GISdevelopment.net ---> AARS ---> ACRS 1990 ---> Forestry Analysis of function of forest using artificial satellite data and geographical information Masahiro Setojima, Yoko Hirose , Ken-ichi Shibata Kokusai Kogyo Co. Ltd. 3-6-1 Asahgaoka, Hino-shi, Tokyo 191 Japan Abstract In recent years, there is a nation-wide phenomenon in Japan that green cover of land is destroyed and living environment in urban areas is deteriorated along with the development of cities. To prevent such tendency, many measures have been taken for the promotion of greenery conservation tree planting plan in urban areas, it is important to grasp the actual state of greenery of cities and to analyze the function of such green areas. Forest has variety of function and they are classified into (1) function to prevent disaster and conserve the land, (2) function relation to living environment, (3) function to conserve the natural ecology (4) cultural function, (5) function relating to biological index and (6) educational function. In this report, we took up, as an example, the forests in greater Sapporo area which is the central city on north part of Japan, and tried to analyze the present state of forest distribution and the functi9on of forest from macro view point using the artificial satellite data and geographical information. Introduction Along with the rapid advancement of urbanization and deterioration of living environment in Japan in recent years, there have arisen increasingly strong voices to seek for comfortable and well off life in urban living environment. Under such circumstances, it is considered urgent to conserve and arrange better environment for suburban forest to enhance the recognition for the roles of forest adjacent to cities as well as to improve the environment. In proceeding with the maintenance ad conservation of forest, it is necessary to grasp the actual state of forest over the wide with consistent accuracy from uniformed viewpoint, and to perform the time sequential monitoring continuously. Having such situation as the background, this paper introduces the functional analysis made on suburban forests of cities by using remote sensing data and each kind of geographical information in an attempt to promote the comprehensive green land preservation measures including the conservation of forests. The function of forests Suburban forests as well as urban forests have variety of functions. The forest id formed by (1) topographic feature, geological feature, soil, shape of slope, slope aspect, and (2) its direct composing elements of water, atmosphere, animals and plants. Quality/features and quantity of them, mutually supplementing each other, give effects tot eh adjacent cities. Many functions have been observed to forest (or green land), and they can be classified systematically from various standpoints. Environment conservation function: The forest has function to maintain and improve the healthy environment of cities such as to provide purification of atmosphere, mitigation of climate change, and preservation of sunshine and ventilation, giving comfort and relaxing to the human life. Recreational function : the forest (or green land) provides indispensable outdoor space for recreation for the residents of cities. Disaster prevention function ; The disaster prevention function is further sub divided in to land conservation function such as prevention of degradation and land slide, prevention of flooding and preservation of water-head, mitigation function to absorb noise, vibration and atmospheric pollution, and a function to prevent the spread of fire and preserve the shelter at the time of disaster. Productive function : It also has a function to provide forestry products or agricultural products at the suburbs of city. Function to prevent the expansion of city : It can prevent the disordered expansion and lead to the healthy development of cities. Scenic function : The scenic function is very significant to build up comfortable and relaxing city environment. Especially in case of suburban forest, it has an important function to constitute the near views and far views of urban scape. Subject area of investigation In present study, we selected and made analysis on Sapporo City which is the central city in north part of Japan (fig.1). Sapporo is the largest city following Tokyo, Osaka, Nagoya, etc and has the most abundant green among these large cities. The urban district spreads over the plain land, and the forest area called Satoyama is located as if to surround the. The forests in Satoyama its located as if to surround the city. The forests in Satoyama area hold important position as the green are abutting on city playing an important role in forming the full-of-green of Sapporo city. Fig. 1 Studt area The data used for the study MSS CCT (PATH 116 -Row 030 , Aug.29.1972 ) TM CCT (PATH 108 -ROW 030 , Sep.11.1985 ) Altitude data file (1982), vegetation data file (1984), River basin data file (1984), geological map (1/50,000, 1946-1950), Soil map (1/200,000,1975) Method of analysis The analysis procedures are as shown in fig.2. Grasping of regional characteristics of study area For the purpose to grasp the regional characteristics of study, we made land cover classification using LANDSAT TM data, and grasped present state of distribution and secular change of the forest. We also grasped the geographical characteristics by collecting data of topography, geology, soil and climate. Study on the functions to be analyzed and establishment of analysis standard We discussed the functions to be analyzed in this study based on the present state of forest and regional characteristics grasped in (1) above. We also established the analysis standard referring to past analyses already performed in Japan. Construction of image database The basic data of for analysis were converted into image database of the uniformed pixel size 100m x 100m, and stored into disk. The map data such as geological map and soil map were digitized by using scanner. The data field of altitude data, vegetation data and river basin data were converted into image by calculation and compiled in a database. The topographic data were analyzed by using altitude data, and slope aspect, slope, relief volume were obtained as image data. The images of present state of forest obtained from TM data were re-sampled in a manner so that the pixel size would be 100m x 100m and compiled in a database. Analysis of forest function Analysis of forest function was performed by the overlay of images based on the analysis standard. The analysis results were compared and checked with the present, state and if contradiction was found thereon, the analysis standard was reviewed, and analysis was performed again. Grasp of forest characteristics The characteristics of forests around Sapporo city were grasped by the forest function individually grasped as well as by comprehensive analysis. Fig. 2 Method of analysis Results of analysis Functions subject to analysis We discussed the functions to be analysed based on the consideration that the forests around Sapporo city which are the study subject of this report had the function of both urban Greenland and suburban forest. The function which were analyzed were are as follows : Land conservation function ... Mountain disaster prevention function, flood prevention function, water head preservation function. Environment conservation function ... function o mitigate climate conditions, function as atmospheric pollution index, wind arresting function, animal ecology conservation function, plant ecology conservation function. Recreational function. Scenic function. Regional characteristics of suburban forest of Sapporo. The present state and secular change of Sapporo suburban forest were grasped by the analysis using LANDSAT data geographical information of two different times (See photo 1 and photo 2). Nearly 50% of suburban forest of Sapporo city are secondary forest of broadleaf trees, and about 15% is aforesaid trees. Natural woods are hardly seen. Toyohira River runs across almost center of this forest area. The mountain area with the altitude of 600-800m at the north side of the river is the andesite belt with acute relieves, and south side of the river is relatively gradual hill land mainly composed of Tuff. Result of analysis on forest area Table 1 shows the summation result of analyzed area. As for land conservation function, the analysis was made on the functions such as mountain disaster prevention, flood prevention and water-head preservation etc (see photo 3). Land and sand slide were mainly considered as mountain disaster. As a result, the mountain disaster prevention function was observed to be high at the north side forest where the land shape is more acute. As for flood prevention function, the forest at the upstream of river were observed to have higher function. The water head Preservation function was failry high all over the suburban forest area, indicating that it is precious water reservoir for Sapporo city. In the environment conservation function, distance form urban area or road was taken as an important factor for analysis (see photo4). As the majority of Sapporo suburban forest is broad leaf tress which have relatively large influence for mitigation of climate condition and as the index of atmospheric pollution, the environment conservation function tended to be high in general. As a result of analysis, the recreational function was high all over the suburban areas of Sapporo City, indicating that they are precious recreational resources for that area. The analysis of scenic function was performed through the analysis of visible and invisible area using DTM, and taking visibility as the factor (see photo 6). As a result the forests were clearly identified to which the highest consideration should be pain in urban development from the view point of scenic view. Table 1. Summation of study area (the function is "high") Function/ basin no. Land conservation function Environment conservation function Recreational function Scenic function Mountain disaster prevention function Flood preservation function Waterhead prevention function Climate condition mitigation function Atmospheric pollution index Wind arresting function 1 4039 24.1 134 8.0 5892 49.0 4663 78.5 4734 79.4 2084 17.3 10,392 86.5 156 1.3 2 44 6.3 5 0.7 226 64.6 0 0 7 63.6 103 29.4 350 100.0 0 0 3 374 9.8 1123 29.3 1647 51.6 1080 77.0 1109 79.0 574 18.0 3053 95.7 155 4.9 4 35 3.3 294 27.8 64 6.8 771 82.9 772 83.0 30 3.3 930 100.0 280 30.1 5 703 21.6 931 28.0 1236 52.5 1274 87.2 1274 88.7 746 31.6 2355 99.5 425 18.0 Summary In this study, forest function was analysed from a macro view point using LANDSAT data and each kind of geographical information. As the data used for the analysis was huge in quantity, the forest distribution data obtained by automatic classification of LANDSAT data as well as geographical information were compiled into database. As a result, it became easy to overlay the images each other according to each kind of functions. Consequently, ti was possible to anlayse the images basing on the analysis standard complying with the regional situation of study area, to correct the standard if necessary, and to perform the analysis basing on the standard best suitable for the area. In the future it is considered necessary to make analysis from the view points which are nearer to the earth to rationally perform the conservation and utilization of forests basing on the data obtained by present study. Bibliography Forestry Agency (19760: Guidelines for Investigation on Forest by its Function. Sapporo City (1983) : Report on Sapporo City Forest Environment conservation Study. Setojima, Akamatsu, Oyama, Shibata (1987) ; Functional analysis of Urban Green Land Using SPOT data and Geographic information Academic Lecture Meeting of Japan Society photogrammetry and Remote Sensing. Setojima, Hirose, Shimohirao, Kadotani (1988) : Extraction of urban Green Land by Overlaying TM data and geographic information, proceedings of annual, academic lecture Meeting of Japan society Photogramemtry and Remote Sensing.