Time-series change and evaluation of factors on Bamboo stands expansion in country-side forests Using GIS

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The time-series change of bamboo stands was analyzed from 2004 to 2006 in 12 areas from central to northern parts of Miyazaki Prefecture in order to obtain information on the bamboo stand expansion, related environmental site factors and plan for bamboo stand expansion in southern Kyushu island. The study was conducted through a period of 30 years from 1970s to 2000s at intervals of about 10 years with aerial orthophotographs and GIS soft wares. Moso-chiku (Phyllostachys pubescens), Madake Phyllostachys bambusoides), Hachiku (Phyllostachys nigra var. henonis) and Medake (Pleioblastus simonii) were observed and Moso-chiku was most abundant. The bamboo stands distributed near farm, rice fields and houses and did not show remarkable change for about 30 years. Bamboo stands expansion was recognized. The area of bamboo stands on each study area after 30 years was 1.2-9.1 times the value of the beginning. The extent of bamboo expansion was considered low because the value was less than three times except three areas. The number of bamboo stands of each study area was 0.6-1.4 times, 83 %; less than 1.4 times, 50 %; less than 1.0 time. The area of individual bamboo stands increased in recent years. This suggests, that increase of the area of individual bamboo stand resulted in the bamboo stand expansion. The change of individual bamboo stand was complicated and various change types were observed such as appearance, expansion, union, disappearance. Further more each type was divided into several different types. This seems to bring about that appearance of the bamboo stand did not increase the number of bamboo stand. A relationship between bamboo stand distribution and expansion and site environmental factors were not apparent though a relationship between bamboo stand expansion and altitude, inclination, direction and forest type was found partly.