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SAFARI 2000 LEAF-LEVEL VOC EMISSIONS, MAUN, BOTSWANA, WET SEASON 2001
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Summary:

Biogenic volatile organic compounds (VOCs) comprise a significant proportion of trace gases in the atmospheric environment and play an important role in the formation of secondary air pollutants. Emissions of monoterpenes from vegetation were studied at adjacent sites in Botswana as part of the SAFARI 2000 (Southern African Regional Science Initiative). Using a LI-COR leaf cuvette, VOC emissions were measured from the dominant tree species (Colophospermum mopane) and other vegetation near Maun, Botswana. The aims of this work were to: (1) determine the VOC emission potential of C. mopane; (2) investigate any differences in VOC emission potential between the tall and short C. mopane morphology types; (3) investigate environmental controls of VOC emissions from C. mopane; and (4) screen other non-dominant vegetation for high VOC emission potential.

The data are contained in an ASCII text file (maun_leaf-level_voc.csv) in comma-delimited format with column headers. The data file contains leaf-level VOC emission rates for C. mopane and other plant species growing near Maun, Botswana recorded under different types of experiments associated with the measurements (e.g., preliminary light dependency, emission potential, tall/short and water potential, light dependency, screening). In addition, the data file contains physical measurements, such as leaf area and dry biomass, which are used in calculating leaf-level emissions rates. Environmental parameters in the leaf cuvette (PAR, temperature, relative humidity, and CO2 concentration) are also recorded. All measurements were made during the wet season campaign (February) of 2001.

Data Citation:

Cite this data set as follows:

James, A. E., S. M. Owen, C. N. Hewitt, J. Greenberg, A. Guenther, L. Otter, E. M. Veenendaal, and K. Mantlana. 2004. SAFARI 2000 Leaf-Level VOC Emissions, Maun, Botswana, Wet Season 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. doi:10.3334/ORNLDAAC/763.

References:

Greenberg, J. P., A. Guenther, P. Harley, L. Otter, E. M. Veenendaal, C. N. Hewitt, A. E. James, and S. M. Owen. 2003. Eddy flux and leaf-level measurements of biogenic VOC emissions from mopane woodland of Botswana. J. Geophys. Res., 108(D13): 8466, doi:10.1029/2002JD002317.

Midgley, G. F., J. N. Aranibar, K. B. Mantlana, et al. 2004. Photosynthetic and gas exchange characteristics of dominant woody plants on a moisture gradient in an African savanna. Global Change Biol., 10(3): 309-317.

Veenendaal, E. M., O. Kolle, and J. Lloyd. 2004. Seasonal variation in energy fluxes and carbon uptake in a broad-leaved semi-arid savanna in Southern Africa. Global Change Biol., 10(3): 318-328.

Data Format:

The data file contains records of biogenic VOC measurements and associated leaf-level physical and environmental parameters from sites in the Maun area during the wet season campaign of 2001. The data are contained in an ASCII text file (maun_leaf-level_voc.csv) which contains the columns described below, in comma-delimited format with column headers. A zero means that a measurement was made, but was under the detection limits. Blank fields mean there are no data for that cell. Either it was not measured, did not exist, the instrument failed for that particular measurement, or any other circumstance that resulted in missing data.

Column Description Units/Format
date date sample was taken dd-mon-yy
time local start time of sample hh:mm
site orc = mopane tree outside Harry Oppenheimer Okavango Research Centre (orc); short/pan = mopane growing on "pan"; tall mopane = mopane growing near tower; orc-wh = behind research centre-wild hog character field
species plant species investigated genus species
experiment the type of experiment associated with measurement (preliminary light dependency, emission potential, tall/short and water potential, light dependency, screening) character field
leaf usually a 2-letter code with prefix T=tall or P=pan and a letter (A-V) that labels a different leaf on the same plant (a different tree was sampled each day) or single leaf, which means it was a different tree, not used before, and the same leaf used for all measurements. Also see note below table. character field
par photosynthetically active radiation µmol m-2 s-1
tleaf leaf temperature degrees C
tcham temperature inside leaf cuvette degrees C
P atmospheric pressure mb
Leaf area area of leaf enclosed by leaf cuvette cm2
Leaf dry weight dry weight of that part of leaf enclosed in leaf cuvette g
isoprene_l leaf area based emission rate of isoprene µg cm-2 h-1
a-pinene_l leaf area based emission rate of alpha pinene µg cm-2 h-1
camphene_l leaf area based emission rate of camphene µg cm-2 h-1
b-pinene_l leaf area based emission rate of beta pinene µg cm-2 h-1
myrcene_l leaf area based emission rate of myrcene µg cm-2 h-1
3-carene_l leaf area based emission rate of 3-carene µg cm-2 h-1
limonene_l leaf area based emission rate of limonene µg cm-2 h-1
isoprene_d dry biomass based emission rate of isoprene µg gdw-1 h-1
a-pinene_d dry biomass based emission rate of alpha pinene µg gdw-1 h-1
camphene_d dry biomass based emission rate of camphene µg gdw-1 h-1
b-pinene_d dry biomass based emission rate of beta pinene µg gdw-1 h-1
myrcene_d dry biomass based emission rate of myrcene µg gdw-1 h-1
3-carene_d dry biomass based emission rate of 3-carene µg gdw-1 h-1
limonene_d dry biomass based emission rate of limonene µg gdw-1 h-1

NOTE: In the leaf column, there are a few measurements not defined in the description above, used only once, and are samples of different leaves of the same tree. These are:

Tdark1     leaf 1, which was darkened with a black bin-liner over the cuvette
Tshade2   leaf 2, which was growing naturally in the shade
Tdark2     leaf 3, which was darkened with a black bin-liner over the cuvette (i.e., dark leaf 2)
Tsun2      leaf 4, which was growing naturally in the sun

Additional information about the site conditions, VOC sampling, sample analysis, data format, and calculation of VOC emission rates is found in the companion file: http://daac.ornl.gov/daacdata/safari2k/field_campaign/leaf_voc_emissions/comp/leaf_voc_emissions_readme.pdf

Document Information:

2004/9/28

Document Review Date:

2004/9/28

Document Curator:

webmaster@www.daac.ornl.gov

Document URL:

http://daac.ornl.gov