Part II Workshop Working Group Papers

Water, Air, and Soil Pollution

, Volume 70, Issue 1, pp 71-94

First online:

Tropical forests: Their past, present, and potential future role in the terrestrial carbon budget

  • Sandra BrownAffiliated withDepartment of Forestry, University of Illinois
  • , Charles A. S. HallAffiliated withDepartment of Environmental and Forest Biology, College of Environmental Science and Forestry, State University of New York
  • , Wilhelm KnabeAffiliated withEnvironmental Research and Consultancy
  • , James RaichAffiliated withDepartment of Botany, Iowa State University
  • , Mark C. TrexlerAffiliated withTrexler and Associates
  • , Paul WoomerAffiliated withTSBF, c/o UNESCO-ROSTA

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access


In this paper we review results of research to summarize the state-of-knowledge of the past, present, and potential future roles of tropical forests in the global C cycle. In the pre-industrial period (ca. 1850), the flux from changes in tropical land use amounted to a small C source of about 0.06 Pg yr−1. By 1990, the C source had increased to 1.7 ± 0.5 Pg yr−1. The C pools in forest vegetation and soils in 1990 was estimated to be 159 Pg and 216 Pg, respectively. No concrete evidence is available for predicting how tropical forest ecosystems are likely to respond to CO2 enrichment and/or climate change. However, C sources from continuing deforestation are likely to overwhelm any change in C fluxes unless land management efforts become more aggressive. Future changes in land use under a “business as usual” scenario could release 41–77 Pg C over the next 60 yr. Carbon fluxes from losses in tropical forests may be lessened by aggressively pursued agricultural and forestry measures. These measures could reduce the magnitude of the tropical C source by 50 Pg by the year 2050. Policies to mitigate C losses must be multiple and concurrent, including reform of forestry, land tenure, and agricultural policies, forest protection, promotion of on-farm forestry, and establishment of plantations on non-forested lands. Policies should support improved agricultural productivity, especially replacing non-traditional slash-and-burn agriculture with more sustainable and appropriate approaches.