No abstract

Range expansion of unmanaged invasive Phyllostachys bamboo stands is one of the most serious problems in ecosystem management in Satoyama area across Japan. It is feared to be accelerated by depopulation and climate change. In this study, we analyzed changes in vegetation and land use by using aerial photography between 1977 and 2014 in a deserted area in Ikusaka village, Nagano Prefecture, central Japan. We also conducted field surveys in 2017, 2018, and 2020. Consequently, the areas of bamboo stands were estimated to have expanded 13.54 times from 0.26 ha of 3 stands in 1977 to 3.52 ha of 17 stands in 2014. The annual expansion ratio of the whole area was estimated to be 1.073 ha･ha -1 ･year -1 , which was in the range (0.96-1.11) of those previously reported majorly for moso bamboo (Phyllostachys edulis). Among the 17 bamboo stands recognized in the aerial photography in 2014, 14 were identified as hachiku (P. nigra var. henonis) and 3 as madake (P. bambusoides) bamboos by the field surveys. The annual expansion ratios of individual stands that were comparable between 1977 and 2014 were 1.016, 1.056 (for 2 hachiku stands), and 1.036 (for 1 madake stand). These results imply that there are risks of range expansion of hachiku and madake bamboos even in cooler hilly 特集「竹林放置に関する問題とその対策」 長野県生坂村の無居住化地域における竹林拡大 -138 -and mountainous areas comparable to those of moso bamboo in western Japan.

The expansion of bamboo groves has become a deep-seated problem throughout Japan. This study aimed to clarify what is necessary for continuous bamboo-grove maintenance and to envision future ways to utilize bamboo groves in Kukizaki village, Tsukuba city, Ibaraki prefecture, which has implemented many bamboo-grove maintenance projects using prefectural forest and lake environmental taxes. We conducted interviews with relevant personnel from Ibaraki prefecture and Tsukuba city and with village leaders, and we conducted a questionnaire survey among local residents on their opinions of bamboo groves, the degree of their recognition of the current situation of bamboo groves, the specific impact of bamboo groves on their lives and their thoughts on the future use of bamboo groves. Analysis of the resulting data revealed that many residents recognize that bamboo groves strengthen the ground and produce bamboo shoots, but currently regard bamboo groves as "devastating". However, there was no overt recognition of bamboo groves "expanding" and awareness of Ibaraki prefectureʼs bamboo-grove maintenance project was low. Conversely, various opinions such as ʻinvasion into farmlandʼ were expressed as concrete evidence of the devastating effects of expanding bamboo groves, and it became clear that there are many residents who desire bamboo-grove maintenance in 森林計画誌 ５ １ No.２ １ ８

Phyllostachys edulis (Carrière) Houz.) ， マダケ (Phyllostachys reticulata (Rupr.) K.Koch) ， ハチク (Phyllostachys nigra (Lodd. ex Loud.) Munro var. henonis (Mitford) Stapf ex Rendle)の 3 種である。モウソウチクは，1736 年に中国から持ち込まれ