Introduction of the forest renovation activity by fishermen in northeast Japan, using RS and GIS

摘要

There is an activity of forest renovation focused on the relationships between forest and coastal region ecosystems. The activity has been performed in the watershed of Ohkawa River pouring into Kesennuma Bay in northeast Japan. Since the latter 1960s the production of oysters and laver decreased in Kesennuma Bay. Fishermen thought that was because nutrients from the river into the coast decreased and the nutrients were supplied from forest and forest soil. Therefore, fishermen wanted to recover natural forest, and they started the forest renovation activity from coniferous to broad-leaved trees. The activity is important for the study of the integrated ecosystems; thereby we researched this renovation of the forest. Study areas were Mt. Murone and Mt. Yagoshi that are in the watershed of Ohkawa River. We made graphs of spectral patterns and band relationships of the vegetation of the afforestation areas, using some satellite data of those areas. As a result, the bands of red (R) and near-infrared (NIR) spectrum showed clear patterns of band relationships. Just after afforestation, the digital number (DN) of R was higher and that of NIR was lower than those of broad-leaved forest. After some years since afforestation, the DN of the afforestation areas approached gradually to the DN of broad-leaved forest. That was because, as soon as the activity started, a lot of weeds grew up and occupied all of the area, and after a few years, some young trees grew up.