Conserving Deciduous Forests Around the World

Is the Japanese or North American approach to conservation of the world’s vulnerable deciduous forests more effective, or should we combine elements of both approach?

| July 2014

Mountainous View of Deciduous Forests

Fifteen million years ago, before the repeated advance and retreat of glaciers across northern Eurasia and North America, deciduous forest encircled the northern continents.

Photo by Fotolia/drhfoto

Deciduous forests have been remarkably resilient throughout their history, recovering from major shifts in climate and surviving periods of massive deforestation. But today the world’s great forests confront more ominous threats than ever before. Saving the World’s Deciduous Forests (Yale University Press, 2014) by Robert A. Askins examines forests to reveal their common origin back in time and the approaches to conservation that have been attempted on their behalf. The following excerpt is from chapter 1, “Parallel Worlds.”

The inspiration for this book was a walk along a forest stream in the mountains north of Kyoto on a clear morning in early spring. After working in the forests of eastern North America for many years, I found Japanese forests a mix of the familiar and the strange. My surroundings were mostly familiar. Leaves were just emerging from buds on the overhanging branches of maples and oaks. Splashes of color—clumps of violets, anemones, and trilliums—dotted the mottled brown leaf litter of the forest floor. Straight gray beech trunks, the shallow angle of spring sunlight, and the songs of returning migratory songbirds evoked the scenes and sounds of a New England forest in spring. The hemlocks, oaks, and Indian pipes were similar to those along a stream near my home in Connecticut.

On closer inspection, however, the details were distinctly different. The bird songs were new and strange. Although the general types of plants were familiar, the particular species were new to me. And there were many more species, making plant identification a greater challenge. Instead of a single species of beech there were two; instead of three types of maple trees there were more than a dozen; and the field guide showed a multitude of different species of similar-looking violets. In this respect, it was as if I were visiting a North American forest 8 million years ago, before the Pleistocene extinctions. The comparable North American forest can only be viewed dimly by examining fossil imprints of plants from that period.

Despite the differences in particular species of plants, however, East Asia and eastern North America have remarkably similar types of woodlands, with subtropical forests in the south, deciduous hardwood forests in the central region, and boreal coniferous forests in the north. The change in vegetation between Key West and Nova Scotia parallels the change between Okinawa and northern Hokkaido. A traveler on either journey begins on white sandy beach fringed by mangroves and ends on a rocky coast surrounded by spruce, fir, and birch. Both journeys traverse diverse deciduous forests for much of the way.

Of course, the geography and biology of Japan and North America differ in many ways. Japan lacks the extensive prairies, savannas, and deserts that dominate much of the North American landscape. Japan consists of a series of islands, so it has some of the biological characteristics of islands, such as lower species diversity than comparable areas on the continental mainland. And the history of land use and style of agriculture are distinctly different in most parts of Japan and North America. But the great expanses of deciduous forest dominated by oaks, maples, and other hardwoods in Japan and eastern North America result in parallel ecological worlds. If you want to see spectacular displays of autumn color, there are few places on earth that will rival the Appalachians of the United States or the mountains of Honshu. Outsiders may perceive both regions as densely populated and long settled, with little remaining natural habitat, but this is a misconception. Forest covers 60–70 percent of the land in both Japan and the northeastern United States. Both regions are dominated by second-growth woodland interrupted by roads and towns, but both have some surprisingly large expanses of continuous forest. And in both regions many forests are maturing and slowly acquiring the large trees, closed canopy, and dead wood of an ancient forest.

Why Are North American and Japanese Forests Similar?

Fifteen million years ago, before the repeated advance and retreat of glaciers across northern Eurasia and North America, deciduous forest encircled the northern continents. These Miocene forests were remarkably diverse, with a great number of plants and animals that are now extinct. Some of these species succumbed to habitat change and hunting pressure as people spread throughout the Northern Hemisphere, but most disappeared long before the evolution of technologically skilled humans. They vanished because they did not survive a changing global climate, especially the severe disruptions of the Pleistocene, when kilometer-deep glaciers and cold, dry winds made much of the North Temperate Zone uninhabitable for all but the most flexible and hardy plants and animals.