た石に付着していた,もしくは鳥が胞子を運んだと
する₂つの説が提唱されている2)。
ヒカリゴケの培養はそれほど難しくないとされる
3)
が ,低地,市街地での培養には,夏の高温期間を
いかに過ごすかが問題となる。培養実験によると,
直射日光を避け,雨水が直接当たらず,湿潤を保つ
ような環境がよいと報告されている6)。一方,湿気
が多すぎると他のコケ類が洞窟内に広がって競争関
係が生じる危険があり,明るすぎるとシダ類や種子
植物が侵入してしまうことになる。北海道羅臼町で
のヒカリゴケ生育地の照度は40~100 lux で,他の
コケ類や植物が入り込まないためには150 lux 以下
に抑えることが必要と報告されている5)。
これらの情報を考え合わせると,下古田のヒカリ
ゴケ(標高約830 m)は,低地の集落内にある数少
ない生育地の₁つとして注目に値する。横穴斜面の
₁)樋口正信・村田和彦・伴 邦教(2012)東京都北
の丸公園のヒカリゴケ.蘚苔類研究,10⑻:253-
254
₂)井上 浩(1971)東京都心のヒカリゴケ雑記.蘚
苔類雑報,₅(10-12)
:173
₃)岩月善之助・水谷正美(服部新佐監修)(1972)原
色日本蘚苔類図鑑.保育社,大阪.pp.105-106
₄)岩月善之助編(2001)日本の野生植物 コケ.平
凡社,東京.p.108
₅)神田啓史(1988)羅臼町マッカウス洞窟のヒカリ
ゴケの現状と保存.日本蘚苔類学会会報,₄⑽:
165-166
₆)小池保次(1991)ヒカリゴケの培養法.日本蘚苔
類学会会報,₅⑼:146
₇)富永孝昭(2009)栃木県の低地で見つかったヒカ
リゴケ.蘚苔類研究,₉⑾:355-356
箕輪町天然記念物「下古田のヒカリゴケ」の現状と保全
69
Current status and conservation of luminous moss in
Shimo-furuta; a protected natural habitat designated as a
cultural asset by Minowa Town
Teruo ARASE*, Hazuki IZAWA** and Hideki SHIBA**
**
Faculty of Agriculture, Shinshu University
Local museum of Minowa Town, 399-4695 Minowa Town, Nagano Pref.
Summary
There is considerable conservation value for a scarce luminous moss that grows in Shimo-furuta, a
protected natural environment that has been designated a cultural asset by Minowa Town, Nagano
Prefecture, Japan. The unique luminous moss, Schistostega pennata, is found in two caves –the western cave
and the eastern cave– in a low-elevation area within a residential area. Of the two caves, the conservation
status of the western cave is considered to be the most serious. We therefore surveyed the locational
environment and the vegetation in the caves in order to better understand the present condition of the
habitat. The results showed that the slope on which the western cave was located was susceptible to
erosion because the soil surface was covered with little native ground cover. As a result, soil had
accumulated inside the cave and at the cave entrance, and weeds had invaded the cave. Conservation and
management initiatives need to be implemented in order to conserve the luminous moss in Shimo-furuta.
These initiatives need to be developed in conjunction with experts and land owners, and need to focus on
protecting the slope through revegetation techniques and recovering a suitable habitat by removing
accumulated soil.
Key Words: Luminous moss (Schistostega pennata), Minowa Town, Cultural assets, Vegetation, Conservation
...