Results and Discussion

Table 4 Land use statistics

3.2 Fragmentation analysis

Temporal LU data was used as input for the fragmentation analysis and computation of the spatial metrics. Prioritized metrics based on the earlier work (Ramachandra et al. 2012a b) were considered. Intact forests were prevalent in the 1970s, but post-1990, there was a sharp increase in the number of patches as evident from Fig 5. This has also contributed to higher patch density (>1 in 2012) indicating enhanced forest fragmentations. Further investigation of total edges in the landscape proved that the number of edges which were less in 1973 and phenomenally increased highlighting that the forest continuity or intactness has been lost resulting in the discontinuous animal habitats. Landscape shape based on forest LU showed a complex and convoluted pattern (since the value of LSI is very high (>330) during post-2002 compared to 1973 (<235). Forest area was of simple shape in 1973 indicating contiguity and intactness of forests. AI shows the forested area was more aggregated till 2002 and has become disaggregated due to uneven LU. The more non-forest patch types resulted in AI value reduction from 78 to 65 (from 1973-2018).

Forest status of Shimoga district is assessed through the computation of Pf and Pff and the results are depicted in Fig 6 and Table 5 lists category wise spatial extent of forests over a different time period. The 26.41% of forest cover was under interior cover in 1973 which is reduced to 11% in 2018 due to anthropogenic interventions. The interior cover was disrupted by non- forest LU categories through conversion into agriculture and horticulture plantations. The large tracts of forests were de-notified for other purposes (for short term political gains). Market based cropping pattern has been threatening hydrologic regime due to over exploitation of water coupled with the declined water retention capability with the removal of vast tracts of native vegetation. The common grassy blank areas under the revenue department are being mismanaged, rampant grazing inside core forest areas are impacting the regeneration. The non-forest area cover 79% of the landscape (2018).

Fig. 3. Land cover analysis of Shimoga

Fig. 4. Temporal Land use analysis of Shimoga

Fig. 5. Temporal pattern analysis through spatial metrics

Fig. 6. Interior forest cover of Shimoga (1973-2018)

Table 5 Fragmentation analysis of Shimoga

3.3 Agents of forest fragmentation in Shimoga

Geo-registered and verified forest boundaries of the district were overlaid on high resolution classified remote sensing data and verified with the Google earth and Bhuvan data to assess the extent of forest land conversion to other categories. Fig. 7 illustrates the spatial estimate of the land conversions in the reserve forest area. The estimate shows the conversion of forest to agriculture and horticulture is to the tune of 36,105 hectares. Verification of these LU in the field revealed most of these changes are unauthorized or encroachments. 18% of the reserved forest area is encroached in the Bhadravathi division, followed by 14% in Shimoga and 13% in the Sagara forest division.

Fig. 7. Forest area encroachment across the divisions

3.4 ESR prioritization

The ecologically sensitive regions or ESR in the Shimoga district are delineated at grid levels considering diverse (geo-climatic, ecological, hydrologic, social) themes. A total of 114 grids covering the study were considered and weightages were assigned to the analyzed variables, which were aggregated and grids are prioritized (Fig 8 a-t) based on the relative scores into four categories as ESR1 (highest sensitivity), ESR2 (higher sensitivity), ESR3 (high sensitivity) and ESR4 (moderate sensitivity).

LULC analysis of the district revealed that the district has a forest cover of 33.9%. The villages situated in the western part of the district (Western Ghats) have good forest cover. The grids of Agumbe rainforest, Thirthahalli taluk, Sharavathy Wildlife Sanctuary had the highest forest cover of greater than 80 percent as compared to the grids on the eastern side of Soraba, Shimoga and Shikaripura taluk (<20-40%). The weightages are assigned based on forest cover across the district (Fig. 8a, b). Forest fragmentation analysis of the district revealed an interior forest cover of 11.32%. The grids on the western side of the district showed the highest percentages of interior forest cover > 80 percent, while the eastern and northern grids of the district had <20 percent of interior forest (Fig. 8c, d).

Fig. 8. variables considered and their respective weightages

The spatial distribution of the flora and faunal species across the district was compiled through field sampling and literature review. The distribution of the species endemic to the Western Ghats as well as the threatened species (according to the IUCN Conservation Status) has been analyzed, which are concentrated in the grids in and around Sharavathy Wildlife Sanctuary, Sagar taluk, Agumbe Rainforest, Thirthahalli taluk and towards the Bhadra Wildlife Sanctuary in Shimoga taluk (Fig. 8 e-h). There are about 209 unique flora species under 60 different families distributed across the district. Dominant flora families of the district are Euphorbiaceae (19 species), Rubiaceae (16), Moraceae (13), Anacardiaceae (10), Fabaceae (10), Lauraceae (9), Ebenaceae (8), etc. As per IUCN conservation status, the number of species present in various categories are Critically Endangered (3 species), Vulnerable (17), Endangered (11), Near Threatened (6), Least Concern (11), Data Deficient (3), Not Evaluated (158). There are about 497 unique faunal species under various categories. Dominant fauna are amphibians (37 species), birds (206), fish (154), mammals (20), reptiles (80). As per IUCN category, the number of species identified under conservation groups are as follows Critically Endangered (3 species), Data Deficient (17), Endangered (29), Extinct (3), Least Concern (332), Near Threatened (23), Not Evaluated (160), Vulnerable (64).

Protected areas refer to a geographical space, that are significant in terms of their biological, ecological, or cultural values and hence are recognized, dedicated and managed, to achieve the long term conservation of nature, through appropriate environmental legislations. These regions are with the limited human occupation or the limited exploitation of resources. Protected areas constitute about 4.93% of the country’s geographical area which includes national parks, sanctuaries, conservation reserves, and community reserves. Fig. 8i and 8j depict protected areas in the district.

Geo-climatic variables such as the altitude or elevation, the percentage slope of the region, annual average precipitation or rainfall received by the region, and the agroclimatic zones were analyzed village wise, for the entire district. The altitude or elevation of the Shimoga district varies between 38 to 1335 meters above mean sea level and weightages assigned asper higher elevations (Fig. 8k, l). The regions on the western side of the district, towards the Ghats, had a higher slope of between 15 and 20 percent and more. The weightages are assigned based on slope values across each grid as the disturbing slope of the regions will aggravate instances of landslides.

Shimoga receives rainfall between the ranges of 592 to 7628 mm annually. Eastern sides of the taluks of Sagar, Hosanagara, and Thirthahalli receive the highest rainfall of more than 5000 mm as an annual average (Fig. 8m, n). Based on the agro-climatic zones, the district can be divided into 2 main zones, namely, the hilly zones comprising the Sahyadris and the southern transition zone comprising the plains, respective weightages were assigned (Fig. 8o, p).

The population density was analyzed at the village level and villages in Shimoga taluk have higher population density and Shimoga City Municipal Corporation (SCMC) has the highest population density of 4206 persons per square km. The villages of Sagar, Hosanagara, and Thirthahalli taluks have the lowest population densities, as the forests of Western Ghats are present here, as well as the Sharavathy Valley wildlife sanctuary (Fig. 8q, r). The proportion of Scheduled Tribe (ST) population was also analyzed village wise, which contributes to 3.7 percent of the whole population. Most of the villages have a scheduled tribe population of less than 25% (Figures 8s, t). The aggregated weightages were analyzed and grids are prioritized based on the relative score that also the respective ecological sensitivity. The 27 grids are under ESR1, 27 under ESR2, 36 under ESR3, and 24 under ESR4 (Fig 9a). Out of the 1585 villages, 184 were prioritized as ESR1, 472 as ESR2, 565 as ESR3, and 364 villages as ESR 4 (Fig 9b). The ESR-1 represents a zone of highest conservation, no further degradation allowed. ESR-2 has the potentiality to become ESR-1 provided with strict regulations and improvement of forests and its environs by more protection. A small change in ESR-2 will have more adverse effects in ESR-1. It is recommended to impose a complete ban on illegal occupations, illegal NTFP collection, over-exploitation of forest resources. River diversion, stream alternations should not be allowed even for drinking water projects as the region is already facing a severe water crisis. Many river diversion projects are being pushed by the lobby (timber and power lobby) under the guise of drinking water projects (deliberately misleading judiciary). Diversion of the river should not be allowed to ensure the sustenance of biodiversity and the management of ecological flow. Forest conservation is possible only through active participation of local people and self-help women group through (i) development of nurseries of native forest trees and medicinal plants, (ii) NTFP collection (removal of contract system of middlemen) and (iii) value additions - developing bee-keeping in addition to the administrative mechanisms. Suggestions for prudent management of these ESR are given in Annexure A. Species suitable for reforestation in the degraded landscapes are also listed in the Annexure (Table 6 and 7).

Fig. 9. ESR of Shimoga at village wise

Forest ecosystems provide a rich habitat for diverse flora, fauna and the survival of the organism that depends on biotic and abiotic factors of its respective habitat. The fragmentation of contiguous forests into patches or islands surrounded by human habitations, which leads to the decline of species richness and the equilibrium of dependence as trees lose its native area and fauna will lose its food. The rampant use of fire for clearing the evergreen vegetation for converting to cultivation areas or creating grassy area or plantations have caused the change of climax evergreen vegetation to savannas, scrub and secondary deciduous forests with diminished water flow in the streams and rivers, which can be detrimental to the livelihoods of people in Malnad and beyond - even the drier Deccan plains. Fragmentation of animal habitat leads to increased instances of human-animal conflicts, inbreeding, and ultimately the extirpation of species. Many parts of Shimoga have been experiencing higher instances of crop raid by animals, human-animal conflicts during the last two decades. Further regionally the climate and the microclimate in the patch and surrounding the patch will differ and will increase the temperature in the human habitat surrounding the patch (Bharath et al. 2013). These edges will also be exposed to high winds, and the incidence of fires will be higher since the forest edges are drier as the climate is higher than the moist interior this in turn might lead to natural disasters (Chen et al. 1993; Malhi et al. 2008). The edge effect may even perish large trees within 300 m of the forest edge and are replaced by densely spaced short-lived pioneers (Laurance 1999), resulting in the decline of forest biomass (Harper et al. 2005).

Mapping of land use changes in each forest division helps the decision makers and forest managers in the prudent management of forest habitats through an understanding of forest fragmentation, etc. Large scale land use conversions alter the contiguous intact forests to perforated and edge fragments leading to the loss of connectivity. Mitigation of forest fragmentation provides better connectivity, which improves species richness and biogeographical environment while reducing their endangerment. The restoration of forest patches with native species would aid in improving the considerable share of endemic species in the large core fragments thereby reducing the influence of perforated and edge fragments (Paul and Banerjee 2020). The conservation of biodiversity is achieved through better connectivity with the restoration of fragmented landscapes. This helps in establishing the necessary habitat linkages, which minimizes inbreeding and consequent extirpation of species. This approach is referred as either habitat corridor, movement corridor, wildlife corridor, dispersal corridor, or biodiversity corridors, and fulfill the broader conservation needs (Kale et al. 2010). Prudent management of forest ecosystems entails maintaining forest habitat structural integrity, which will improve habitats of diverse organisms inhabiting forests, minimize ecological disturbances, reduces human-animal conflicts, species extinction, colonization of invasive species, etc. (Mandal et al. 2020). The designation of a region as ‘Protected Area’ based on the ecological significance of a region is an appropriate strategy to arrest deforestation and improve forest resources with biodiversity. These unique natural areas with sustainable management strategies, considering human communities as their integral component will lead to the conservation of characteristic ecosystems covering different biogeographic regions (Satish et al. 2014). Implementation of the national strategies such as National Action Plan on Climate Change (NAPCC), Reducing Emissions from Deforestation and forest Degradation (REDD +)  through effective involvement of all stakeholders would aid in mitigating carbon dioxide (CO₂) through carbon sequestration. The success of these programs depends on the level of involvement of tribal (indigenous) and local people in conservation. As part of the United Nations agenda on sustainable development, several countries have adopted Sustainable Development Goals (SDGs) that emphasize the protection of the planet’s ecosystems. In Canada, ecological regions have been used over the last few decades as the basis for a state of the environment and state of human activities on terrestrial and marine wildlife habitats. This was done to improve the capabilities of monitoring systems to track changes in an ecological context and to understand why these changes are taking place (Wiken and Gauthier 1997). In Sri Lanka, a five-year pilot project was initiated jointly by the Ministry of Mahaweli Development and Environment in collaboration with the United Nations Development Programme (UNDP), funded by the Global Environmental Facility and the Government of Sri Lanka to provide the capacity to manage Environmentally Sensitive Areas or ecologically sensitive regions (ESR). ESR denotes the region of lower resilience and difficult to be restored to its natural state if disturbed by external influences, which are either anthropogenic or natural. The demarcation of ecologically sensitive regions spatially is essential for effective conservation planning and management.