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

通过对2004年至2006年宫崎县中部至北部12个地区竹林的时间序列变化进行分析，以了解九州岛南部地区竹林扩展情况、相关环境立地因素及竹林扩展规划。研究采用航空正射摄影技术和地理信息系统软件，时间跨度为30年，从20世纪70年代到21世纪初，每隔10年左右进行一次。毛竹(Burllostachys Pubescens)、毛竹(Madake Phyllostachys Bambusoides)、黑竹(Phyllostachys ngra var.Heonis)和Medake(Pleioblastus Simonii)，其中Moso-chiku最为丰富。竹林分布在农场、稻田和房屋附近，近30年来没有明显的变化。竹林规模扩大得到认可。30年后，各研究区域的竹林面积是开始时的1.2~9.1倍。竹材膨胀度较低，除3个区域外，其余均不到3倍。各研究区竹林数量为0.6~1.4倍，占83%；不足1.4倍，占50%；近年来，个体竹林面积有所增加。这说明，竹林个体面积的增加导致了竹林的扩张。竹林个体的变化较为复杂，表现为出现、扩张、结合、消失等多种变化类型。此外，每种类型都被分为几种不同的类型。这似乎导致了竹林的出现并没有增加竹林的数量。竹林扩展与海拔、倾角、方向和森林类型有一定的关系，但与立地环境因子的关系不明显。

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.