1Energy and Wetlands Research Group, Centre for Ecological Sciences [CES],
Indian Institute of Science, Bangalore – 560012, India.
2 Centre for Sustainable Technologies [CST], Indian Institute of Science.
3Centre for Infrastructure, Sustainable Transport and Urban Planning [CiSTUP],
Indian Institute of Science, Bangalore 560 012.
*Corresponding author:
trv@iisc.ac.in
Introduction
Forests ecosystems play a vital role in sequestering carbon from the atmosphere which helps
in mitigating carbon footprint and aid in moderating the global warming and consequent changes in the climate.
Atmospheric carbon gets stored in the above and below ground biomass, dead organic matter and soil organic matter.
Mismanagement of forests leading to deforestation and enhanced emissions during the post industrial revolution has
increased carbon dioxide concentration in the atmosphere to 400 ppm from 270 ppm (pre-industrial era). Forest ecosystems
aid in capturing 45% of terrestrial carbon and are responsible for ~50% net ecosystem production (McGarvey et al. 2015).
Forests and soil plays a vital role in the carbon cycle, evident from sequestration of about 30% of annual global
anthropogenic CO
2 emissions (2 petagrams (Pg) of carbon per year) from the atmosphere (Lal 2005; Achat et al.
2015) and hence are aptly regarded as moderators of climate (Bellassen and Luyssaert 2014). Quantification of carbon
sequestered by forests across the globe was estimated as 861 ± 66 Pg C (Pan et al. 2011), with 383 ± 30 Pg C (44%) in
soil (to 1-m depth), 363 ± 28 Pg C (42%) in live biomass (above and below ground), 73 ± 6 Pg C (8%) in deadwood, and 43
± 3 Pg C (5%) in litter respectively. Soil carbon is the major pool of carbon terrestrial ecosystem, with major
ecosystem services of advancing nutritional security, quality of water, improving biodiversity, and strengthening
elemental recycling. The retention of carbon in soil depends on land use, anthropogenic pressure, disturbance regimes
and climate. The native and intact forests enhance mean residence time of carbon sinks with minimal re-emission (Lal et
al. 2015). The land use land cover (LULC) changes in forest ecosystem have been altering forest structure with increase
in forest fragmentations (loss of contiguity), biodiversity loss, alteration in biogeochemical cycles and hydrological
processes (Bharath et al. 2013; Vinay et al. 2013; Ramachandra et al. 2016; Armenteras et al. 2019; Ramachandra and
Bharath 2019). Deforestation due to LULC changes is the prime causal parameters of global warming and increase of
earth’s ambient temperature due to carbon emissions and loss of ecosystem ability to sequester carbon.
Large scale
land cover changes leading to deforestation with land degradation contribute to 20-25% of anthropogenic carbon
emissions (Pachauri and Reisinger 2007) with the regional impacts on climate patterns altering the hydrological
regime. The immediate effect of deforestation is increase in carbon load in the atmosphere and cumulative impacts
are global warming, changes in the climate and ecosystem degradation. The loss of forest cover has modified local
rainfall regime due to the changes in thermodynamic and mesoscale circulation processes (Lawrence and Vandecar
2015), with consequences of extreme weather conditions. The large and intact forest areas are responsible for
transforming sensible heat to latent heat through the leaves, leaf area and forest canopy thereby an increase in
dynamics of wind and increases precipitation events. Lower evapotranspiration with deforestation across the region
has consequences of delay in the onset of the rainy season, decline in the number of rainy days with higher dry
conditions (Debortoli et al. 2017). The delay in onset rainfall is positively correlated with forest cover change
and extended length of the dry season (Funatsu et al. 2012). It will influence the adaptive capacity of populations
and cause a shift in their diversity. Additionally, persistent drier conditions in a region can aggravate the
probability of tropical evergreen forest to transform dry forest and savannah (Malhi et al. 2009). The plant
metabolic activity and respiration gets intensified with higher temperatures resulting in vegetation die-off due to
unavailability of water. Unfavorable conditions with loss of moisture releases the soil carbon escape to the
atmosphere. The biophysical variations due to deforestation has significantly altered the microclimate conditions
with rapidly increasing air and land surface temperature (Alkama and Cescatti 2016; Ramachandra et al. 2018). The
higher temperature changes induce higher annual water demand resulting in the loss of canopy, microflora,
microclimate alteration and also higher incidences of forest fire.
Availability of the spatial data acquired at regular intervals through space borne sensors (remote sensing data)
helps in analyzing LULC dynamics, deforestation, forest cover status and quantification of carbon stock. This helps
in framing appropriate policies for sustainable management of forests and mitigation of degradation. Traditionally,
forest inventories were based on ground data, which is time and labour intensive. Integration of geo-informatics
with temporal remote sensing data and ground inventory data help in the cost-effective estimation of surface
characteristics such as total biomass across various biomes (Gallaun et al. 2010; Rodríguez-Veiga et al.
2019). Realizing the impacts of global warming with escalating greenhouse gas emissions, due to accelerated
deforestation process necessitated measures towards adaptation and mitigation of effects of climate changes. In this
regard, Kyoto Protocol was the first global initiative proposed at 3rd Conference of Parties (COP) of the
United Nations Framework Convention on Climate Change (UNFCCC) in 1997 to curb deforestation and promote forest
conservation (Humphreys 2008). Reduced Emissions of Deforestation (RED) has emerged as an initiative for
conservation in 2005 at 11th COP meeting to support developing countries. REDD+ materialized at the
18th COP proposed to offer incentives for the conservation and enhancement of the forest carbon stock and
the sustainable management of forests in 2012. It has been playing a significant role in forest conservation and
helps in addressing challenges, supporting direct/indirect costs involved in forest management (Ghazoul et al.
2010). REDD+ adaptation is a form of Payments for Ecosystem Services (PES), while providing economic benefits to the
local communities, has improved natural resource management in developing countries (Agarwal et al. 2011). This
necessitates a comprehensive understanding of the carbon stock and the dynamic drivers of LULC change, to devise
effective policy measures to mitigate global deforestation.
Objectives
The current study investigates landscape dynamics with climate trends and carbon sequestration potential in the
ecologically fragile Western Ghats (WG). This involves
- Analyses of land use dynamics (using temporal remote sensing data), assessment of fragmentation of forests,
modeling and visualization of LU dynamics in the WG;
- evaluating rainfall and climate dynamics associated with deforestation;
- quantification of carbon sequestration potential and productivity of forests;
- Formulating appropriate management strategies to arrest deforestation and ecological security of forests.