Report of the Western Ghats Ecology Expert Panel - Part II : Human Pressure and Ecological Impacts : 3.*Steep slopes, *Origins of rivers, *Auxiliary Criteria : *Species based, *Geo-morphological features based; *Centres of less known food plants, *Grasslands, *Upper catchment areas, *Not so steep slopes, *High rainfall areas, ....

Opinion
       08/11/2018
                 1528.

SUB : Report of the Western Ghats Ecology Expert Panel - Part II : Human Pressure and Ecological Impacts :

REF : 3. *Steep slopes, *Origins of rivers, *Auxiliary Criteria : *Species based, *Geo-morphological features based; *Centres of less known food plants, *Grasslands, *Upper catchment areas, *Not so steep slopes, *High rainfall areas, 

*Steep slopes :

Application to Western Ghats :
The Western Ghats is a region rich in many localities with steep slopes. Fortunately, we now have good digital databases providing elevation data, and WGEEP has been able to access databases on Slopes and Elevation.

*Origins of rivers :

DEFINITION :
A glacier, mountain, hill or spring from where a water stream originates is referred to as the origin of a river.

AREA :
The area relevant to the origin of a river is not strictly limited to the natural point of origin of the river itself (for example, the exact point at which the water spring emerges), but the entire area necessary for preserving the geological and hydrological features which are critical for the sustainability of the river sources. Thus, it is not enough to protect only the glaciers or the snow receiving slopes which feed the river, but also the channels, fissures and other features which are intrinsic to the process of recharging the water source. Similar considerations would apply to the recharging of spring and rain-fed rivers.

Application to Western Ghats :
Western Ghats are a veritable water tower of the Indian Peninsula and therefore the source of numerous east- and west-flowing streams. Evidently the entire Western Ghats region must be considered as ecologically sensitive for preserving the geological and hydrological features which are critical for the sustainability of the river sources of the Indian Peninsula.

*Auxiliary Criteria :
The principal objective of identifying these seven auxiliary criteria is to draw attention to characteristics which indicate the potential for ecological sensitivity without necessarily being definitive in this regard.

*Species based :
1. Areas or centers of less known food plants
Ecosystem based
2. Wetlands
3. Grasslands

*Geo-morphological features based
4. Upper Catchment areas
5. Not so Steep Slopes
6. High Rainfall Areas
7. Other uninhabited Islands

*Centres of less known food plants :

DEFINITION
Areas associated with the origin of/ or containing the wild progenitors of less known plants of potential food and horticultural values.

AREA
The entire area of occurrence of a viable population of such plant species.

Application to Western Ghats
The Western Ghats are very rich in a wide variety of lesser known food plants, including leafy vegetables, tubers and fruit. Evidently the entire Western Ghats region must be considered ecologically sensitive as being associated with the origin of/ or containing the wild progenitors of lesser known plants of potential food and horticultural values.
Wetlands

DEFINITION
Wetlands are submerged or water saturated lands, both natural and man-made, permanent or temporary, with water that is static or flowing, fresh, brackish, salty, including areas of marine water, the depth of which at low tide does not exceed six meters.

AREA
As identified by the natural boundaries of the water body.

Application to Western Ghats
The Western Ghats region has a number of natural, as also many man-made wetlands that are important from the perspective of aquatic organisms and migratory waterfowl. These are distributed throughout the region; hence, the entire Western Ghats region needs to be considered as being ecologically sensitive as a repository of wetlands.

*Grasslands :

DEFINITION
Grasslands are terrestrial ecosystems characterised by plant communities belonging to the grass family - "graminoids? and "forbs?.

AREA
Areas containing small, isolated or remnant patches of any type of natural grassland supporting livestock, native wild animals and avi-fauna.
Grasslands may be classified as temperate or tropical grasslands. Within the temperate zone, the natural grasslands are distinguished from semi-natural types. The semi-natural types have been divided further into those used primarily for hay and those that are grazed by domesticated livestock. Likewise, scattered and small tropical natural grasslands are found in arid and semi-arid areas, where climate is the prime controlling factor, under light to moderate grazing pressure by ungulates. In general, majority of the natural grasslands (arid, semi-arid, wet and tall and temperate) have been severely impaired. Now only small, isolated fragments or remnant patches of grassland habitats are seen. However, even in this category, several sites have undergone considerable modification because of excessive livestock grazing.

Application to Western Ghats
Western Ghats region has a number of natural, as also many man-made grasslands that are important from the perspective of herbaceous flora as also herbivorous animals. These are distributed throughout the region; hence, the entire Western Ghats region needs to be considered as being ecologically sensitive as harbouring extensive grasslands.

*Upper catchment areas :

DEFINITION
Catchment area, also referred to as drainage area, is a basin like structure for collecting and draining water. Upper Catchment Area typically refers to a basin which collects precipitation, mostly in the mountainous or hilly region or the upper reaches of a river following its origin. The water collected is absorbed by the soils or drains into the river.
AREA
The designated „upper catchment area? from which water is collected into the upper stretch of a river varies widely from river to river. It is dependent on various factors viz. location of origin of the river, slopes of the basin, tributaries, annual discharge, geology, soil characteristics and forest cover.

Application to Western Ghats
As discussed above, Western Ghats are a veritable water tower of the Indian Peninsula and therefore the source of numerous east- and west-flowing rivers. Evidently the entire Western Ghats region must be considered as ecologically sensitive as being ‘upper catchment areas’ critical for the sustainability of the rivers of the Indian Peninsula.

*Not so steep slopes :

DEFINITION
A slope greater than 10 degree but less than 20 degree.

AREA
An area which may have its upward or downward inclination to horizontal plane between 10 and less than 20 degrees. Since the horizontal planes near the top and base of a slope are prone to landslides and receive boulders /debris of a slide respectively, suitable buffer zones are designated. In general, a minimum horizontal distance of 200m at both the ends of a slope is recommended as buffer zones.
In mountainous ecosystems, buffer zones need to be extended in landslide prone slopes which tend to possess certain destructive features, including various combinations of steep slopes, residual soil, high pore water pressure, thick and deeply weathered soil cover, undercutting of the base of the slope, and weak material outcropping below stronger material.

Application to Western Ghats
The Western Ghats are a region with either steep or not so steep slopes. Fortunately, we now have good digital databases providing elevation data, and WGEEP has been able to access databases on Slopes and Elevation.

*High rainfall areas :

DEFINITION
Areas having precipitation intensity greater than 200 cm per year.

AREA
Areas which receive high precipitation on a “normal” basis as identified by the Indian Meteorological Department (IMD) or from Remote Sensing Data. This would exclude areas which receive such levels of precipitation only on an episodic basis.

Application to Western Ghats
Western Ghats are a veritable water tower of the Indian Peninsula and much of the region receives rainfall greater than 200 cm per year. Evidently most of the Western Ghats region must be considered as an ecologically sensitive region with high precipitation.

*WGEEP exercise on assessing relative levels of ecological sensitivity in different areas of the Western Ghats

In view of the above, WGEEP concluded that the entire Western Ghats tract should be considered as ecologically sensitive. Regrettably, WGEEP had to initiate its work in 2010, without any substantial progress having been achieved in terms of organizing a national mission on developing an ecological sensitivity database as suggested by the Pronab Sen Committee. Furthermore, the Pronab Sen Committee had not provided any guidance on the management regime for ecologically sensitive areas. Since a uniform regime for the entire Western Ghats tract is not feasible, WGEEP decided on adopting a layered approach and attempted to assign relative levels of ecological sensitivity to different areas.

*For this purpose, WGEEP divided the entire Western Ghats region into 5 minute x 5 minute grids. WGEEP is naturally constrained to using only the readily available datasets to decide on relative levels of ecological sensitivity of different areas.

These included:
1. Endemic plants : Number of endemic plant species
2. IUCN_max: Number of IUCN Red listed mammal species
3. Unique per cent: Percentage of area covered by unique evergreen ecosystems such as shola forests
4. Comp3 per cent : Percentage of area covered by relatively undisturbed forest with low edge
5. Forest per cent: Percentage of forest area
6. Elevation
7. Slope
8. Riparian Forests/Vegetation

Admittedly, these tend to emphasize forest biota and ignore issues such as habitat continuity. However, perforce we have had to focus on readily available datasets. It is hoped that the Western Ghats Ecology Authority would be able to take this exercise further.

Western Ghats are a highly heterogeneous region with a marked north-south gradient in terms of rainfall and length of rainy period. There is also much variation in elevation and geology. It is therefore to be expected that there will be substantial variation from state to state in terms of ecological endowments and sensitivity. At the same time, it is proper that ecological protection efforts should be fairly evenly distributed through the Western Ghats region. Hence it is appropriate to look separately at each state to assess relative levels of ecological sensitivity of different areas within the state.

The relative and not absolute values of the parameters are pertinent for our purpose. With this in view, we normalized these parameters separately for each state. For instance, the highest recorded altitude in a state was assigned the score of 10 and all other grids in that state were ranked on a scale from 1 to 10. This was followed by calculation of the average of the ranks for all available parameters for each grid. As a result, a particular grid could be assigned a very high value, close to 10 , only if it, simultaneously has, for that state, relatively very high elevation, very high slope, very high number of endemic plants, very high number of red listed mammalian species, very high percentage of area covered by unique evergreen ecosystems, very high riparian forest and so on. Consequently, grids of substantial biodiversity endowments could still exhibit apparently low values such as 3 or 4.

This procedure also implies that a large proportion of grids would tend to be assigned quantitatively lower values if there is high grid-to-grid variation in the parameter values, and higher values if there is low grid-to-grid variation in the parameter values. This has the result that the largely homogeneous Western Ghats tracts of Gujarat have the largest area in the score class 5–7, while the major part of the Western Ghat area in other states is in the score class 3–5. Another apparently anomalous result is that a number of Important Bird Areas fall in apparently low scoring grids.

This is related to the fact that, as Daniels and Gadgil (1992) have shown, evergreen forests of the Western Ghats tend to possess low levels of bird diversity compared to drier, generally deciduous forests.

Given these effects, it is clear that the conservation significance of a particular grid is not to be judged on the basis of the absolute score, but scores in comparison with areas independently assessed to be of high conservation value. Areas that have already been incorporated in the network of Protected Areas, viz Wildlife Sanctuaries and National Parks, provide a convenient yardstick. WGEEP has therefore used the thumb rule that the highest ecological sensitivity status of ESZ1 will be assigned only to grids which have, at a minimum, a score at least as high as the lowest score assigned to a PA grid in the concerned state.

NEXT : Future climate change and the vulnerability of ecosystems across the Western Ghats

To be continued.....

JAIHIND
VANDEMATHARAM