During the 21st century, climatic change and non-climatic stressors are likely to impact forests leading to large-scale forest and biodiversity loss, and diminished ecological benefits. Assessing the vulnerability of forests and addressing the sources of vulnerability is an important risk management strategy. The overall goal of this research work is to develop methodological approaches at different scales and apply them to assess the vulnerability of forests in India for developing strategies for forest adaptation. Indicator-based methodological approaches have been developed for vulnerability assessment at local, landscape and national scales under current climate scenario, and at national scale under future climate scenario. Under current climate scenario, the concept of inherent vulnerability of forests has emerged by treating vulnerability as a characteristic internal property of a forest ecosystem independent of exposure. This approach to assess vulnerability is consistent with the framework presented in the latest report of Intergovernmental Panel on Climate Change (IPCC AR5 2014). Assessment of vulnerability under future climate scenario is presented only at national scale due to challenges associated with model-based climate projections and impact assessment at finer scales. The framework to assess inherent vulnerability of forests at local scale involves selection of vulnerability indicators and pair wise comparison method (PCM) to assign the indicator weights. The methodology is applied in the field to a 300-ha moist deciduous case study forest (Aduvalli Protected Forest, Chikmagalur district) in the Western Ghats area, where a vulnerability index value of 0.248 is estimated. Results of the study indicate that two indicators - ‘preponderance of invasive species’ and ‘forest dependence of community’ - are the major drivers of inherent vulnerability at present. The methodology developed to assess the inherent vulnerability at landscape scale involves use of vulnerability indicators, the pair wise comparison method, and geographic information system (GIS) tools. Using the methodology, assessment of inherent vulnerability of Western Ghats Karnataka (WGK) landscape forests is carried out. Four vulnerability indicators namely, biological richness, disturbance index, canopy cover and slope having weights 0.552, 0.266, 0.123 and 0.059, respectively are used. The study shows that forests at one-third of the grid points in the landscape have high and very high inherent vulnerability, and natural forests are inherently less vulnerable than plantation forests. The methodology used for assessment of forest inherent vulnerability at the national scale was same as used at landscape scale. 40% of forest grid points in India are assessed with high and very high inherent vulnerability. Except in pockets, the forests in the three biodiversity hotspots in India i.e., the Western Ghats in peninsular India, northeastern India, and the northern Himalayan region are assessed to have low to medium inherent vulnerability. Vulnerability of forests under future climate scenario at national scale is estimated by combining the results of assessment of climate change impact and inherent vulnerability. In the present study, ensemble climatology from five CMIP5 (Coupled Model Intercomparison Project phase 5) climate models for RCP (Representative Concentration Pathways) 4.5 and 8.5 in short (2030s) and long term (2080s) is used as input to IBIS (Integrated Biosphere Simulator) dynamic vegetation model. Forest grid points projected to experience vegetation-shift to a new plant functional type (PFT) under future climate are categorized under ‘extremely high’ vulnerability category. Such forest grid points in India are 22 and 23% in the short term under RCP4.5 and 8.5 respectively, and these percentages increase to 31 and 37% in the long term. IBIS simulated vegetation projections are also compared with LPJ (Lund-Potsdam-Jena) simulated projections. Both the vegetation models agree that forests at about one-third of the grid points could be impacted by future climate but the spatial distribution of impacted grid points differs between the models. Vulnerability assessment is a powerful tool for building long-term resilience in the forest sector in the context of projected climate change. From this study, three forest scenarios emerge in India for developing adaptation strategies namely: (a) less disturbed primary forests; (b) degraded and fragmented primary forests; and (c) secondary (plantation) forests. Minimizing anthropogenic disturbance and conserving biodiversity are critical to reduce forest vulnerability of less disturbed primary forests. For disturbed forests and plantations, adaptive management aimed at forest restoration is necessary to build resilience. Mainstreaming forest adaptation in India through Forest Working Plans and realignment of the forestry programs is necessary to manage the risk to forests under climate change.

Research leading to this thesis aims to assess the policy relevant mitigation potential of Indian forests as well as aims to assess the impact of climate change on carbon stocks, vegetation boundary shifts, Net Primary Productivity (NPP) and the mitigation potential of Indian forests. To project the impact of climate change we chose a dynamic global vegetation model ‘Integrated Biosphere Simulator’ (IBIS V.2.6b4). We selected A2 and B2 scenarios for projecting the impacts. Mitigation potential was assessed using the ‘Generalized Comprehensive Mitigation Assessment Process’ (GCOMAP) model. We assess the mitigation potential of Indian forests in the light of India’s long-term policy objective of bringing 33% of its total geographical area under forest cover. We analyzed the mitigation potential of this policy objective under two scenarios: the first comprising of rapid afforestation scenario with the target to achieving the goal by 2020 and the second a moderate afforestation scenario in which this goal is achieved by 2030. We estimate that afforestation could offset about 9% of India’s average national emissions over the 2010-2030 period, while about 6.7% could be mitigated under the moderate afforestation scenario over the same period. We analyze the impact of climate change on the four key attributes of Indian forests, i.e. impact on vegetation distribution, impact on forest productivity (NPP), impact on soil carbon (SOC) and impact on biomass carbon. IBIS simulations suggest that approximately 39% and 34% of forest grids are projected to experience change in vegetation type under A2 and B2 climate scenarios, respectively over the period 2070¬2100. Simulations further indicate that NPP is projected to increase by an average of 66% under the A2 scenario and 49% under the B2 scenario. The increase is higher in the northeastern part of India. However, in the central and western Indian forests NPP remains stable or increases only moderately, and in some places even decreases. Our assessment of the impact of climate change on Soil Organic Carbon (SOC) suggests a trend similar to NPP distribution, which is to be expected as increased NPP is the primary driver of higher litter input to the soil. However, the quantum of increase in this case is lower, around 37% and 30%, for the A2 and B2 scenario respectively (averaged over India). The biomass carbon is also projected to increase all over India on the lines similar to NPP gains. However, projected gains in biomass, NPP and SOC should be viewed with caution as IBIS tends to simulate a fairly strong CO2 fertilization effect that may not necessarily be realized under conditions of nutrient and water limitations and under conditions of increased pest and fire outbreaks. Further we analyzed the impact of climate change on the mitigation potential of Indian forests by linking impact assessment models to mitigation potential assessment model GCOMAP. Two impact assessment models BIOME4 and IBIS are used for simulating the impact of climate change. IBIS is a dynamic vegetation model while BIOME4 is an equilibrium model. Our assessment suggests that with the BIOME4 simulations the cumulative mitigation potential increases by up to 21% under the A2 scenario over the period 2008 to 2108, whereas, under the B2 scenario the mitigation potential increases only by 14% over the same period. However cumulative mitigation potential estimates obtained from the IBIS simulations suggest much smaller gains, where mitigation potential increases by only 6% and 5% over the period 2008 to 2108, under A2 and B2 scenarios respectively. To enable effective policy analysis and to build a synergy between the mitigation and adaptation efforts in the Indian forest sector, a vulnerability index for the forested grids is constructed. The vulnerability index is based on the premise that forests in India are already subjected to multiple stresses including over extraction, insect outbreaks, live¬stock grazing, forest fires and other anthropogenic pressures -with climate change being an additional stress. The forest vulnerability index suggests that nearly 39% of the forest grids in India are projected to be vulnerable to the impacts of climate change under the A2 scenario, while 34% of the forest grids are projected to be vulnerable under the B2 scenario. The vulnerability index suggests that forests in the central part of India, a significant part of the western Himalayan forests and northern and central parts of the Western Ghats are particularly vulnerable to the impacts of climate change. Forests in the northeastern part of India are seemingly resilient to the impacts of climate change. It also suggests that given the high deforestation rate in northeast, this region be prioritized for reducing deforestation and forest degradation (REDD) projects under the United Nations Framework Convention on Climate Change (UNFCCC) mechanisms.