V. Krishna Prasad

Biomass burning and related trace gas emissions from tropical dry deciduous forests of India: A study using DMSP-OLS data and ground-based measurements

Biomass burning is one of the major sources of trace gas emissions in the atmosphere. In India the major sources of biomass burning include deforestation, shifting cultivation, accidental fires, controlled burning, fire wood burning, burning from agricultural residues and burning due to fire lines. Studies on biomass burning practices gain importance due to increasing anthropogenic activities and increasing rates of deforestation. Satellite data have been widely used over the globe to monitor the rates of deforestation and also with respect to biomass burning studies. But, much of the polar orbiting satellites, due to their repetitive cycle, have limitations in observing such events and in the tropics, due to cloud cover, getting a cloud-free image during the daytime is difficult. In this study we used Defence Meteorological Satellite Program Operational Line Scanner (DMSP-OLS) night-time data to study the biomass burning events over a period of 10 years from 1987 to 1998 for the Eastern Ghats region, covering the northern part of Andhra Pradesh, India. Two ground-based experiments were carried out to quantify the emissions from biomass burning practices. The results of the study with respect to trace gases suggested emission ratios for CO, CH4, NOx and N20 during the burning to be about 12.3%, 1.29%, 0.29% and 0.07% at the first site and 12.5%, 1.59%, 0.29% and 0.05% at the second site, suggesting low inter-fire variability between the sites. The variation has been attributed to the fuel load, vegetation characteristics, site conditions and local meteorological parameters affecting the relative amounts of combustion. Using the DMSP OLS derived areal estimates of active fires, the trace gas emissions released from the biomass burning were quantified. The results suggested the emissions of 8.2 2 10 10 g CO 2, 1.8 2 10 8 g CO, 6.0 2 10 6 g N 2 O, 3.0 2 10 6 g NO x and 1.2 2 10 8 8 g CH 4 during March 1987. The emissions increased to 1.0 2 10 11 g CO 2, 2.3 2 10 g CO, 7.8 2 10 6 g N 2 O, 3.9 2 10 7 g NO x and 1.6 2 10 8 g CH 4, over a period of 10 years. The results of the analysis suggest the possible use of monitoring biomass burning events from DMSP-OLS night-time data.

Variation in aerosol properties over Hyderabad, India during intense cyclonic conditions

In this study, we examine the changes in aerosol properties associated with an intense tropical cyclone, the so‐called ‘Mala’, that occurred during April 2006, over the Bay of Bengal. This cyclone, accompanied by very strong surface winds reaching 240 km h−1, caused extensive disasters in houses and beach resorts in the coastal areas of Myanmar. Ground‐based measurements of aerosol optical depth (AOD), particle‐size distribution and erythemal UV radiation in the neighbouring urban environment of Hyderabad, India, showed significant variations due to changes in wind velocity and direction associated with the cyclone event. The results show an increase in ground‐measured PM1.0, PM2.5, and PM10 concentrations, probably associated with the strong surface winds on 28 April, the day on which the cyclone affected the study region. In contrast, the AOD on that day exhibited a significant decrease, since the winds probably acted as a ventilation mechanism for the atmosphere. The Terra‐MODIS satellite images showed a prevalence of dust particles over the study region on the next day of the cyclone. Results from ground‐based AOD sun‐photometer observations matched well with satellite AOD retrievals. Aerosol index obtained from Ozone Monitoring Instrument (OMI) during the cyclone events suggested increasing trend, indicating the presence of an elevated dust‐aerosol layer during and after the cyclone. Results on the effects of wind and air mass fields in affecting the AOD during cyclone events are also presented.

Studies on aerosol optical depth in biomass burning areas using satellite and ground-based observations

Biomass burning in the tropics is a source of trace gas fluxes and particulate matter. During the last decade, the shifting cultivation practices have been increased in the tropical forest of Eastern Ghats, Andhra Pradesh, India. In order to quantify the fluxes emitted from the biomass burning due to shifting cultivation practices, a field experiment has been conducted on February 16-25, 1999. The present study provides the variation of aerosol optical depth over the shifting cultivation areas of Rampa Revenue Division, Eastern Ghats using a sunphotometer in synchronism with satellite data. Optical depth values increased up to 2.0 during the burning phase and then returned to normal values (0.2-0.5). The atmospheric correction of the satellite data using the optical depth values suggested improvement in the overall contrast of the image and increase in the dynamic range of the normalized difference vegetation index (NDVI) values of various features in the image.

CH4 emissions from biomass burning of shifting cultivation areas of tropical deciduous forests – experimental results from ground-based measurements

Abstract Context Abstract : Tropical deciduous fires from shifting cultivation process in India are characterized by the highly differential nature of fire behavior due to fragmented burning patterns. Our study from ground-based experiments from biomass burning of tropical deciduous forest fires suggests smoldering combustion as the dominating process during biomass burning which leads to evolution of more incompletely oxidized products such as Methane when compared to other ecosystems such as Savannas. In the study, we report emission ratios and emission factors for methane from biomass burning of tropical deciduous forests. As tropical deciduous forests in India cover more than 50% of overall forests, the emission factors obtained in the present study can be used widely for methane emission estimation from forest biomass burning studies in other parts of India and in modeling studies of Methane from forest biomass burning in India. Main Abstract : Biomass burning is an important source of trace gas emissions to the atmosphere. Methane emitted from the biomass burning contributes to the atmospheric greenhouse effect and is sufficiently long-lived to enter the stratosphere and take part in the stratospheric ozone cycles. In India, though CH 4 emissions from the different sources such as rice paddy fields and domestic animals have been well studied, there are relatively no field-based studies with respect to CH 4 emissions from biomass burning. In the present study, we report for the first time, the CH 4 emissions from biomass burning of tropical deciduous forests cleared for shifting cultivation purposes. Trace gas emissions from the biomass burning plumes have been collected through grab sampling in canisters as well as from online measurements through instruments. Site characteristics with respect to species composition, amount of biomass burnt and relative amounts of combustion, viz., flaming, mixed and smoldering have been determined. Modified combustion efficiency has been used to differentiate relative amounts of combustion. Emission ratios were calculated with respect to CO 2 and emission factors based on the amount of biomass consumed. Results of the study with respect to biomass estimations prior to burning suggested values of 12–14 t ha −1 at the first site and 13.5–15.3 t ha −1 at the second site. The mean modified combustion efficiencies during flaming, mixed and smoldering combustion phases for the first site were found to be 95.7%, 91.1% and 74.4% and 95.31%, 90.63% and 72.89%, respectively, for the second site. The average biomass consumed during the fire ranged from 4.7 t ha −1 (site 1) to 3.4 t ha −1 (site 2), indicating low amount of biomass burnt during the first phase of burning in shifting cultivation areas. Results suggested the CH 4 emission ratios of 1.29% at the first site and 1.59% at the second site. The CH 4 emission ratios obtained in the present study are closer to the most accepted estimates of 1.2±0.5% obtained for tropical forests elsewhere. Using the emission ratios obtained in the study and estimating the amount of methane emissions from biomass burning suggests that nearly 0.99 Tg of methane is emitted annually from shifting cultivation process in India. Also, in the study, a detailed comparison of emission ratios and emission factors of CH 4 has been made.

Algorithm for detection of active fire zones using NOAA AVHRR data

Abstract Forest fires in tropical countries have become one of the important sources of Green House Gases and cause damage to the forest ecosystems. Information relating to the extent and location of active fire zones needs immediate attention to facilitate effective management and mitigation of forest fires. The spectral intervals that are most suitable for the detection of forest fires are 3.5–4.2 and 4.4–5.0 μm. The maximum thermal emission of fires is localized using middle infrared and thermal infrared bands for automatic recognition of fire active zones. The algorithm considers the thresholds for middle infrared on the basis of channel saturation to discriminate the fire zones from background warm surface and thermal infrared (10.3–11.3 μm) to ensure it to be free from cloud and water bodies. Advanced Very High Resolution Radiometer (AVHRR) data of 1 km resolution have been taken and we apply a spatial technique using background information to dynamically define thresholds appropriate for identifying fire pixels. The study suggests that satellite data provide a unique tool to detect and monitor active fire distribution.

CENTURY ecosystem model application for quantifying vegetation dynamics in shifting cultivation areas: A case study from Rampa Forests, Eastern Ghats (India)

In India, slash and burn agriculture is one of the major factors contributing to deforestation, especially in the hilly north-eastern region and Eastern Ghats. Studies on vegetation dynamics associated with slash and burn agricultural practices have been intensively studied in the north-eastern part of India. These have covered semi-evergreen/evergreen vegetation, but similar studies on tropical mixed dry deciduous ecosystems are not as common. In the present study, we used the century ecosystem model to study vegetation dynamics in shifting cultivation areas on the mixed dry deciduous forests covering the Eastern Ghats of India. The site-specific parameters, temperature, precipitation, biomass and nutrient pools were used, and, by collecting information from local management practices, a 12-year shifting cultivation cycle during a 70-year period from 1960 to 2030 was simulated. century estimated a total loss of 239 tonnes carbon (tC) in soil organic matter over the simulation period, and the total nitrogen content of the soil organic matter showed an initial increase followed by a decline (344.3 g m2 during 1960 to less than 318.3 g m2 during 2030). century estimated that 66 tC ha−1 would be lost from the forest system, reducing the initial forest system carbon level from 118.5 tC ha−1. An increase in productivity from 0.49 tC ha−1 during 1960 to 1.2 tC ha−1 during the initial forest slash and burn in 1962 was observed, but thereafter productivity declined to 0.7 tC ha−1 during the year 2030. Results obtained in other studies of similar types of agricultural practices are also reviewed.

Soil surface nitrogen losses from agriculture in India: A regional inventory within agroecological zones (2000–2001)

We present soil surface nitrogen (N) budgets for the agricultural sector of India, calculated as inputs minus outputs over 21 agroecological zones (AEZ), for 2000–2001. Nearly 35.4 Tg N was input from different sources, with output from harvested crops of about 21.2 Tg N. Soil surface N balance for agricultural lands showed a surplus of about 14.4 Tg. Livestock manure constituted 44% of total inputs, followed by 32.5% from inorganic fertilizer, 11.9% from atmospheric deposition and 11.6% from N fixation. Though the N balance was negative in some states, due to aggregation of states in agroecological regions, all regions showed surplus N loads, with a range of about 19–110 kg/ha. The lowest loads were found for AEZ 17 in the Eastern Himalaya, with 19 kg/ha surplus, and the highest surplus N load in AEZ 7 with 111 kg/ha in Deccan plateau and the Eastern Ghats. Temporal trends in fertilizer consumption from 1950–2000 for India suggested a massive increase of ∼47-fold, whereas production of major crops, rice, wheat and maize, increased nearly ∼4.0-, 10- and 6-fold, respectively. Fertilizer consumption patterns were highly concentrated in Tamilnadu (204.6 kg/ha), Haryana (132.0 kg/ha) and Punjab (148.6 kg/ha). The paper addresses the role of agricultural intensification and its implications for water quality in agroecological regions of India.

Implications of Land Use Changes on Carbon Dynamics and Sequestration—Evaluation from Forestry Datasets, India

Forests and soils are a major sink of carbon, and land use changes can affect the magnitude of above ground and below ground carbon stores and the net flux of carbon between the land and the atmosphere. Studies on methods for examining the future consequences of changes in patterns of land use change and carbon flux gains importance, as they provide different options for CO2 mitigation strategies. In this study, a simulation approach combining Markov chain processes and carbon pools for forests and soils has been implemented to study the carbon flows over a period of time. Markov chains have been computed by converting the land use change and forestry data of India from 1997 to 1999 into a matrix of conditional probabilities reflecting the changes from one class at time t to another class time t+1. Results from Markov modeling suggested Indian forests as a potential sink for 0.94 Gt carbon, with an increase in dense forest area of about 75.93 Mha and decrease of about 3.4 Mha and 5.0 Mha in open and scrub forests, if similar land use changes that occurred during 1997–1999 would continue. The limiting probabilities suggested 34.27 percent as dense forest, 6.90 as open forest, 0.4 percent mangrove forest, 0.1 percent scrub and 58 percent as non-forest area. Although Indian forests are found to be a potential carbon sink, analysis of results from transition probabilities for different years till 2050 suggests that, the forests will continue to be a source of about 20.59 MtC to the atmosphere. The implications of these results in the context of increasing anthropogenic pressure on open and scrub forests and their contribution to carbon source from land use change and forestry sector are discussed. Some of the mitigation aspects to reduce greenhouse gas emissions from land use change and forestry sector in India are also reviewed in the study.

Emissions from grassland burning in Kaziranga National Park, India – analysis from IRS-P6 AWiFS satellite remote sensing datasets

Biomass burning from vegetation fires is an important source of greenhouse gas emissions. In this study, we quantify biomass burning emissions from grasslands from the highly sensitive Kaziranga National Park, Assam, Northeast India. Most of the fires in the park are ‘controlled burning fires’ set by the park officials for management purposes. We evaluated the short-term impacts of fires and the resulting air pollution through integrating biomass burnt information from satellite remote sensing datasets. IRS-P6 Advanced Wide Field Sensor (AWiFS) data during March and April corresponding to dry season were evaluated to delineate the burnt areas. These burnt area estimates were then integrated with biomass data and emission factors for quantifying the greenhouse gas emissions. Results suggested that of the total study area of 37,822 ha, nearly 3163.282 ha has been burnt during March, 2005. Within one month, the burnt area increased to 7443.92 ha by April, i.e., from 8.36% to 19.68%. In total, biomass burning from the grasslands contributed to 29.65 Tg CO2, 1.19 Tg CO, 0.071 Tg NOx, 0.042 Tg CH4, 0.0625 Tg total non-methane hydrocarbons, 0.152 Tg of particulate matter, and 0.062 Tg of organic carbon and 0.008 Tg of black carbon during April. The importance of ‘fire’ as a management tool for maintaining the wildlife habitat has been highlighted in addition to some of the adverse affects of air pollution resulting from such management practices. The results from this study will be useful to forest officials as well as policy makers to undertake some sustainable forest management practices to maintain an ideal habitat for Kazirangas wildlife.

Vegetation discrimination using irs-p3 wifs temporal dataset - a case study from rampa forests, eastern ghats, a.p.

Multitemporal data sets from coarse resolution sensors of Indian Remote Sensing Satellites provides an opportunity to classify various forest types using their phenological attributes reflected in temporal NDVI profiles. The present study attempts to classify various vegetation classes using time integrated NDVI (T-NDVI) values derived from IRS-P3 WiFS data. The algorithm explores the differential characteristics in T-NDVI values of different features and the results suggest the possible use of the methodology for forest type classification.