Geospatial assessment and monitoring of historical forest cover changes (1920–2012) in Nilgiri Biosphere Reserve, Western Ghats, India

Abstract

Deforestation in the biosphere reserves, which are key Protected Areas has negative impacts on biodiversity, climate, carbon fluxes and livelihoods. Comprehensive study of deforestation in biosphere reserves is required to assess the impact of the management effectiveness. This article assesses the changes in forest cover in various zones and protected areas of Nilgiri Biosphere Reserve, the first declared biosphere reserve in India which forms part of Western Ghats-a global biodiversity hotspot. In this study, we have mapped the forests from earliest available topographical maps and multi-temporal satellite data spanning from 1920's to 2012 period. Mapping of spatial extent of forest cover, vegetation types and land cover was carried out using visual interpretation technique. A grid cell of 1 km × 1 km was generated for time series change analysis to understand the patterns in spatial distribution of forest cover (1920-1973-1989-1999-2006-2012). The total forest area of biosphere reserve was found to be 5,806.5 km(2) (93.8 % of total geographical area) in 1920. Overall loss of forest cover was estimated as 1,423.6 km(2) (24.5 % of the total forest) with reference to 1920. Among the six Protected Areas, annual deforestation rate of >0.5 was found in Wayanad wildlife sanctuary during 1920-1973. The deforestation in Nilgiri Biosphere Reserve is mainly attributed to conversion of forests to plantations and agriculture along with submergence due to construction of dams during 1920 to 1989. Grid wise analysis indicates that 851 grids have undergone large-scale negative changes of >75 ha of forest loss during 1920-1973 while, only 15 grids have shown >75 ha loss during 1973-1989. Annual net rate of deforestation for the period of 1920 to 1973 was calculated as 0.5 followed by 0.1 for 1973 to 1989. Our analysis shows that there was large-scale deforestation before the declaration of area as biosphere reserve in 1986; however, the deforestation has drastically reduced after the declaration due to high degree of protection, thus indicating the secure future of reserve in the long term under the current forest management practices. The present work will stand as the most up-to-date assessment on the forest cover of the Nilgiri Biosphere Reserve with immediate applications in monitoring and management of forest biodiversity.

Predictive modelling of the spatial pattern of past and future forest cover changes in India

“…India has 590 protected areas -500 wildlife sanctuaries and 90 national parks covering an area of 156,700 km 2 . At present, under the provisions of the act, 4.7% of the total geographic area of the country is devoted to in situ conservation (MOEF 2008) which has resulted in effective conservation of forests in many protected areas since the 1990s (Harikrishna et al 2013;Satish et al 2014;Dutta et al 2016). Of the 43 selected protected areas in Northeast, only four, i.e., Manas, Sonai-Rupai, Nameri and Marat Longri are still undergoing deforestation (table 5).…”

Terrestrial carbon cycle: tipping edge of climate change between the atmosphere and biosphere ecosystems

“…This has prompted researchers to proposed an impossible state to quantify the uncertainties in the carbon variations due to the agricultural LUC. 6,160 They also affect other biogeochemical cycles such as the CH 4 , nitrogen and hydrological cycles at the ecosystem level, leading to regional climate changes, which are blind spots in climate change.…”

“…Due to its heterogenetic geographical nature, studies on carbon fluxes in India are site-specific on a regional scale. 160 Without the assistance of models and RS, estimations of carbon fluxes are inventory based, which inherits high spatial and temporal bounds in the estimated magnitude.…”

“…Consistently, multi-model assimilation studies suggested higher uncertainty in the estimation based on the model approaches. 35,82,160,186 Furthermore, forest fires emit carbon similar to the NBP, about ∼3 Pg C per year, 137 which significantly varies inter-annually and drives the global change. In the study by Sannigrahi et al , 137 using the CASA and VPM model, they showed that various burnt indices on coupling with NPP cause synergistic and trade-off interactions between the ecosystem productivity and the fire attributes.…”

Assessment of forest cover and carbon stock changes in sub-tropical pine forest of Azad Jammu & Kashmir (AJK), Pakistan using multi-temporal Landsat satellite data and field inventory

“…Hence, deforestation is responsible for approximately 20% of anthropogenic emissions worldwide [5,6] with varying regional statistics [7]. Globally, a net decrease of 1.7% in the forest area with an annual rate of change of 0.11% was reported for the period 1990-2005 [8] and it was estimated that during the period 2005-2010 the reduction in global forest area led to decrease in forest biomass carbon stock by an amount of 0.5 Gt annually [7]. Sustainable forest management (SFM) greatly relies on the important components like assessments of forest cover, forest carbon stocks and carbon emissions from deforestation and degradation [9].…”