Cairns, Michael A., J. K. Winjum, Donald L. Phillips, T. P. Kolchugina, and T. S. Vinson. 1997. Biogenic carbon flux: case studies in the former Soviet Union, the coterminous United States, Mexico, and Brazil. Mitigation and Adaption Strategies for Global Changes 1:363-83
This research assessed land-use impacts on C flux at a national level in four countries: former Soviet Union, United States, Mexico, and Brazil, including biotic processes in terrestrial ecosystems (closed forests, woodlands, and croplands), harvest of trees for wood and paper products, and direct C emission from fires. The terrestrial ecosystems of the four countries contain approximately 40% of the worlds terrestrial biosphere C pool, with the FSU alone having 27% of the global total. Average phytomass C densities decreased from south to north while average soil C densities in all three vegetation types generally increased from south to north. The C flux from land cover conversion was divided into a biotic component and a land-use component. We estimate that the total net biotic flux (Tg/yr) was positive (= uptake) in the FSU (631) and the U.S. (332), but negative in Mexico (-37) and Brazil (-16). In contrast, total flux from land use was negative (= emissions) in all four countries (TgC/yr): FSU -342; U.S. -243; Mexico -35; and Brazil -235. The total net effect of the biotic and land-use factors was a C sink in the FSU and the U.S. and a C source in both Brazil and Mexico.