Egoist! Chinese silver grass and us

 

In Japanese psyche, Chinese silver grass (Miscanthus sinensis) is closely related with autumn. I guess some of you have seen the plant depicted in Japanese paintings, including Ukiyoe. The grass is important for decorations of seasonal festivals, such as Moon Viewing Festival. Hakone Sengokubara National Treasure site 箱根仙石原 is famous for its swinging silver grass field in fall (: my post on October 29, and November 5, 2021). In autumn, its green sword-like leaves turn into light brown with their fluffy ears. The vegetable forms large colony and tends to cover vast sunny space. So, in autumn, en masse they carelessly sway as wind blows. If setting sun cast autumnal light over them, it’s perfect scenery for feeling quiet and chilly dawn of the season. Mmmmmmmmm … meditative.

Chinese silver grasses in Sengokubara

Well, so it is, if we just admire them from a window. When we have to think about it in terms of environmental management, it’s a different matter. As Americans know, it can be invasive species and wreck a havoc for indigenous ecology. In Japan, as long as the land is dry and has full sunshine, the grass can form massive cluster whose uber-robust rhizome spreads in shallow topsoil. It is a species dominating a field at the final stage of plant succession. After establishing their kingdom, the grass field will gradually turn into a dry forest, first by invasion of drought-resistant trees like red pines. Unless artificially (oh, yes) controlling their dominance over the field, smaller wild vegetations such as violets et al cannot find a space. Moreover, if the march of silver grass is entering a wet land, such as Sengokubara, it’s a signal for the end of bogs. The plants that love soggy soil will be exterminated. If we want to preserve the ecosystem of swamp, Chinese silver grass can certainly be invasive species.

Sengokubara whose vegetation varies according to its undulation.
 When we see the site from outside,
the place looks like flat.
Nope.
Once we enter the national treasure site,
it has many tiny ups and downs
and so the varying availability of water
for living things on the ground.

To maintain the national treasure site of Sengokubara wetland, Hakone Town officially burns off the field once a year in the middle of March. The main target of this annual event is silver grass. Segokubara has three kinds of environment in terms of grasses. The driest part is for silver grass. The soil which is along streams where its not boggy but with enough moisuture is for common reed. The bog or shallow ponds are for Typha latifolia. When people burning the field, they first mow the border area of the field to make a fire buffer, then ignite fire on the silver grasses immediately inside of the firebreak. By doing so, aridification of marsh can be stopped. After the burning, spring ephemeral can come out in Sengokubara (; my post on May 12, 2023). The area near water streams will welcome common reed that can somehow stop the advance of silver grass.

The photo is taken 1 month after the burning.
Shoots of common reed are thriving along the artificial waterway.

Young spring leaves of Cirsium sieboldii,
a Japanese endemic thistle loving bogs.
It can come out only after the burning.

Viola hirtipes, the largest violet in Japan,
which also comes out after the burning in Sengokubara.

Their ability to suffocate the other plants over the land is not only alarming for marshes. They can also dominate small land patches of suburbs. Their hard rhizome causes headaches for gardeners or people who maintain walking paths in our neighborhood. The best way to control their invasion is digging them out while they are still young. The saving grace is silver grass takes time to be a large cluster. Even when they are seedlings, it’s hard to pull their root out, but definitely easier than dealing with established grass. Our battle with the wild grass continues ad infinitum …

For the silver grass to reach this size,
it must have taken enough time …
and I guess
the landlord gave it up at certain point of time.

Asphalt? What is asphalt?

Along a city road.
The City Office of Yokohama is supposed to
 be responsible for the management
of shrubbery for such road.
It seems to me the Office cannot keep pace
 with the advancement of grass …
 more to it next week.

From silver grass’ point of view, all of this fuss would be pure egoism of humans … One time we admire them as a cultural icon. Then for another occasion, we regard them as nuisance. Anthropocene … Next week, I will tell you about one neighborhood’s endeavor to minimize the nuisance of wild grass, in the framework of Yokohama’s green policy. Please stay tuned. 😊

I took this photo for one of the urban river of Yokohama.
Silver grass is supposed to love dry land,
but no matter here …
Tough guys.

If you find environmental issues in Kanagawa Prefecture, please make a contact with Kanagawa Natural Environment Conservation Center 神奈川県自然環境保全センター

657 Nanasawa, Atsugi City, 243-0121
〒243－0121　厚木市七沢657
Phone: 046-248-0323

You can send an enquiry to them by clicking the bottom line of their homepage at http://www.pref.kanagawa.jp/div/1644/