Intact rainforests have a long-term storage capacity.
With fossil-fuel combustion and land-use activities threatening to double atmospheric carbon dioxide this century1, maintaining large forests as carbon reservoirs becomes an additional conservation incentive. We have developed a stochastic-empirical model that simulates forest-carbon cycling and now use this model to explore the response of the central Amazonian forest to an increase in biomass productivity. Our results show that these trees will accumulate carbon in their wood for more than a century after a productivity increase, underscoring the value of intact tropical forests.
Evidence from eddy covariance studies2, analysis of forest inventory plots3, and atmospheric inversion models4 indicate that undisturbed neotropical forests remove a significant portion of human-derived CO2 emissions from the atmosphere. Although these results do not provide insight into causal factors, open-top chamber experiments indicate that CO2 doubling enhances the production of woody tissue per unit leaf area by about 25% (ref. 5), and plant physiological ecology provides a mechanistic basis for this response6.
The response of forest carbon storage to higher productivity is a function of the fraction of production allocated to, and the residence time of, the component reservoir6. Large wood (trunks and branches of or over 10 cm diameter and roots over 5 cm diameter) in central Amazon forest represents about 45% of total carbon storage and 30% of above-ground production, with a mean residence time of 80 years. Thus, compared with other ecosystem components, large wood has a high storage capacity, with a relatively long lag time after disturbance. Passive soil organic matter also has a large storage capacity, but carbon movement into this pool is very slow7.
Our model8 was parameterized using extensive field data of individual trees larger than 10 cm base diameter (Db), including recruitment, growth and mortality (n=18 hectares), tree allometry (327 trees)9, maximum size of trees (n=220 species), wood density (n=268 species), and wood decomposition10 rates (155 dead trees). The model starts by filling 20 × 20 m cells (stands) with a variable number of trees whose characteristics are assigned using random deviates from the empirical distributions. Each year, variation in recruitment, growth, mortality and decomposition determines the carbon balance of the entire plot (and aggregate of stands).
We demonstrated model reliability by comparing predictions with the same field data (respectively), including large wood (predicted, 164 Mg C ha−1; field value, 156 Mg C ha−1) and coarse litter (16 vs 15 Mg C ha−1) carbon stocks, large wood growth (1.6 vs 1.7 Mg C ha−1 yr−1) and mortality (1.8 vs 2.1 Mg C ha−1 yr−1) rates, mean Db (20.4 vs 21.1 cm), mean age for trees with greater than 100 cm Db (383 vs 425 yr), and maximum tree age11 (1,192 vs 1,372 yr).
We used this model to investigate the response of large-wood carbon storage to a 25% increase in production distributed over 50 years for a 100-ha plot. As expected, carbon accumulated during years of increasing productivity. But once the productivity increase stopped (as a result of other limiting factors), large wood continued to accumulate carbon for over a century (Fig. 1).
Central Amazon upland (non-flooded environments) trees grow very slowly (mean, 1.1 mm Db yr−1), and carbon storage only reached a new dynamic equilibrium once most trees had grown for their entire lives (mean age, 175 years) under conditions of enhanced productivity and the mass of a tree of mean Db had stabilized at a higher value.
Forests respond in complex ways to increased atmospheric CO2 and other global changes12, and our model does not include potential limitations to a productivity increase or changes in vegetation characteristics. But for a given increase in productivity, it reveals that large-wood carbon storage will exhibit a lengthy lag time.
Avoiding deforestation will help industrialized countries to meet their Kytoto protocol emission-reduction obligations. Deforestation not only transfers carbon stocks directly to the atmosphere by combustion, but it also destroys a valuable mechanism for controlling atmospheric CO2.
Given a large increase in productivity, we calculate the rate of carbon sequestration to be of the order of 0.2–0.3 petagrams of carbon per year (which amounts to US$2–3 billion per year at $10 per Mg C) for large wood of the intact forest in Amazonia (Fig. 2), compared to fossil-fuel emissions of roughly 6 Pg of C per year. In all scenarios that reduce emissions to levels commensurate with the Kyoto protocol, numerous net biospheric exchanges of carbon are important. But terrestrial sequestration can only offer a partial solution, so controlling atmospheric CO2 will require substantial reductions in fossil-fuel emissions in the coming decades.
References
Tans, P. P. et al. Science 247, 1431–1438 (1990).
Malhi, Y. & Grace, J. Trends Ecol. Evol. 15, 332–337 (2000).
Phillips, O. L. et al. Science 282, 439–442 (1998).
Keeling, R. F. et al. Nature 381, 218–221 (1996).
Norby, R. J. Plant Cell Environ. 22, 683–714 (1999).
Lloyd, J. Funct. Ecol. 13, 439–459 (1999).
Trumbore, S. E. et al. Glob. Biogeochem. Cycl. 9, 515–528 (1995).
Chambers, J. Q. The Role of Large Wood in the Carbon Cycle of Central Amazon Rain Forest. Thesis, Univ. California (1998).
Chambers, J. Q., Santos, J., Ribeiro, R. J. & Higuchi, N. For. Ecol. Manage. (in the press).
Chambers, J. Q. et al. Oecologia 122, 380–388 (2000).
Chambers, J. Q., Higuchi, N. & Schimel, J. P. Nature 391, 135–136 (1998).
Cox, P. M. et al. Nature 408, 184–187 (2000).
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Chambers, J., Higuchi, N., Tribuzy, E. et al. Carbon sink for a century. Nature 410, 429 (2001). https://doi.org/10.1038/35068624
Issue Date:
DOI: https://doi.org/10.1038/35068624
This article is cited by
-
A statistical modeling approach based on the small-scale field trial and meteorological data for preliminary prediction of the impact of low temperature on Eucalyptus globulus trees
Scientific Reports (2023)
-
Sound absorption properties of wood-based pulp fibre foams
Cellulose (2021)
-
Legacy effects of land-use modulate tree growth responses to climate extremes
Oecologia (2018)
-
Evaluation of Carbon Sequestration Potential in Amla (Emblica officinalis Gaertn.) Orchards in Semi-arid Region of India
Proceedings of the National Academy of Sciences, India Section B: Biological Sciences (2018)
-
Long-term carbon sink in Borneo’s forests halted by drought and vulnerable to edge effects
Nature Communications (2017)
Comments
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.