ESTIMATION OF GLOBAL CO_2 EMISSION FROM SOIL USING TEMPERATURE AND WATER CONTENT MEASURED BY MODIS

摘要

Soil is a major carbon (C) reserve in terrestrial ecosystems, and the CO_2 flux from soil (soil respiration: SR) is an important component of the C balance between terrestrial ecosystems and atmosphere. SR rate was affected by soil temperature and/or soil water content, therefore with their spatial and temporal variations. Few studies had estimated the global annual soil respiration based on experimental equations by field observation and actual climate data. The object of the this study is to estimate the annual SR on the global scale using the experimental equations and climate products of land surface temperature and Keetch-Byram drought index from MODIS measurements. The empirical equations for estimation of SR rate were selected from field observations at 14 ecosystems. The field observation studies indicated that SR rates in boreal and tropical region were dependent on soil temperature and soil water content respectively. SR in temperate region was deminated by temporal variation of both soil temperature and water content. Annual mean SR at 14 ecosystems were estimated, although they ranged from 291 to 1883 gC m~(-2) y~(-1). In the future work, we will compare the result of biogeochemical model (VISIT) and previous studies (e.g. Bond-Lamberty and Thomson, 2010) with that of this study.