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LBA-ECO ND-02 CO2 Flux from Soils in Forests and Pastures, Acre, Brazil: 1999-2001
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Revision date: February 28, 2012

Summary:

This data set reports soil CO2 flux and results of physical and chemical characterization of soils from pastures, secondary forests, and mature forests near Rio Branco, Acre, Brazil. CO2 flux measurements were made in the field on a monthly basis at 16 sites from June of 1999 to January 2001. In addition, a set of diel CO2 flux measurements were made at 1-hour intervals at selected pasture, mature and secondary forest sites in June and July 2000. Litter was collected monthly from 2001-2002 at each of the mature forest sites and at four of the secondary forest sites, and mean litter mass is reported. Soil samples were collected and analyzed from several land cover types at two sites during this same time period. There are six comma-delimited ASCII data files with this data set.

Data Citation:

Cite this data set as follows:

Salimon, C.I., E.A. Davidson, R.L. Victoria, and A.W.F. Melo. 2012. LBA-ECO ND-02 CO2 Flux from Soils in Forests and Pastures, Acre, Brazil: 1999-2001. Data set. Available on-line [http://daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. http://dx.doi.org/10.3334/ORNLDAAC/1066

Implementation of the LBA Data and Publication Policy by Data Users:

The LBA Data and Publication Policy [http://daac.ornl.gov/LBA/lba_data_policy.html] is in effect for a period of five (5) years from the date of archiving and should be followed by data users who have obtained LBA data sets from the ORNL DAAC. Users who download LBA data in the five years after data have been archived must contact the investigators who collected the data, per provisions 6 and 7 in the Policy.

This data set was archived in February of 2012. Users who download the data between February 2012 and January 2017 must comply with the LBA Data and Publication Policy.

Data users should use the Investigator contact information in this document to communicate with the data provider. Alternatively, the LBA websitee [http://lba.inpa.gov.br/lba/] in Brazil will have current contact information.

Data users should use the Data Set Citation and other applicable references provided in this document to acknowledge use of the data.

Table of Contents:

1. Data Set Overview:

Project: LBA (Large-Scale Biosphere-Atmosphere Experiment in the Amazon)

Activity: LBA-ECO

LBA Science Component: Nutrient Dynamics

Team ID: ND-02 (Davidson / Carvalho / Dias-Filho / Moller / Moutinho / Sa / Vieira)

The investigators were Salimon, Cleber Ibraim; Davidson, Eric A.; Melo, Antonio Willian Flores de; Brown, Irving Foster; Victoria, Reynaldo Luiz and Pereira, and Jorcinei Widson . You may contact Salimon, Cleber Ibraim (clebsal@cena.usp.br) and Davidson, Eric A. (edavidson@whrc.org).

LBA Data Set Inventory ID: ND02_Soil_CO2_Flux

Conversion of forest to cattle pastures and subsequent abandonment of those pastures is occurring throughout the Amazon Basin, including regions with eutrophic (nutrient rich) and dystrophic (nutrient poor) soils. The objectives of this project were to determine the effects of land-use change and native soil fertility on soil respiration in pastures, secondary forests, and mature forests near Rio Branco, Acre.

2. Data Characteristics:

Data are provided in four comma-delimited ASCII files. Sampling plots were in  pastures, secondary forests, and mature forest locations. File # 4 provides  descriptions of the sites.

File #1: ND02_Soil_CO2_fluxes.csv

ColumnHeadingUnits/format Description
1 Site  Sampling location. For additional information see  file #6: ND02_CO2_Flux_Study_Site_Descriptions.csv
2MonthmmMonth of the year in which measurements were taken (1 - 12), where 1=January, 2=February, etc.
3Yearyyyy Year in which measurements were taken (1999 - 2002)
4Nutrient_class  Soil nutrient class: dystrophic=nutrient poor, eutrophic=nutrient rich
5Land_use Dominant land use: Pasture, Secondary forest, or Mature forest
6Plot Plot identification number within the Humaita and Peixoto sites (1, 2, or 3)
7Chamber_ID Chamber identification number (1 - 8 )
8Transect_ID Transect identification code: where the first character indicates land use (C=Secondary forest, F=Mature forest, P=Pasture); the number in the second position indicates the research area; and the third character indicates soil nutrient class (E=eutrophic, D=dystrophic)
9Flux_CO2mg CO2-C per m2 per hFlux of CO2 from the soil to the atmosphere measured in milligrams of carbon in the form of CO2 per meter squared per hour
10Flux_CO2_std_errmg CO2-C per m2 per hStandard error of the CO2 flux rate calculated during the five minute sampling period
11T_airdegrees CMean air temperature within the sampling chamber during the five minute sampling period reported in degrees Celsius
12T_soildegrees CSoil temperature measured at 10 cm depth adjacent to the sampling chamber
 
Missing data represented as -9999

Example data records:

Site,Month,Year,Nutrient_class,Land_use,Plot,Chamber_ID,Transect_ID,CO2_flux,CO2_flux_SE,T_air,T_soil

Zoobotanical Park,6,1999,dystrophic,Secondary forest,3,1,C5D,220.96,1.96,30.5,-9999
Zoobotanical Park,6,1999,dystrophic,Secondary forest,3,2,C5D,217.99,1.26,30.53,-9999
Zoobotanical Park,6,1999,dystrophic,Secondary forest,3,3,C5D,226.99,1.79,30.6,-9999
...
Humaita,6,1999,eutrophic,Secondary forest,1,1,C1E,215.5,4.35,29.5,-9999
Humaita,6,1999,eutrophic,Secondary forest,1,2,C1E,320.24,12.91,29.3,-9999
Humaita,6,1999,eutrophic,Secondary forest,1,3,C1E,232.29,7.23,-9999,-9999
...
Peixto,1,2002,dystrophic,Mature forest,2,6,F2D,212.97,-9999,-9999,-9999
Peixto,1,2002,dystrophic,Mature forest,2,7,F2D,300.29,-9999,-9999,-9999
Peixto,1,2002,dystrophic,Mature forest,2,8,F2D,288.26,-9999,-9999,-9999

File #2: ND02_24hr_CO2_Flux_Acre.csv

ColumnHeadingUnits/format Description
1 Land_use  Dominant land use: Pasture, Secondary forest, or Mature forest
2TimehourSampling time: Samples were taken once an hour over a 24 hour period
3Sampling chamber Chamber identification number (1 - 4 )
4CO2 fluxmg CO2-C per m2 per h Flux of CO2 from the soil to the atmosphere reported in milligrams of carbon in the form of CO2 per meter squared per hour. Note for the Secondary forest site no individual chamber data are available the reported value is the mean of 4 chambers
5SE_fluxmg CO2-C per m2 per hStandard error of the CO2 flux rate calculated during the five minute sampling period
6T_airdegreesAir temperature in the sampling chamber reported in degrees Celsius
 
Missing data represented as -9999

Example data records:

Land_use,Time,Sampling chamber,CO2 flux,SE_flux,T_air
Mature Forest, 1, 1, 119.47, 1.66, 21.9
Mature Forest, 1, 2, 81.53, 0.64, 21.9
Mature Forest, 1, 3, 72.07, 2.43, 21.9
...
Pasture, 1, 1, 181.57, 2.81, 17.9
Pasture, 1, 2, 175.39, 2.71, 18.3
Pasture, 1, 3, 157.43, 3.82, 17.7
...
Secondary Forest, 22, mean, 177.24, 41.44, 24.1
Secondary Forest, 23, mean, 181.98, 37.21, 23.8
Secondary Forest, 24, mean, 185.36, 51.35, 23.5

File #3: ND02_Litter_2001-2002.csv

ColumnHeading Units/format Description
1 Site  Sampling location. For additional information see file #6 ND02_CO2_Flux_Study_Site_Descriptions.csv
2Nutrient_class  Soil nutrient class: dystropic=nutrient poor, eutropic=nutrient rich
3Land_use Dominant land use: Pasture, Secondary forest, or Mature forest
4Transect_ID Transect identification code: where the first character indicates land use (C=Secondary forest, F=Mature forest, P=Pasture); the number in the second position indicates the research area; and the third character indicates soil nutrient class (E=eutrophic, D=dystrophic)
5YearyyyyYear in which measurements were collected (2001 or 2002)
6MonthmmMonth of the year in which measurements were collected (1 - 12), where 1=January, 2=February, etc.
7 Litter_meang m-2 Mean litter mass from the 5 baskets at each site reported as grams of litter per meter squared per month
8Litter_SEg m-2Calculated standard error of the mean litter mass
 
Missing values are indicated as -9999

Example data records:

Site,Nutrient_class,Land_use,Transect_ID,Year,Month,Litter_mean,Litter_SE
Humaita,eutrophic,Secondary forest,C1E,2001,7,121.92,16.02
Humaita,eutrophic,Secondary forest,C2E,2001,7,79.71,11.4
...
Peixoto,dystrophic,Secondary forest,C2D,2002,1,40.26,4.46
Zoobotanical Park,dystrophic,Secondary forest,C5D,2002,1,48.1,13.57
...

File #4:  ND02_Soil_characteristics.csv
Note: Secfor means secondary forest; matfor means mature forest; numbers after the names stand for the age (i.e. Secfor 18, secondary forest with 18 years of age) (Salimon et al., 2004)

ColumnHeading Units/format Description
1 Site  Sampling location. For additional information see file #6: ND02_CO2_Flux_Study_Site_Descriptions.csv
2Nutrient_class  Soil nutrient class: dystrophic=nutrient poor, eutrophic=nutrient rich
3Land_use Dominant land use: Pasture, Secondary forest , or Mature forest
4Transect_ID Transect identification code: where the first character indicates land use (C=Secondary forest, F=Mature forest, P=Pasture); the number in the second position indicates the research area; and the third character indicates soil nutrient class (E=eutrophic, D=dystrophic)
5Depth Sampling depth class: A= 0 to 5 cm, B= 5 to 10 cm, C= 20-30 cm, and D= 50 to 60 cm depth
6SandpercentPercent by weight of soil particles classified as sand (diameter greater than or equal to 2 mm)
7Siltpercent Percent by weight of soil particles classified as silt (diameter less than 2 mm and greater than or equal to 2 um)
8ClaypercentPercent by weight of soil particles classified as clay (diameter less than 2 um)
9pH Soil pH determined in a CaCl2 solution
10SOMpercentSoil organic matter reported in percent of total soil weight
11Pmg per kg soilSoil phosphorus concentration
12Kcmol charge per kg soilSoil potassium concentration
13Cacmol charge per kg soilSoil calcium concentration
14Mgcmol charge per kg soilSoil magnesium concentration
15Alcmol charge per kg soilSoil aluminum concentration
16Hcmol charge per kg soil Soil hydrogen concentration
17Sum_of_bases cmol charge per kg soil Sum of bases: sum of measured calcium magnesium and potassium ion concentrations
18CECcmol charge per kg soilCation exchange capacity: calculated as the sum of bases plus the hydrogen ion concentration
19Base_saturationpercentBase saturation calculated as the sum of bases divided by cation exchange capacity
 
Values below the detection limit are designated as -6999
The scientific community often expresses CEC of a soil as cmol/kg. This is centimoles (cmol) of charge per kilogram of soil. Many soil testing laboratories, however, express CEC as meq/100 g. This should not cause confusion since: 1 meq/100 g = 1 cmol/kg. (NOTE: 'milli' charge multiplied by 10 equals 'centi' charge and 100 g multiplied by 10 equals kg; thus, the proportions remain the same)

Example data records:

Site,Nutrient_class,Land_use,Transect_ID,Depth,Sand,Silt,Clay,pH,SOM,P,K,Ca,Mg,Al,H,Sum_of_bases,CEC,Base_saturation

Peixoto,dystrophic,Secondary forest,C1D,A,15,32,53,4.2,39,14,3.2,31,14,7,80,48.2,128.2,38
Peixoto,dystrophic,Secondary forest,C1D,A,12,39,49,4.2,47,12,3.2,40,13,6,109,56.2,165.2,34
Peixoto,dystrophic,Secondary forest,C1D,A,17,32,51,3.2,49,15,3.8,17,8,25,253,28.8,281.8,10
...
Humaita,eutrophic,Mature forest,F1E,C,19,41,40,3.2,13,4,1.6,1,3,33,166,5.6,171.6,3
Humaita,eutrophic,Mature forest,F1E,D,8,31,61,3.4,10,3,2.9,2,6,65,386,10.9,396.9,3
Humaita,eutrophic,Mature forest,F1E,D,12,25,63,3.1,12,3,2.5,1,4,65,477,7.5,484.5,2
...
Peixoto,dystrophic,Pasture,P1D,A,16,23,61,3.9,56,10,8.2,15,10,11,121,33.2,154.2,22
Peixoto,dystrophic,Pasture,P1D,A,22,24,54,4.4,96,17,6.4,48,19,3,88,73.4,161.4,45
Peixoto,dystrophic,Pasture,P1D,A,18,22,60,4.1,69,16,5,42,15,5,121,62,183,34
...


File #5: ND02_Soil_Physical_Properties.csv

 
ColumnHeading Units/format Description
1DateYYYYMMSampling year and month
2Season Sampling was done once in the dry season and once in the wet season
3Land_use Dominant land use: Pasture, Secondary forest, or Mature forest
4Site Site identification
5VWCgrams H2O per gram of soilSoil volumetric water content reported in grams of water per gram of soil
6SE_VWCgrams H2O per gram of soilStandard error of the soil volumetric water content
7Bulk_densityg cm-3Soil bulk density reported in grams of soil per cubic centimeter
8Porosity%Soil porosity reported in percent. Calculated as 1- ( soil bulk density/ particle density (assumed to be 2.65))
9WFPS Water filled pore space calculated as (volumetric water content times soil bulk density) divided by soil porosity and reported as a proportion of total space
10SE_WFPS Standard error of the soil water filled pore space

Example data records:

Date, Season, Land_use, Site, VWC, SE_VWC, Bulk_density, Porosity, WFPS, SE_WFPS
200202, Wet, Mature forest, Humaita, 1, 0.3,5 0.01, 1.06, 0.6, 0.62, 0.011
200202, Wet, Secondary forest, Humaita, 1, 0.3, 0.02, 0.99, 0.63, 0.48, 0.024
200202, Wet, Pasture Humaita, 1, 0.35, 0.01, 1.24, 0.53, 0.8, 0.022
...
200106, Dry, Mature forest, Peixoto, ,1 0.16, 0, 1.06, 0.6, 0.27, 0.007
200106, Dry, Secondary forest, Peixoto, 1, 0.15, 0, 0.99, 0.63, 0.24, 0.002
200106, Dry, Pasture, Peixoto, 1, 0.23, 0.02, 1.24, 0.53, 0.53, 0.04

File #6: ND02_CO2_Flux_Study_Site_Descriptions.csv

ColumnHeading Units/format Description
1Site Region where study was located
2Site name Plot locations within the sites: two secondary forests at the Zoobotanical Park (PZ) at the Federal University of Acre, Rio Branco, Acre State, and also at two government sponsored settlements: Peixoto Settlement Project and Humaita Settlement Project
3Nutrient class Dystrophic or Eutrophic 1, 2, or 3
4Sampling site Mature forest (Matfor), secondary forest (Secfor), or pasture site (Pasture). * See note below for further description
5Transect_ID Transect identification code: where the first character indicates land use (C=Secondary forest, F=Mature forest, P=Pasture); the number in the second position
6Latitudedecimal degreesLatitude (decimal degrees south) of sampling location
7Longitudedecimal degreesLongitude (decimal degrees west) of sampling location
8History of site Description of forests and pastures
9Previous use Description of prior land use of forest and pastures
10Soil type Dystrophic podzol or eutrophic podzol
11Soil description Nutrient poor soils where leaching is a major force in soil development
 
* Note: Secfor means secondary forest; matfor means mature forest; numbers after the names stand for the age (i.e. Secfor 18, secondary forest with 18 years of age) (Salimon et al., 2004)

Example data records

Site,Site name,Nutrient class,Sampling site,Transect_ID,Latitude,Longitude,History of site,
Previous use,Soil type,Soil description

Zoobotanical Park,Zoobotanical Park,Dystrophic 3,Secfor12(c5d),C5D,-9.95,-67.87,Secondary Forest around 12 years old,
Agriculture and pasture,Dystrophic podzol,Nutrient poor soils where leaching is a major force in soil development
Zoobotanical Park,Zoobotanical Park,Dystrophic 3,Secfor182(c6d),C6D,-9.95,-67.87,Secondary Forest around 18 years old,
Agriculture and pasture,Dystrophic podzol,Nutrient poor soils where leaching is a major force in soil development
...
Peixoto,Peixoto Settlement Project,Dystrophic 1,Matfor (f1d),F1D,-9.88,-67.08,Mature forest,
Mature forest,Dystrophic podzol,Nutrient poor soils where leaching is a major force in soil development
Peixoto,Peixoto Settlement Project,Dystrophic 2,Pasture12 (p2d),P2D,-9.94,-67.12,Pasture around 12 years old,
Mature forest,Dystrophic podzol,Nutrient poor soils where leaching is a major force in soil development
...
Humaita,Humaita Settlement Project,Eutrophic 1,Pasture14 (p1e),P1E,-9.77,-67.66,Pasture around 14 years old
Mature forest, eutrophic podzol,Nutrient poor soils where leaching is a major force in soil development
Humaita,Humaita Settlement Project,Eutrophic 2,Matfor (f1e),F1E,-9.77,-67.66,Mature forest
Mature forest, eutrophic podzol,Nutrient poor soils where leaching is a major force in soil development

Site boundaries: (All latitude and longitude given in decimal degrees)

Site (Region) Westernmost Longitude Easternmost Longitude Northernmost Latitude Southernmost Latitude Geodetic Datum
Acre - Parque Zoobotanico (Acre)-
Secfor12 (c5d)
Secfor18 (c6d)
-67.87 - 67.87-9.95 -9.95 South-American Datum, 1969 (SAD-69)
Acre - Projeto de Assentamento Peixoto (Acre)-Pasture13 (p1d) -67.07 - 67.07-9.87 -9.87 South-American Datum, 1969 (SAD-69)
Acre - Projeto de Assentamento Peixoto (Acre)-
Secfor11 (c1d)
Matfor (f1d)
-67.07 - 67.07-9.88 -9.88 South-American Datum, 1969 (SAD-69)
Acre - Projeto de Assentamento Peixoto (Acre)-
Pasture12 (p2d)
Secfor12 (c4d)
-67.12 - 67.12-9.94 -9.94 South-American Datum, 1969 (SAD-69)
Acre - Projeto de Assentamento Peixoto (Acre) -Matfor (f2d) -67.13 - 67.13- 9.95 - 9.95 South-American Datum, 1969 (SAD-69)
Acre - Projeto de Assentamento Humaita (Acre)-Secfor3 (c1e)
Pasture14 (p1e)
Matfor (f1e)
Secfor3 (c1e)
-67.66 - 67.66- 9.77 - 9.77 South-American Datum, 1969 (SAD-69)

Time period:

Platform/Sensor/Parameters measured include:

3. Data Application and Derivation:

Carbon dioxide fluxes from pastures and forests in tropical regions are important components of the global carbon budget. These time series of soil-atmosphere gas exchange of CO2 reveal important seasonal variations in flux and provide insight to the role of soil nutrients as well as land cover in controlling CO2 fluxes from these systems.

4. Quality Assessment:

All data have been quality checked and no further changes to the data are anticipated.

5. Data Acquisition Materials and Methods:

The study areas are located in the southwestern corner of the Brazilian Amazon Basin, near the city of Rio Branco in the state of Acre, Brazil. The regional climate has a mean annual temperature of 26 degrees C; rainfall of 1,940 (plus or minus 230) mm with a well-defined dry season (with less than 50 mm per month from June through August); mean annual relative humidity of 85 percent (Duarte et al., 2000). The soils are classified as dystrophic and eutrophic Ultisols with patches of Oxisols (RADAMBRASIL, 1976). Natural vegetation is classified as Ombrophilous Open Forest (RADAMBRASIL, 1976) with patches of bamboo-dominated forest (Silveira, 1999). Where natural forests have been converted, 60 percent is now used for cattle ranching and agriculture, and almost 40 percent is in some stage of secondary succession.

Plots for this study were located in two secondary forests at the Zoobotanical Park (PZ) at the Federal University of Acre, Rio Branco, Acre State, and also at two government sponsored settlements: Peixoto Settlement Project and Humaita Settlement Project. In both settlements the main animal products are cattle and chickens and the principal crops are manioc, maize, banana, and rice. Four pasture sites were all between 12 and 15 years old, dominated by Brachiaria brizantha and had from zero to three burning events. Eight secondary forest sites were more heterogeneous in age, ranging from 3 to 18 years old, and were also diverse with respect to previous land use. Four mature forest sites had no historical sign of clear-cutting, but all had been used for rubber tapping, Brazil nut extraction, and for game hunting.

Soil sampling

In order to characterize soils at the Peixoto and Humaita sites, we sampled soils from each land cover to 60 cm depth. For this purpose, three soil pits (60 x 60 x 60 cm) were dug in each of the following sites: Peixoto: in Secfor 11, Secfor 3a, Pasture 13 and Matfor, and Humaita: in Secfor 3b, Pasture 14 and Matfor (see file #4 for site codes and descriptions: ND02_CO2_Flux_Study_Site_Descriptions.csv).

Soil temperature was measured at 10 cm depth by inserting a temperature probe near each soil respiration chamber while each flux measurement was in progress.

CO2 flux measurements

Fluxes were measured once per month from June 1999 to July 2000 at all sites, except for October when no measurement was made. Measurements were continued through January 2001 on a less regular sampling schedule. Eight CO2 flux measurements were made at each site and date. Carbon dioxide flux from soil to atmosphere was measured using an infrared gas analyzer (IRGA), LICOR-6252, coupled to a vented dynamic chamber system (Davidson et al., 2002). Eight PVC rings (20 cm diameter and 10 cm height) were inserted 3 cm into the soil at each site. At the time of sampling, a PVC opaque chamber, with an inner diameter at the bottom just slightly larger than the outer diameter of the ring, was placed snugly over the ring, and air was circulated between this chamber (volume of the chamber with the top was 7.1 L) and the IRGA with an air pump at 0.5 L min_1. A vent (5 cm long, 2.16 mm inner diameter stainless steel tube) was installed in the chamber top through a Swaglok fitting to equalize pressure with the atmosphere. CO2 concentrations in the chamber were recorded every 12 s for 5 min and were stored in an HP 200 XL palmtop connected to the IRGA. Measurements were always conducted between nine am and two pm. In order to evaluate whether the time of sampling was representative of soil respiration during the day, we also conducted diel flux measurements at 1-hour intervals at pasture, mature and secondary forest sites in June and July 2000, with four flux measurements at each site and hour.

The flux was calculated from linear regression of the difference of CO2 concentration over time. The first few measurements during the first minute were discarded from the regression to avoid any artifact of closing the chamber, and only the data showing a linear increase in CO2 concentration (usually during a 1-5 min interval) were used to calculate fluxes (Salimon et al., 2004). The IRGA was calibrated every morning by using zero air that had been run through a soda lime scrubber and by using a White Martins certificated standard gas of 610 (plus or minus 2%) ppmv of CO2 (nitrogen as the balance gas).

Soil Analyses

Physical and chemical analyses were carried out at the Soil Laboratory at Escola Superior de Agronomia, following van Raij et al. (2001). Carbon concentration in soil was determined at the Isotopic Ecology Laboratory at the Centro de Energia Nuclear na Agricultura, University of Sao Paulo, using an Element Analyzer Carlo Erba, model 1110 CNHS.

Litterfall mass

Litter traps were constructed of 1 x 1 m squares of 5 mm nylon mesh suspended 30 cm above the soil surface. Five traps were installed in each of the mature forests and in four of the secondary forests. Litter was collected monthly, stored in paper bags, sorted for removal of coarse material with diameter 45 cm, dried at 70 degrees C for 72 h, and then weighed.

6. Data Access:

This data is available through the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

Data Archive Center:

Contact for Data Center Access Information:
E-mail: uso@daac.ornl.gov
Telephone: +1 (865) 241-3952

7. References:

Blake GR, Hartge KH (1986) Bulk density. In: Methods of Soil Analysis. Part 1: Physical and Mineralogical Methods, 2 (ed. Klute A), pp. 363-376. ASA, Madison.

Davidson EA, Savage K, Verchot LV et al. (2002) Minimizing artifacts and biases in chamber-based measurements of soil respiration. Agricultural and Forest Meteorology, 113, 21-37.

Duarte AF, Artaxo Neto P, Brown IF et al. (2000) O clima em Rio Branco Acre Brasil entre os anos 1970 e 2000. Technical report to Conselho Nacional de Desenvolvimento Cientifico e Tecnologico, Rio Branco, AC.

RADAMBRASIL (1976) Folha SC.19 Rio Branco. Ministerio das Minas e Energia, Departamento Nacional da Producao Mineral, Projeto RADAM BRASIL, Rio de Janeiro, RJ.

Salimon, C.I., E.A. Davidson, R.L. Victoria, and A.W.F. Melo. 2004. CO2 flux from soil in pastures and forests in southwestern Amazonia. Global Change Biology, Vol. 10, No. 5, pp. 833-843.

Silveira M (1999) Ecological aspects of bamboo-dominated Forest in southwestern Amazonia: an ethnoscience perspective. Ecotropica, 5, 213-216.

van Raij B, de Andrade JC, Cantarella H et al. (2001) Analise quimica para avaliacao da fertilidade de solos tropicais. Editora IAC, Campinas.