HR: 0800h
AN: B51C-0235    [Abstracts]
TI: Apparent Trends in Productivity of Monsoon Asia from 1982 to 2002
AU: * Alexandrov, G A
EM: g.alexandrov@nies.go.jp
AF: National Institute for Environmental Studies, Onogawa 16-2, Tsukuba, 305-8506 Japan
AU: * Alexandrov, G A
EM: g.alexandrov@nies.go.jp
AF: Institute of Atmospheric Physiscs (RAS), Pyzhevsky 3, Moscow, 305-8506 Russian Federation
AU: Yamagata, Y
B51C-0235 AF: National Institute for Environmental Studies, Onogawa 16-2, Tsukuba, 305-8506 Japan
AB: The rapid economic growth of Monsoon Asia raises concerns about the future of carbon stored in the terrestrial ecosystems of the region, especially in connection with climate change. The regional carbon budget for 1980s suggests that Monsoon Asia as a whole acted as source [Tian et al., 2003], although some parts of the region acted as sink. Here we provide some evidence from satellite data that productivity of the region changed in the manner that suggests similar conclusion. Comparing the period 1982-1992 and the period 1992-2002, we found that the productivity of the territory generally decreased in the forest zone and increased in the non-forest zone of the region. The productivity of a territory strongly depends on the area covered with photosynthetically active vegetation (PAV) and, therefore, we introduce a grid variable, FPAV, which stands for the fraction of a grid cell covered with PAV. (Grid, here, means geographic grid of half-degree resolution.) Deciduous plants are leafless during the dormant season, and so FPAV may vary on seasonal basis. The amplitude enlarges with the ratio between deciduous and evergreen species. The minimal value of FPAV gives the fraction of a grid cell covered with evergreen vegetation. The maximal value gives the fraction of the cell that covered either with deciduous or evergreen vegetation and, thus, tells us which fraction of the cell is vegetated. The changes in FPAV were tracked by using monthly values of AVHRR-NDVI for the period from July 1981 to December 2002 that were recently compiled into a public data set, so called GIMMS-NDVI [see Slayback et al., 2003 and references therein]. We calculated average monthly values of GIMMS-NDVI for two 11-year periods: from 1982 to 1992 and from 1992 to 2002, and used them to evaluate the trends in productivity of the region, characterized by the product of FPAVmax and Pn, where Pn is net primary production of potential natural vegetation, calculated by using TsuBiMo-model, FPAVmax is the maximal value of FPAV. This net increase in vegetated area of non-forest zone implies additional net primary production of 19 MtC/yr. However, this cannot compensate the losses associated with the net decrease in vegetated area of the forest zone. Therefore the total productivity of the region is estimated to drop by 64 MtC/yr. (It is worth to mention here, that comparing the 11-year periods we filter out the effects related to short-term monsoon variability, but this cannot exclude the effects related to "monsoon epochs".)
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0426 Biosphere/atmosphere interactions (0315)
DE: 0428 Carbon cycling (4806)
DE: 0466 Modeling
DE: 0480 Remote sensing
SC: Biogeosciences [B]
MN: Fall Meeting 2005