Yokohama is approaching fast to rainy season. It’s funny. Data of meteorological agency says we didn’t have enough rain during winter. But few days of cloudy and rainy May let us think the world is wet and gloomy … Yeah, we need water to survive, but we don’t need that many no-sunshine days, do we? Or, don’t we? Really? Recently, we Niiharu Lovers have noticed something is going on.
In Niiharu Citizen Forest 新治市民の森, we can find many kinds of ferns. Mr. Hideshige Uchino, Director for Nagaike Park 長池公園, Hachioji City, Tokyo, said Niiharu Forest covers roughly 80% kinds of Kanagawa’s ferns. It means, the place has enough humidity for them to thrive ... (Oh, by the way, Mr. Uchino is a member for Flora Kanagawa Association. They published last fall Flora of Kanagawa 2018, the latest of comprehensive study regarding the flora in our prefecture. This is one of the most authoritative studies of flora in Japan. It is accessible online from here. If you are a serious student for Japanese flora, this is a must-have reading.) … Though, we know the ponds near Yatoda 谷戸田 area have lower water level than that for few years back. The north and north east of Yatoda is fully developed residential district, concreated, paved and manicured perfectly. There is a possibility artificially covered ground cannot receive rain water as in 100 years ago, which makes Yatoda area slowly desiccated. Also, Niiharu Lovers Association is struggling to keep Jokenyato 常見谷戸 marsh with water by stopping the spread of reeds. The district next to Jokenyato is for campuses of Toyo Eiwa University and YokohamaSoei University. Yap, their places have relatively more greenery, but large buildings and paved road system plus manicured lawns could do something for underground water for Niiharu Forest. Here and there, Niiharu forest may show possible drying.
Niiharu’s Ikebuchi-Hiroba いけぶち広場 open space is a kind of small valley surrounded by slopes from 3 directions, north, east and west. When Mr. Okutsu, the former landlord of Niiharu Forest, had his horticultural business some 30 years ago, the place was used for nurturing Quercus myrsinifolia that were sold to the City of Yokohama for tree-lined roads. Small underground stream runs around Ikebuchi Open Space. Mr. Okutsu used the natural water system for irrigation. He made a reservoir under the ground of open space, collecting water seeping out from the slopes. In 1999, Mr. Okutsu died and the place became Niiharu Citizen Forest. Lovers of Niiharu cleared the site of commercial activity, in 2005 made a small road running around the slopes to look down the open space, and waited. Now the place is called Niiharu Nature Observation Route that shows amazingly diverse flora and fauna (mainly bugs) that are sometimes VERY rare to meet in the middle of mega city. The underground tank of Mr. Okutsu is expected to control water flow from the forest, pouring to Umeda River 梅田川, then to Tsurumi River 鶴見川. This area is a tiny demonstration of natural water source forest. Or, it is supposed to be so.
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| A part
of Nature Observation Route still has lots of Osmunda japonica Thumb. which loves wetland. |
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| My
encounter with rare Nemophora amatella in Nature Observation Route.😄 |
Several senior Lovers of Niiharu have noticed a peculiar thing in the Nature Observation Route. “Well, before, Lysimachia clethroides were near the ridge of Maruyama 丸山 (: it’s the highest point in Niiharu Forest, ASL 67m), weren’t they?” “Yeah, they were in higher slopes of Nature Observation Route.” “But now, they started to dominate the entire west slope.” “Hmmmm …” To be fair, Lysimachia clethroides have pretty white flowers open from June to July. They look like a tail of a tiger covered by tiny pink-white flowers, and so it has Japanese monikar, Okatorano’o (= “Tail of Land Tiger”). To find them covering the slope is impressive. But, do they help promoting biodiversity of the Nature Observation Route? Or? Then, one spring day this year, we found several young stumps of Carex alopecuroides var. chlorostachya. “Have we had this here?” “I didn’t know this in Niinaru.” “Hmmmm …” This is a Carex that loves dryland. What does it mean?
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| Lysimachia clethroides in Nature Observation Route, May this year. They’ll be |
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| this soon. |
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| Lysimachia clethroides is pretty, isn’t it? |
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| Carex alopecuroides var. chlorostachya in Nature Observation Route. |
We Lovers decided to see how it turns out such succession of flora in the Nature Observation Route. The edge of Ikebuchi Hiroba Open space has been a dwelling place for flora and fauna that loves small water. But if the flora of dryland dominates the spot, that’s the end of their peaceful life. There would be two ways of thinking for this. One: as for the Yatoda Area, a possible explanation for drying of Niiharu Forest is urbanization and residential development surrounding the forest. If drying kills off such water loving ecosystem, the sinner is we. And so, we have responsibility to protect it. We have to engage in the workings of original ecosystem, which includes mowing, thinning, etc. etc. OK. Two: there is no definite answer for the cause of drying, in the end. Besides, it could be a normal natural cycle for a wetland to turn into a dryland. Drying of Nature Observation Route is just another example of natural succession. We simply accept the fact, do nothing, and only record the changes in the area ... It’s very interesting. The first option is calling for nature protection, and human intervention to the nature. The second option has started from a sort of whatever stance, and ended up with “protection” by doing nothing. Which way would be better for Niiharu Forest? I don’t know. One thing is for sure. My senior Lovers for Niiharu have watched the changes of Ikebuchi Open Space and Nature Observation Route for more than 20 years, and found something is going on. Perhaps, that would be a take-away from the appearance of Carex here. Patient, patient, patient …
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| Staphylea bumalda in Niiharu Citizen Forest |
If you find a
problem in Niiharu Citizen Forest, please make a contact with
Office for the Park Greeneries in the
North北部公園緑地事務所
Yokohama Municipal Government
Creative Environment Policy Bureau横浜市環境創造局
Phone: 045-311-2016
FAX: 045-316-8420
Niiharu Administrative Office /
Satoyama Exchange Center新治管理事務所・里山交流センター
Phone: 045-931-4947
Fax: 045-937-0898
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