Forest and Conservation History最新文献

{"title":"Logging the Virgin Forest: Northern Sweden in the Early-Nineteenth Century","authors":"L. Östlund","doi":"10.2307/3983957","DOIUrl":"https://doi.org/10.2307/3983957","url":null,"abstract":"Market-oriented exploitation of northern Sweden's vast forests began during the first decades of the nineteenth century.' Prior to that time in Sweden, human use of the forest and human influence on forest ecosystems was limited. But during the nineteenth century, logging grew to encompass almost all forestland in the region. By the beginning of the twentieth century, successive felling of the largest trees had drastically changed the structure, age distribution, and species composition of many forests. Logging also brought about changes in forestland ownership and changes in the economic and social structures for inhabitants of northern Sweden. During the last decades of the nineteenth century, private companies bought from independent farmers almost half the productive forestland.' The farmers entered a new marketoriented economy that involved selling timber, timber concessions, and forestland to sawmill owners. They were also involved in cutting timber during winter, sledding the logs out of the forest, and then floating them downriver in the spring to sawmills on the coast. Nineteenth-century logging in Scandinavia was characterized by a timber-frontier movement that shifted toward new, unexploited oldgrowth forests further inland and further north on the Scandinavian peninsula in a constant search for pine forests containing large-diameter timber.' Rapidly increasing demand for sawn wood and square timber in the industrially developing countries of Western Europe drove the frontier movement, which started in Norway during the early-nineteenth century but soon crossed the border to Sweden and advanced northward. At midnineteenth century several institutional changes facilitated timber exports from northern Sweden. New technology and new means of communication, such as steam-powered sawmills and the telegraph, were introduced, and northern Sweden's dense network of rivers facilitated exploitation. The rivers drain the interior forestland and flow southeasterly; their long periods of high water level make it possible to float timber from far inland. All these factors contributed to the expansion of the Swedish sawmill industry. In 1850, timber exports accounted for 15 percent of the total value of Sweden's exports. Twenty years later this share had increased to 51 percent, and the total export value had more than tripled.\" Almost all sawmill expansion took place in northern Sweden, with Vasternorrland County and the area around the city of Sundsvall becoming centers for the developing industry. Mills took timber from the vast forests in the counties of Vasternorrland and jamtland. The timber that sustained the economy of the Sundsvall district was mainly floated to the coast on two rivers, Ljungan and Indalsalven, and their tributaries (see figure 1). By the end of the nineteenth century this district had become a leading sawmill area and Sweden was the world's leading exporter of sawn wood products. Swedes regarded timber export as an importan","PeriodicalId":425736,"journal":{"name":"Forest and Conservation History","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122692680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Forerunner of American Conservation: Naturalist Thomas Say","authors":"P. Stroud","doi":"10.2307/3983959","DOIUrl":"https://doi.org/10.2307/3983959","url":null,"abstract":"","PeriodicalId":425736,"journal":{"name":"Forest and Conservation History","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122178361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Laborers of Nature: Economic Ornithology and the Role of Birds as Agents of Biological Pest Control in North American Agriculture, ca. 1880–1930","authors":"Matthew D. Evenden","doi":"10.2307/3983958","DOIUrl":"https://doi.org/10.2307/3983958","url":null,"abstract":"Itriculture has been blamed, on occasion, for creating its own pests. In 1864 George Perkins Marsh wrote in Man and Nature that \"[w]ith the cultivated plants of man come the myriad tribes which feed or breed upon them, and agriculture not only introduces new species, but so multiplies the number of individuals as to defy calculation. \"1 Since early in the twentieth century, the solution to insect pests in North American agriculture has been the heavy use of insecticides. Although biological control techniques were important early in the century and have become a focus of attention more recently, the place of insecticides in the twentieth-century history of agricultural pest control is central and remains so. Over the past twenty years, environmental and agricultural historians have sought to analyze the origin and course of pest control regimes in modern North American agriculture.? They have placed particular emphasis on determining why over the course of the past century pesticides came to prevail in pest control regimes. Historians have proposed a variety of possible factors, including the role of agribusiness and statefunded science in institutionalizing and promoting pesticides, the cachet of pesticide research in entomological science following World War II, and the attractiveness of pesticides to farmers. Less attention within this overarching question has been given to the history of biological control, and even when it has been considered, the definition of biological control has been narrowly conceived.' With rare exceptions, biological pest control has been understood to be the use of insect predators (whether introduced into an ecosystem or emergent through habitat modification) in the control of insect or weed pests. This definition, although it covers the broad scope of biological control, ignores various other techniques on its margins. One of these other, marginal techniques is the role of birds as agents of biological control. In the late-nineteenth and early-twentieth centuries, scientific ideas about this method of pest control developed within the context of popular debates over bird preservation and conservation generally. These ideas, although predominantly generated in the United States, were diffused and debated in the Canadian and American agriculrural literature, with little respect for political borders. Avian agent biological control has long been used throughout the world in forestry and has received attention recently in the integrated pest management literature.\" But in the late-nineteenth and early-twentieth centuries the notion of using birds to help control pests, among the gamut of methods that were proposed and debated within the agricultural literature, commanded significant attention.' Growing out of the natural historical concern for teleological design in nature and debates over bird importation, systematic studies of the potential role of birds as pest control agents were first produced","PeriodicalId":425736,"journal":{"name":"Forest and Conservation History","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123910063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Natural Landscapes, Natural Communities, and Natural Ecosystems","authors":"K. Shrader-Frechette, E. McCoy","doi":"10.2307/3983518","DOIUrl":"https://doi.org/10.2307/3983518","url":null,"abstract":"Human Intervention, Disturbance, and Defining \"Natural\" More than a century ago, Ralph Waldo Emerson, in his essay on \"The Uses of Natural History,\" argued that \"[right action] is conformity to the laws of nature.\"! Many ecologists, environmentalists, and policymakers since then have urged conformity to these \"laws of nature.\" They have defined \"natural ecosystems,\" as opposed to \"artificial ecosystems,\" and established biocentric principles for how humans should treat these \"natural ecosystems.\"? Indeed, natural history and much of ecology presuppose some concept of natural place.' Likewise biogeography presupposes that the earth has \"natural divisions,\" and island biogeography, the developmental basis for landscape ecology, arose from a series of \"natural experiments.?' Because direct experimental manipulation of all relevant variables is rarely possible, landscape or regional ecology continues to progress by relying on quasi-experiments in the \"natural laboratories\" of various regions.' An important goal of many discussions about \"natural history,\" \"natural ecosystems,\" \"natural places,\" \"natural divisions,\" \"natural experiments,\" and \"natural laboratories\" is not only to learn more about these \"natural\" phenomena but also, as one ecologist put it, to \"protect natural systems.\"! A fundamental argument is that people ought to \"respect nature\" because the structures and functions of the natural world themselves have provided a guide for conservation and preservation decisions.' Indeed, if ecology and environmental policy-making are to avoid being arbitrary, terms such as \"ecosystem\" and \"community\" do not name mere concepts or human constructs but instead describe real characteristics of the natural world. The goal of protecting natural ecosystems or communities, however, often fails to provide direction for environmental policy because ecologists cannot always specifyeither what is \"natural\" or when human actions are in accord with nature.","PeriodicalId":425736,"journal":{"name":"Forest and Conservation History","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131245958","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improving the Wilderness: Common Factors in Creating National Parks and Equivalent Reserves During the Nineteenth Century","authors":"J. Shultis","doi":"10.2307/3983516","DOIUrl":"https://doi.org/10.2307/3983516","url":null,"abstract":"Well-to -do tourists try theirhand at icehockey in Banff National Park, 1896. At that date, only those with considerable wealth and leisure could access national parks. Photo courtesy of the Whyte Museum of the Rockies, Banff, Alberta. Federal and regional governments throughout the Englishspeaking New World began during the nineteenth century to esta blish a variety of protected areas in the public domain. ' The most famous of these became known as national parks. The United States was the first country to establish this new type of protected area when it established Yellowstone Park in 1872. Within twenty-one years, six other governments designated lands either as national parks or equivalent reserves. Each park served similar funct ions, in large part because the fundamental reason ing behind their creat ion emanated from common social, cultural , economic, and political condition s. The purpose of this articl e is to identify the cultural factors leading to the prol iferation of national parks and equivalent reserves in the nineteenth century, and to distinguish commonalities and differences in th e establ ishment of these areas. Th is art icle will identify the prototypes of nat ional parks, discuss the American \"invention\" of the national park, and review the establishment of parks in New South Wales , Australia (1879); Canada (1885); New Zealand (1887); and Ontario, Canada (1893). 2 Old World Prototypes","PeriodicalId":425736,"journal":{"name":"Forest and Conservation History","volume":"131 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121057662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Century of Rain Forest Use in Western Amazonia: Lessons for Extraction-Based Conservation of Tropical Forest Resources","authors":"O. Coomes","doi":"10.2307/3983515","DOIUrl":"https://doi.org/10.2307/3983515","url":null,"abstract":"W idespread concern over the fate of humid tropical forests has prompted an urgent search for new approaches to rain forest conservation. Of particular interest are extraction-based systems that promise economic benefits to rain forest dwellers while leaving the forest standing. For millennia the rain forest has provided diverse societies throughout the tropical world with a wide range of subsistence, ceremonial, and trade products. Today, conservationists, forest peoples, and researchers look to traditional extractive systems-from wild rubber tapping in Amazonia to rattan gathering in Indonesia-as more appropriate models for the conservation of biotic and cultural diversity. The importance of such alternate models for forest conservation is reflected in the recent creation of extractive reserves, expanded international marketing of rain forest products, pro-extraction policies of conservation groups, and a growing literature on indigenous forest resource use and management.1 An issue of particular relevance to rain forest conservation is the longterm sustainability of extractionbased systems. In the popular mind, native or folk peoples often are seen a living in quiet harmony with the rain forest, harvesting nature's generous and steady bounty for food, fiber, medicine, and, more recently, ash income. Scholars are increasingly revising this view, acknowledging the positive aspects of indigenous resource use practices but pointing to the impacts of traditional peoples since prehistory on the forest landscape, the varied needs and circumstances of indigenous peoples, and contemporary cases of less than sustainable though \"traditional\" resource use.2 Such understanding underscores the need to go beyond vigorous promotion (or criticism) of extractive schemes toward an improved understanding of the specific conditions and circumstances that lead to more, or less, sustainable forest extraction by traditional peoples. A potentially rich source of insight into the sustainability of extractive systems lies in the regional histories of tropical rain forests and peoples. Although a vibrant literature is developing on the environmental history of tropical forests, few works as yet attempt to consider the full range of forest resources used through time in a given region or the complete set of factors that influence resource use both directly and indirectly.3 Studies that examine how forest peoples use their resources today also tend to overlook the historical and geographical context within which such use has arisen, lending a static, even timeless quality to depictions of contemporary extractive activities. Moreover, little attention has been given to the problem of how indigenous extractive systems change through time with varying economic, political, and social conditions. Historical analysis of forest resource use would not only serve to contextualize and enliven descriptive work on","PeriodicalId":425736,"journal":{"name":"Forest and Conservation History","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117210169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Foundation for a Park: Explorer and Geologist Bailey Willis in the Area of Glacier National Park","authors":"J. Desanto","doi":"10.2307/3983517","DOIUrl":"https://doi.org/10.2307/3983517","url":null,"abstract":"From 1855 to 18QS the Blackfoot Indian Reservation extended to the Continental Divide, which the Blackfeet called the Backbone of the World. At the urging of American naturalist George Bird Grinnell, the Blackfeet sold the land between the present eastern boundary of Glacier National Park and the divide to the United States for $1.5 million. Despite his misgivings about it, Grinnell believed the sale would provide the best owner for the land. I The Blackfeet had even more misgivings, but acquiesced since illegal prospectors had brought them stories of alleged mineral wealth, so they believed they would ultimately lose the land anyway. The purchased land , known as the Ceded Strip, became part of the Lewis and Clark Forest Reserve. Preserving the land was not the government's motivation for acquiring the eight hundred thousand acres from the Blackfeet tribe; the purpose was to open the land to prospecting , and the government opened it to legal pro specting in 1898. Nevertheless, for the preceding ten years there had been sentiment favoring placing Bailey Willis, ca. 1902, photographer unknown. Photo courtesy of the photo library, United States GeologicalSurvey Earth Science Information Center, Denver, Colorado. the mountainous area east of the divide under some kind of reserved status. Lieutenant John T. Van Orsdale in 1883 recommended that the area be made a national park. He expressed concern for the forests and the water of the three river systems that the area encompassed. Grinnell, whose attraction to the Glacier area began in 1885, at the early stages was more interested in preserving the water resources than in establishing a national park. But by 1901 he began to lean toward a more protective status for the lands. The pressure James J. Hill and his son Louis Hill of the Great Northern Railroad brought to bear was perhaps of greater","PeriodicalId":425736,"journal":{"name":"Forest and Conservation History","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133670698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Shifting Forests: Historical Grazing and Forest Invasion in Southwestern Montana","authors":"K. Hansen, W. Wyckoff, J. Banfield","doi":"10.2307/3983662","DOIUrl":"https://doi.org/10.2307/3983662","url":null,"abstract":"Forest distribution often changes as a result of land use disturbances. In southwestern Montana we suspected, based on visual evidence and on knowledge of the region's historical land use, that livestock grazing caused changes in forest tree distributions, specifically tree invasions into grasslands and shrublands. To test that theory we undertook this study to look at the historical changes in grazing and in the distribution of the forest. The study's conclusions could assist in a better analysis of management options, allowing both for conservation of environmental resources and for sustained grazing. In this study, we reconstructed the history of livestock grazing for the region, documented climate changes, measured the extent and the timing of forest changes, and then tested for associations among the data. Coniferous trees in southwestern Montana have migrated into lowerelevation grasslands and shrublands over which domestic livestock have grazed for the last eighty to one hundred thirty years (see figure 1). These changes in tree distribution have become exaggerated with time, wR;::t ? Rh.t : .","PeriodicalId":425736,"journal":{"name":"Forest and Conservation History","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129365069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Land Beyond the Rim: Sigurd Olson's Wilderness Theology","authors":"D. Backes","doi":"10.2307/3983661","DOIUrl":"https://doi.org/10.2307/3983661","url":null,"abstract":"In some men, the need of unbroken country, primitive conditions and intimate contact with the earth is a deeply rooted cancer gnawing forever at the illusion of contentment with things as they are. For months or years this hidden longing may go unnoticed and then, without warning, flare forth in an all consuming passion that will not bear denial. Perhaps it is the passing of a flock of wild geese in the spring, perhaps the sound of running water, or the smell of thawing earth that brings the transformation. Whatever it is, the need is more than can be borne with fortitude, and for the good of their families and friends, and their own particular restlesssouls, they head toward the last frontiers and escape.' The article-ealled \"Why Wilderness?\"-was written by a thirtynine-year-old junior college dean and canoe trip outfitter named Sigurd Olson. This was not his first article promoting the wilderness idea, but it was the first to appear in a national conservation magazine, and it was among the articles helping to shape debate about the meaning of wilderness. Bob Marshall, founder and financial supporter of the Wilderness Society, wrote to Olson full of excitement about the article. \"I really think it's as good an article on the wilderness as I have ever read,\" he wrote. \"It certainly explains better than anything I know what the wilderness does to people psychologically.\" Marshall added, \"One thing that distinguishes it especially is its beautiful writing.\"! Bob Marshall had identified Olson's strongest gift: the ability to describe the effects of wilderness on the human psyche in an unpretentious yet lyrical style that commanded people's attention and held their interest. In 1938 Olson was still struggling to develop an effective writing style, sometimes succeeding and often failing, but eventually he became known as \"the poetic voice of the modern wilderness movement.?\" Recipient of the John Burroughs Medal for his nature writing, and also of the highest honors of the Wilderness Society, the Sierra Club, the Izaak Walton League of America, and the National Wildlife Federation, Sigurd Olson was one of the twentieth century's most influential wilderness promoters. According to philosopher Max Oelschlaeger, \"One mark of intuitive geniuses is that, in climbing to the top of the mountain, they can share that vantage point with ordinary men and women.\"! Olson's trail up that metaphorical mountain began with childhood experiences that led him to seek the mountain, then to wilderness experiences that brought him to the top. Along the way he was influenced by works that added intellectual support to his conclusions about the spiritual values of wilderness.","PeriodicalId":425736,"journal":{"name":"Forest and Conservation History","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116953798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Conserving Habitat and Biological Diversity: A Study of Obstacles on Gwaii Haanas, British Columbia","authors":"G. Ingram","doi":"10.2307/3983663","DOIUrl":"https://doi.org/10.2307/3983663","url":null,"abstract":"W ith concern growing for protecting natural ecosystems, biological diversity, genetic resources, and subsistence economies, it is useful to construct frameworks to evaluate institutional capabilities for expanding conservation planning programs. The experience of the Haida, a northwestcoast Native American people inhabiting the Queen Charlotte Islands (also called Haida Gwaii) on the north coast of British Columbia, provides an opportunity to examine the evolution of conservation frameworks leading to joint and comanagement of natural areas and resources.' The Haida Gwaii example is distinct, particularly compared with the United States, because of the use of sovereignist strategies to stop unsustainable exploitation of ancient temperate rainforests. Unresolved questions of sovereignty and land and resource ownership provided the backdrop for unique alliances between non-Native environmentalists and Native activists, some of whom are nationalistic. Although recent efforts to resolve issues of hereditary titles over the southern part of the archipelago, Gwaii Haanas, which was formerly referred to as South Moresby, have been partially successful, various obstacles continue to undermine conservation efforts.2 Institutional obstacles to habitat protection and ecosystem management began in 1851 when the Crown colony of British Columbia began to annex the islands.3 Despite repeated Haida assertions of sovereignty and traditional tenure since that time, the colonial and subsequent British Columbia provincial and Canadian federal governments denied these rights and managed the land and its wealth based on non-Native priorities. Until recently, respective governments did not support a framework for establishing viable protected areasespecially for the conservation of local biological diversity. Nonrenewable extractive operations, particularly clearcut logging of old-growth forest and mining, have been contentious throughout the region because of subsequent losses of traditional resources. Furthermore, Parks Canada, a federal agency that became involved in Gwaii Haanas land management after British Columbia ceded its responsibility for management to the Canadian government in 1988, had not emphasized management of natural habitat and protection of biological resources. Instead this agency had historically been more concerned with providing public services for tourism. In the 1974-87 \"South Moresby conflict,\" the Canadian government reacted slowly to the dispute between interests supporting rapid, largescale clearcut logging versus those advocating conservation of temperate rainforest, until as a compromise the provincial government agreed to cede jurisdiction. This 1988 agreement involved an expensive compensation package for wilderness preservation. But the Haida Nation and the Canadian federal government only forged a basis for joint management of Gwaii Haanas in 1993, and vestiges of colonial land management patterns still hinder the stewardship of fo","PeriodicalId":425736,"journal":{"name":"Forest and Conservation History","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121607379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}