西の湖におけるヨシ群落の管理頻度と植生変化の関係

概要

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The broad-scale reed communities around Lake Nishino in Shiga are habitats for many rare plant species, and also essential components of the local cultural landscape. Their conservation is reported to be a result of traditional reed-land management (cutting and burning) conducted along with the use of reeds for the production of reed-derived goods. However, continuation of management has become difficult due to a decline in the production of reed goods. This study aimed to evaluate the relationship between management frequency and vegetation change. Based on a vegetation survey on 160 plots around Lake Nishino conducted between 1999 and 2002 using the Braun-Blanquet method (Fujii 2005), we conducted a follow-up survey on 89 plots in 2010. We assessed management frequency according to three categories (no, occasional, annual). After vegetation data ordination by DCA, we compared the management frequency categories in regard to vegetation change. The results showed that there was a much greater vegetation change in the 'no' management category than in the other two categories. That change consisted of soil aridification and increase of succession degree. Occasional management could thus be effective for limited-labor maintenance of broad-scale reed communities.