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Investigation:

CD-05 (Nepstad / Klink / Moutinho)

LBA Dataset ID:

CD05_MICROMET

Originator(s):

1. NEPSTAD, D.C.
2. MOUTINHO, P.R.
      3. BRANDO, P.

Point(s) of Contact:

ORNL DAAC User Services Office Oak Ridge National Laboratory Oak Ridge, Tennessee 37 (ornldaac@ornl.gov)

Dataset Abstract:

These data were collected as part of a rainfall exclusion experiment implemented in the Tapajos National Forest, Santarem, Para, Brazil. Two one-hectare plots were established to monitor the effects of water stress on the forest. Following a one year intercalibration period, plastic panels were installed in the understory of the treatment to exclude rainfall during the rainy season. These measurements allow us to compare rainfall and temperature in the period of the experimental treatment to long term averages. In addition the soil moisture measurements allow us to quantify the timing and degree of impact of the treatment.

Beginning Date:

1999-01-01

Ending Date:

2007-04-20

Metadata Last Updated on:

2013-06-21

Data Status:

Archived

Access Constraints:

PUBLIC

Data Center URL:

http://daac.ornl.gov/

Distribution Contact(s):

ORNL DAAC User Services Office Oak Ridge National Laboratory Oak Ridge, Tennessee 37 (ornldaac@ornl.gov)

Access Instructions:

PUBLIC

Data Access:

IMPORTANT: The LBA-ECO Project website is no longer being supported. Links to external websites may be inactive. Final data products from the LBA project can be found at the ORNL DAAC. Please follow the fair use guidelines found in the dataset documentation when using or citing LBA data.
Datafile(s):

LBA-ECO CD-05 Soil VWC and Meteorology, Rainfall Exclusion, Tapajos National Forest :  http://daac.ornl.gov/cgi-bin/dsviewer.pl?ds_id=1169

Documentation/Other Supporting Documents:

LBA-ECO CD-05 Soil VWC and Meteorology, Rainfall Exclusion, Tapajos National Forest :  http://daac.ornl.gov/LBA/guides/CD05_Micromet.html

Citation Information - Other Details:

Nepstad, D.C., P.R. Moutinho and P. Brando. 2013. LBA-ECO CD-05 Soil VWC and Meteorology, Rainfall Exclusion, Tapajos National Forest. Data set. Available on-line [http://daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, USA. http://dx.doi.org/10.3334/ORNLDAAC/1169

Keywords - Theme:

Parameter Topic Term Source Sensor
HUMIDITY ATMOSPHERE ATMOSPHERIC WATER VAPOR GROUND STATION HUMIDITY SENSOR
RAINFALL BIOSPHERE ECOLOGICAL DYNAMICS GROUND STATION RAIN GAUGE
SOIL MOISTURE/WATER CONTENT BIOSPHERE ECOLOGICAL DYNAMICS FIELD CAMPAIGN TIME DOMAIN REFLECTOMETER

Uncontrolled Theme Keyword(s):  DRY-DOWN, RAINFALL EXCLUSION, RELATIVE HUMIDITY, SOIL MOISTURE, TAPAJOS NATIONAL FOREST, TEMPERATURE

Keywords - Place (with associated coordinates):

Region
(click to view profile)
Site
(click to view profile)
North South East West
Pará Western (Santarém) km 67 Seca-Floresta Site -2.75000 -2.75000 -55.00000 -55.00000

Related Publication(s):

Brando, P. M., D. C. Nepstad, E. A. Davidson, S. E. Trumbore, D. Ray, and P. Camargo. 2008. Drought effects on litterfall, wood production and belowground carbon cycling in an Amazon forest: results of a throughfall reduction experiment. Philosophical Transactions of the Royal Society of London. Series B, Biological sciences 363:1839â�â�œ1848.

Markewitz, D., S. Devine, E. A. Davidson, P. Brando, and D. C. Nepstad. 2010. Soil moisture depletion under simulated drought in the Amazon: impacts on deep root uptake. New Phytologist 187:592�607.

Nepstad,D.C., P. Moutinho, M. B. Dias-Filho, E. Davidson, G. Cardinot, D. Markewitz, R. Figueiredo, N. Vianna, J. Chambers, D. Ray, J. B. Guerreiros, P. Lefebvre, L. Sternberg, M. Moreira, L. Barros, F. Y. Ishida, I. Tohlver, E. Belk, K. Kalif, K. Schwalbe. 2002. The effects of partial throughfall exclusion on canopy processes, aboveground production, and biogeochemistry of an Amazon forest. Journal of Geophysical Research 107:8085

Data Characteristics (Entity and Attribute Overview):

Data Characteristics:

Data are provided in a three comma-delimited ASCII files:

File #1: Rainfall_REE_plots_1999_2006.csv

File #2: Temp_RH_REE_plots_2000_2003.csv

File #3: VWC_REE_plots_1999_2007.csv





File organization is as follows:



File # 1

File name:,Rainfall_REE_plots_1999_2006.csv,,

File date:,25-Feb-13,,

Associated LME file:,CD05_Micromet,,

,,,

Column,Column_heading,Units/format,Explanation

1,Date,YYYYMMDD,Sampling date

2,Ppt_Casa,mm,Rainfall over previous 24 hours measured at the Casa Onca site approximately 1 km from the experimental plots and reported in mm: Note collections were not done on weekends so Monday collections represent 3 days minus some evapotranspiration

3,Ppt_REE_tower,mm,Rainfall over previous 24 hours measured at tower located in the control plot and reported in mm: Note collections were not done on weekends so Monday collections represent 3 days minus some evapotranspiration

4,Exclusion,,Indicates whether the exclusion panels were in place with 1 indicating yes and 0 indicating no

,,,

,missing data are indicated by -9999,,



Sample data for File #2

Date,Ppt_Casa,Ppt_REE_tower,Exclusion

19990101,0,-9999,0

19990102,-9999,-9999,0

19990103,-9999,-9999,0

19990104,0,-9999,0

19990105,0,-9999,0

19990106,0,-9999,0

19990107,0,-9999,0

....

20060126,7,6.4,0

20060127,0,0,0

20060128,-9999,-9999,0

20060129,-9999,-9999,0

20060130,0,0,0

20060131,0,0,0





File #2



File name:,Temp_RH_REE_plots_2000_2003.csv,,,,,,,

File date:,28-Feb-13,,,,,,,

Associated LME file:,CD05_Micromet,,,,,,,

,,,,,,,,

Column,Column_heading,Units,Explanation,,,,,

1,Treatment,,Plot identification: control or exclusion,,,,,

2,Sensor_code,,Sensor identification,,,,,

3,Location,,Sensors were located in both gap and closed forest locations,,,,,

4,Height,m,Height of sensor reported in meters above the soil,,,,,

5,Date,YYYYMMDD,Sampling date in local time,,,,,

6,Time,HH:MM,Sampling time in local time ( local time is UTC-4),,,,,

7,T_air,degrees C,Air temperature reported in degrees Celsius,,,,,

8,T_dewpoint,degrees C,Dewpoint temperature reported in degrees Celsius,,,,,

9,RH,percent,Relative humidity reported in percent,,,,,

,,,,,,,,

,missing data are indicated by -9999,,,,,,,



Sample data for File #2

Treatment,Sensor_code,Location,Height,Date,Time,T_air,T_dewpoint,RH

Exclusion,05RHT,Gap,15,20020709,9:33,27.91,26.8,93.7

Exclusion,05RHT,Gap,15,20020709,10:03,28.31,25.5,84.8

Exclusion,05RHT,Gap,15,20020709,10:33,28.7,25.53,83

Exclusion,05RHT,Gap,15,20020709,11:03,28.7,25.89,84.8

Exclusion,05RHT,Gap,15,20020709,11:33,29.5,25.53,79.3

Exclusion,05RHT,Gap,15,20020709,12:03,28.31,25.93,87

Exclusion,05RHT,Gap,15,20020709,12:33,29.5,25.93,81.2

Exclusion,05RHT,Gap,15,20020709,13:03,30.71,25.85,75.4

...

Control,14RHT,Closed forest,15,20030710,0:53,22.48,22.48,100

Control,14RHT,Closed forest,15,20030710,1:23,22.48,22.48,100

Control,14RHT,Closed forest,15,20030710,1:53,22.09,22.09,100

Control,14RHT,Closed forest,15,20030710,2:23,22.09,22.09,100

Control,14RHT,Closed forest,15,20030710,2:53,22.09,22.09,100

Control,14RHT,Closed forest,15,20030710,3:23,22.09,22.09,100

Control,14RHT,Closed forest,15,20030710,3:53,22.09,22.09,100

Control,14RHT,Closed forest,15,20030710,4:23,22.09,22.09,100

Control,14RHT,Closed forest,15,20030710,4:53,22.09,22.09,100

Control,14RHT,Closed forest,15,20030710,5:23,22.09,22.09,100



File #3

File name:,VWC_REE_plots_1999_2007.csv,,,,,

File date:,1-Mar-13,,,,,

Associated LME file: ,CD05_Micromet,,,,,

,,,,,,

Column,Column_heading,Units/format,Explanation,,,,

1,Treatment,,Plot identification: control or exclusion,,,,

2,Date,YYYMMDD,Sampling date ,,,,

3,Pit,,Pit identification,,,,

4,Side,,Location of the sensor in the pit, either the right or left wall,,,,

5,Depth,cm,Depth in the soil at which the sensor is located reported in centimeters below the soil surface,,,,

6,VWC_original,cm3 per cm3,Volumetric water content reported in centimeters cubed of water per centimeter cubed of soil,,,,

7,VWC_reprocessed,cm3 per cm3,Where original values were determined to be unreliable the reprocessed value is -9999,,,,

8,Reprocessed,,Flag to indicate that the original VWC value was reprocessed: 1 indicates reprocessing was necessary; 0 indicates original values are considered valid and -9999 indicates there were no original values to consider.,,,,

,,,,,,,

,missing data is indicated by -9999,,,,,,

Sample data for File #3

Treatment,Date,Pit,Side,Depth,VWC_original,VWC_reprocessed,Reprocessed

Control,19990517,4,L,30,0.3649,0.3649,0

Control,19990608,4,L,30,0.2957,0.2957,0

Control,19990804,4,L,30,0.3369,0.3369,0

Control,19990824,4,L,30,0.3334,0.3334,0

Control,19990928,4,L,30,0.3746,0.3746,0

Control,19991027,4,L,30,0.2598,0.2598,0

Control,19991123,4,L,30,0.3466,0.3466,0

Control,19991214,4,L,30,0.3453,0.3453,0

Control,20000125,4,L,30,0.3027,0.3027,0

Control,20000222,4,L,30,-9999,-9999,0

Data Application and Derivation:

This data set has the following main applications:



Assessments of the effects of soil water stress on Amazonian vegetation. This topic is of wide interest given that several lines of evidence suggest that Amazon forests may experience increased drought intensity and frequency in the future as a result of increased atmospheric CO2 and deforestation.



Development, parametrization, and validation of dynamic global vegetation models. Several models have been developed to predict the potential effects of drought on Amazonian vegetation. However, there is a lack of datasets that can be used to improve these models.

Quality Assessment (Data Quality Attribute Accuracy Report):

Quality Assessment:

VWC. Where original values were determined to be unreliable the reprocessed value was set to -9999.



Precipitation. Measurements noted on Mondays resulted from the accumulated precipitation over the weekend minus evaporation. This bias in our measurements is expected to consistently reduce precipitation estimates.



Relative humidity, dew point, and air temperature. Although some extreme unrealistic values were removed from this dataset due to problems with the sensors, temperature is still consistently lower than expected during some rainy-season periods.

Process Description:

Data Acquisition Materials and Methods:

The Seca Floresta experiment was located in the Tapajos National Forest, in east-central Amazonia at the LBA km 67 research site. This forest receives in average approximately 2000 mm of rainfall per year. The forest is situated on a flat terrace of Tertiary sediments capped by the Belterra Clay Formation, and is approximately 90 m above the water level of the Tapajos River, located 10 km to the west. The Oxisol soil is dominated by kaolinite clay minerals and is free of hardpan or iron oxide concretions in the upper 12 m. This soil is similar to the clay soils described for a study site located in the same forest, and on the same Belterra Clay terrace, 10 km from the throughfall exclusion experiment, where surface soil (0 to 10 cm depth) is 60 percent clay and 38 percent sand, bulk density is 1.02 � 1.23 (g per cm3), pH (H2O) is 4.2, and total C is 4.2 to 4.3 percent (Silver et al., 2000).



Throughfall was partially excluded from the treatment plot during the rainy seasons between 2000 and 2004, from late January to early August, using 5660 panels made of clear, PAR-transmitting greenhouse plastic mounted on wooden frames. The panels were removed during the dry season to reduce their influence on the forest floor through shading and heating. While they were in place, the panels were flipped on their sides every 2 to 3 days to transfer accumulated litter onto the forest floor beneath. Each 3 by 0.5 m panel drained into a plastic-lined, wooden gutter (30 cm wide) that carried the water into the trench, which was also lined with plastic. The gutters served as catwalks for various measurements and panel maintenance. Water flowed by gravity from the perimeter trench into a deeper drainage ditch (1.7 to 2.3 m depth), which extended 220 m away from the plot into a small valley. The panels and gutters covered apporoximately 75 percent of the forest floor, because we left openings around tree stems.





Volumetric soil water content

Volumetric soil water content (VWC) (cm3 water per cm3 soil) was monitored to 11 m depth in both the treatment and control plots using Time Domain Reflectrometry (TDR), in which an electromagnetic wave is propagated along three, 30-cm, parallel, stainless steel rods imbedded in the soil to determine the soil�s average dielectric moment (which is mostly a function of soil water content). The rods of each sensor were imbedded at one end in an epoxy resin head. Each sensor was installed at the end of a 1.5-m auger hole drilled horizontally into the wall of the shaft (the rods pushed into the intact soil) to avoid shaft effects on soil moisture; the holes were then back-filled with soil. Each of the shafts had two vertical sensors at the soil surface, and two horizontal sensors, in opposite walls, at 0.5, 1, 2 m, and at 1 m intervals to 11-m depth. VWC measurements were made using a cable tester (Tektronix 1502C) and the calibration equation developed in a similar Belterra clay formation, in eastern Amazonia. TDR waveforms were recorded and analyzed using the WATTDR program (v3.11, Waterloo Centre of Groundwater Research, 1996). Each waveform was visually inspected for possible errors generated by the WATTDR algorithm.



Precipitation

Precipitation was monitored using two wedge rain gauges from 1999 to 2006. One rain gauge was located in the control plot of the Seca Floresta experiment on top of 35-m wood tower, where no trees could obstruct rainfall collection. The other gauge was located in a clearing at a distance of approximately 1 km from the experimental area.



Micrometeorological measurements

To evaluate the effects of drought-induced changes in microclimatic conditions, a total of 17 sensors (Hobo Pro RH Temp Data Logger; Onset Computer Corp., Bourne, MA 02532, USA) were installed the dry (N=8) and control (N=9) plots. These sensors measured at different time intervals relative humidity (percent), air temperature (degrees C), and dew point temperature(degrees C).The sensors were distributed across the experimental plots to measure microclimate conditions in two types of environments: a gap and dense forest. These sensors were also distributed to capture the vertical variability microclimatic conditions. In the control, sensors were installed at 1.5 m, 15 m and 25 m along the vertical profile of the forest, while in the dry plot the sensors were installed at 2 m, 15 m, and 25 m. To avoid the effects of direct radiation on the measurements, the sensors were protected by a PVC cover.

References:

Silver, W. L., et al., (2000). Effects of soil texture on belowground carbon and nutrient storage in a lowland Amazonian forest ecosystem, Ecosystems, 3, 193-209. doi:10.1007/s100210000019

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