Summary:

Productivity of a steppe grassland was determined at the Tumentsogt Research Station in Mongolia, between 1982 and 1990. Measurements were made of seasonal dynamics of above-ground live biomass for each year. The Mongolian steppe occupies a major part of eastern Mongolia and northern China, characterised by an arid continental climate with most rain falling between June and August. Land use is dominated by grazing, historically by nomadic pastoralists and more recently for cooperative livestock production. Private livestock grazing has been increasing since 1990.

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:

NPP Grassland: Tumentsogt, Mongolia, 1982-1990

Introduction:

The Tumentsogt study site of the Mongolian Academy of Sciences is located on the Eastern Mongolian Plains at Tumentsogt sub-region (47.4 N 112.5 E), in Sukhbaatar administrative region. The Mongolian steppe ecosystem has been described by Dashnyam (1974), and its soils by Bespalov (1964). The ecology of plants and animals in the Tumentsogt region has been studied by Sheremet'ev and Jargalsaikhan (1990) and Dmitriev et al. (1990).

Objective/Purpose:

Environmental and management factors affecting productivity of the Mongolian steppes were studied by Chuluun and Ojima (1996), using a combination of field observation and model simulation to investigate long-term and short-term sustainability.

Summary of Parameters:

There are seven (7) parameters for this dataset. Items 1 and 2 refer to the site and the treatment of the site. Items 3, 4, 5, and 6 indicate the date of data collection. 1. Site 2. Treatment 3. Year 4. Month 5. Day 6. Date in decimal year 7. Above ground biomass

Discussion:

Early growing seasonal precipitation is one of the major driving factors for plant productivity in this ecosystem. The sandy soils of the Mongolian Steppe contribute to plant productivity, and are more susceptible to soil carbon losses under increased grazing intensity. Over most of their area, Mongolian grasslands are in good condition in terms of soil organic matter content. However, these grassland ecosystems are susceptible to changes in grazing management. Chuluun and Ojima (1996) suggested that land use policies in the Mongolian Steppe should incorporate traditional approaches in developing a sustainable grazing system.

Related Data Sets:

NPP data from other grassland sites are available elsewhere in this archive. Summary tables containing site characteristics and metadata for all the grassland

2. Investigator(s):

Investigator(s) Name and Title:

Dr. Chuluun Togtohyn

Title of Investigation:

Determination of net primary productivity of a steppe grassland at Tumentsogt, Mongolia.

Contact Information:

Dr. Chuluun Togtohyn
Institute of Botany
Mongolian Academy of Science
Ulaanbaatar 210351
MONGOLIA
Fax: Not Currently Available
Email: Not Currently Available

Alternative Contact:
Dr. D.S. Ojima
Natural Resource Ecology Laboratory
Colorado State University
FOrt Collins
Colorado 80523
USA
Telephone Number: +1 (970) 491-1976
Fax: +1 (970) 491-1965
Email dennis@nrel.colostate.edu

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:

• 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

Principles of Operation:

See "3. Theory" Above

Sensor/Instrument Measurement Geometry:

Not Applicable

Manufacturer of Sensor/Instrument:

Information Not Available

Calibration:

Not Applicable

5. Data Acquisition Methods:

Refer to literature or Principal Investigator/ Contact for details

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): 1100

mean annual precipitation (mm): 280

mean monthly min temperature (C): -23.5 (Jan)

mean monthly maximum temperature (C): 27.5 (July)

vegetation type: typical steppe

dominant species: Stipa grandis (C3 photosynthetic types)

historical long-term management regime (estimated): annual seasonal grazing

maximum aboveground live biomass (typical month): 160 g/m2 (August)

soil type: dark chestnut mollisol

soil pH: DATA NOT AVAILABLE

soil texture (sand/silt/clay): 0.60/ 0.20/ 0.20

soil carbon content: 7500 g/m2 (0-20 cm)

soil nitrogen content: DATA NOT AVAILABLE

7. Data Description:

Spatial Characteristics:

Spatial Coverage:

Study site located at 47.4 N, 112.5 E

Spatial Coverage Map:

Not Available

Spatial Resolution:

Not Applicable

Projection:

Not Applicable

Grid Description:

Not Applicable

Temporal Characteristics:

Temporal Coverage:

July 1982 to August 1990. Preview data set to check for data gaps, missing values, etc.

Temporal Coverage Map:

Not Applicable

Temporal Resolution:

One month

Data Description:

1.
variable=Site
definition=site where data were gathered
code=tmn: Tumentsogt

2.
variable=Treatmt
definition=long term management of site
code=lngtrm: annual seasonal grazing

3.
variable=Year
definition=year in which data were collected
units=year
minimum=1982
maximum=1990

4.
variable=Mn
definition=month in which data were collected
units=month
minimum=05
maximum=09

5.
variable=Dy
definition=day in which data were collected
units=day
minimum=10
maximum=30

6.
variable=Tyear
definition=Date in decimal year
units=year plus the Julian date divided by 365
minimum=1982.520
maximum=1990.660

7.
variable=AGbiomass
definition=Above ground live biomass
units=[g][m^-2]
minimum=12
maximum=235

Sample Data Record:

Site   Treatmt   Year   Mn   Dy   Tyear     AGbiomass
----------------------------------------------------
tmn    lngtrm    1982   07   10   1982.520  117.0

8. Data Organization:

Data Granularity:

The data file associated with the Tumentsogt Grassland is listed below.

1. Data File tmn_npp.txt 3.8 KBytes
Period: 10 Jul 1982 through 30 Aug 1990
Latitude: 47.4N, Longitude: 112.5E

A general description of data granularity as it applies to the IMS appears in the EOSDIS Glossary.

Data Format:

The dataset is an ASCII file. The first 18 lines are metadata; data records begin on line 19. The variable values are delimited by semi-colons. The value -999.9 is used to denote missing values.

Site;Treatmt;Year;Mn;Dy;Tyear;AGbiomass [units g/m2]
tmn;lngtrm  ;1982;07;10;1982.520; 117.0
tmn;lngtrm  ;1982;07;20;1982.550; 158.0

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

NPP Data Dictionary

Graphs and Plots

Information Not Available

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 1966 to 1983 (monthly maximum and minimum temperature and monthly rainfall) are available for this study site in the file /data/npp/grassland/comp/tmn_cli.txt">tmn_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. Ground-based data are also required for calibration of remote sensing measurements, and parameterisation and validation of models based on remote sensing.

13. Future Modifications and Plans:

Refer to Principal Investigator for details of continuing data collection.

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: +1 (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: +1 (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://

Data Center Status/Plans:

NPP data may be ordered from the ORNL DAAC. Please contact the ORNL DAAC User Services Office for the most current information about these data and how to order them.

16. Output Products and Availability:

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

17. References:

Bespalov, N.D. (1964) Soils of Outer Mongolia. Israel Program for Scientific Translations, Jerusalem.

Chuluun, Togtohyn and D.S. Ojima (1996) Simulation studies of grazing in the Mongolian steppe. Proceedings of the Fifth International Rangeland Congress (Vol. 1). Society of Range Management, Denver, CO, USA.

Dashnyam, B. (1974) Flora and Vegetation of the Eastern Mongolian Steppe. Mongolian Academy of Sciences Publ., Ulaanbaatar (in Mongolian).

Dmitriev, P.P., O.I. Khudyakov and L. Jargalsaikhan (1990) A succession of dark-chestnut soils and vegetation in Eastern Mongolia in conjunction with rodents life-activity. Bull. Mosk. O-va ispytatelei prirody. Otd. biol. 95, 3-15.

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 C.F. Mason (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.

Sheremet'ev, S.N. and L. Jargalsaikhan (1990) Water relations ecology of the steppe plants of Mongolia. USSR Academy of Sciences, Leningrad.

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.

Togtohyn, C. 1996. Net Primary Production for Tumentsogt (Mongolia) Grassland Site Dataset, In Togtohyn, Chuluun and D.S. Ojima (1996) Simulation studies of grazing in the Mongolian steppe. Proceedings of the Fifth International Rangeland Congress (Vol. 1). Society of Range Management, Denver, CO, USA.

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://wist.echo.nasa.gov//v0ims/glossary.of.terms.html.

19. List of Acronyms:

A general list of acronyms for the DAAC is available at http://cdiac.esd.ornl.gov/cdiac/pns/acronyms.html.

The EOSDIS Acronym and Abbreviation List is located at http://wist.echo.nasa.gov//v0ims/acronyms.html

20. Document Information:

December 12, 1997 (data citation revised on September 23, 2002)

Review Date:

January 15, 1998

Document ID:

ORNL-NPP_TMN

Citation:

Togtohyn, C., and D. Ojima. 1996. NPP Grassland: Tumentsogt, Mongolia, 1982-1990. Data set. Available on-line [http://www.daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A.

Document Curator:

webmaster@www.daac.ornl.gov

Document Author:

Dr. J.M.O. Scurlock

Document URL:

http://daac.ornl.gov

Revision Date: June 27, 2012 webmaster