Carbon Stock in Slash and Burn and Alternative Land Uses at ASB Benchmark Sites in the Humid Tropics
Entry ID: CGIAR_ASB_CStock

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Summary
Abstract: Carbon stocks were measured in the soils and vegetation in 94 sites in the
three ASB benchmark countries (Brazil, Cameroon, Indonesia) and in an
additional 22 sites in PerĂº. The sites sampled in each country included
undisturbed or selectively logged forests as the reference point; areas that
had been recently slashed, burned, and cropped; and areas that were
subsequently planted to pastures, tree plantations or agroforests, or areas
abandoned to fallow regrowth. This dataset, compiled by the ASB benchmark team,
is unique in that it provides data collected and analyzed by standardized
methods across sites. In addition, the information in this dataset on the
carbon stocks and carbon accumulation rates in young fallow vegetation and
agroforestry and plantation systems are rare for the tropics.

Geographic Coverage
 N: 12.0 S: -55.0  E: 55.0  W: 10.0

Data Set Citation
Dataset Originator/Creator: Consultative Group on International Agricultural Research (CGIAR)
Dataset Title: Carbon stock in slash-and-burn and alternative land uses at ASB Benchmark sites in the humid tropics


Temporal Coverage
Start Date: 2000-01-01
Stop Date: 2000-12-31


Location Keywords
CONTINENT > AFRICA > CENTRAL AFRICA > CAMEROON
OCEAN > INDIAN OCEAN > INDONESIA
CONTINENT > SOUTH AMERICA > BRAZIL
CONTINENT > SOUTH AMERICA > PERU


Science Keywords
LAND SURFACE >SOILS >CARBON    [Definition]


ISO Topic Category
BIOTA


Quality
The current dataset allows for general comparison of C stocks and time-averaged
C values among general land-use types, but some caution must be taken in using
these estimates. There are several steps in which errors may affect the
accuracy of the estimates. These include small plot sizes for estimating the
biomass of large trees, insufficient numbers of replicates, and inappropriate
allometric equations for estimating tree biomass for some of the systems.

The total area sampled for tree biomass at each site was 500 m2 (= quadrat size
(00m2) multiplied by five (quadrats per site). Although this may be sufficient
in areas where trees are small, < 25 cm diameter at breast height (dbh), it is
much less than the 2,500 m2 recommended by Brown et al., (1995) for obtaining
accurate measurements in tropical forests where much larger trees are
encountered. The protocol has now been modified to increase the quadrat size
to 5m X 100m in areas where there are trees with a dbh >25cm.

The above- and below-ground C estimates for most of the land-use systems were
obtained from only three or four true field site replicates (in each field
site, estimates were obtained from an average of five quadrats =
pseudoreplicates). In some cases the variability was quite low, but in others
it was unacceptably large, and in other cases the estimates were obtained from
only two field site replicates. If these C values are to be used for modeling
and national inventories, then the accuracy must be improved by increasing the
number of replicates.

Another source of error could be related to the allometric equation used for
estimating the biomass of trees based on their diameter. The current equation
was developed primarily for mature forests that often included only trees
greater than 10 or even 25 cm in diameter (Brown et al., 1989). In addition,
the density of the wood in these mature systems may be greater than that in
young, regrowing systems. There are indications that this equation may
overestimate the C of trees of dbh < 25cm, which, in fact, includes most of the
trees in the secondary forests, fallows, agroforestry and tree plantations
measured at the ASB sites. New equations being developed based on extensive
sampling of trees in young fallows (Ketterings and van Noordwijk for Indonesia
and Palm and Szott for PerĂº) give estimates half those obtained from the Brown
equation. Several other recent studies have shown a considerable range in
allometric equations for both primary and secondary forests in the humid
tropics of Brazil (Alves et al., 1997; Araujo et al., 1999; Nelson et al.,
1999).

Application of these new equations to young, regrowing fallow and agroforestry
systems will affect carbon stock estimates and rates of C accumulation. Such
systems are currently of interest to the global change community as there is
debate on how much C is taken up by regrowing vegetation. Once new equations
for smaller diameter trees and for specific agroforestry species have been
agreed upon, then C stocks, C accumulation rates, and time-averaged C values
for many of these systems can be improved relatively rapidly. In addition,
since most of the C in these systems is in the trees, we would recommend
sampling several more young fallows, mature or growing plantations and
agroforestry systems. The tree biomass will be estimated by measuring dbh of
the individual trees, noting which species, and then applying the specific
allometric equations.

Root sampling and estimation of the C stored in roots has proven to be the most
difficult of all the parameters measured. The estimates for roots have not
been included in the tables and figures presented in this report. If one
assumes that the root-to-shoot ratio remains relatively constant for the
different systems within a site, then there is a means of estimating the C
stored in the root systems. At the very least, it is possible to say that
including roots in the C stock comparisons made above will only magnify the
loss of C. As an example, the roots in a plantation will be less than the
roots of a forest system, as is the above-ground C, and therefore the
difference in total C between the two systems is larger than, but in proportion
to, that estimated by above-ground C only.


Access Constraints
ASB encourages free dissemination of its work when reproduction and use are for
non-commercial purposes, provided all sources are acknowledged. ASB strives for
open, public access to its datasets and will consider requests for access to
ASB datasets on a case-by-case basis in consultation with the ASB Consortium
partners who generated the data.


Use Constraints
None


Keywords
slash and burn
carbon stock
land uses
benchmark sites
humid tropics


Data Set Progress
IN WORK


Data Center
Alternate Slash and Burn, Consultative Group on International Agricultural Research    [Information]
Data Center URL: http://www.asb.cgiar.org/

Data Center Personnel
Name: JOYCE KASYOKI
Phone: +254 2 524139/524000 0r +1 650 833 6645
Fax: +254 2 524001 or +1 650 833 6646
Email: asb at cgiar.org
Contact Address:
ASB Programme
ICRAF
P.O. Box 30677
City: Nairobi
Country: Kenya


Personnel
JOYCE KASYOKI
Role: TECHNICAL CONTACT
Phone: +254 2 524139/524000 0r +1 650 833 6645
Fax: +254 2 524001 or +1 650 833 6646
Email: asb at cgiar.org
Contact Address:
ASB Programme
ICRAF
P.O. Box 30677
City: Nairobi
Country: Kenya



Creation and Review Dates
DIF Creation Date: 2006-01-26
Last DIF Revision Date: 2012-12-21

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