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16 Mar2008

Overstory #204 - Nature is a beauty with perfect taste

Written by Akira Miyawaki and Elgene O. Box.

Introduction

Nature is the world's greatest beauty. The German word for nature (die Natur) is a feminine noun, as was also its Latin predecessor natura. Nature has always worn her dress of green-plant life-in the style most appropriately suited to each location and season. In the lowlands of Japan, this means the deep green of evergreen broadleaf forests of castanopsis and evergreen oak species. In the mountains, the deciduous broadleaf forests of Siebold beech (Fagus crenala), mizunara oak (Quercus crispula, formerly Q. mongolica var. grosseserrata) , and daimyo oak (Quercus dentata) change their dress with the four seasons, wearing pale new leaves in spring and bright colors in autumn. The subalpine areas of Honshu wear the dark green of certain fir species and northern Japanese hemlock (Tsuga diversifolia), while in Hokkaido comparable coniferous forests take on the appearance of. boreal forests of Yezo spruce (Picea jezoensis) and Sakhalin fir (Abies sachalinensis). The alpine belts are garbed in creeping pine (Pinus pumila), and in summer, meadow flowers show the primary colors of red, yellow, and blue-violet.

The evergreen castanopsis and oak forests of the lowlands, plains, and foothills are the original home of the Japanese people and the place where they continue to pursue their daily lives. Most of nature's green robe, its natural plant life, was obliterated hundreds of years ago. Similarly, during the twentieth century, the original deciduous forests of mizunara oak and beech higher up in the mountains were also rapidly destroyed, cut down and replaced through a government policy of planting conifers on formerly forested sites, species such as cryptomeria (Cryptomeria japonica), Japanese cypress (Chamaecyparis obtusa), and Japanese larch (Larix kaempferi). The natural coniferous forests of the subalpine belt also suffered great destruction as a result of the late twentieth-century burgeoning of tourism, and in particular the construction of tourist roads and related facilities. Even the alpine flowers, which hang on stubbornly through years or even decades of harsh conditions before they finally bloom, are being trampled or dug up by insensitive visitors.

In this way, the beautiful, harmonious green robe of nature has been rapidly stripped away, from the seashores right up to the mountain summits. Nature, though, always tries to cover exposed bare ground and hastens to dress the bare patches with substitute vegetation, even if this clothing is temporary.

Where bare dirt is exposed, as when large tracts of land are reclaimed from the sea, the first substitute vegetation that hurries to cover the area is usually composed of mantle species. If regular logging, burning, underbrush gathering, livestock pasturing, or other human disturbance persists for decades or even centuries, however, a particular deviant kind of simple substitute vegetation takes over, one that is adapted to the recurring disturbance. What results is a continuing transitional phase of natural plant succession .that persists as long as the recurring disturbance continues. When natural plant life is destroyed and substitute vegetation moves in to cover the bare spots, this does not mean that any plant can grow. The particular species that grow are those members of the natural flora that can tolerate the new conditions, plus a limited number of characteristic substitute plant species.

Existing vegetation

Most of the plant life we see around us is substitute vegetation that has grown up after the original vegetation of the area was destroyed by human activities. If you look at a map of the natural vegetation zones of Japan, you will see that the distribution of human population and vegetation zones is clearly correlated. As of 2003, Japan had sixty-five large cities with populations greater than 300,000 people. Except for Sapporo and Asahikawa, in more recently settled Hokkaido, all these cities (and about 93 percent of the Japanese population) are located in the evergreen broadleaf forest zone.

But can we now actually observe any large evergreen broadleaf forests in Japan? The landscapes we see around us are made up of rice paddies, agricultural fields, abandoned farmland, roadside and other weed communities, miscanthus grass fields, nezasa and azuma-nezasa bamboo, and so on. There are also trees and forests, but most of these are deciduous oak forests, Japanese black pine at the coast, Japanese red pine inland, and cryptomeria and Japanese cypress in tree plantations. It is apparent that most of Japan's current existing vegetation, or actual vegetation, is plant life that grew in after the original vegetation, or at least the previous natural vegetation, was removed, over long periods of time.

Natural vegetation

If we define original vegetation as that which has been totally unaffected by human activity, we are forced to say that original vegetation is now limited to exceedingly few areas in the world. In the evergreen broadleaf forest zone of Japan, there are remnants on steep slopes rising from the sea and on hillsides around Shinto shrines or Buddhist temples, though sometimes the forest in these latter places is vegetation that has recovered or has been restored to locally appropriate evergreen broadleaf forest but really cannot be called either substitute or original vegetation. What term do we use to describe this kind of plant life?

When the vegetation of a site has been destroyed, as by human activity, but locally appropriate vegetation has returned, or when the combination of species is very close to the original vegetation in spite of some human impact, we call this natural vegetation. As long as the plant community is composed of the appropriate fundamental species, even though it may have sustained a certain level of human disturbance in either the near or distant past, it qualifies as natural vegetation. Thus some kinds of mature secondary vegetation can also be natural vegetation. The definitions of original vegetation, natural vegetation, and substitute vegetation have slightly different nuances for different experts.

Natural vegetation acts like a mirror

Natural vegetation is sustained by and thus reflects the sum total of environmental factors affecting a site. Thus, as a model for future development, conservation, and restoration of nature, we must leave in place representative examples of natural vegetation that continue to express the original biological and ecological character of each locality. We must also strive to restore to their original state those biological types that have already been lost.

Of course, if all that we want from plants is organic products, shade, or rows of street trees, then any number of species can substitute for the natural vegetation. The exotic species of grasses that are planted nowadays on slopes flanking expressways or the imported tulip poplars (Liriodendron), sycamores (Platanus), or deodar cedar (Cedrus deodara) trees planted along roadsides should suffice as tolerable substitute vegetation for the potential natural vegetation in each place, as long as growth can be sustained.

When planning the redevelopment of particular sites for new purposes, such as existing industrial or urban zones, fields, riversides, hilly sites, or mountains now covered with substitute vegetation, or when encouraging effective reforestation or vegetation restoration, one thing must be kept' in mind. Planners should not expect that they can effectively re-green a bare site bereft of existing vegetation merely by considering measurable environmental factors such as climate, soil conditions, and topography. They must also analyze the habitat biologically, inspecting and inventorying the animal and plant life. From the viewpoint of living things, the natural potential of a locality is expressed most completely where natural vegetation remains. This remaining plant life should serve as a template when planning new use of the land.

Restoration of plant life in accordance with a site's natural potential results in an enduring, wise, and less expensive balance between development and conservation. Trees and other plants that people arrogantly plant without understanding the potential natural vegetation of a site are expensive to maintain and do not last long.

 

Original source

This article was excerpted with the kind permission of the publisher from:

Miyawaki, A., and E.O. Box. 2006. The Healing Power of Forests. Kosei Publishing Co., Tokyo.

Contact: International Publishing Section Kosei Publishing Company 2-7-1 Wada, Suginami-ku, Tokyo 166-8535 Tel: +81-3-5385-2319; Fax: +81-3-5385-2331 E-mail: t-nishino@kosei-shuppan.co.jp

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About the authors

Akira Miyawaki, a professor emeritus at Yokohama National University established the world-renowned Institute of Environmental Science and Technology and is director of the Japanese Center for International Studies in Ecology. A former president of the International Association for Ecology and vlce-president of the International Association for Vegetation Science, he has conducted afforestation projects at more than fifteen hundred sites in Japan and abroad. He is a recipient of the 2006 Blue Planet Prize.

Elgene O. Box is a professor in the Department of Geography and Faculty of Ecology at the University of Georgia and has served three terms as president of the International Association for Vegetation Science. Creator of some of the first global models and predictive maps in ecology, he also initiated the use of envelope models to study biotic responses to global climate change. Dr. Box has conducted field research on all continents.

 

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