@article{oai:ir.kagoshima-u.ac.jp:00002529,
 author = {NAKANO, Kazutaka and WATANABE, Toshiharu and USMAN, Rustam and Syahbuddin},
 issue = {2},
 journal = {南海研紀要},
 month = {2016-10-27},
 note = {For a fundamental study of nature conservation in a region with the headwaters
of big rivers in the humid tropics, surveys of vegetation, land-use, and water
quality were made around the relatively small lakes of Diatas, Dibaruh, and Talang,
in the volcanic highlands of the Province of West Sumatra. Owing partly to
the relatively high population density, the area of the natural forests, most of
which are legally protected, has decreased to less than one-third of the total area
of the terrestrial parts of the catchment basins. Much more than half of the
terrestrial area of the basins of both Lake Diatas and Lake Dibaruh is classified
as actually cultivated or abandoned upland fields plus residential districts. Most
abandoned fields, whose area is far more than that of actually cultivated ones,
are covered dominantly by bracken (Pteridium aquilinum). The application of
chemical fertilizers has become a normal process during the cultivation in both
the upland and wet paddy fields., The evaluation of the water quality in the lakes using a biological index
based on diatom assemblage as well as the results of the measurements of
transparency and the standing crops of phytoplankton led to a conclusion that neither Lake Diatas nor Lake Dibaruh were eutrophicated as a whole. Some
symptoms of eutrophication, however, were also, at least, partially confirmed by
means of the values of the index. The results of the analyses of chemical factors
and plankton flora there correspond with those symptoms and can be explicated
without contradiction when we take other physical factors of the water of the
lakes and their inflows into consideration. In addition, the water quality of Lake
Dibaruh, which is mostly encircled by very steep slopes, is worse than that of
Lake Diatas despite more favorable conditions of the former in regard to the
factors of the load of pollutants and lake depth. The above-mentioned phenomena
suggest that the eutrophication in both Lake Diatas and Lake Dibaruh is closely
connected with the severity of the erosion of surface soil and runoff which contain
the nutrients derived from chemical fertilizers. Therefore, the restoration of natural forests in the abandoned fields is necessary to abate the soil erosion and the
runoff around the two lakes. The results of a quantitative investigation have
demonstrated the strong possibility of the natural reversion of the vegetation in
those abandoned fields to the forest stage if no fires occur there.},
 pages = {87--124},
 title = {A Fundamental Study of Overall Conservation of Terrestrial and Freshwater Ecosystems in a Montane Region of Western Sumatra : Vegetation, Land-use, and Water Quality},
 volume = {8},
 year = {}
}