GENERAL ARTICLES CURRENT SCIENCE, VOL. 120, NO. 3, 10 FEBRUARY 2021 479 Vibha Singhal is in the ICAR-Indian Institute of Soil and Water Con- servation, Dehradun 248 195, India; Dinesh Jinger is in the ICAR- Indian Institute of Soil and Water Conservation, Research Centre, Vasad, Anand 388 306, India; Jyotirmoy Ghosh is in the ICAR-Indian Institute of Natural Resins and Gums, Namkum 834 010, India. *For correspondence. (e-mail: singhalvibha76@gmail.com) Are we conscious of isoprene emissions from our poplar plantations? Vibha Singhal*, Dinesh Jinger and Jyotirmoy Ghosh The growing energy demand and increasing pollution due to conventional energy sources prompted the concept of bioenergy plantations, which are considered as carbon neutral. The area under bio- energy plantations is increasing rapidly to meet economical and ecological societal needs. Poplar is one of the most important sources of green energy amongst all species. It is widely cultivated as a bioenergy crop due to its fast growth, short rotation and carbon neutrality. However, one of the major aspects that we must consider is that it is a strong emitter of isoprene which can alter ozone flux in the atmosphere. Owing to its extremely reactive nature, isoprene may substantially influence the tropospheric composition by affecting its oxidative capacity with serious impact on air health, global warming, ecological functions and thus human life. We should assess isoprene emissions from existing poplar plantations and the expected increase in isoprene load with future expansion of poplar plantations in India, to know their long-term effect on atmospheric chemistry and climate change. This will help in deciding whether we should further promote poplar plantations, or look for suitable alternative non-/low-emitting species for bioenergy plantations. Keywords: Bioenergy plantations, global warming, isoprene, ozone, poplar. INCREASING pollution, deficit resources of fossil fuels and issues of energy security paved the way for the exploration of green energy sources. Use of woody bio- mass is increasing in India and all over the world. Amongst all green energy sources, poplar has emerged as the most potential source of bioenergy. Poplar, being a fast-growing and short-rotation crop, is suitable and highly productive for energy plantations. It is being extensively used in short-rotation bioenergy plantations for the production of cellulose worldwide. Such energy plantations of poplar are common in India and China 1,2 . Poplar as a source of bioenergy is a renewable substitute to fossil fuels 3 . The green sources of energy are carbon neutral and possess carbon sequestration potential. There- fore, the attraction of bioenergy plantations is not limited to economic interests alone, but these energy sources also have tremendous potential to mitigate climate change and global warming 4 . However, one facet of the bioenergy plantations has not been given due attention which certainly impacts their environment-friendly status. This aspect is the release of BVOC (biogenic volatile organic compounds) by vegetation, particularly the chosen bio- energy trees. Vegetation-originated emission of VOCs has been estimated to be ten times higher than those released by anthropogenic sources on the global basis 5 . Isoprenoid is one of the most abundant and significant groups of BVOCs. Isoprene, a chemical constituent of the isoprenoid group, represents about 50% of the global BVOCs emission. It produces a diversity of compounds on reacting with OH and NO x through a chain of reac- tions. These compounds are carbon monoxide, ozone, organic acids, nitrates, peroxyacetyl nitrate and aerosols 6 . Most of the tree species planted in the bioenergy planta- tion (poplar, willow, eucalyptus and oil palm) across the world are strong emitters of isoprene. Green sources of bioenergy are considered as carbon neutral, but isoprene emission from bioenergy trees may have a greater impact than CO 2 on atmospheric composition. Poplar plantations are expanding rapidly for production of biomass, which would enhance tropospheric ozone by increased isoprene emission, detrimental to ecosystem and human health. International and national status of poplar The poplar cover under plantations was estimated to be 31.4 million ha in 2016 across the world 7 . Different pro- portions of global area under poplar plantations serve different purposes, such as 58% area is managed for mul- tifarious uses, 30% for procurement of wood, 9% for environmental health and management, and rest 3% for meeting the energy needs in terms of fuelwood. Canada recorded the highest area under poplar (69% of the global