Expansion of industrial logging in Central Africa

Industrial logging has become the most extensive land use in Central Africa, with more than 600,000 square kilometers (30%) of forest currently under concession. With use of a time series of satellite imagery for the period from 1976 to 2003, we measured 51,916 kilometers of new logging roads. The density of roads across the forested region was 0.03 kilometer per square kilometer, but areas of Gabon and Equatorial Guinea had values over 0.09 kilometer per square kilometer. A new frontier of logging expansion was identified within the Democratic Republic of Congo, which contains 63% of the remaining forest of the region. Tree felling and skid trails increased disturbance in selectively logged areas.     

Tropical deforestation and habitat fragmentation in the Amazon: satellite data from 1978 to 1988

Landsat satellite imagery covering the entire forested portion of the Brazilian Amazon Basin was used to measure, for 1978 and 1988, deforestation, fragmented forest, defined as areas less than 100 square kilometers surrounded by deforestation, and edge effects of 1 kilometer into forest from adjacent areas of deforestation. Tropical deforestation increased from 78,000 square kilometers in 1978 to 230,000 square kilometers in 1988 while tropical forest habitat, severely affected with respect to biological diversity, increased from 208,000 to 588,000 square kilometers. Although this rate of deforestation is lower than previous estimates, the effect on biological diversity is greater.     

Land-use allocation protects the Peruvian Amazon

Disturbance and deforestation have profound ecological and socioeconomic effects on tropical forests, but their diffuse patterns are difficult to detect and quantify at regional scales. We expanded the Carnegie forest damage detection system to show that, between 1999 and 2005, disturbance and deforestation rates throughout the Peruvian Amazon averaged 632 square kilometers per year and 645 square kilometers per year, respectively. However, only 1 to 2% occurred within natural protected areas, indigenous territories contained only 11% of the forest disturbances and 9% of the deforestation, and recent forest concessions effectively protected against clear-cutting. Although the region shows recent increases in disturbance and deforestation rates and leakage into forests surrounding concession areas, land-use policy and remoteness are serving to protect the Peruvian Amazon.     

Distributional Ecology of New Guinea Birds: Recent ecological and biogeographical theories can be tested on the bird communities of New Guinea

The concepts by which MacArthur and Wilson have transformed the science of ecology in the past decade, and the results of ecological studies such as mine on New Guinea bird communities, have implications for conservation policies. For example, primary tropical rain forest, the most species-rich and ecologically complex habitat on earth, has for millions of years served as the ultimate evolutionary source of the world's dominant plant and animal groups. Throughout the tropics today, the rain forests are being destroyed at a rate such that little will be left in a few decades. When the rain forests have been reduced to isolated tracts separated by open country, the distribution of obligate rain forest species will come to resemble bird distributions on New Guinea land-bridge islands after severing of the land bridges. The smaller the tract, the more rapidly will forest species tend to disappear and be replaced by the widespread second-growth species that least need protection (13). This ominous process is illustrated by Barro Colorado Island, a former hill in Panama that became an island when construction of the Panama Canal flooded surrounding valleys to create Gatun Lake. In the succeeding 60 years several forest bird species have already disappeared from Barro Colorado and been unable to recolonize across the short intervening water gap from the forest on the nearby shore of Gatun Lake. The consequences of the species-area relation (Fig. 1) should be taken into consideration during the planning of tropical rain forest parks (13). In a geographical area that is relatively homogeneous with regard to the fauna, one large park would be preferable to an equivalent area in the form of several smaller parks. Continuous nonforest strips through the park (for example, wide highway swaths) would convert one rain forest "island" into two half-size islands and should be avoided. If other considerations require that an area be divided into several small parks, connecting them by forest corridors might significantly improve their conservation function at little further cost in land withdrawn from development. Modern ecological studies may also be relevant to the understanding of human populations. For instance, during a long period of human evolution there appear to have been not one but two coexistent hominid lines in Africa, the Australopithecus robustus-A. boisei ("Zinjanthropus") line, which became extinct, and the Australopithecus africanus-A. habilis line, which led to Homo sapiens (27). The need to maintain niche differences between these lines must have provided one of the most important selective pressures on the ancestors of modern man in the late Pliocene and early Pleistocene. Thus, any attempt to understand human evolution must confront the problem of what these ecological segregating mechanisms were. To what extent were contemporaneous species of the two lines separated by habitat, by diet, by size difference, or by foraging technique, and were their local spatial distributions broadly overlapping or else sharpened by behavioral interactions as in the case of the Crateroscelis warblers of Fig. 6? To take another example, there are striking parallels between the present distributions of human populations and of bird populations on the islands of Vitiaz and Dampier straits between New Guinea and New Britain. Some of these islands were sterilized by cataclysmic volcanic explosions within the last several centuries. The birds that recolonized these islands have been characterized as coastal and small-island specialists of high reproductive potential, high dispersal powers, and low competitive ability, unlike the geographically closer, competitively superior, slowly dispersing, and breeding birds of mainland New Guinea (10, 11, 13). It remains to be seen whether the people of the Vitiaz-Dampier islands, the Polynesians, and other human populations that colonize insular or unstable habitats also have distinctive population ecologies.     

Human adaptation and plant use in highland New Guinea 49,000 to 44,000 years ago

After their emergence by 200,000 years before the present in Africa, modern humans colonized the globe, reaching Australia and New Guinea by 40,000 to 50,000 years ago. Understanding how humans lived and adapted to the range of environments in these areas has been difficult because well-preserved settlements are scarce. Data from the New Guinea Highlands (at an elevation of ~2000 meters) demonstrate the exploitation of the endemic nut Pandanus and yams in archaeological sites dated to 49,000 to 36,000 years ago, which are among the oldest human sites in this region. The sites also contain stone tools thought to be used to remove trees, which suggests that the early inhabitants cleared forest patches to promote the growth of useful plants.     

近30年铁岭县地表覆盖时空变化特征

地表覆盖变化已成为全球变化研究的核心领域和热点问题之一。以Landsat系列卫星影像为主要数据源,提取铁岭县1990-2020年地表覆盖变化图斑,构建土地利用变化转移矩阵,对铁岭县地表覆盖变化情况进行时空分析,识别土地利用变化热点区域。结果表明：近30年铁岭县地表覆盖面积呈现 “四增两减”特征,其中增加和减少最多的地表覆盖类型分别是建设用地(增加了85.27km2)和林地(减少105.39km2),其他几种类型动态变化不明显。近30年区域地表覆盖类型受人类活动的影响较为明显,对于揭示地表覆盖变化规律和可持续发展具有重要意义。     

Multi-party responses to environmental problems. A case of contaminated dairy cattle

This paper presents a framework for exploring the temporal and behavioral aspects of the responses of various involved parties that may lead to governmental intervention in situations involving exposure of the public to hazardous substances. The activities of key individuals are closely scrutinized. Relevance of the framework to agricultural and food concerns is also indicated. The exemplary case is the contamination of livestock in Michigan that began in 1973, but other cases are discussed that conform closely to the pattern described by the framework.George Morren is Associate Professor of Anthropology and Ecology in the Department of Human Ecology at Cook College, Rutgers, the State University of New Jersey, where he coordinates the International Environmental Studies Program. His areas of interest include tropical human ecology and social responses to hazards. He has done field research in Papua, New Guinea, northern Europe, and the U. S. and is currently studying public participation in environmental affairs in New Jersey and long term forest change in Papua, New Guinea. He is co-author (with Kathleen Wilson) ofSystems Approaches for Improvement in Agriculture and Resource Management, MacMillan, 1990.     

Area-perimeter relation for rain and cloud areas

Following Mandelbrot's theory of fractals, the area-perimeter relation is used to investigate the geometry of satellite- and radar-determined cloud and rain areas between 1 and 1.2 x 10(6) square kilometers. The data are well fit by a formula in which the perimeter is given approximately by the square root of the area raised to the power D [See equation in the PDF], where D is interpreted as the fractal dimension of the perimeter. It is concluded that rain and cloud perimeters are fractals-they have no characteristic horizontal length scale between 1 and 1000 kilometers.     

Melanesian prehistory: some recent advances

Human occupation of New Guinea had begun 50,000 years ago, but islands further east were settled only in Recent times. In part of the New Guinea highlands, wet and dry horticultural systems began by 9000 years ago. Local intensification is evident until the present, but only the most recent major crop (sweet potato, which has been grown in the region for less than 300 years) is documented. On the south coast, exchange systems and economies locally diversify over the last two millennia. In the Melanesian islands, exotic materials were moved 3000 kilometers 3000 years ago, but whether traders or colonists were involved is not yet clear. The prehistory of the area is proving more complex than was believed even a decade ago.     

Outward-dipping ring-fault structure at rabaul caldera as shown by earthquake locations

The locations of a large number of earthquakes recorded at Rabaul caldera in Papua New Guinea from late 1983 to mid-1985 have produced a picture of this active caldera's structural boundary. The earthquake epicenters form an elliptical annulus about 10 kilometers long by 4 kilometers wide, centered in the southern part of the Rabaul volcanic complex. A set of events with well-constrained depth determinations shows a ring-fault structure that extends from the surface to a depth of about 4 kilometers and slopes steeply outward from the center of the caldera. This is the first geophysical data set that clearly outlines the orientation of an active caldera's bounding faults. This orientation, however, conflicts with the configuration of many other calderas and is not in keeping with currently preferred models of caldera formation.     

Political economic history,culture, and Wounaan livelihood diversity in eastern Panama

A growing literature on scholarly and practical approaches to conservation and development uses a livelihood approach to understand rural peoples’ diverse assets and activities, especially as they serve to minimize vulnerability to economic and ecological shocks. In recent years, the suite of potential assets available to rural households has been theorized as human, natural, physical, social, and cultural capitals and includes the context in which they are used. Here we explore Wounaan livelihood strategies and how they articulate with the dynamic political economic history of eastern Panama. Known in Panama as forest dependent swiddeners, semi-structured interviews and participant observation revealed Wounaan’s increasing reliance on fishing, artisanship, and ecotourism in their income profiles. While these income sources are linked to decreasing land availability and increasing market opportunities, we address the role of cultural beliefs and values in Wounaan negotiation of their income strategies. J. Vela′squez Runk has studied ecology and anthropology in eastern Panama for ten years. Presently she is a Resident Scholar at the School of American Research in Santa Fe, New Mexico. Gervacio Ortíz is a business student at the University of Panama and a resident of Majé, Panama. Wilio Quintero is a resident of Boca Lara, Panama. Cristobalino Quiróz is a resident of Boca Lara, Panama.     

基于QuickBird卫星影像的沈阳城市森林景观格局

运用景观生态学原理、GIS技术和景观格局分析软件Fragstats,选取斑块数、斑块面积、斑块密度、Shannon多样性指数、分维数、聚集度等指标,对沈阳城市森林景观格局进行了分析.结果表明:沈阳三环内城市森林斑块数为42 703个,森林面积101.24 km2;斑块数以附属林为主,占总数的65%,斑块面积以生态公益林最大,占总面积的47%;城市森林总体呈现斑块分布不均衡,结构不合理.附属林和道路林的破碎化程度高,分布分散,形状最为复杂;风景游憩林破碎化程度低,自然连接性和聚集度较好.沈阳城市森林整体景观多样性高,均匀度接近于1,优势度较小,表明斑块类型丰富,景观中优势类型不明显,异质性高.     

福建酸竹低效林的改造效应

对福建省建瓯市野生福建酸竹低效林实施松土、施肥等低效改造抚育措施,比较分析改造前后竹林立竹密度、地径、林龄结构及笋产量的变化情况,结果表明:与对照区相比,2007年改造区竹林立竹密度增加5021株.km-2,平均地径提高0.3 cm,Ⅰ-Ⅲ度竹所占比例提高42%,产笋量增加433 kg.km-2,经济效益明显,低效改造基本成功。     

青海省退耕还林的现状及效益分析

经济的发展带动了社会进步,在社会发展的过程当中,也伴随着生态问题的出现.近年来,我国的水土流失面积已经超过了三百六十万平方千米,是全球水土流失最严重的国家之一,国家对此加强了退耕还林举措.青海省作为中国省级行政区之一,也出现了水土流失现象,在进行退耕还林后,不但可以产生经济效益和社会效益,还会带来生态环境效益.本文对青...     

Expansion and contraction of the sahara desert from 1980 to 1990

Data from polar-orbiting meteorological satellites have been used to determine the extent of the Sahara Desert and to document its interannual variation from 1980 to 1990. The Sahara Desert ranged from 8,633,000 square kilometers in 1980 to 9,982,000 square kilometers in 1984. The greatest annual north-south latitudinal movement of the southern Saharan boundary was 110 kilometers from 1984 to 1985 and resulted in a decrease in desert area of 724,000 square kilometers.     

Shuttle imaging radar experiment

The shuttle imaging radar (SIR-A) acquired images of a variety of the earth's geologic areas covering about 10 million square kilometers. Structural and geomorphic features such as faults, folds, outcrops, and dunes are clearly visible in both tropical and arid regions. The combination of SIR-A and Seasat images provides additional information about the surface physical properties: topography and roughness. Ocean features were also observed, including large internal waves in the Andaman Sea.     

ECOLOGY: Louisiana's Vanishing Wetlands: Going, Going ..

An ambitious $14 billion plan known as Coast 2050 attempts to protect more than 10,000 square kilometers of Louisiana's wetlands, which are disappearing at a rate of up to 90 square kilometers per year, one of the highest rates of land loss in the world. But a number of unanswered scientific questions swirl around the plan. And it could run afoul of powerful interests in the shipping, petroleum, and fishing industries.     

Selective logging in the Brazilian Amazon

Amazon deforestation has been measured by remote sensing for three decades. In comparison, selective logging has been mostly invisible to satellites. We developed a large-scale, high-resolution, automated remote-sensing analysis of selective logging in the top five timber-producing states of the Brazilian Amazon. Logged areas ranged from 12,075 to 19,823 square kilometers per year (+/-14%) between 1999 and 2002, equivalent to 60 to 123% of previously reported deforestation area. Up to 1200 square kilometers per year of logging were observed on conservation lands. Each year, 27 million to 50 million cubic meters of wood were extracted, and a gross flux of approximately 0.1 billion metric tons of carbon was destined for release to the atmosphere by logging.     

Colonization of exploded volcanic islands by birds: the supertramp strategy

After volcanic explosions or tidal waves had defaunated several islands near New Guinea, bird species number rapidly returned to equilibrium on coral islets and rapidly returned to quasi-steady-state values limited by regrowth of vegetation in lowland forest of larger islands. However, reequilibration in montane forest has been limited by slow dispersal of the birds. Colonists have been drawn disproportionately from r-selected "supertramrip" species, which maintain much higher population densities than do K-selected faunas, perhaps due to selection for resource overexploitation by the latter.     

Long-term change in the nitrogen cycle of tropical forests

Deposition of reactive nitrogen (N) from human activities has large effects on temperate forests where low natural N availability limits productivity but is not known to affect tropical forests where natural N availability is often much greater. Leaf N and the ratio of N isotopes (δ(15)N) increased substantially in a moist forest in Panama between ~1968 and 2007, as did tree-ring δ(15)N in a dry forest in Thailand over the past century. A decade of fertilization of a nearby Panamanian forest with N caused similar increases in leaf N and δ(15)N. Therefore, our results indicate regional increases in N availability due to anthropogenic N deposition. Atmospheric nitrogen dioxide measurements and increased emissions of anthropogenic reactive N over tropical land areas suggest that these changes are widespread in tropical forests.