Herwig Oliver:Featherweights /anglais: Light, Mobile and Floating Architecture (Architecture in Focus S.)
- Taschenbuch 2001, ISBN: 9783791328560
United States Department of Agriculture Forest Service Cooperative State Research Service Technical Bulletin No. 1696Martha H. Brookes is Information Coordinator for CANUSA-West in Corval… Mehr…
United States Department of Agriculture Forest Service Cooperative State Research Service Technical Bulletin No. 1696Martha H. Brookes is Information Coordinator for CANUSA-West in Corvallis, OR.J. J. Colbert and Rüssel G. Mitchell are Program Manager and Applications Coordinator, respectively, of CANUSA- West in Portland, OR.R. W. Stark was formerly Program Manager of CANUSA-West and at the University of Idaho, Moscow. Washington, D.C. February 1987Paperback8 1/4 x 10 7/8 inches, 88 pagessee Table of ContentsThe western spruce budworm is a native insect that finds a variety of tree species to its Hking in forests of western North America. Host forests are those that provide the conditions needed by the budworm to complete its full life cycleincluding sites for feeding, pupation, egg-laying, and overwintering. Host forests are usually comprised of both host and nonhost species; nonhosts can serve as substrate during some part of the life cycle, such as for overwintering sites. Forests sometimes consist of a single speciesoften a shade- tolerant species that has advanced well along the successional path for that forest type. Serai species may have been present earlier in the succession but have dropped out because they matured and died or were eliminated by cutting or some other cause. Under some ecological conditions, such as the cool, dry phases of the climax interior Douglas-fir forests, the budworm- susceptible Douglas-fir is essentially the only conifer that can grow on those particular sites. Western forests have been classified several different ways over the years. Some classifications, such as the Society of American Foresters' cover types (Eyre 1980), are based on what species actually predominate on the site at a given timeothers, on what the composition is expected to be in the long term. Where natural succession has proceeded without any significant disturbance for a long time, composition of the present forest (cover type) may be about the same as that described for the eventual climax vegetation. Conversely, a forest may be dominated by serai species and classified into a forest cover type that does not reflect the understory shade-tolerant species thatleft undisturbed in the successional processwill eventually dominate the site. A commonly used broad classification of potential natural vegetation in the United States was compiled by Küchler (1964). Daubenmire and Daubenmire (1968) developed a more detailed hierarchical vegetation classification that, like Küchler's, is also based on potential vegetation. Commonly referred to as "habitat types," this widely accepted system has been refined and developed for areas beyond eastern Washington and northern Idaho, where the Daubenmires did most of their work. Hall (1973) developed a plant- community classification for eastern Oregon and southeast Washington, and Franklin and Dyrness (1973) summarized the habitat classifications used in Oregon ^Authors' affiliations are given in appendix 2. and Washington; Pfister and others (1977) expanded and refined the habitat classification scheme to fit Montana conditions; Steele and others (1981) completed the habitat classification for central Idaho; and Steele and others (1983) recently completed it for eastern Idaho and western Wyoming. Similar work, based on the potential vegetation concept, such as that of Krajina (1969) in British Columbia, is completed or underway in other regions of both the United States and Canada. Interior Douglas-fir, the true firs, and the spruces account for most of the budworm feeding substrate in western forests (Johnson and Dentón 1975). All are moderately to very shade tolerant. Shade tolerance is generally related to budworm feeding preferencethe more shade tolerant the tree species, the greater the budworms' preference for feeding on its foliage (Schmidt and others 1983). The true firs are very shade tolerant and are nearly always climax species in the vegetative associations in which they occur. Douglas- fir, intermediate in shade tolerance, plays both serai and climax roles, depending on its associations. For example, Douglas-fir is a climax species in its associations with ponderosa pine but serai when growing with subalpine or grand fir. The spruces are somewhat more shade tolerant than Douglas-fir but less shade tolerant than the true firs. Each geographic region of the West that supports forests serving as hosts to the budworm has its own unique combination of species, but some species serve as hosts over extremely broad areas. Douglas-fir grows over the broadest area, but the budworm usually prefers true firs to Douglas-fir when these two species are growing on the same site. Although budworms feed on many conifers, six speciesDouglas-fir, grand fir, white fir, subalpine fir. Engelmann spruce, and western larchstand out as the primary hosts (fig. 1-1). These six host species occur in 11 StatesIdaho, Montana, Wyoming, Utah, Colorado, Arizona, New Mexico, Nevada, California, Oregon, and Washingtonand 2 Provinces, Alberta and British Columbia (Little 1971). A minor portion of the subalpine fir range extends into the Yukon Territory and Alaska, and Douglas-fir and white fir extend into Mexico. The ranges of Douglas-fir, subalpine fir, and Engelmann spruce are surprisingly similar. On much of this area, they occupy many of the same sites; but at lower elevations. Engelmann spruce and subalpine fir---------------------------------------Choristoneura freemani, the western spruce budworm, is a species of moth of the Tortricidae family. It is the most destructive defoliator of coniferous forests in western North America.It is now widely distributed throughout the Rocky and Coast Mountains. The first recorded outbreak was in 1909 on the southeastern part of Vancouver Island in British Columbia, Canada. Since that year, infestations have frequently been reported in western Canada.The budworm was first recorded in 1914 in the United States, in Oregon. However, it was not initially recognized as a serious threat to coniferous forests in the western U.S. Aerial spraying apparently terminated some smaller epidemics in the southern and central Rockies; others subsided naturally. The insect then appeared to be dormant in US forests until 1922, when two outbreaks were reported near Priest Lake in northern Idaho. Since then, significant outbreaks in the Rockies and in the Pacific Northwest have caused top-killing and serious economic losses in tree growth. Tree mortality from budworm can occur in regeneration, sapling, and pole-sized trees. Trees in mature stands severely defoliated by the western spruce budworm may become susceptible to bark beetles, which kill mature trees.Considered the most destructive defoliator in British Columbia, sustained outbreaks of the western spruce budworm resulted in defoliation of over 100,000 hectares (250,000 acres) in the Fraser Canyon - Lillooet - Pemberton area from 1949-58. From 1970 -2001 further outbreaks occurred over a much larger area including the area of the previous outbreaks, as well as the Thompson and South Okanagan areas in 1970-2001.There is no typical pattern for western spruce budworm epidemics. Most of the early epidemics subsided naturally after a few years. Others persisted longer, but without spreading over large areas. An epidemic which began in 1949 in the northern Rocky Mountains has persisted for over 30 years despite insecticidal treatment of more than 6,000,000 acres (24,000 km2) between 1952 and 1966.Adult moths are about 1/2 inch (12.7 mm) long and have a wing-spread of 7/8 to 11/8 inches (22 to 28mm). Moths of both sexes are similar in appearance, although the females are a bit more robust than males. Both sexes fly. The gray- or orange-brown forewings are banded or streaked, and each usually has a conspicuous white dot on the wing margin. Eggs are oval, light green, and about 3/64 inch (1.2mm) long and overlap like shingles.Larvae develop through six stages. Newly hatched larvae are yellow-green with brown heads. In the next three stages, larvae have black heads and collars and orange- or cinnamon-brown bodies. In the fifth stage, larvae have reddish-brown heads marked with black triangles, black collars, and pale olive-brown bodies marked with small whitish spots. Mature larvae are 1 to 11/4 inches (25 to 32 mm) long, with tan or light chestnut-brown heads and collars and olive- or reddish-brown bodies with large ivory-colored areas.Pupae are 1/2 to 5/8 inch (13 to 16 mm) long, broad at the head end, and narrower toward the tail. They are brownish yellow or brownish green at first, and later turn reddish brown.Throughout most of its range, the western spruce budworm completes one cycle of development from egg to adult within 12 months. Moths emerge from pupal cases usually in late July or early August; in the southern Rockies, adults often begin emerging in early July.The adults mate, and within 7 to 10 days, the female deposits her eggs and then dies. Each female deposits approximately 150 eggs, usually on the underside of conifer needles. Eggs are laid in one to three-row masses containing a few to 130 eggs, with an average of 25 to 40 eggs per mass.Larvae hatch from eggs in about 10 days. Larvae do not feed, but seek sheltered places under bark scales or in and among lichens on the tree bole or limbs. Here, they spin silken tents in which they remain inactive through the winter.In early May to late June, larvae leave their hibernacula to search for food. They first mine or tunnel into year-old needles, closed buds, or newly developing vegetative or reproductive buds.New foliage, which is normally the preferred food, is usually entirely consumed or destroyed before larvae will feed on older needles. Larvae become full grown usually in early July about 30 to 40 days after leaving their overwintering sites.Larvae pupate in webs of silk they have spun either at the last feeding site or elsewhere on the tree. The pupal stage usually lasts about 10 days.The species was originally named Choristoneura occidentalis by Freeman. However, this name was already in use for an African species described by Walsingham. The replacement name for this North American species is Choristoneura freemani., United States Department of Agriculture, Forest Service, 2/1987, 0, Very Good. From Bruno Taut's glass house to the Crystal Palace, geodesic domes to the Millennium Dome, this illustrated exploration of lightness in architecture explains how and why the movement began, and shows where it might take us in the future. Architecture has been moving towards lightness since the beginning of the 20th century. As new building materials become available, and as land disappears, architects have focused on efficiency, impermanence and flexibility in structures. Illustrating the achievements of the most visionary architects of the past and present, ""Featherweights"" traces the evolution of lightness in architecture from the fantastic glass structures of the early 20th century to hi-tech materials for the third millennium. Covering everything from the pre-fab houses to inflatable buildings, utopian architecture to virtual cities, this exploration illustrates the ongoing dialogue between shelter and society and offers exciting glimpses into a future in which gravity is optional., 3<
