Biomass estimation in the Tapajos National Forest, Brazil : examination of sampling and allometric uncertainties
Changes in the biomass of Amazon region forests represent an important component of the global carbon cycle but the biomass of these forests remains poorly quantified. Minimizing the error in forest biomass estimates is necessary in order to reduce the uncertainty in future Amazon carbon budgets. We examined forest survey data for trees with a diameter at breast height (DBH) greater than 35cm from four plots with a total area of 392ha in the Tapajos National Forest near Santarem, Para, Brazil (3°04′S, 54°95′W). The average frequency of trees greater than 35cm DBH was approximately 55ha−1. Based on tree diameters, allometric relations, and published relations for biomass in other compartments besides trees of DBH>35cm, we estimated a total biomass density of 372Mgha−1. We produced a highly conservative error estimate of about 50% of this value. Trees with diameters greater than 35cm DBH accounted for about half of the total biomass. This estimate includes all live and dead plant material above- and below-ground with the exception of soil organic matter. We propagated errors in sampling and those associated with allometric relations and other ratios used to estimate biomass of roots, lianas and epiphytes, and necromass. The major sources of uncertainty in our estimate were found in the allometric relations for trees with DBH greater than 35cm, in the estimates of biomass of trees with DBH less than 35cm, and in root biomass. Simulated sampling based on our full survey, suggests that we could have estimated mean biomass per hectare for trees (DBH≥35cm) to within 20% (sampling error only) with 95% confidence by sampling 21 randomly selected 0.25ha plots in our study area.
| Main Authors: | , , |
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| Format: | Texto biblioteca |
| Language: | eng |
| Published: |
Amsterdam Elsevier
2001
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| Subjects: | BIOMASA, ALOMETRIA, ESTIMACION, MUESTREO, CICLO DEL CARBONO, ARBOLES, MEDICION, DIAMETRO A LA ALTURA DE PECHO, ECUACIONES ALOMETRICAS, BIOMASS, ERROR ESTIMATION, ALLOMETRY, AMAZON, BRAZIL, AMAZONAS (BRASIL), |
| Online Access: | http://orton.catie.ac.cr/repdoc/A11166i/A11166i.pdf |
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