Abha Chhabra

Growing stock-based forest biomass estimate for India

The total standing biomass (including above ground and below ground) in Indian forests for the year 1992–93 was estimated using information on state and union-territory field inventory based growing stock volume and the corresponding area under three different crown density classes (very dense forests with crown cover 70 percent and above, dense forest with crown cover 40 percent but <70 percent and open forests with crown cover between 10 and 40 percent) grouped under four major forest categories (hardwood, spruce-fir, pine and bamboo) by Forest Survey of India. The growing stock volume was converted to total biomass using biomass expansion factors as function of growing stock volume density. The average growing stock volume density in Indian forests for the study year 1992–93 was but it varied amongst states, with a range of in Punjab to in Jammu and Kashmir. The total standing biomass (above ground and below ground) was estimated as . The aboveground and belowground biomass was estimated as 6865.1 and , contributing 79 and 21 percent to the total biomass, respectively. The mean biomass density in Indian forests was estimated as and amongst the states it varied from in Punjab to in Jammu and Kashmir, respectively. The estimates have been compared with previous studies, which had estimated biomass in the range of 4400– for the corresponding period. Our results are an improvement over previous estimates as these incorporate biomass expansion factors which relate wood volume to biomass as a function of growing stock volume density, four forest types and three crown density classes of Indian forests. These improved biomass estimates are crucial to assess the total C pool of forests and further for use as inputs to models to estimate net C flux to atmosphere from Indian forests due to deforestation and landuse changes.

Non-point source pollution in Indian agriculture: Estimation of nitrogen losses from rice crop using remote sensing and GIS

abstract The paper presents a detailed understanding of nitrogenous fertilizer use in Indian agriculture and esti-mation of seasonal nitrogen loosses from rice crop in Indo-Gangetic plain region, the ‘food bowl’oftheIndian sub-continent. An integrated methodology was developed for quantification of different forms ofnitrogen losses from rice crop using remote sensing derived inputs, field data of fertilizer application,collateral data of soil and rainfall and nitrogen loss coefficients derived from published nitrogen dynam-ics studies. The spatial patterns of nitrogen losses in autumn or ‘kharif’ and spring or ‘rabi’ season rice at1×1km grid were generated using image processing and GIS. The nitrogen losses through leaching informofurea-N,ammonium-N(NH 4 -N)andnitrate-N(NO 3 -N)aredominantoverammoniavolatilizationloss. The study results indicate that nitrogen loss through leaching in kharif and rabi rice is of the orderof 34.9% and 39.8% of the applied nitrogenous fertilizer in the Indo-Gangetic plain region. This studyprovides a significant insight to the role of nitrogenous fertilizer as a major non-point source pollutantfrom agriculture.© 2010 Elsevier B.V. All rights reserved.