Site ID:
BR-Ma2
Site Name:
Manaus - ZF2 K34
Variables:
Leaf gas exchange
Date Range:
Feb. 15, 2015
-
March 16, 2017
Description:
This data package contains raw leaf gas exchange data from the NGEE Tropics K34 tower site on a plateau near Manaus, Brazil. Data was collected using sensor and leaf sample measurements. Leaves on a target tree were chosen by accessing a branch near the tower. In some cases, the branch was naturally positioned near the tower and in other cases, a small rope was used to pull the branch closer to the tower for better access to leaves. Mature leaves were targeted in nearly all cases. The gas exchange system was hauled with a climbing rope to the level of the branch on the tower and the sensor head/leaf enclosure was installed near the branch of interest using a magic arm. We measured leaf gas exchange from 5:00 AM to 5:00 PM, randomly cycling through the approximately 20 leaves in the targeted branch(es). Data were collected over two time periods, detailed within the files. The attached data files contain raw data, sensor manuals, and PDFs with detailed methods and procedures separated into multiple folders. Data is in Excel file format. See data references for data package containing related metadata. This dataset replaces the leaf gas exchange data of two retired packages, NGT0019 and NGT0040.
QA/QC:
None
Methods Description:
Leaves on a target tree were chosen by accessing a branch near the tower. In some cases, the branch was naturally positioned near the tower and in other cases, a small rope was used to pull the branch closer to the tower for better access to leaves. Leaves within one arm length from the tower were then analyzed for gas exchange using a Li6400XT. Young leaves were generally avoided if present, and mature leaves were targeted in nearly all cases. The gas exchange system was hauled with a climbing rope to the level of the branch on the tower and the sensor head/leaf enclosure was installed near the branch of interest using a magic arm. Upon installation, the flow rate through the chamber was set to 400 micromoles/min, and the
zero CO2 and H2O levels were checked by fully scrubbing both with the soda lime (CO2) and water vapor (dririte). Following this, the CO2 in the reference line was set to 400 ppm constant, and the relative humidity was adjusted to between 60-90 %. Finally a single log file was opened. In some cases, we used identified branches per tree species for repeated leaf campaigns, while a single campaign was performed for other tree species. We measured leaf gas exchange from 5:00 AM to 5:00 PM, randomly cycling through the approximately 20 leaves in the targeted branch(es). For each measurement cycle, the Licor6400XT was configured with the Red/Blue LED light source with the standard (6 cm^2) broad leaf chamber and the light level was controlled and set constant by setting equal to that of the external environment by the included
external PAR sensor. A leaf was chosen near the top of the branch and the leaf (top) surface temperature was measured using a NIST calibrated infrared camera (Flir E5) or using in situ IR radiometers (SI111,standard field of view, Apogee) positioned on a nearby branch. In some cases, the leaf temperature images from the Flir E5 camera were saved and using the timestamp we can correlate to the diurnal gasexchange
measurements (i.e., the photo timestamp will be occur prior to the 5 minute measurement period described below). However, after setting the setpoint leaf temperature, the gas exchange system often took >10-20 minutes to reach the leaf temperature setpoint without a leaf. After stabilization, the IRGAs were matched and a leaf was placed inside the cuvette. Following a 30-60 s leaf equilibration period, environmental, gas exchange, and physiological data was saved into the file every 15 seconds for 5 minutes. Following this period, the autolog was paused, the leaf was removed, and the cycle was repeated. Because the environmental, gas exchange, and physiological processes change rapidly in the morning, little to no delay (<= 5 min) was used between subsequent leaf samples. However, after 11:00, a delay of 10-20 min was used between individual leaf samples. As leaf temperatures warm throughout the day, the sample chamber RH tends to decrease, despite increased transpiration rates. Although RH is not really controlled, we normally bypassed completely the water scrubber at leaf temperatures above 27-28 C. In all cases, low leaf
temperatures in the morning (e.g. 25 C) required substantial scrubbing of incoming moisture.
Access Level:
Public
Originating Institution(s):
Lawrence Berkeley National Laboratory; National Institute for Amazon Research
Sponsor Organization(s):
None
Contact:
Jardine, Kolby - Lawrence Berkeley National Laboratory (kjjardine@lbl.gov)
Version:
1.0
Dataset Citation:
Jardine K; Fernandes de Araujo R; Rosa L (2022): Leaf gas exchange raw data, 2015 - 2017, at Manaus, Brazil. 1.0. NGEE Tropics Data Collection. (dataset). http://dx.doi.org/10.15486/ngt/1560859
Acknowledgement:
This material is based upon work supported as part of the Next Generation Ecosystem Experiments-Tropics (NGEE-Tropics) funded by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research through contract No. DE-AC02-05CH11231 to LBNL, as part of DOE's Terrestrial Ecosystem Science Program. Additional funding for this research was provided by the Brazilian Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq). Logistical and scientific support is acknowledged by the Forest Management (MF), Climate and Environment (CLIAMB), and Large Scale Biosphere-Atmosphere (LBA) programs at the National Institute for Amazon Research (INPA).
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