NPP Grassland: Klong Hoi Khong, Thailand, 1984-1990

Summary:

Net primary production of a humid savanna grassland was determined at the Klong Hoi Khong study site belonging to Prince of Songkla University in southern Thailand. Monthly dynamics of live biomass and dead matter, above and below ground, were monitored from 1984 to the present, together with monthly litter bag estimates of decomposition rates above and below ground. The method for calculating net primary production accounted for simultaneous growth and death, and carbon flows to all trophic levels. Work was carried out under the UNEP (United Nations Environment Programme) Project on "Primary productivity of grass ecosystems of the tropics" and has continued under subsequent UNEP and Thai-Austrian research projects.

Climate data for this site are also available: see Any Other Relevant Information in section 11 of this document.

More information on the entire Net Primary Production Project can be found at the NPP homepage.

Table of Contents

1. Data Set Overview
2. Investigator(s)
3. Theory of Measurements
4. Equipment
5. Data Acquisition Methods
6. Observations
7. Data Description
8. Data Organization
9. Data Manipulations
10. Errors
11. Notes
12. Application of the Data Set
13. Future Modifications and Plans
14. Software
15. Data Access
16. Output Products and Availability
17. References
18. Glossary of Terms
19. List of Acronyms
20. Document Information

1. Data Set Overview:

Data Set Identification:

Data Set Introduction:

The study site of several hectares is situated within a larger experimental field area (6.33 N 100.93 E), about 40 km south-west of Hat Yai. Ancient shifting cultivation in the region originally converted the tropical forest to a savanna-like tree-grass mosaic on poorer soils. The study site has supported a humid savanna for at least the last 50-100 years, and is typical of the semi-natural pastures in the Thai/Malaysian Peninsula which were commonly maintained by burning until recently. However, much of the region is now under pressure for conversion to arable crops or rubber plantations (Kamnalrut and Evenson, 1992; Long et al., 1989).

Objective/Purpose:

Net primary productivity was determined, initially under the auspices of an international collaborative UNEP Project, since there was a lack of information on the productive capacity and carbon cycling of the region.

Summary of Parameters:

1. Site

2. Treatment

3. Year

4. Month

5. Day

6. Date in decimal Year

7. Above Ground Live Biomass

8. Standing Dead Matter

9. Litter

10. Above Ground Total Matter

11. Below Ground Live Biomass

12. Below Ground Dead Biomass

13. Below Ground Total Matter

14. Above Ground Net Primary Production (calculated)

15. Below Ground Net Primary Production (calculated)

Discussion:

Complete data are available 1984-1990, including accidental burning in 1985, 1986 and 1989. Data were not collected during 1987. From 1984 to 1986, standing dead matter and litter were combined into one category, reported as "standing dead".

Related Datasets:

2. Investigator(s):

Investigator(s) Name and Title:

Dr. Apinan Kamnalrut

Title of Investigation:

Determination of net primary productivity of a humid savanna near Hat Yai.

Contact Information:

Contact 1:

Department of Plant Science
Faculty of Natural Resources
Prince of Songkla University
Hat Yai 90110
THAILAND

Telephone: Not Currently Available
Fax: +66 (74) 212823
Email Address: Not Currently Available

3. Theory of Measurements:

Net primary production (NPP), sensu stricto, is the total photosynthetic gain (less respiratory losses) of vegetation per unit ground area. For a given period, this is equal to the change in plant mass plus any losses due to death and decomposition, measured for both above ground and below ground plant parts. Earlier estimates of grassland NPP were based on peak standing dry matter only, and the studies of the International Biological Programme (IBP) in the late 1960s and early 1970s were based mainly on above-ground biomass changes, with few estimates of below-ground production.

Peak above-ground live biomass (or in some cases, the difference between maximum and minimum biomass) has been used as an estimate of net primary production - usually where only one or two measurements per year are available. Sometimes a conversion factor has been applied to take account of estimated turnover and the estimated ratio of above-ground to below-ground dry matter.

The "IBP Standard Method" of Milner and Hughes (1968) assumes that where live biomass increases between successive samples, production equals this increase; where biomass decreases or remains the same, production is assumed to be zero. Annual production is then obtained by summing the estimates for each sample interval.

Essentially, this method was used for the IBP synthesis by Singh and Joshi (1979), in particular for their estimates of below-ground production. A modified method was used for above-ground production, determined by a decision matrix (Singh et al., 1975); where increments in live biomass coincided with increases in standing dead matter, the latter were added to the monthly production.

The limitations of the above methods are discussed in detail by Long et al. (1989). In particular, the peak biomass method and variations on the IBP method underestimate production by not accounting for simultaneous growth and death. This may be significant in temperate grasslands with a long growing season, and is particularly a problem in tropical grasslands where the growing season may extend over much of the year. Some limited overestimation may occur by not accounting for periods of negative NPP (due to stress, or translocation between above and below ground plant parts) but underestimation of root turnover is probably the largest source of error. Long et al. (1989) estimated NPP for three terrestrial tropical grassland sites by summing monthly changes in live biomass plus losses due to death and decomposition for above and below ground vegetation. Monthly losses were determined as the change in dead matter plus the estimated disappearance of dead matter through decomposition. Dead matter disappearance was calculated each month as the product of relative decomposition rate and mean amount of dead matter.

Although some correlation between estimates obtained using different methods has been reported (Singh et al., 1975), the degree of underestimation may be strongly site-specific (Linthurst and Reimold, 1978; Long and Mason, 1983). Where sufficient data are available for a given grassland site, it may be possible to estimate NPP according to the different methods for the purposes of comparison. This may involve entry of data into algorithms or a spreadsheet containing these algorithms.

4. Equipment:

Sensor/Instrument Description:

• soil corer
• quadrat sampling frame
• laboratory balance

Collection Environment:

Ground level

Platform/Source:

Field investigation

Platform/Source Mission Objectives:

Determination of net primary productivity

Key Variables:

Above-ground live biomass/ standing dead matter/ litter;

Below-ground live/dead root biomass;

Principles of Operation:

See "3. Theory" Above

Sensor/Instrument Measurement Geometry:

Not Applicable

Manufacturer of Sensor/Instrument:

Information Not Available

Calibration:

Not Applicable

Specifications:

Not Applicable

Tolerance:

The number of replicate quadrats was sufficient to ensure a Standard Error of less than 20% of the mean.

Frequency of Calibration:

Not Applicable

Other Calibration Information:

Not Applicable

5. Data Acquisition Methods:

Changes in live biomass and dead matter, above and below ground, were measured at monthly intervals (Kamnalrut and Evenson, 1992; Long et al., 1989).

Dry weight of each above ground category was determined each month by clipping to ground level within 20 quadrats, 1.0 m x 0.25 m, located by a randomized block design. Clipped material from each quadrat was sub-sampled to approx. 100 g fresh weight before sorting. Litter (fallen dead matter) was carefully swept and collected from the area of each quadrat. Live leaves were separated from dead on the basis of tissue necrosis, dead portions being removed from otherwise green leaves. Similar sorting methods were used for stems, paying attention to removal of dead sheaths from live stems.

Below-ground plant matter was sampled by removing soil cores from the center of each quadrat. For the first two years of data collection, 5-10 soil cores were taken each month. Later measurements comprised 40 soil cores combined in groups of four to make 10 samples (in order to reduce sample variance). Soil cores were taken to a 15 cm depth, since initial studies showed that this accounted for more than 90% of the root system. Soil cores were washed over a 2 mm sieve, since ability to pass through a 2 mm mesh was taken as the arbitrary division between recognizable dead matter and particulate organic matter (for both above and below-ground matter). Large roots were removed and weighed separately from fine roots (less than about 1 mm diameter). Fine roots were sub-sampled to about 1.0 g fresh weight. Live and dead roots were separated on the basis of tissue necrosis, using vital staining with tetrazolium salts where visual discrimination was not otherwise possible.

All sorted plant matter was thoroughly washed and dried to constant weight at 90 C.

Monthly decomposition rates were determined using litter bags. Dead above-ground matter was placed at the ground surface, and dead below-ground matter was inserted at 5 cm depth with the soil carefully replaced above the litter bag. Litter bags were of 2 mm nylon mesh, 8 cm x 6 cm, containing approx. 2.0 g dead matter obtained at random from the previous monthly sample. They were recovered from the field after one month, their contents washed over a 2 mm mesh sieve and dried to constant weight. Loss of material was taken to be the rate at which a random sample of dead matter would decompose over that month, and was expressed as a relative rate of decomposition.

6. Observations:

Data/Field Notes:

Contact Principal Investigator (see 2. above) for details of any peculiar conditions at the time of data collection

site elevation (m): 30

mean annual precipitation (mm): 1541.1

mean monthly min temperature (C): 21.4 (Jan)

mean monthly maximum temperature (C): 34.3 (Apr)

some daily weather data is available - contact Principal Investigator.

vegetation type: humid savanna

dominant species: Eulalia trispicata (C4 photosynthetic type)

historical long-term management regime (estimated): converted from forest 50-100 years ago; fire every 5 years

Maximum aboveground live biomass (typical month): 442 [g][m^-2] (Nov)

soil type: humic gley

soil pH: 5.5 (0-20 cm)

soil texture (sand/silt/clay): 0.58/ 0.40/ 0.02

soil carbon content: 1.1% OM (0-20 cm)

soil nitrogen content: 0.066% (0-20 cm)

7. Data Description:

Spatial Characteristics:

Spatial Coverage:

Study site located at 6.33 N, 100.93 E

Spatial Coverage Map:

Map not available.

Spatial Resolution:

Not Applicable

Projection:

Not Applicable

Grid Description:

Not Applicable

Temporal Characteristics:

Temporal Coverage:

April 1984 to present. Preview data set to check for data gaps.

Temporal Coverage Map:

Not Applicable

Temporal Resolution:

One month

Data Description:

Parameter/Variable:

There are fifteen (15) parameters for each of these 2 datasets. There are 2 treatments at this site, but the same types of data were collected for each treatment and both data files are presented in exactly the same format. Items 1-2 refer to the site and the treatments, respectively. Minimum and maximum values for the remaining parameters are for the combined treatments.

1.
variable=Site
definition=site where data were gathered
code=kln: Klong Hoi Khong

2.
variable=Treatmt
definition=long term management of site
code=1_lngtrm: converted from forest 50-100 years ago; fire every 5 years; Burned January 1985, January 1989
code=2_burn86: converted from forest 50-100 years ago; fire every 5 years; Burned January 1985

3.
variable=Year
definition=year in which data were collected
units=year
minimum=1984
maximum=1990

4.
variable=Mn
definition=month in which data were collected
units=month
minimum=01
maximum=12

5.
variable=Dy
definition=day in which data were collected
units=day
minimum=15
maximum=15

6.
variable=Tyear
definition=Date in decimal year
units=year plus the Julian date divided by 365
minimum=1984.290
maximum=1990.540

7.
variable=AGbiomass
definition=Above ground live biomass
units=[g][m^-2]
minimum=0.0
maximum=450.2

8.
variable=Stdead
definition=Standing dead
units=[g][m^-2]
minimum=0.0
maximum=988.6

9.
variable=litter
definition=dead biomass found above ground
units=[g][m^-2]
minimum=0.0
maximum=34.1

10.
variable=AGtotmatter
definition=above ground total matter
units=[g][m^-2]
minimum=0.0
maximum=1367.2

11.
variable=BGbiomass
definition=below ground biomass
units=[g][m^-2]
minimum=198.4
maximum=1103.1

12.
variable=BGdead
definition=below ground dead
units=[g][m^-2]
minimum=51.0
maximum=583.3

13.
variable=BGtotmatter
definition=below ground total matter
units=[g][m^-2]
minimum=265.0
maximum=1608.1

14.
variable=ANPP
definition=above ground net primary production
units=[g][m^-2]
minimum=-231.9 (negative value)
maximum=424.5

15.
variable=BNPP
definition=below ground net primary production
units=[g][m^-2]
minimum=-400.4 (negative value)
maximum=391.0

Sample Data Record:

Site   Treatmt   Year   Mn    Dy    Tyear      AGbiomass    

----------------------------------------------------------------

kln   1_lngtrm  1984   04    15    1984.290   308.4

Stdead  litter  AGtotmatter  BGbiomass

---------------------------------------------------------

427.4  -999.9  735.7        284.6

BGdead  BGtotmatter   ANPP    BNPP
----------------------------------------------------
372.8   657.4        -999.9   -999.9

8. Data Organization:

Data Granularity:

Data file associated with the Klong Hoi Khong Grassland are listed below.

A general description of data granularity appears in the EOSDIS Glossary.

Complete Dataset (Data Files Total 8.9 KBytes)

1. Data File kln1_npp.txt 6.9 KBytes
Period: 15 Apr 1984 through 15 Jul 1990
Latitude: 6.33N, Longitude: 100.93E

2. Data File kln2_npp.txt 2.0 KBytes
Period: 15 Jan 1985 through 15 Dec 1985
Latitude: 6.33N, Longitude: 100.93E

Data Format:

Site;Treatmt;Year;Mn;Dy;Tyear;AGbiomass;Stdead;litter;AGtotmatter;BGbiomass;BGdead;BGtotmatter;ANPP;BNPP [units g/m2]  

kln;1_lngtrm;1984;04;15;1984.290; 308.4; 427.4;-999.9; 735.7; 284.6; 372.8; 657.4;-999.9;-999.9
kln;1_lngtrm;1984;05;15;1984.370; 446.6; 648.8;-999.9;1095.4; 338.8; 153.2; 492.1; 424.5;-136.2

9. Data Manipulations:

Formulae:

Derivation Techniques and Algorithms:

Algorithms and/or software available for calculating NPP from data sets using different methods are not currently available.

Data Processing Sequence:

Information Not Available

Calculations

Graphs and Plots:

10. Errors:

Information Not Available

11. Notes:

Limitations of the Data:

Net primary production of grasslands is subject to a number of different methods of estimation from biomass data, some of which may be inappropriate for particular biome types. Methodology of estimation/calculation needs to be taken into account, as well as methodology of measurement, when making comparisons between different regions.
Errors in biomass measurement may also occur between different study sites. For short time series of data it may be assumed that measurement methodology remains consistent; however, over very long time series changes in staff, tools, etc. may lead to "calibration" errors.

Known Problems with the Data:

Information Not Available

Usage Guidance:

See "Limitations of the Data" above

Any Other Relevant Information About the Study:

Monthly climate data from 1954 to 1983 (monthly maximum and minimum temperature and monthly rainfall) are available for this study site in the file "kln_cli.txt".

12. Application of the Data Set:

Data on net primary production of particular ecosystem types worldwide is in demand from modellers working at a variety of scales from Global Climate Models (GCMs) to regional or national estimates of carbon fluxes between atmosphere, biosphere and soils.

The detailed monthly above and below ground biomass data obtained by the UNEP tropical grasslands project are particularly suitable for validation of models running on a monthly time step.

13. Future Modifications and Plans:

Refer to Principal Investigator for details of continuing data collection and data from nearby improved pastures and agricultural study sites.

14. Software:

Software Description:

Utility software is planned to available for (i) generating quasi-real daily/hourly climate data from the monthly data; (ii) calculating NPP from data sets using different algorithms, crude root/shoot ratios, etc.

Software Access:

Not Yet Available

15. Data Access:

Contact Information:

ORNL DAAC User Services Office
Oak Ridge National Laboratory
Oak Ridge, TN
U.S.A.

Telephone: 865-241-3952
Email Address: ornldaac@ornl.gov

Data Center Identification:

ORNL Distributed Active Archive Center
Oak Ridge National Laboratory
Oak Ridge, TN
U.S.A.

Telephone: 865-241-3952
Email Address: ornldaac@ornl.gov

Procedures for Obtaining Data:

Users may place requests by telephone, electronic mail, or FAX. Data are also available via the World Wide Web at http://daac.ornl.gov.

Data Center Status/Plans:

NPP data are available from the ORNL DAAC. Please contact the ORNL DAAC User Services Office for the most current information about these data.

16. Output Products and Availability:

Available on-line, as computer FTP file (zipped or unzipped), on CDs, or on IBM-formatted diskettes.

17. References:

Kamnalrut, A. 1990. Net Primary Production for Klong Hoi Khong (Thailand) Grassland Site Dataset, In Kamnalrut, A. and J.P. Evenson (1992) Monsoon grassland in Thailand. In: Primary Productivity of Grass Ecosystems of the Tropics and Sub-tropics. (Long, S.P., M.B. Jones and M.J. Roberts, eds.). Chapman and Hall, London. pp. 100-126.

Kamnalrut, A. and J.P. Evenson (1992) Monsoon grassland in Thailand. In: Primary Productivity of Grass Ecosystems of the Tropics and Sub-tropics. (Long, S.P., M.B. Jones and M.J. Roberts, eds.). Chapman and Hall, London. pp. 100-126.

Linthurst, R. and R.J. Reimold (1978) An evaluation of methods for estimating the net primary production of estuarine angiosperms. J. Applied Ecology 15, 919-932.

Long, S.P. and Mason, C.F. (1983) Saltmarsh Ecology. Blackie, Glasgow.

Long, S.P., E. Garcia Moya, S.K. Imbamba, A. Kamnalrut, M.T.F. Piedade, J.M.O. Scurlock, Y.K. Shen and D.O. Hall (1989) Primary productivity of natural grass ecosystems of the tropics: a reappraisal. Plant and Soil 115, 155-166.

Milner, C. and R.E. Hughes (1968) Methods for the Measurement of the Primary Production of Grassland. IBP Handbook No.6. Blackwell, Oxford.

Singh, J.S. and M.C. Joshi (1979) Tropical grasslands primary production. IN: Grassland Ecosystems of the World (R.T. Coupland, ed.) Cambridge University Press. pp. 197-218.

Singh, J.S., W.K. Lauenroth and R.K. Sernhorst (1975) Review and assessment of various techniques for estimating net aerial primary production in grasslands from harvest data. Botanical Review 41, 181-232.

Kinyamario, J.I. and S.K. Imbamba (1992) IN: Primary Productivity of grass ecosystems (Long, S.P. et al., eds.) Chapman and Hall, London. pp. 25-69.

Long, S.P. et al. (1989) Plant and Soil 115, 155-166.

18. Glossary of Terms:

A general glossary for the DAAC is located at http://cdiac.esd.ornl.gov/cdiac/glossary.html.

A glossary of EOSDIS terms is available at http://www-v0ims.gsfc.nasa.gov/v0ims/glossary.of.terms.html.

19. List of Acronyms:

The EOSDIS Acronym and Abbreviation List is located at http://www-v0ims.gsfc.nasa.gov/v0ims/acronyms.html

20. Document Information:

Document Revision Date:

December 1, 1997 (data citation revised on September 23, 2002)

Review Date:

January 15, 1998

Document ID:

ORNL-NPP_KLN.

Citation:

Document Curator:

Document Author:

Dr. J.M.O. Scurlock webmaster@www.daac.ornl.gov

Document URL:

http://daac.ornl.gov/NPP/guides/kln_guide.html