NATURE IN SHORT / Flora and fauna on an autumn journey through Chiba Prefecture

Kevin Short / Daily Yomiuri Columnist

Autumn in the southern Kanto is just about ready to show us its great finale. In another week or so the oaks, maples, elms and dogwoods will start changing colors, signaling the start of the local autumn-leaf viewing season. Crowds of enthusiasts will flock to well-known viewing spots, called koyomeisho, in the hills that surround Tokyo, and even in some urban parks and gardens.

The Yoro Gorge (Yoro Keikoku), set deep in the hills on the Boso Peninsula in Chiba Prefecture, is one of the most famous of the Tokyo-area leaf-viewing spots.

The gorge is formed on the upper reaches of the Yorogawa river, where the strong current has cut a steep channel through the hills. The surrounding slopes are heavily forested with maples and other deciduous trees that will soon turn varied hues of scarlet, yellow and orange.

Like most well-known koyomeisho, the Yoro Gorge and the whole southern Boso Peninsula in general are destined to be mobbed with cars and people once the autumn colors arrive. Desiring to beat the leaf-loving crowds and their attendant traffic jams, a colleague and I set out last week for a day of ethnobotanical fieldwork in the Boso Hills. Our plan was to follow the Yorogawa south and east from its mouth at Tokyo Bay, working our way up through the hills to the gorge. En route we would survey the woodlands along the upper reaches of the Yoro, and also inquire into the lifestyles and culture of the local farmers and foresters.

My colleague on this trip, an expert in agricultural products and also a very stylish lady, would drive, while I navigated. Although the Boso Hills are not particularly high--they top out at only 400 meters or so--finding one's way through them is always an adventure. Come round a bend and the spacious modern two-lane you were cruising along suddenly turns into a bumpy farm road just barely wide enough for one vehicle at a time.

A few clicks further on and it turns back into a new two-lane again! Also, I would be doing all this navigating while totally enchanted by my stylish colleague's considerable glamour.

Fortunately, from years of practice I've learned how to function pretty well while enthralled, and with only a few quickly-corrected missed turns, we reached our first stop, a small farming village near the gorge.

The farmers in this region are cultivating Japanese wild yams (Dioscorea japonica) in their hatake fields. Tourists visiting the gorge are a major direct market for these vegetables, so the harvest is timed to coincide with the peak of the leaf-viewing season.

A farmer told us that he grew his yams not from seeds or cuttings, but directly from the mukago, or bulbils, which are vegetative reproductive buds that develop on the yam vine. Each bud is capable of sprouting into a clone of its parent all by itself. The buds are sown in special seedling beds, and then transplanted to the hatake a year later. The mukago themselves are edible, and are sold in bags along with the harvested yams at local stores and roadside stalls. They can be eaten raw, but the farmer's wife suggested we fry them lightly in salt and butter.

After a lunch on the run of mikans for a quick energy burst and roasted sweet potatoes for slow-burn fiber fuel, we backtracked a bit to spend a few hours hiking in the Ichihara Municipal Forest (Ichihara Shimin no Mori). This woodland preserve, which features an excellent mosaic of native woodlands, oak coppices and very well-managed timber plantations, is a surprising gem of a destination.

The main hiking trail runs along a central valley floor, but numerous side-trails step and switchback their way up the steep, densely forested slopes leading to the surrounding ridges. The conifer plantations here consist mostly of sugi cryptomeria (Cryptomeria japonica) and hinoki cypress (Chamaecyparis obtusa). The trees have been thinned out to spacious intervals, and the lower branches loped off to a considerable height. This style of management allows ample room and light for various species of wildflowers and other trees to flourish on the forest floor, increasing the aesthetic appeal and the biodiversity value of the park. Our hike was blessed by the appearance of a beautiful jimuguri burrowing ratsnake (Elpahe conspicillata), a non-poisonous native species with a beautiful red and black underside, which spends most of its time burrowing through leaf litter and soft soil.

The rest of the afternoon we spent just cruising around, stopping here and there to explore various natural, cultural and spiritual wonders. The most lasting impression of the day, however, came from a surprising source--wild boars!

Everywhere we could see rice paddies and vegetable fields surrounded by waist-high barriers and electric fences. Also, all the local people we talked to mentioned problems they are having with boars. Farmers spoke of them wallowing in rice fields, and rooting up yams and other tuber crops in the hatake fields. One resident said he was afraid to take his dog, an immense, snarling, bristling-maned male akita, on a walk after dark because of the boars!

Interestingly, biologists believe that the original population of wild boars on the Boso Peninsula was hunted to extinction. Later, other animals were brought in and released. Their descendents are now increasing rapidly, causing all sorts of ills. Local hunters are licensed to shoot them during the November to February open season, but even these efforts seem to be falling short of stemming the population growth.

Twilight found us far to the south, just inland from the Uraga Strait coast, searching for a particular stone statue of the road guardian deity Dosojin. I always have trouble seeing in the confusing light at day's end. Also, glamour, or any sort of unusual power, seems to gain strength during this transitional hour.

We were well off the main highway, and stumbling up and down farmroads so narrow we often had to proceed miles on just to find a spot to turn around, even after realizing our mistake. My poor little mind was straining to cope with the terrain, but I was fighting a losing battle against deceiving twilight shadows and shimmering glamour!

Short is a naturalist and cultural anthropology professor at Tokyo University of Information Sciences.