Rajiv Kumar Chaturvedi

Trends and Variability of AVHRR-Derived NPP in India

In this paper, we estimate the trends and variability in Advanced Very High Resolution Radiometer (AVHRR)-derived terrestrial net primary productivity (NPP) over India for the period 1982-2006. We find an increasing trend of 3.9% per decade (r = 0.78, R-2 = 0.61) during the analysis period. A multivariate linear regression of NPP with temperature, precipitation, atmospheric CO2 concentration, soil water and surface solar radiation (r = 0.80, R-2 = 0.65) indicates that the increasing trend is partly driven by increasing atmospheric CO2 concentration and the consequent CO2 fertilization of the ecosystems. However, human interventions may have also played a key role in the NPP increase: non-forest NPP growth is largely driven by increases in irrigated area and fertilizer use, while forest NPP is influenced by plantation and forest conservation programs. A similar multivariate regression of interannual NPP anomalies with temperature, precipitation, soil water, solar radiation and CO2 anomalies suggests that the interannual variability in NPP is primarily driven by precipitation and temperature variability. Mean seasonal NPP is largest during post-monsoon and lowest during the pre-monsoon period, thereby indicating the importance of soil moisture for vegetation productivity.

Nitrogen deposition: how important is it for global terrestrial carbon uptake?

Global carbon budget studies indicate that the terrestrial ecosystems have remained a large sink for carbon despite widespread deforestation activities. CO 2 fertilization, N deposition and re-growth of mid-latitude forests are believed to be key drivers for land carbon uptake. In this study, we assess the importance of N deposition by performing idealized near-equilibrium simulations using the Community Land Model 4.0 (CLM4). In our equilibrium simulations, only 12–17 % of the deposited nitrogen is assimilated into the ecosystem and the corresponding carbon uptake can be inferred from a C : N ratio of 20 : 1. We calculate the sensitivity of the terrestrial biosphere for CO 2 fertilization, climate warming and N deposition as changes in total ecosystem carbon for unit changes in global mean atmospheric CO 2 concentration, global mean temperature and Tera grams of nitrogen deposition per year, respectively. Based on these sensitivities, it is estimated that about 242 PgC could have been taken up by land due to the CO 2 fertilization effect and an additional 175 PgC taken up as a result of the increased N deposition since the pre-industrial period. Because of climate warming, the terrestrial ecosystem could have lost about 152 PgC during the same period. Therefore, since preindustrial times terrestrial carbon losses due to warming may have been more or less compensated by effects of increased N deposition, whereas the effect of CO 2 fertilization is approximately indicative of the current increase in terrestrial carbon stock. Our simulations also suggest that the sensitivity of carbon storage to increased N deposition decreases beyond current levels, indicating that climate warming effects on carbon storage may overwhelm N deposition effects in the future.

Assessing “inherent vulnerability” of forests: a methodological approach and a case study from Western Ghats, India

The objective of this study is to present a methodological approach to assess the inherent vulnerability of forests and apply it to a case study. Addressing inherent vulnerability, resulting from current stresses, is a necessary step for building resilience to long-term climate change. The proposed approach includes use of analytical framework that enables selection of vulnerability criteria and indicators systematically, application of pairwise comparison method (PCM) for assigning weights, and synthesis of a composite vulnerability index. This methodological approach has been applied at local scale to Aduvalli Protected Forest in Western Ghats in South India, where a vulnerability index value of 0.248 is estimated. Results of the case study indicate that ‘preponderance of invasive species’ and forest dependence of community are the major sources of vulnerability at present for Aduvalli Protected Forest. Adoption of this methodology can assist in development of forest management plans to enhance adaptability of Aduvalli PF to current as well as future stresses, including climate change. This methodological approach can be applied across forest-types after appropriate changes to criteria and indicators and their weights, to estimate the inherent vulnerability to enable development of adaptation strategy.

Climate change and forests in India

SUMMARY Forests play a critical role in addressing climate change concerns in the broader context of global change and sustainable development. Forests are linked to climate change in three ways. i) Forests are a source of greenhouse gas (GHG) emissions; ii) Forests offer mitigation opportunities to stabilise GHG concentrations; iii) Forests are impacted by climate change. This paper reviews studies related to climate change and forests in India: first, the studies estimating carbon inventory for the Indian land use change and forestry sector (LUCF), then the different models and mitigation potential estimates for the LUCF sector in India. Finally it reviews the studies on the impact of climate change on forest ecosystems in India, identifying the implications for net primary productivity and bio-diversity. The paper highlights data, modelling and research gaps relevant to the GHG inventory, mitigation potential and vulnerability and impact assessments for the forest sector in India.

Challenges in vulnerability assessment of forests under climate change

Forest-management goals in the context of climate change are to reduce the adverse impact of climate change on biodiversity, ecosystem services and carbon stocks. For developing an effective adaptation strategy, knowledge on nature and sources of vulnerability of forests is necessary to conserve or enhance carbon sinks. However, assessing the vulnerability of forest ecosystems is a challenging task, as the mechanisms that determine vulnerability cannot be observed directly. In this article, we list the challenges in forest vulnerability assessments and propose an assessment of inherent vulnerability by using process-based indicators under the current climate. We also suggest periodic assessment of vulnerability, which is necessary to review adaptation strategies for the management of forests and forest carbon stocks.

Lost benefits and carbon uptake by protection of Indian plantations

There is a range of problems in assessing how protection of a specific forest to Reduce Emissions from Deforestation and forest Degradation (REDD+) affect global emissions of greenhouse gases. This paper shows how knowledge and information about the biophysical characteristics of forests can be combined with theories of forest management and economic behaviour to derive the impacts on global emissions of REDD+. A modelling experiment from India, where 10% of the forest plantations in eight different regions are protected, shows that the biophysical characteristics of forests are decisive for the global impacts on emissions. In regions with slow-growing forests, agents in the non-protected forests are able to increase their output significantly to fill the demand from the protected forests. This opportunity is strictly limited in regions with fast-growing forests. Therefore, prices increase far more in regions with fast-growing forests than in slow-growing forests. Over time, the markets for Indian forestry products contribute to reduce the resulting price differences across regions. When the carbon uptake from protected forests approaches zero, the leakage of emissions to other Indian forests is between 20 and 40%. Only a small part of this is international leakage. Combining different models also helps to identify knowledge gaps, and to distinguish gaps that potentially may be filled with data and new knowledge, and gaps due to different angling of modelling biophysical processes and modelling of economic behaviour.

Carbon management in Indian forests: a policy analysis to assess mitigation potential.

The forest sector provides mitigation opportunities to address climate change. Afforestation and reforestation have been identified as important mitigation options. Thus, there is a need for estimating the mitigation potential at local, national and global levels. India has an ambitious plan to bring approximately 33% of its geographical area under forest cover. In this article, we analyze the mitigation potential of this policy over the period of 2010–2030, considering two scenarios: a rapid afforestation rate (scenario-2020, achieving the 33% goal by 2020) and a moderate afforestation rate (scenario-2030, achieving the 33% goal by 2030). Assessment using the generalized comprehensive mitigation-assessment process model shows that afforestation could mitigate 5.2 GtCO2 under scenario-2020 over the 2010–2030 period, compared with 3.96 GtCO2 under scenario-2030, over the same period. Furthermore, we show that the rapid afforestation scenario has the potential to offset approximately 9% of India’s average national emissions projected by five models, for the same period. The afforestation under the two scenarios provides an incremental mitigation potential of 1.8–3.2 GtCO2 over the baseline scenario, for the period of 2010–2030, with the potential to offset 3.0–5.4% of the average national emissions projected for the same period.

Impact of Climate Change on Vegetation Distribution and Net Primary Productivity of Forests of Himalayan River Basins: Brahmaputra, Koshi and Indus

The impacts of climate change in terms of forest vegetation shifts and Net Primary Productivity (NPP) changes are assessed for Brahmaputra, Koshi and Indus river basins for the mid (2021-2050) and long (2071-2100) terms for RCP4.5 and RCP8.5 scenarios. Two Dynamical Global Vegetation Models (DGVMs), Integrated BIosphere Simulator (IBIS) and (Lund Postdam and Jena (LPJ), have been used for this purpose. The DGVMs are driven by the ensemble mean climate projections from 5 climate models that contributed to the CMIP5 data base. While both DGVMs project vegetation shifts in the forest areas of the basins, there are large differences in vegetation shifts projected by IBIS and LPJ. This may be attributed to differing representation of land surface processes and to differences in the number of vegetation types (Plant Functional Types) defined and simulated in the two models. However, there is some agreement in NPP changes as projected by both IBIS and LPJ, with IBIS mostly projecting a larger increase in NPP for the future scenarios. Despite the uncertainties with respect to climate change projections at river basin level and the differing impact assessments from different DGVMs, it is necessary to assess the “vulnerability” of the forest ecosystems and forest dependent communities to current climate risks and future climate change and to develop and implement resilience or adaptation measures. Assessment of the “vulnerability” and designing of the adaptation strategies could be undertaken for all the forested grids where both IBIS and LPJ project vegetation shifts.

Vulnerability of Forests in India: A National Scale Assessment

Forests are subjected to stress from climatic and non-climatic sources. In this study, we have reported the results of inherent, as well as climate change driven vulnerability assessments for Indian forests. To assess inherent vulnerability of forests under current climate, we have used four indicators, namely biological richness, disturbance index, canopy cover, and slope. The assessment is presented as spatial profile of inherent vulnerability in low, medium, high and very high vulnerability classes. Fourty percent forest grid points in India show high or very high inherent vulnerability. Plantation forests show higher inherent vulnerability than natural forests. We assess the climate change driven vulnerability by combining the results of inherent vulnerability assessment with the climate change impact projections simulated by the Integrated Biosphere Simulator dynamic global vegetation model. While 46% forest grid points show high, very high, or extremely high vulnerability under future climate in the short term (2030s) under both representative concentration pathways 4.5 and 8.5, such grid points are 49 and 54%, respectively, in the long term (2080s). Generally, forests in the higher rainfall zones show lower vulnerability as compared to drier forests under future climate. Minimizing anthropogenic disturbance and conserving biodiversity can potentially reduce forest vulnerability under climate change. For disturbed forests and plantations, adaptive management aimed at forest restoration is necessary to build long-term resilience.

Forest carbon management under the changing climate: Research challenges

Historically, deforestation has been the primary driver for GHG emissions from the forest sector. However, in the future, forest dieback induced by climate change could be another reason for significant GHG emissions from the forest sector [2]. Forests are already severely affected by existing disturbances such as forest fires, pests and climatic events including drought, wind, snow and floods. All of these factors have implications for carbon balance and affect approximately 100 million ha of forests annually [3]. Forest fires each year, on average affect 1% of all forests [4]. Climate change is likely to exacerbate these existing threats. Recent studies project far higher increases in global temperatures than projected by the Fourth Assessment Report of IPCC. This report projected a mean warming of 3.2°C by the 2090s, compared with the preindustrial period under the A1B SRES scenario; the A1B scenario is considered close to the business-as-usual scenario [5]. The IEA projects global temperatures to rise 6°C under the current emission scenario by the end of the century [6]. A recent study by the Massachusetts Institute of Technology’s joint program on the science and policy of global climate change concludes that global mean surface temperature could rise by 3.5–6.7°C by the year 2100 [7]. The Met Office (UK) also projects a warming of 4°C by as early as the 2060s [5]. New studies suggest that forests and other terrestrial ecosystems could undergo large-scale change and the terrestrial global carbon sink may weaken over the century. Bergengren et al. project 49% of the Earth’s land surface area to undergo plant community changes and Forest carbon management under the changing climate: research challenges Editorial