沙漠研究 24-1, 175-178 (2014)
Ἃ₍◊✲ 24-1, 175 -178 (2014)
Journal of Arid Land Studies
Journal of Arid Land Studies－ DT11 Refereed Paper －㸫DT11 Refereed Paper㸫

Detection of Grassland Degradation Using MODIS Data in Mongolia
Ayako SEKIYAMA*1), Wataru TAKEUCHI 1) and Sawahiko SHIMADA 2)
Abstract: In this study, we attempted to map the degradation of Mongolian grasslands using MODIS imagery and statistical data
which is number and composition of livestock from 2000 to 2006. Firstly we generated the distribution map by MODIS LAI using abiomass estimation equation which was derived from in-situ measurement of biomass with a geo-located match up database.
Secondly the amount of biomass which is the quantity required for feeding the livestock in each county was calculated using data on
numbers of livestock over the same time period. Thirdly, degradation intensity was determined in overgrazed areas in which thenumber of livestock exceeds grazing capacity and use of many goats creates high grazing intensity. As result,19 counties wereidentified as at high risk for degradation of the grasslands. These areas are located in southern region of Mongolia.
Key Words: Biomass, Grassland degradation, Livestock composition, Overgrazing

1. Introduction
1.1. Background and objective
Livestock husbandry is key industry for nomads inMongolia. However, in recent decades, global climatechange and overgrazing have caused degradation of thegrasslands in this country (Kawamura et al., 2005).
Livestock mortality has occurred as a consequence of forage
shortages caused by grassland degradation (Begzsuren et al.,
2004; IFRC, 2010).
In traditional Mongolian nomadic grazing, it is known thatlivestock herds should be balanced with goat comprising no
more than 30% of the herds because goats have the habit ofgrazing grass down to the roots. However the total number ofgoats has surpassed that of sheep since 2003 owing to theestablishment of cashmere as a major export product aroundurban areas (Yoshihara et al., 2008; Hoshino et al., 2009).
Thus, appropriate management of livestock grazing is needed
for sustainable use of grassland and to preserve the grasslands
from degradation.
Previous studies of natural environments using remotesensing technology include: evaluating phenological patternsof vegetation using NDVI (Lee et al., 2002): the prediction ofplant diversity by vegetation condition from MODIS (Ranjeetet al., 2007): the detection of Poaceae grass abundance inMongolian grasslands (Shimada et al., 2012); and theestimation of vegetation coverage (Muramatu et al., 2007).
On the other hand, some studies have discussed the grassland
degradation using statistical data and research reports onlivestock in the social environment (Lise et al., 2006).
However, few studies have reported that grassland degradationis comprehensively discussed regarding natural and socialenvironment.
This study attempts to map the grassland degradation fromMODIS imagery with the number and herd composition oflivestock present from 2000 to 2006.

2. Methodology
2.1. Data used
The biomass distribution map is generated using MODISLAI (MOD15: Leaf Area Index and Fractional
Photosynthetically Active Radiation) of Institute of Industrial
Science, the University of Tokyo (IIS/UT) during summer (fromJune to August) from 2000 to 2006. In order to eliminate
cloud Covered images and error pixel, the quality flags of all
images were checked, and only images taken during clear
condition were selected in order to generate the resulting map.
Statistical data of livestock used was obtained from theMongolian Statistical Yearbook (2000-2006) of the National
Statistical Office of Mongolia (NSOM). These data provide
the numbers of sheep, goats, cattle, horses and camels in eachcounty within the administrative boundary called soum ofMongolia. There are 347 counties in Mongolia.
2.2. Correlation between biomass and livestock numbers
The biomass distribution map was generated using
MODIS LAI, then a biomass estimation equation (Biomass =48.70e0.82LAI R= 0.62) is applied to these images. Thisbiomass estimation equation was calculated from correlation
between in-situ biomass and LAI value from MODIS(Sekiyama et al., 2012). Next, total biomass in each county
was calculated using biomass distribution map from 2000 to㸦Received, November 11th, 2013; Accepted, March 3rd, 2014㸧

* Corresponding Author: sekiyama@iis.u-tokyo.ac.jp
Ce-505, 4-6-1, Komaba, Meguro, Tokyo, 153-8505, Japan(Present affiliation: Faculty of Regional Environment Science, Tokyo University of Agriculture, a3sekiya@nodai.ac.jp)
1) Institute of Industrial Science, the University of Tokyo2) Faculty of Regional Environment Science, Tokyo University of Agriculture

176

Fig. 1. Biomass distribution map using MODIS LAI of August from 2000 to 2006.

Fig. 2. High composition ratio area of goat from 2000 to 2006.

2006. Regarding the MODIS LAI product, land use data asparameter is used for generating LAI values, so pixels
classified as bare soil and desert are assigned the value of 253
indicating as no leaf area. However, actually there is a small
amount of vegetation in pixels classified as bare soil and desert.
Therefore in this study, such pixels were given minimal
biomass value for each year in the biomass distribution map
from 2000 to 2006.
In order to extract areas of high risk as degraded grasslands,
the grazing capacity was calculated in each county using
biomass distribution map and ratio of goats in the herdcompositions. First, grazing capacity is calculated byassessing the biomass of forage for livestock. As reported by
JICA (Japan International Cooperation Agency), 560 kg of
grass is needed for feeding sheep a year, and goat, cattle, horseand camel is 0.9 times, 6.0 times, 6.6 times and 5.7 timesrespectively for sheep case, so these criteria is used for required
biomass amount for livestock feeding. Next, within counties
grassland was defined as degraded if it was overgrazed byhaving inadequate forage for the number of livestock present
and if the ratio of animals composing the herds was more than
30% goats, during 2000 to 2006. A map of grassland areas at

high risk of degradation was generated.

3. Results and Discussion
Figure 1 shows biomass distribution map in summer from2000 to 2006. In 2000 and 2001, biomass was low
throughout the Mongolia, with only a small area of highbiomass occurring in the northern region. It was reported thatlivestock mortality occurred in winter of these years and wascaused by lack of grass. Thus it was possible to predict theprobable risk of livestock mortality by investigating biomass
distribution in summer. The significant decrease of biomass
was not shown from 2002 onwards.
Figure 2 shows the distribution of areas with herdcomposition ratios with more than 30% of goats from 2000 to2006. The distribution of herds with a high proportion ofgoats increased yearly and was distributed throughout
Mongolia in 2006, except in the eastern region. Grazing oflivestock has not been conducted in eastern regions ofMongolia because there are few lakes and rivers.
Overgrazing was most widespread in 2000 and 2001 (Fig. 3),
then declined in 2002, but has gradually increased after this177

Fig. 3. Overgrazing area from 2000 to 2006.

Fig. 4. High risk area for grassland degradation.
Calculated on the basis of goat composition ratio and overgrazing area from 2000 to 2006.

year. Figure 4 indicates high risk areas of grassland
degradation, with 19 counties being at high risk. All of
extracted counties were located in the southern region.
Mongolia has the Govi desert in south of this country, northof the desert is a transition zone between grassland and desert(ecotone). The counties identified as having a high risk ofgrassland degradation are located in this transition zone. It isconsidered necessary to take immediate action because thetransition zone is easily influenced by environmental changes
such precipitation and heavy grazing pressure.

4. Conclusion and Future Works
Areas at risk of degradation of the grasslands weresuccessfully identified by creating a biomass distribution map
using MODIS LAI and relating this to the numbers oflivestock.
In particular, heavily grazed areas werecharacterized by areas in which goats make up more than 30%of the livestock numbers. This method identified:࣭ Changes in biomass throughout Mongolia from 2002 to2006.
࣭ An annual increase in herds comprising over 30% goats.
࣭ Overgrazing was associated with low biomass production
in 2000 and 2001 but thereafter overgrazing was associatedwith the increased proportion of goats in the herds.
࣭ Nineteen counties were extracted as being at high risk ofgrassland degradation. These counties were located in thetransition zone between grassland and desert.
Future work to augment the quantitative evaluation ofbiomass with evaluation the quality of grass, and vegetation
classification will be conducted using in-situ spectral data andALOS/avnir-2 as high resolution imagery.
Acknowledgement
This research was supported by MEXT Green Network of
Excellence- Environmental Information and JSPS
Grants-in-Aid for Scientific Research (Grant-in-Aid for Young
Scientists (B), No. 24780249).

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