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Wildfires cause enormous damage worldwide, particularly in Victoria, Australia, with growing populations in fire-prone ecosystems. Broad-scale prescribed burning is an established, yet controversial, wildfire management policy in Victoria and Australia. But does broad-scale prescribed burning reduce fire damage? The answer depends on how damage is measured. We propose that different perceptions about the efficacy of broad-scale prescribed burning derive from different disciplinary measures of damage (e.g., biodiversity, area burned, or fatalities). Although broad-scale prescribed burning reduces subsequent wildfire size, there is little evidence that it saves human lives and homes. Evidence suggests that small-scale fuel reduction may be more effective at saving lives. The prescribed burning debate might be better focused on what damage we wish to limit, and which measures are most effective at limiting this damage. In this context, the current policy focus on broad-scale prescribed burning targets may distract efforts from more effective lifesaving strategies. 相似文献
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Influence of anthropogenic land‐use change on hillslope erosion in the Waipaoa River Basin,New Zealand 下载免费PDF全文
European settlement of the Poverty Bay Region resulted in deforestation and conversion of > 90% of the landscape to pastureland. The resulting loss of vegetation triggered a rapid increase in hillslope erosion as widespread landslide complexes and gully systems developed on weak lithologic units in the Waipaoa Basin. To quantify the rate and volume of historic hillslope degradation, we used a 1956–2010 sequence of aerial photographs for a ~16 km2 catchment to map temporal changes in the spatial extent of active landslides. Then we created a ‘turf index’ based on the extent and style of pastoral ground disruption, which correlates with downslope velocity. Based on the movement of trees and other features, we assigned average velocities to the turf classes as follows: (1) minimal disrupted ground: 0.6 m/yr, (2) a mix of disrupted ground and intact blocks: 3.4 m/yr, and (3) no intact blocks or vegetation: > 6 m/yr. We then calculated the average annual sediment flux using these turf‐derived velocities, the width of the landslide‐channel intersection, and an average toe depth of 4.4 ± 1.3 m (mean ± standard deviation [SD]) from 37 field measurements. The resulting catchment averaged erosion rates are (mean ± SD): 29.9 ± 12.9 mm/yr (1956), 28.8 ± 13.7 mm/yr (1969), 13.4 ± 4.9 mm/yr (1979), 17.0 ± 6.2 mm/yr (1988), and 9.9 ± 3.6 mm/yr (2010). Compared with long‐term (post‐18 ka) erosion rates (1.6 mm/yr) and the long‐term uplift rate (~1 mm/yr) for this site, the 50‐year anthropogenically‐driven rate is an order of magnitude larger (~20 mm/yr). Previously, we measured an increase in erosion over the past 3.4 kyr (2.2 mm/yr), and here, we demonstrate this increase could be primarily due to human land‐use change – showing that a century of rapid erosion superimposed on the background geologic rate can profoundly skew the interpretation of erosion rates. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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中外烈度表“人的感觉”和“器物的反应”对比研究 总被引:2,自引:0,他引:2
随着震害经验的积累以及人们对地震认识的深化,不断修改烈度标准,使烈度评定更加客观与科学是地震工程界一直所追求的.人的感觉和器物的反应都是评定一次地震时相应烈度的宏观标志,是烈度表的重要组成部分.鉴于此,本文简要介绍了中国历代地震烈度表(《新的中国地震烈度表》、《中国地震烈度表(1980)》、《中国地震烈度表( 1999... 相似文献
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The growing interest in the understanding of community resilience suggests a need for improving research approaches. This article reviews methods used to date, and suggests opportunities for expanding the range and efficacy of approaches used to understand, improve, and monitor the coupled social and ecological aspects of community resilience. We explore three potential foci: research approaches that enhance understanding of community resilience; those that help to improve community resilience through the research process; and the further development of methods to guide monitoring. Most studies have relied on mixed and multistaged methods, including in-depth interviews and case studies. We comment on the wide range of approaches used, and suggest others that could be valuable. There is particular scope for greater use of cumulative studies, historical or retrospective studies, participatory methods, and systems approaches, and a need for more methods that explore the coupling of social and ecological dimensions. 相似文献
6.
P. K. Haff 《地球表面变化过程与地形》2010,35(10):1157-1166
The surface of the earth is being transformed by a new force in the form of technological systems and processes that move significant quantities of mass large distances. Because movement of mass is perhaps the most basic geomorphic process, and because the continuing rise of technology appears to characterize a new epoch in earth evolution (the Anthropocene), it is of interest to compare technological and natural mass transport mechanisms. A purely dynamical ‘mass‐action’ metric, representing the product of mass displaced, distance moved, and mean speed of displacement, is used to compare the transport effectiveness of selected systems. Systems with large mass‐action tend to be advective, and systems with small mass‐action diffusive. Local environments are conditioned by mass‐action through the introduction of transport corridors, such as roads and rivers, which put constraints on mass transport by embedded diffusive systems. Advection also subjects local environments to externally determined time scales, such as the times for delivery of unit mass of water or sediment to a river mouth, and supports the emergence of associated dynamical processes there, for example those of human activity or delta construction, that are too rapid to be sustained by diffusion. Most of the world's mass‐action is generated by the motion of fluids of global or continental extent, as in atmospheric circulation or river flow. Technological mass‐action exceeds that of all land‐based geomorphic systems except rivers. Technological systems with large mass‐action tend to be comprised of discrete, self‐powered units (e.g. trucks). Discretization of transported mass reflects the different locomotion strategy required for transport of solids on land, compared with the transport requirements of spatially extensive fluids in nature. The principle of maximum entropy production may provide a framework for understanding the emergence of advective, technological mass‐transport systems. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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Thomas M. Rosenberg Frank Preusser Ingo Blechschmidt Dominik Fleitmann Reto Jagher Albert Matter 《第四纪科学杂志》2012,27(1):13-16
Relict fluvial and lacustrine deposits in the interior of Oman near Saiwan consist of waterlain breccias with pebble imbrications and current ripples, covered by algal laminites containing calcified reeds and charcoal pieces. Geomorphological evidence suggests that the palaeolake covered a maximum surface of 1400 km2 and had a maximum depth of about 25 m. Optically stimulated luminescence (OSL) and thermally transferred OSL dating indicate that this palaeolake existed sometime between 132 and 104 ka. The rich archaeological evidence in the area suggests substantial human occupation, possibly at the time when Palaeolake Saiwan existed. Interestingly, the lithic traditions of the archaeological material show no clear relation to coeval findings from neighbouring areas, putting a question mark on the origin of the culture found at Saiwan. This finding raises questions concerning the origin of the population inhabiting Saiwan, as the site lies along one possible route for the dispersal of anatomically modern humans out‐of‐Africa. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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Roger LeB. Hooke 《地球表面变化过程与地形》1999,24(8):687-692
By some measures, the role of humans in shaping the landscape is now greater than that of any other geomorphic agent. This effect varies spatially. In the United States, it is greatest in the east where population density is highest, and particularly in West Virginia and neighbouring states where coal mining is added to more general earth-moving activities. For comparison, rivers in the United States move less soil, and their influence is greatest in the western part of the country where steep, sparsely vegetated slopes contribute to high sediment loads. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
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George D. Kamenov 《Environmental Geology》2008,55(3):669-680
High-precision Pb isotopic measurements on teeth and possible sources in a given area can provide important insights for the
lead (Pb) sources and pathways in the human body. Pb isotopic analyses on soils from the area of Sofia, Bulgaria show that
Pb is contributed by three end-members represented by two natural sources and leaded gasoline. Sequential leaching experiments
reveal that the alumosilicate fraction of the soils is mainly controlled by natural Pb derived from two mountain massifs bordering
the city. Around 1/3 to a half of the Pb in the soil leachates, however, can be explained by contamination from leaded gasoline.
Contemporary teeth from Sofia residents show very similar Pb isotopic compositions to the soil leachates, also indicating
that around 1/3 to a half of the Pb can be explained by derivation from leaded gasoline. The remarkable isotopic similarities
between the teeth and the most labile fractions of the local soils suggest that the lead can be derived from the latter. Pb
incorporation in the human body via soil-plant–human or soil–plant–animal–human chains is unlikely due to the fact that no
significant farming occurs in the city area. The isotopic compositions of the local soil labile fractions can be used as approximation
of the bioaccessible lead for humans. Considering all possible scenarios it appears that soil and/or soil-born dust inhalation
and/or ingestion is the most probable pathway for incorporation of local soil lead in the local population. The high-precision
Pb isotope data presented in this work indicate that apparently the local soil is what plays major role in the human Pb exposure. 相似文献