Resilience: Aquatic lives in Yadoriki Water Source Forest, summer 2021 やどりき水源林

In Yokohama, very urban place, a part of megalopolis Tokyo, people play THE major role for messing up the habitat for aquatic creatures, such as dragonfly. In the same prefecture, I mean Kanagawa Prefecture, story can be different. The case in point: Yadoriki Water Source Forest やどりき水源林. There, the protagonist, it seems to me, is in the end Mother Nature. Let me tell you my recent adventure there.

Kanagawa Forest Instructors are doing a guiding service at Yadoriki Water Source Forest. At 10:00 and 13:00 every weekend between March and November, two forest instructors are on duty at Yadoriki admin cottage near the gate. We are showing the forest for visitors. The place has lots of interesting things like vegetation, animals, and geological features that seasonally change. Our guiding is on demand base. If a visitor request to see flowers in season, for example, we guide the person according to the theme. We also have a rough half-day program to suggest if you don’t have a particular idea about Yadoriki Forest (; the calendar is available from here). The themes we offer every month are,

1. General nature experience, aka small hiking
2. Forest relaxation walk
3. A bit of woodcraft experience, and
4. Visiting Forests of Growing (; my post on June 9, 2017)

In addition, we have a special program only for July and August. It’s a small observation session of aquatic creatures.

Actually, this summer-only program is popular. What we do is catching tiny water creatures from Yadoriki Stream and observing them swimming in a tray. After the session, we return the living things to the stream. The educational level of the program is for 4-5 years old, and up. Often parents, not kids, become too involved in and we instructors must do babysitting to ensure the safety of participating babies. Elementary school kids can have a fun day and finish their homework of “independent research over the summer holiday.” Visitors don’t have to bring anything. We instructors bring all the necessary equipment, including pencil and a note. Above all, it’s free! Bargain, don’t you think?

A larva of caddisfly

So, we, Kanagawa Forest Instructors, are watching Yadoriki Stream all year around to make it sure we will have special summer program safely. Meanwhile two mega-typhoons hit the area during September and October of 2019. The feature of Yadoriki Stream was changed radically + there has been some possibility of debris avalanche to the downstream. Luckily or not last year, due to COVID-19 the entire summer program for Yadoriki was cancelled. The prefectural office was busy stabilizing the banks and riverbed of the Stream. In early spring this year, the scenery of the area where kindergarteners once enjoyed their hunt for aquatic creatures was totally different (; my post on March 18). In March, one of my senior Instructors watched bulldozed riverbed and murmured “… how cheerless …” We were worried if we could have aquatic observation session this summer.

Yadoriki stream in spring 2019.
 It was before the monster typhoons …

In fall 2019. Typhoons changed the scenery.

In April 2021.
 The riverbed of Yadoriki Stream was bulldozed.

The major construction works for Yadoriki Stream was completed in April. Since then, there were several mini storms, if not typhoons, for Yadoriki area. When I returned Yadoriki early June, once mechanically excavated river flow was already altered with crumbling banks constructed by bulldozers. Hmmmmmmm … maybe from civil engineers’ point of view it was a depressing scenery. But for us forest instructors, the situation offered a hope for fun observation of aquatic creatures once again with kids. “Let us check 3 points along Yadoriki Stream. One in the mainstream, and the other for two branch valleys.” We entered the water course with nets and buckets. It turned out we were not disappointed.

Whatever the civil engineers intended,
 the artificial riverbanks are crumbling now,
 by just  tiny storms.

Water was still a bit cold. But we could find several nests of caddisfly larva here and there at the bottom of rocks. Lots of small nymph of stonefly came out of our nets. Tadpoles of Buerger’s flog were swimming in small but many pools of warmer water diverted from the stream. Amphibs of several dragonflies and megaloptera were already in certain size, meaning they were eating well as predator of the other smaller aquatic living things. We even found planarian flatworms, in plural.

A planarian flatworm and friends

“Well, it was needless anxiety, in the end.” “Yes. It may be difficult for kindergarteners to enter several spots we’ve checked today. But there are the other corners of the stream we would bring them for observational sessions.” “Indeed. For adults, we may think to prepare some facilities down to the stream.” “That’s a matter of budget.” “Hmmmm …” In any case, weekends of this summer, we forest instructors could guide you for observation fun of aquatic creatures. Thinking such an industrial vista of last March, it is amazing Yadoriki Water Source Forest recovering its natural environment this quick. Don’t underestimate Mother Nature, I presume.

These days,
 many families are having picnic on the Yadoriki Stream.

Oh, by the way, a wild serow may have decided to make Yadoriki Water Source Forest its territory. As we encounter it so many times, it seems to me the animal doesn’t have any problem having lunch next to us humans. Please let it be naturally in peace if you’re lucky enough to see her/him munching grass along the forestry road.

A photo taken not in a zoo

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

Quiet conqueror: Yadoriki Water Source Forest, early spring 2021 やどりき水源林

Euptelea polyandra in March 2021 for Yadoriki Forest

The last time I’ve been to Yadoriki Water Source Forest やどりき水源林 was October 2020. The place was under heavy reconstruction from the destruction by typhoons in 2019. Early this month, I’ve returned there. The works are still on-going, but several parts are open to hikers.

Japanese green alder (Alnus firma)
 in March 2021 for Yadoriki Forest

The prefecture has almost completed the repair works for the forestry road from the gate of Water Source Forest. We can walk a paved road almost to the end of the former route. The collapsed section is detoured by a new cutting through the western slope of Mt. Nabewari 鍋割山 (ASL 1272.4m). The debris of landslides 2 years ago still remain, but they definitely become a small part of the course. I think finally families with kids can walk there now. Though, we forest instructors have recognized that the prefecture, i.e. the landlord, does not intend to recover the pavement fully that before reached to the starting point to the trail to Ameyama Pass 雨山峠 (ASL 957m). Anyway, there is undeniably an improvement.

The collapsed part of the previous route is detoured.

The work is still going on …

Yadoriki Stream 寄沢, which caused flash floods and debris flows in 2019, is undergoing a substantial intervention. The Prefectural Office flattened the riverbed with heavy machinery and digging artificial water way in the middle. We seriously doubted how long such synthetic river can last if another monster typhoon hits the area again … In 2019, the Open Space near toilets suffered heavy erosion to be reduced in half. The place is still off-limit. We hope the site becomes accessible by summer holiday. But … could we find a place for kids to play with water, I wonder …?

This is the flattened riverbed.
 We cannot see the stream from this point,
 but a fissure at the foot of these destroyed logs
 is artificially dug water way.

Woooooooow.
 The stream looks like a road now …
 the construction work is going-on.

The afforestation expanded on the western slope of Yadoriki Stream is receiving an intense forestry by thinning cedars and cypresses. The prefecture told us the place is accessible only for professional foresters who contracted the work from the Office. In 2019, Yadoriki Stream was flooded with broken and uprooted afforested trees. So, doing professional forestry up there to stabilize the slope certainly has a good reason. They say the work will continue at least until summer this year. We will be able to have a quiet autumn walk in Hadano Forestry Road 秦野林道 this year …

The trolley line for forestry to the western slope is
 fully operational now.

We found lots of Astraeus sp. as well.
 They love gravelly place so that encountering them
 in Yadoriki of under-construction may not be surprising.

Despite of massive civil engineering, I personally find the nature of Yadoriki Forest is recovering strongly. After the typhoons in 2019, I felt sad to find many decimated points where before beautiful mosses secretly but cheerfully sprouted their capsule to procreate. Now they are coming back, if not fully. Impressive. In Chinese character, mosses are written as 苔. It’s a hieroglyph. The top part which looks like a hat means “row of grasses.” The middle symbolizes “plow”, and the bottom is “mouth.” When a farmer starts his/her work in the spring, the first thing s/he normally does is plowing the ground like opening the mouth of soil. So, the Chinese character for mosses means “it’s the beginning of vegetation.” Yeah. Yadoriki Water Source Forest was covered with mountain debris two years ago. Aside from the endeavor of humans restoring the place, tiny mosses may be quietly taking a lead for the recovery of the forest ... Petit conquerors!

I think, they are Palamocladium leskeoides.
 Such delicate apparitions of mosses were
 gone after monster typhoons of 2019
 … Now, they’re back!

The beloved Racomitrium japonicum are recovering in Yadoriki.
 Hurrah!

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/