There is still large uncertainty over the status of global forest cover owing to the paucity of comprehensive and holistic studies related to long term forest cover change. The aim of the present work is to prepare a nation-wide multi-date forest cover database which describes and quantifies historical and recent changes in natural forests of India. This analysis facilitated the determination of the state of Indian forest cover changes over last eight decades. Here, we have mapped the total area under forest cover, evaluated the spatial tracking of changes in natural forests, estimated the rate of deforestation and afforestation, analysed the biogeographic zone wise and state wise forest cover change, existing land use in deforested area, influence of environmental factors such as terrain on deforestation and implication of different definitions of forest used by agencies reporting deforestation in India. The results indicated that forests covered an area of 869,012 km2 in 1930 which has decreased to 625,565 km2 in 2013, a net loss of 243,447 km2 (28 %) in eight decades. The highest annual average forest loss was found to be 4795 km2 during 1930–1975, 1476 km2 during 1975–1985, 767 km2 during 1985–1995, 356 km2 during 1995–2005 and 209 km2 during 2005–2013. Between 1930 and 1975, forest experienced large scale deforestation at gross annual rate of 0.77 % which has declined to 0.29 % and 0.14 % for the 1975–1985 and 1985–1995 periods respectively. Quantification of annual rate of gross deforestation for the recent period indicates 0.07 % during 1995–2005 and 0.05 % during 2005–2013. The lower rates of deforestation during recent period support effectiveness of conservation measures taken at national level. It was found that deforestation rate has decreased in many biogeographic zones by 2005, except for Andaman & Nicobar Islands and North East. The major deforestation has mostly occurred due to conversion of forests to agriculture. The construction of reservoirs contributed to 4.1 % of forest loss. The tropical forests have experienced large scale deforestation followed by subtropical forests. The findings of the study will be useful to prioritize conservation and protection of forest cover at the regional level. It shall also provide a base for future research on the impacts of deforestation on carbon flux and biodiversity.

Quantification and monitoring of deforestation in India over eight decades (1930–2013)

The South Asian summer monsoon is a complex coupled human‐natural system that poses unique challenges for understanding its evolution alongside increasing anthropogenic activities. Rapid and substantial changes in land‐use, land‐management and industrial activities over the subcontinent, and warming in the Indian Ocean, have influenced the South Asian summer monsoon. These might continue to be significant drivers in the near‐term along with rising global greenhouse gas emissions. Deciphering the region's vulnerability to climate change requires an understanding of how these anthropogenic activities, acting on a range of spatial scales, have shaped the monsoon spatially and temporally. This review summarizes historical changes in monsoon rainfall characteristics, associated mechanisms, and the role of anthropogenic forcings, focusing on subseasonal variability and extreme events. Several studies have found intensified subseasonal extremes across parts of India and an increase in spatial variability of rainfall despite an overall weakening of seasonal rainfall in the monsoon core. However, understanding these changes remains challenging because of uncertainties in observations and climate models. The mechanisms and relative influences of various anthropogenic activities, particularly on subseasonal extremes, remain relatively underexplored. Large biases in the representation of relevant processes in global climate models limit the ability to attribute historical changes and make reliable projections. Nevertheless, recent advances in modeling these processes using higher‐resolution modeling frameworks provide new tools to investigate the Indian summer monsoon's response to various anthropogenic forcings. There is an urgent need to understand how these forcings interact to shape climate variability and change in this vulnerable region. This article is categorized under: Paleoclimates and Current Trends > Earth System Behavior

Indian summer monsoon: Extreme events, historical changes, and role of anthropogenic forcings

India, a mega-diverse country, possesses a wide range of climate and vegetation types along with a varied topography. The present study has classified forest types of India based on multi-season IRS Resourcesat-2 Advanced Wide Field Sensor (AWiFS) data. The study has characterized 29 land use/land cover classes including 14 forest types and seven scrub types. Hybrid classification approach has been used for the classification of forest types. The classification of vegetation has been carried out based on the ecological rule bases followed by Champion and Seth's (1968) scheme of forest types in India. The present classification scheme has been compared with the available global and national level land cover products. The natural vegetation cover was estimated to be 29.36% of total geographical area of India. The predominant forest types of India are tropical dry deciduous and tropical moist deciduous. Of the total forest cover, tropical dry deciduous forests occupy an area of 2,17,713 km(2) (34.80%) followed by 2,07,649 km(2) (33.19%) under tropical moist deciduous forests, 48,295 km(2) (7.72%) under tropical semi-evergreen forests and 47,192 km(2) (7.54%) under tropical wet evergreen forests. The study has brought out a comprehensive vegetation cover and forest type maps based on inputs critical in defining the various categories of vegetation and forest types. This spatially explicit database will be highly useful for the studies related to changes in various forest types, carbon stocks, climate-vegetation modeling and biogeochemical cycles.

Nationwide classification of forest types of India using remote sensing and GIS

Mapping and assessment of vegetation types in the tropical rainforests of the Western Ghats using multispectral Sentinel-2 and SAR Sentinel-1 satellite imagery

Landsat-8 and Sentinel-2 based Forest fire burn area mapping using machine learning algorithms on GEE cloud platform over Uttarakhand, Western Himalaya

India has experienced significant Land-Use and Land-Cover Change (LULCC) over the past few decades. In this context, careful observation and mapping of LULCC using satellite data of high to medium spatial resolution is crucial for understanding the long-term usage patterns of natural resources and facilitating sustainable management to plan, monitor and evaluate development. The present study utilizes the satellite images to generate national level LULC maps at decadal intervals for 1985, 1995 and 2005 using onscreen visual interpretation techniques with minimum mapping unit of 2.5 hectares. These maps follow the classification scheme of the International Geosphere Biosphere Programme (IGBP) to ensure compatibility with other global/regional LULC datasets for comparison and integration. Our LULC maps with more than 90% overall accuracy highlight the changes prominent at regional level, i.e., loss of forest cover in central and northeast India, increase of cropland area in Western India, growth of peri-urban area, and relative increase in plantations. We also found spatial correlation between the cropping area and precipitation, which in turn confirms the monsoon dependent agriculture system in the country. On comparison with the existing global LULC products (GlobCover and MODIS), it can be concluded that our dataset has captured the maximum cumulative patch diversity frequency indicating the detailed representation that can be attributed to the on-screen visual interpretation technique. Comparisons with global LULC products (GlobCover and MODIS) show that our dataset captures maximum landscape diversity, which is partly attributable to the on-screen visual interpretation techniques. We advocate the utility of this database for national and regional studies on land dynamics and climate change research. The database would be updated to 2015 as a continuing effort of this study.

Jyotihman Deka

Papers

Development of Decadal (1985–1995–2005) Land Use and Land Cover Database for India