The Forest in Winter
The bare forest is blanketed in snow beginning in late December or early January. Icy winds known as the Nasu Oroshi blow down from the northwest, giving Nasu a colder winter climate than Tokyo to the south. Snowfall in the area is moderate, with an average accumulation between 20 and 30 centimeters, but this is more than enough to turn the forest into a glittering snowscape.
Black bears hibernate during the winter, but winter is also the season when their cubs are born and lie sheltered in the den until spring. Wild boar, which did not previously inhabit the forest, have been sighted in recent years. Viewed as detrimental to the ecosystem, they damage plants as they dig up the ground looking for insects.
The forest floor is densely covered with two varieties of bamboo grass from different climatic zones. Miyakozasa is usually found on the Pacific coast of Japan in areas with less than 50 centimeters of snow, and the leaves’ undersides are covered in fine hair. Chishimazasa, common to the snowy Sea of Japan coast, has a highly pliable stalk that will not break under heavy snow.
In February, the somber forest begins to reverberate with the sounds of woodpeckers drumming on tree trunks. Actual nestbuilding takes place months later, but already the birds are staking out territories and attracting mates. Four species of woodpecker—the Japanese pygmy woodpecker, great spotted woodpecker, Japanese green woodpecker, and white-backed woodpecker—inhabit Nasu Heisei-no-mori Forest year-round. The pygmy woodpecker is found in urban parks and forests in Japan, but the other three are more reclusive and breed deep within natural forests.