To assess the long-term trends of isoprene emissions in northern China andthe impact of the Three-North Shelter Forest Program (TNRSF) onthese trends, a database of historical biogenic isoprene emissions from 1982to 2010 was developed for this region using a biogenic emission model forgases and aerosols. The total amount of the biogenic isoprene emissionsduring the 3 decades was 4.4 Tg in northern China and 1.6 Tg in the TNRSF,with annual emissions ranging from 132 000 to 176 000 t yr andfrom 45 000 to 70 000 t yr, respectively, in the two regions.Isoprene emission fluxes have increased substantially in many areas of theTNRSF over the last 3 decades due to the growing trees and vegetationcoverage, especially in the central north China region where the highestemission incline reached to 58 % from 1982 to 2010. Biogenic isopreneemissions produced from anthropogenic forests tended to surpass thoseproduced from natural forests, such as boreal forests in northeastern China.The estimated isoprene emissions suggest that the TNRSF has altered thelong-term emission trend in north China from a decreasing trend during 1982to 2010 (slope = −0.533, = 0.05) to an increasing trend for thesame period of time (slope = 0.347, = 0.014), providing strongevidence for the change in the emissions of biogenic volatile organiccompounds (BVOCs) induced by the human activities on decadal or longertimescales.
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