4.2. Methodology 
The widely-used and feasible method for interpretation of grassland 
resources by means of Landsat images is visual geo-correlated 
interpretation (Dai 1981) To set up the interpretation keys for 
grassland resources, the following aspects should be born into mind: 
(1) Local natural conditions/features, such as landscape, climate, 
soils; 
(2) Zonal distribution of vegetationland units, including vertical 
zonality, horizontal zonality, and grassland biomes distribution; 
(3) Features of remotely sensed data, like tone, color, shape, size, and 
texture of representative targets; 
(4) Analysis of topographical maps and available thematic maps, 
including making of geographical base maps. 
Spectral information of Landsat TM image consists of bnghtness, 
vegetation index, thermal index and humility (Dai & Fu 1989). 
Grassland degeneration, or formation of black beach, generally 
results in a discemible decrease of vegetation coverage or phytomass. 
Therefore, the processing of image should enhance the stretch of 
vegetation index and brightness in the resulted false-colour 
composite, while band combination of TM 4, 3, and 2 assigned to 
red, green, and blue gun match the experiences of interpretation 
experts since the use of MSS. 
The optimal season's image is not available and a scene of middle 
December was acquired, but it does not look very good with a 
unified tone of grey. A scene of summer, Which is supposed to 
represent more information of vegetation, therefore, was purchased 
for comparison and interpretation and it also helps to resolve the area 
of temporal cloud and snow and to cancel the seasonal changes. To 
identify the geographical position and to register the image 
geographically, topographical maps were intensively used. 
43. Signatures of Typical Targets 
Table 2 shows list of image features of supposed categories. 
e Table 2 Signatures of land/grassland categories on Landsat TM 
  
  
  
  
  
  
  
  
  
and or dark | smooth 
smooth brown 
3 Light Mixed Light Mixed 
gray, blue and 
white and lor hght 
/or blue gray 
43 Light Stnps White Strips 
blue 
5 Light Spots White Spots 
blue and/or 
light 
blue 
42 Blue or | Lincar Azure Linear 
dark blue 
41 | Blue or | Linear Azure Linear 
| dark blue 
61 Wlute Lines White Lines 
62 White Lines & | White Lines & 
uregular uregular 
  
  
  
  
  
  
Table 3 shows geographical signatures of grassland categories 
considered by the interpreters during their operations. 
e Table 6.2 Geographical keys for grassland categories 
  
It locates on south, southwest 
and southwest of slopes, valleys, 
terraces, hummock and, 
occasionally, shaded side of 
slope, between 3920 and 47(X) 
meters above the sea level. 
1 1. Typical alpme meadow 
  
It locates on north, northeast and 
northwest of slopes, mountain 
toot, and flood plam between 
3920 and 4700 meters above the 
sea level. 
12. Alpine shrub meadow 
  
  
  
It locates on over-wet valley 
terrace, tlood plain, stream head, 
col, and shaded slope foot 
between 4000 and. 4600 meters 
above the sea level. 
13. Alpine swamp meadow 
  
  
  
degenerated | It locates on sunny foot of 
mountains, flood plain, valley, 
and peaks. Average vegetation 
coverage is below 30%. 
14. Alpine 
grassland 
  
  
  
  
  
14]. Severely deteriorated | Vegetation coverage is below 
grassland 10%. 
142. Moderately deteriorated | Vegetation. coverage is below 
grassland 30%. 
143. Sliehtly” deteriorated | Vegetation coverage is below 
grassland 50%. 
  
  
  
15. Prunary alpine meadow It locates at the foot of high 
mountams over 4600 meters 
above the sea level and on the 
edge of barren rock. 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
Category Landsat TM Landsat TM (13/12/1996) 
code (20/07/1995) 
Color Texture & | Color Texture & 
shapes shapes 
11 Red, Smooth Light Smooth 
fresh red brown 
12 Darkred | Granular Brown Granular 
13 Dark red, | Spotted Dark Spotted or 
red with brown, polygons 
black dark 
spot, dark gray 
brown 
141 White Smooth Dark Smooth 
gray 
142 Blue, red, | Stnpped Grey & | Stipped or 
and/or or mixed light mixed 
white blue 
143 Light red, | Stripped Dark Spotted 
white, orspotted | gray, 
and/or brown 
gray blue and/or 
gray 
blue 
15 Red, Mixed Orange Mixed 
and/or and/or 
grayısh lıght 
blue blue 
2 Dark red | Shaded Orange Shaded and 
302 
5. DIGITAL MAPPING AND GIS ANALYSIS 
Digital mapping and GIS database building involves six transparent 
sheets of grassland interpretation map and related geo-base maps in 
the scale of 1: 100,000. It is required to input all maps into computers, 
to transfer the data structure into a format accepted by MAPINFO, 
and to make statistical summary and GIS analysis of 
vegetation/land units. 
e Digitizing and editing 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXII, Part 7, Budapest, 1998 
  
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