GISとリモートセンシングを用いた遊牧移動と生態的条件の関連性の評価
北ケニア・レンディーレランドにおける例
2000 年 2000 巻 56 号 p. 21-36
詳細
2000 年 2000 巻 56 号 p. 21-36
The relationship between pastoral movement and spatio-temporal changes of ecological conditions was analyzed in this case study. Movement of camel camp in 1975-1976 in the Rendille Land, northern Kenya was dealt with as an illustration. The Rendille Land, included in the Marsabit District is comprised of central lowland and surrounding mountains. The annual rainfall precipitated mainly during two rainy seasons, is 200mm in the lowlands and over 1, 000mm in the mountainous area. The lowland is vegetated with annual grasses with sparse trees, while the skirts of mountains are covered with evergreen to semi-deciduous trees with perennial grasses. Dense forest is observed only near the top of mountains.
In this study the distribution of water points and change in vegetation cover has been estimated using satellite images, these were considered as ecological conditions. Locations of water points were obtained from the map published by the Kenya Government in 1970. Positive films of Landsat/MSS images were scanned into the analysis system and transformed into physical values using regression analysis between different dates/forms. The scanned data was used for deriving NDVI (normalized differential vegetation index), popular index for vegetation cover, on the five dates from September 2-3rd, 1975 to February, 11-12th, 1976. These data were then overlaid with the movement of camel camps in 1975 and 1976 surveyed by an anthropologist.
The results are summarized as follows:
1. Predominant area is included within the range of 30km from water points. This is marked merit for nomads compared to other dry lands.
2. Water is not a determinant for the location of camel camps. Camel camps were primarily established on the skirts of mountains. Vegetation is more significant in these locations.
3. When rain is plentiful the lowland is also utilized for camel camps.
4. For cattle and small stock such as goats and sheep, water is an important factor. Camp sites were limited to near Mt. Kural, Mt. Mara, Mt. Marsabit and the highlands extending to Samburu, bordered by Marsabit on the south.
5. In bushland, vegetation growth after some rainfall, within about two months delay promotes the shift of camel camps. In the semi-desert grassland, on the other hand, that delay appears to be shorter.
