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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.
Figure 1. Land cover map of Mongolia, 1992
Figure 2. Land cover map of Mongolia, 1997
Assessment of pasture condition
From the comparison of multi-date land cover map of 1992 and 1997 found that the total forest area in Mongolia including deciduous needleleaf, deciduous broadleaf, coniferous forest and all mixed forest is about 12.7%.
NOAA/NDVI monthly data set is useful information for pasture vegetation monitoring of Mongolia. The spectral characteristics of different pasture vegetation zones, derived from NOAA/NDVI was distinguishable from each other.
According to the accepted new technology for pasture vegetation condition mapping the outputs from NOAA/NDVI would be increased for the end users and also for decision makers. In this case we could estimate current situation of pasture vegetation and compare with a long term condition.
The results of study will sober to strengthen the pasture management related to the decision support system of the country, after integration with other socio-economic information.
References
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
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,
- The Classification schema
Considering the resolution of the AVHRR data and seasonal spectral curve of all classes, minimum mapping unit and expert's views in the field, the following 11 land cover types were identified for Mongolia. The methodology of producing the land cover maps for 1992/1993 and 1997 is almost the same.
Land cover types of Mongolia in 1992/1993 and 1997 are given in the Table 1. The Land cover map is in UTM project (zone utm-48n). Both classification results are converted to IGBP classification scheme. - Land Cover Distribution and Assessment
From the interpretation of multi-date NOAA/AVHRR data of 1992/1993 and 1997 found that the total forest area in Mongolia including deciduous needleleaf, deciduous broadleaf, coniferous forest and all mixed forest is about 12.7% (see Table 1). But there were some difficulties to distinguish saxaul forest in southern part of territory, which is included into official total amount of forest area.
Grassland consisting of permanent pastureland and a tall and a short mountain grasses with shrubs. In Mongolia the cropland has complex cropping patterns depending upon the topography, seasonal climate, vegetation condition.
However, in Southern part of Mongolia is gobi desert area and it has too sparsely vegetation.
Table 1. Land cover types of Mongolia
1992 1997 Category Class Name Class Id Area (in Ha) Area (in Ha) Water Water body 1 1606834 1226685 Barren Desert shrubland 2 5226704 High mountain (rocks) 3 15990 2742531 Barren or sparse vegetated 8 38379477 45308976 Grassland Grassland 4 67018933 15930215 Steppe 5 37902374 Dry steppe 6 21422068 24433793 Cropland 7 7601494 3264166 Forest Needleleaf forest 9 12893895 15402268 Broadleaf forest 10 859230 3185248 Mixed forest 11 6042591 1328226 Total area 155890514,0 155901185,3
- Analysis of 1992 and 1997 land cover maps
Before making comparison analysis we made some corrections to the land cover map of 1992. Previous version of 1992 land cover map forest was not clearly identified and in version of 1997, we made DEM analysis to distinguish grassland area and forest and finally we got more better classification of forest in central part (the Khangai mountain area) and north eastern part, where locates the Khentii mountain ridge. And also we made some changes in classification scheme and name of classes in order to compare both maps of 1992 and 1997.
Figure 1. Land cover map of Mongolia, 1992
Figure 2. Land cover map of Mongolia, 1997
Assessment of pasture condition
- Vegetation dynamics by NOAA data
NDVI value has becoming the main tool to estimate vegetation dynamics for whole territory of Mongolia. According to the monthly NDVI composite images we can determine the temporal and spatial vegetation changes i.e. onset, pick and die time of vegetation growth. From the general dynamics of pasture we can say that better grazing time for the pasture animals begins from latest April to latest October till suffering full snow coverage and the best grazing time is too short as, from July to August.
Using 13 years NDVI data we calculated the long term normal values for each months and for each year of whole Mongolia.
Figure 3. Long term normal NDVI map of Mongolia (August 1985-1997)
With comparison above maps we have distinguished normal (1985, 1987, 1988), drought (1989, 1992, 1995) and good vegetated (1990, 1991, 1993, 1994, 1996, 1997) years within 13 years. - Vegetation zone classification
According to the vegetation zone map of Mongolia (Figure 4a) we have classified the vegetation zone map using NDVI data Figure 4b, which is highly correlated with first one (r = 0.9619). The regression function determined like,
Y = 0.078968 + 0.977887X
Figure 4. a. Vegetation zone map (source from National Atlas of Mongolia)
b. Vegetation zone classification map (classified by NDVI)
Based on time series analysis of above classified map and multi temporal NDVI data calculated the monthly spectral curves of 6 types of vegetation zones, as high mountain, mountain taiga, forest steppe, steppe, desert steppe and desert.
According to the above results we could make decision that the NOAA NDVI GAC data is available to estimate vegetation condition, in particular the pasture condition during a year. As analysis, all vegetation zones are different by NDVI values specially, in growing season (Figure 5).
Figure 5. a. Area difference of vegetation zones from original map and calculated from NDVI
b. Spectral characteristics (yearly NDVI changes) of different vegetation zones
We have a new technology of preprocessing of NOAA/NDVI data and producing following numbers of outputs as,
- Current NDVI map of Mongolia with summer condition score (point type at the meteorological station) and drought index (pattern type by whole country)
- NDVI difference map, in %
- Hay and Pasture map with VCI map (pattern) and biomass data (point)
- Drought index map with Pedi index (point)
- Biomass map estimated by NDVI
- Pasture carrying capacity
In other hand, the pasture vegetation condition depends not only upon natural (drought) condition, but also on human activities.
From the comparison of multi-date land cover map of 1992 and 1997 found that the total forest area in Mongolia including deciduous needleleaf, deciduous broadleaf, coniferous forest and all mixed forest is about 12.7%.
NOAA/NDVI monthly data set is useful information for pasture vegetation monitoring of Mongolia. The spectral characteristics of different pasture vegetation zones, derived from NOAA/NDVI was distinguishable from each other.
According to the accepted new technology for pasture vegetation condition mapping the outputs from NOAA/NDVI would be increased for the end users and also for decision makers. In this case we could estimate current situation of pasture vegetation and compare with a long term condition.
The results of study will sober to strengthen the pasture management related to the decision support system of the country, after integration with other socio-economic information.
References
- Adyasuren Ts. "Environment and Development issues in Mongolia". Ulaanbaatar, 1998.
- Batima P. Dagvadorj D. "Climate Change and its Impacts in Mongolia". Ulaanbaatar, 2000.
- Batima P., Dagvadorj D. "Mongolia National Action Programme on Climate Change", Ulaanbaatar, 2000.
- Chandra P.Giri, Surendra Shrestha. Developing land cover classification system for NOAA AVHRR applications in Asia.
- Khudulmur S, Erdenetuya M, Munkhtuya Sh. and Odbayar M, Classification and Monitoring of land cover of Mongolia. Report 1997.
- Mongolian Development Strategy Research Project: "Some issues of environment and development of pasture and animal husbandry of Mongolia", Ulaanbaatar 1999.
- Mongolia - 21 century. New policy of economy and social problems, Ulaanbaatar, 1997.