GISdevelopment.net ---> AARS ---> ACRS 1992 ---> Poster Session Q The Application of TM Lmagery to grassland resources investigation in loess plateau region Saiyinbatu,RenZhibi,Su He Grassland Research Institute of Chinese Academy of Agriculture Science, Hobbit china Abstract The project which is the application of remote sen-sing technology to investigate the grassland resources in Loeas Plateau region was carried out recent years and more than 110, 000 square kilometers of investigation work has been completed. The remote sensing information used in the project is mainly TM imagery. After use comprehensive analyzing of image features and combining with ground truth survey information, the comprehensive interpretation symbols of TM imagery were established and visual interpretation technique has been used as the fundamental processing method. The research area covers the 110,000 square kilometers. Among them, the area of grassland accounts for 27%. According to the spatial resolution features of TM imagery and combined with the ground truth information, the grassland resources in the area were classified into 8 classes ( the high unit of the classification system), 87 groups and 63 types ( basic unit of the classification system. Topographic feature of the investigated region is that the north western part of the region is sandy plain and the southern part of the region is sandy plain and the southern part of the region belongs to hilly-gully area. With the change of topography and water supply condition, are distribution of grassland vegetation appears regularity from north to south and zonalization of grassland vegetation from north to south is warm steppe – warm meadow – warm shrub respectively. The changing feature of grassland vegetation can be interpreted on TM imagery according with the change of colour. The characteristics of grassland resources in the investigated region are as follows: ) the regularity of grassland vegetation distribution based on animate condition 2) grassland vegetation appears in small pieces and mainly distributed under the bankline of ditches 3) shrub grassland distributed broadly, 4) the main body of grassland resources of this region belongs to middle level of quality and quantity. Introduction During 1988 – 1990, we had carried out the study of investigation and mapping of grassland resources in Loess Plateau region with the aid of TM imagery, and had made a scientific analysis for quantity and quality characteristics of grassland resources and its distribution features and zonalization. Finally, the scientific basis for multi-purpose utilization and development of Loess Plateau was provided through the study. Technical Idea and Study Procession TM imagery can provide accurate, timely and reliable information about the location and condition of natural resources, at the same time, it provides the new datum and ways for investigation of large area of grassland resources. The key elements for applying TM image information effectively and accurately are decided by establishing an integrative interpretation symbols which combined with TM imagery and the distribution features and conditions of local grassland resources. Based on the general plan and task of the study at this time, the technical ideas were applied : a) taking TM imagery as main data source to do macrocontrol for grassland resources and referring to infrared air – photo to make microanalysis for typical sampled pots b ) combined with field survey information and TM data to take quantity analysis for grassland biomass 0 ) applying the basic principles of grassland sciences and the other related sciences to establish interpretation symbols, which are used to take visual interpretation for grassland resources on TM imagery and, making quantitative statistics for grassland resources. ( see Fig. 1) Data source selection The work of data source selection included three aspects, which were selection of remotely sensed data, waveband composition and selection of image temporal. Many studies of TM data have clearly shown that the 30 meter pixel size of the data can provide a vastly superior spatial resolution The application of TM Lmagery to grassland resources investigation in loess plateau region image and data set. After making geometric correction, TM imagery is convenient to match same scale of topographic maps. Usually, ch4 of TM is optimal wavelength for investigating vegetation and grassland biomass, then, the products which combination of ch3,4,5 of TM data are also suitable for visual interpretation of grassland resources on imagery. According to phenological phase of grassland vegetation and its spectrum features, data captured from last spring to first summer or from last autumn to first winter are more effective for grassland investigation , and are helpful to identify different types of grassland on imagery. 2) Field survey The field survey included general survey, ground truth sampled survey and collection of information’s related to local grassland resources. The ground truth sampled survey is an essential work for further analysis for grassland resources, so, the data of sampled plot must be provided with representative characteristics of whole investigated area, and when we determined sampled plots, the following aspects must be emphasized a) making the macrocontrol of whole research area through sampled plot investigation b) establishing correct interpreting symbols employing the datum of sampled plots; e ) comparing with TM imagery to draw grassland resources map on plots, 3) TM Imagery mapping Grassland resource maps can directly mirror the quantitative and qualitative characteristics of grassland and its distribution features. Applying the TM imagery to map grassland resource map is an important content of remote sensing investigation of grassland resources. Based on the information of ground truth survey, integrative interpretation symbols and the theory of grassland classification system, used the topographic map as base map, taken the water systems and obvious topographic elements as control points, the grassland resource map can be mapped on TM imagery directly, ( Fig. 1) Grassland types and interpretation symbols Determination and division of grassland types are the essential work for studying grassland resources. For the idea of “grassland type” it contains not only its own special meaning which including species composition and structure and structure of community and economical property, but special ecological conditions including topography, soil structure and water condition. In general, grassland is usually in changing situation, but, for “grassland type” it is in relative stable. In according with the present situation of vegetation, topography, climate and soil structure, and following the rules of ( Division Standard of Chinese Grassland Types and Classification System of Chinese Grassland (, combining with the characteristics of remote sensing investigating and mapping of grassland resources on Loess Plateau Region, the grassland in research region was classified into 9 classes, 37 groups and 63 types. (table 1) There is an inflation sandy plain in north part of research area. The characteristics of this areas is that the grassland vegetation community is uncomplicated and low level in vegetation coverage and biomass production. Because of high reflective features of sandy area, colour of this area is mainly light yellow and light blue on TM imagery, and topographics features and distribution characteristics of grassland vegetation caused the outlines of grassland clear disternible on TM imagery The south part of research area is hilly – gully region. With the change of topography and water supply condition from north to south, warm steppe -- warm meadow -- warm shrub appear respectively, and corresponding with the change of grassland vegetations from north to south, colours on TM imagery of this region is grey blue - grey green or green - dark green or brown green respectively, and with the increase of coverage and biomass of grassland vegetation, colour density of TM imagery become well - distributed and the red increased gradually. In addtion, azonal grassland, artificial and semi-artificial grassland also have their own special image oharacteriatics, for example, the flat meadow appears on TM imagery with the colour of light red, light pink red, light blue red, red or dark red colour. Air sown A siragalus adurgacs apperas with light brown, brown, brown or darkbrown colour, and with clear geometric shape. Grassland resource and its distribution peatures The research are has covered both sides of Yellow River gore region which including 56 Coun. ties of Sharnxi Province, and accounting for 26.2% of territory of the whole country. (table 1). Zonal distribution regular of grassland type is obvious The long time comprehensive effects of climate, topography, soil and human aets have caused the complication of grassland types and its distribution regularity in Loess Plateau region. 1) Warn Desert Steppe It is distributed mostly in northern part of research area, which covers the area of 18000 hectares. The dominant species of the class are Ni tratia sibirica and Caladium foliatum. 2) Warm Steppe The Warm Steppe is distributed in north part of Loess Plateau region and it can further divided into two subclasses; the sandy warm steppe, the plain and hilly warm steppe. The first one is distributed to north of Greatwall in Shaanxi Province, and the dominant species are Allmerica arenaraia,. The second subclass is distributed in the gullies and hillsides to south of Greatwall and dominant species are Stipa bunqeana, Arternisia giraldii, Artemisia gmelinii, Thgmus monqolicus, Lespedeza devurica and Artemisia frigid. 3) Warm Meadow Steppe The kind of grassland is distributed in the model part of the research area and which develops on rockland along Yellow River. Dominant species of this grassland are Both rioohloa isch aemuin, Theoxeda triandra var.aponiox, Stipa spp. ( all these grasses are growing up on north slopes of hills. At the same time, some species of shrubs, for example, IIipopphea rhamaoides, Sophora viciifolipeared frequently inhills These kind of grasslands are all distributed in south part of the study area, and many species, high biomass. 5) Flat Meadow It is distributed in the banks of rivers, lakes, and lowland of sandy of alkali – salinization. The grassland vegetation communities of first meadow are consisted of hygraophytic and mesophytic perennial herbages and it has a high grass coverage and biomass. But, the flat meadow on Loess Plateau is in degenerated states because of overgrazed. 6) Artificial Grassland Artificial Grassland are developed mostly in the north part of Shaanxi Province, which are including large area o air – sown Astragalus adsurgens and manpower plant 1 Medicago stiva and Melilotus officinaliha Most of artificial grasslands in research area are in high productivity and good quality situation ad they are also main sources for supplementing high quality o forage for local animal husbandry development. ( table 1.) Grasslands are not well – distributed In loess Plateau region, the percentage of grassland of the whole area increases gradually from south to north. Particularly, to the west of yellow River , proportion of grassland area account for 19%, 27% and 34% respectively in south, middle and north part, and to the east of Yellow River, the Percentage of grassland area account for 29% in south, 22% in middle and 29% in north of whole area. SO, it is clear that the more the soil erosed, the less the grassland resources appeared. Grasslands are broken up in small pieces Apart from the sandy plain in northern part of Loess Plateau, the grassland resources in research region are all broken up in small pieces and mostly distributed under the backline of gullies and ditches. For instance, we have analyzed the grassland resources of Yu Lin County on infrared air – photo. There are 2586 pieces of grassland in whole county, and pieces of grasslands which are is 2 - - 20 hectares accounts for 71.4% of the whole pieces. Shrub – grassland distributed broadly For the purpose of protecting soil erosion, people planted the Caragana korahiaskii, Sliz app. and Sophora viciifolia broadly on natural grassland. At present , the shrub – grassland distributed wide – ranging in northern part of Shaanxi Province. The application on TM Lmagery to grassland resources investingation in loess plateau region Particularly, in sand area, this kind of grasslands account for 65% of whole area. The grassland resources of Loess Plateau region are in middle and low lever of quality and quantity In research region, most of grassland resources area in middle or low level of quality. High quality of grassland which dominated by Gramineae and Fabaceae just occupied less the 25% of whole, and contrary, the grassland which dominated by Artemisia spp. occupied more than 65%. At the same time, unsuitable utilization of grassland caused the grassland degeneration in large area and the grassland production is decreasing rapidly. The way of Grassland resources development and application Grassland resource is a kind of renewable resource, Its succession and development is mostly controlled y at lot of natural conditions and affected by human acts. So, it is very important to take the correct ways to affect the trend of succession of grassland community and applying the grassland resources scientifically. 1) To take a comprehensive analysis for natural resources and its existing conditions , and to formulate a scientific policy which used for long term of development of animal husbandry. 2) To stress the utilization of grassland resources scientifically and to control the stock capacity of grassland effectively. As we known, the developing of animal husbandry and controlling of stock capacity is two sides of a contradictions. For solving this contradictions, it is necessary to develop artificial grassland to increase the quality and commodity rate of livestock, it utilize crop straw effectively and to graze rotationally. 3) It is important to formulate a policy and make a plan for developing animal husbandry based on local conditions and developing potentials of natural grassland resources. Table 1. Grassland resource area and its theoretical stock capacity of Loess Plateau Hegion No. Class area (hectare ) % of wholegrassland stock capacity ( sheep unit ) 1 Warm desert steppe 17972 0.58 16567 2 Warm steppe 1561476 50.16 1674362 3 Warm mcadow steppe 848689 27.26 1614166 4 Warm hassock 460604 14.79 848674 5 Warm shrub and hassock 175671 5.64 274014 6 Warm shrub and hassock with trees 27584 0.89 10159 7 Flat meadow 15909 0.51 23388 8 Artificial grassland 5345 0.17 40693   Total 3113250 100.00 4598455 The application on TM Lmagery to grassland resources investingation in loess plateau region Fig.1 The flowchart of remote sensing investigation of grassland resource and mapping References (Study of Remote Sensing Application in The Loess Plateau of North Shaanxi), 1991, Scientific Press. (Remote Sensing Comprehensive Research in water and Soil Conservation Forest Region of Loess ( Plateau ), 1990, Chinese Scientific and Technical Press.