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Land cover change and pasture estimation of Mongolia from space
M. Erdenetuya
Remote Sensing specialist
S. Khudulmur
Director of ICC (NRSC)
Information and Computer Center
National Remote Sensing Center of Mongolia
Ministry for Nature and Environment of Mongolia
Khudaldaany Str - 5, Ulaanbaatar 11, MONGOLIA
Tel: 976-11-329984, Fax/Tel: 976-11-326649
Email: m.erdenetuya@mailcity.com
mtt@magicnet.mn
Introduction
Land use/land cover information is essential for a number of planning and management activities. The existing land use patterns, because of their strong influence on how land could be used in future, become a crucial factor in deciding as to how land development, management and planning activities should be undertaken. Most of the natural resources are directly or indirectly related to the surface cover in a given locality. Therefore, to maintain harmony among sustainable resources and socio-economic needs, land cover and land use studies should be dealt with care.
Land cover has visual effects, visible by the remote sensor, as it is what covers the land at the time of satellite observation (4). Meteorological satellites of the TIROS-N series have been subject to increased interest for land use/cover studies. The increased awareness of environmental issues and the need to strive for sustainable management of natural resource has focused attention on the need to study and monitor land use/cover, and its change at different temporal and spatial scales.
Geographical position and associated climatic influences can be a negative environmental condition that affects sustainable use of land resources, especially pastoral livestock production.
According to the extreme changes in land resources we have tried to estimate land cover types and their changes, particularly to assess the pasture condition by satellite data.
Study area
The country of Mongolia
Mongolian territory is lifted at relatively high altitude above the sea level, 81.2 percent of which situated at the level higher than 1,000 meters or 50 percent - higher than 1,500 meters and the average altitude is 1,580 meters above sea level. The greater part of the highlands consist of mountainous areas with gentle to steep slopes, which are placed western, northern and southwest part of Mongolia. The Altai Mountains in the southwest rise to heights above 4267 meters (14,000 ft).
The pastureland occurs more than 80 percent of total territory of Mongolia and the main economic branch of our country is the pasture animal husbandry, which directly depends on nature and weather condition. In Mongolian pastureland counted more than 2200 species of plants and its 600 provides the curtain amount of forage and natural hay for the livestock during whole year.
Climate of the Mongolia is sharp changeable continental with short dry summer and long cold winter season. The extreme minimum temperature is -31.1° and -52.9°C in winter (January) and 28.5° and 43.1°C in summer (July). The annual precipitation amount is low, averaging 200-220 mm and ranging from less than 50 mm per year in South (Gobi Desert region) to 400 mm in limited areas in North. The occurrence of most precipitation between middle of June and the end of August limits the potential productivity of Mongolian land resources. During last 60 years the average temperature in Mongolia has increased by about 1.56oC. The maximum temperature increased in 3.6oC in the winter season, but in summer months it decreased in 0.3oC.
Mongolia has on an average 3,000 hours of sunshine annually, which is well above the amount received by other countries of same latitude.
Within last several years the pasture condition degraded much intensive due to harsh weather and increasing of livestock population and concentration of people, especially around urban or town area due to the transition period to free marketing economy.
Used data
To classify and monitor the land cover types particularly, the pasture vegetation coverage of whole territory of Mongolia used the normalized difference vegetation index (NDVI) data derived from NOAA/AVHRR data. The NDVI dataset is unique in that it is global, multi seasonal, multi annual, and multi spectral.
In this study we used following satellite data.
- Maximum NDVI composite from April 1992 to March 1993, which supported by USGS EROS Data Center,
- NOAA AVHRR 1km data received by ICC. Then geometrically corrected and made max NDVI composite for each 10 days of 1997
- NOAA/NDVI 8 km resolution monthly GAC data from 1985 to 1997,
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