorny bushes. Such areas were identified from their yellowish tone and their association with uplands, and their irregular shapes. These areas are found near Srivilliputhur, Sivakasi and their surroundings. The total area under this category is about 265.64 sq. km. (15.75%).
- Land without scrub
These lands area also found associated with higher topography and are formed by degradation or erosion. It could be identified in the satellite data from its light yellow tone, and its association with the higher altitudes. The absence of vegetation distinguishes this category form the earlier described one. In the northern part of Sivakasi and near Sattur such areas are found to occur. This category occupies 71.08 sq. km. (4.21%).
- Barren rocky
These are rocky exposures of varying lithology often barren and devoid of soil cover and vegetation. They occur amidst hill forests as openings or scattered as isolated exposures or loose fragments of boulders or as sheet rocks on uplands and plains. In the study area, these lands are appeared as brownish colour and they are irregular in shape. These barren rocky and stony wastes are found in surroundings of the hilly regions. The barren rocky areas are cover 15.5 sq.km.(0.91%).
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