BIOMASS
Amazonian forests play a key role in the global carbon cycle, thus increases
their significance, but there is much uncertainty about the quantity and
distribution of carbon stored in these forests.
The rapid conversion of tropical forests is a major source of greenhouse
gases such as carbon dioxide, methane, and nitrous oxide, which are the principle
causes of global warming (Houghton and Fearnside). Nowhere is deforestation
occurring more rapidly than in Brazilian Amazonia, which contains about
40% of the world's remaining tropical rainforests ( Laurance et al., 2001a).
From 1995 to 1999, deforestation rates in the Brazilian Amazon averaged nearly
2 million hectares per year ( INPE, 2000), not including extensive forest
areas degraded by logging, ground fires, forest fragmentation, illegal gold-mining,
and overhunting ( Skole; Laurance; Cochrane and Nepstad).
Despite the important role of Amazonian forests in the global carbon cycle
(Fearnside, 1997a), data on biomass and carbon storage in the region are
clearly inadequate (e.g. Brown; Brown and Brown). Biomass estimates for Amazonian
forests have been the subject of considerable debate (e.g. Brown; Brown;
Fearnside; Fearnside and Fearnside) because of limited data, methodological
differences among investigators, and small or incomplete measurements of biomass
in some studies (cf. Houghton et al., in press). Current estimates of total
carbon storage in Brazilian Amazonia vary by more than a factor of 2, from
39 to 93 Pg C, largely as a result of uncertainty in the quantity and spatial
distribution of forest biomass ( Houghton et al., in press). Houghton et
al. (2000) concluded that 60% of the uncertainty in their estimates of annual
carbon flux from Brazilian Amazonia resulted from varying estimates of forest
biomass. Clearly, there is a need for additional measurements of biomass
across large expanses of the Amazon basin.
In a recent study, Laurance et al. (1999) assessed the relationship between
soil features and aboveground biomass of live trees for 65 1 ha plots arrayed
across an extensive (ca. 1000 km2) central Amazonian landscape.
Biomass estimates in this study were generated by measuring diameters
of all large (10 cm diameter-at-breast-height (DBH)) trees and then using
a correction factor to approximate biomass of small (<10 cm DBH) trees.
Here they provide a much more comprehensive estimate of aboveground biomass
for the same study area; based on 20 randomly selected 1 ha plots in which
biomass of all live and dead material (large trees, small trees, seedlings,
palms, lianas, downed wood debris, snags, litter, and aboveground root mat)
was quantified.
Next page
References:
Brown, J.K., 1974. Handbook for Inventorying Downed Woody Material. USDA
Forest Service, Ogden, UT, 25 pp.
Brown, S., 1997. Estimating Biomass and Biomass Change of Tropical Forests:
A Primer. Forestry Paper 134, FAO, Rome.
Brown, S. and Lugo, A.E., 1984. Biomass of tropical forests: a new estimate
based on forest volumes. Science 223, pp. 1290¯1293. Abstract-GEOBASE
Brown, S., Lugo, A.E., 1990. Biomass estimates for Brazil's Amazonian moist
forests. In: Forest'90: Annals of the First International Symposium on Environmental
Studies on Tropical Rain Forests, Manaus, Brazil, pp.46¯52.
Brown, S. and Lugo, A.E., 1992. Aboveground biomass estimates for tropical
moist forests of the Brazilian Amazon. Interciencia 17, pp. 8¯18.
Brown, S., Lugo, A.E. and Iverson, L.R., 1992. Processes and lands for sequestering
carbon in the tropical forest landscape. Water Air Soil Pollut. 64, pp.139¯155.
Abstract-Compendex | Abstract-GEOBASE | Abstract-EMBASE
Brown, I.F., Nepstad, D.C., Pires, O., Luz, L.M. and Alechandre, A.S., 1992.
Carbon storage and land-use in extractive reserves, Acre, Brazil. Environ.
Conserv. 19, pp. 307¯315. Abstract-GEOBASE
Brown, I.F., Martinelli, L.A., Thomas, W.W., Moreira, M.Z., Ferreira, C.A.
and Victoria, R.A., 1995. Uncertainty in the biomass of Amazonian forests:
an example from Rondônia, Brazil. Forest Ecol. Mgmt. 75, pp. 175¯189. Abstract
| PDF (1041 K)
Cochrane, M.A., Alencar, A., Schulze, M.D., Souza, C.M., Nepstad, D.C.,
Lefebvre, P. and Davidson, E., 1999. Positive feedbacks in the fire dynamics
of closed canopy tropical forests. Science 284, pp. 1832¯1835. Abstract-EMBASE
| Abstract-Elsevier BIOBASE | Abstract-Elsevier BIOBASE | Abstract-EMBASE
| Full Text via CrossRef
Fearnside, P.M., 1985. Brazil's Amazon forest and the global carbon problem.
Interciencia 10, pp. 179¯186.
Fearnside, P.M., 1986. Brazil's Amazon forest and the global carbon problem:
reply to Lugo and Brown. Interciencia 11, pp. 58¯64.
Fearnside, P.M., 1992. Forest biomass in Brazilian Amazonia: comments on
the estimate by Brown and Lugo. Interciencia 17, pp. 19¯27.
Fearnside, P.M., 1997. Wood density for estimating forest biomass in Brazilian
Amazonia. Forest Ecol. Mgmt. 90, pp. 59¯87. Abstract | PDF (1489 K)
Fearnside, P.M., 2000. Global warming and tropical land-use change: greenhouse
gas emissions from biomass burning, decomposition and soils in forest conversion,
shifting cultivation and secondary vegetation. Climatic Change 46, pp. 115¯158.
Abstract-GEOBASE | Abstract-Elsevier BIOBASE | Abstract-BIOTECHNOBASE |
Full Text via CrossRef
Fearnside, P.M. and Barbosa, R.I., 1998. Soil carbon changes from conversion
of forest to pasture in Brazilian Amazonia. Forest Ecol. Mgmt. 108, pp.
147¯166. SummaryPlus | Full Text + Links | PDF (198 K)
Houghton, R.A., Lawrence, K.T., Hackler, J.L., Brown, S., in press. The spatial
distribution of forest biomass in the Brazilian Amazon: a comparison of estimates.
Glob. Change Biol.
Laurance, W.F., Laurance, S.G., Ferreira, L.V., Rankin-de Merona, J.M., Gascon,
C. and Lovejoy, T.E., 1997. Biomass collapse in Amazonian forest fragments.
Science 278, pp. 1117¯1118. Abstract-EMBASE |
Abstract-GEOBASE | Full Text via CrossRef
Laurance, W.F., Fearnside, P.M., Laurance, S.G., Delamonica, P., Lovejoy,
T.E., Rankin-de Merona, J.M., Chambers, J.Q. and Gascon, C., 1999. Relationship
between soils and Amazon forest biomass: a landscape-scale
study. Forest Ecol. Mgmt. 118, pp. 127¯138. SummaryPlus | Full Text + Links
| PDF (164 K)
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