尼泊尔用于缓解人与野生动物冲突之电篱笆经济效用分析     

Saraswoti SAPKOTA  ;Achyut ARYAL  ;Shanta Ram BARAL  ;Matt W.HAYWARD  ;David RAUBENHEIMER 《资源与生态学报(英文版)》2014,5(3):237-243

人与野生动物冲突是全世界自然保护工作所面临的最大挑战之一。为降低这些冲突的影响,各国采取了各种保护策略,但这些策略常常得不到足够的监测,其效力也得不到充分的评估。近年来,作为降低人与野生动物冲突的一项措施,尼泊尔各保护区周围建起了电篱笆。到目前为止,未见有其他针对保护工作中采用电篱笆的成本效率及其功效开展分析的研究。本研究的目的是检验尼泊尔近年来设立于旺国家公园东区的电篱笆的成本效率。印度犀牛（Rhinoceros unicornis）、野猪（Sus scrofa）、亚洲象（Elephas maximus）、老虎（Panthera tigris）是该国家公园周边缓冲区涉及人与野生动物冲突的主要物种,这里建有电篱笆。电篱笆使庄稼受损减少78%,家畜损失减少30%-60%。研究区的人类死亡数未表现出显著下降,而是继续维持较低数值。我们的分析表明,至2009/2010财政年度,电篱笆成本的总净现值,卡根社区（KMUC）为1 517 959尼泊尔卢比（21 685美元）,姆瑞加社区（MKUC）为3 530 075卢比（50 429美元）;而净现收益,卡根社区为16 301 105卢比（232 872美元）,姆瑞加社区为38 304 602卢比（547 208美元）。至2009/2010基准财政年度,电篱笆的成本-效益比率,卡根社区为10.73,姆瑞加社区为10.85。这些结果表明,在大型哺乳动物出没的保护区周围,电篱笆计划在降低人与野生动物冲突方面,既有经济效益,又有很好的社会效益。  相似文献   

An integrated field and numerical modelling study of controls on Late Quaternary fluvial landscape development (Tabernas,southeast Spain)          下载免费PDF全文

Martin R. Geach  Willem Viveen  Anne E. Mather  Matt W. Telfer  William J. Fletcher  Martin Stokes  Odile Peyron 《地球表面变化过程与地形》2015,40(14):1907-1926

The variability of Quaternary landforms preserved in the Tabernas basin of southeast (SE) Spain raises numerous questions concerning the roles of external forcing mechanisms (e.g. tectonics and/or climate) and internal landscape properties (e.g. lithological controls) in the evolution of the basin‐wide fluvial system over Late Quaternary timescales. In this study, we apply the FLUVER2 numerical model to investigate the significance of these landscape controls upon patterns of landscape evolution. We highlight the complications of generating realistic input datasets for use in the modelling of long‐term landscape evolution (e.g. discharge and runoff datasets). Model outputs are compared to extensive field mapping of fluvial terraces, their sedimentary architecture and optically stimulated luminescence dating results of the terraces. The results demonstrate the significance of non‐linear rates of flexural tectonic uplift towards the west of the Tabernas Basin which have controlled base levels throughout the Quaternary and promoted the formation of a series of diverging fluvial terraces. Our numerical model results further highlight the importance of climate cycles upon river terrace formation. Basin‐wide aggradation events were modelled during the transition from Marine Isotope Stage (MIS) 6 to 5 and the Last Glacial Maximum (LGM) as supported by field evidence. This aggradational pattern supports the regional hypothesis of terrace formation during global glacial cycles and cold‐to‐warm stage transitions and supports the use of sea surface temperature climate proxy data in the modelling exercise. The availability of sediments derived from the surrounding hillslopes and adjacent alluvial fans explains the generation of substantial terrace aggradations. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

The influence of habitat structure on juvenile fish in a New Zealand estuary     

Darren M. Parsons  Mark A. Morrison  Simon F. Thrush  Crispin Middleton  Matt Smith  Keren T. Spong  Dane Buckthought 《Marine Ecology》2013,34(4):492-500

Estuarine and sheltered coastal habitats that contain physical structure are potentially important nurseries for juvenile fish. Many of these structured habitats, however, are potentially vulnerable to stressors such as elevated turbidity. Quantifying the benefits that structured habitats provide to juvenile fish may therefore be an important step in the management process. We investigated the value of structured habitat for juvenile fishes in northeastern New Zealand, using artificial seagrass units (ASUs) with varying blade density. ASUs were predominantly settled by juvenile snapper (Pagrus auratus) and spotty (Notolabrus celidotus). The density of both snapper and spotty was greatest on ASUs with the highest blade density. For snapper, a gradient in abundance was present (with higher abundance closer to the harbour mouth), suggesting either a gradient in the supply of recruits or a potential recruitment shadow effect. The size distribution of juvenile snapper (12–70 mm fork length) was very similar on both sampling trips, despite the 2‐month interim period, suggesting an ontogenetic habitat shift dependent on size. The condition of juvenile snapper from ASUs with the highest blade density was also greater than the other ASU treatments. Overall, these results provide new empirical evidence that habitats with physical structure within shallow estuarine systems are important to early stage juvenile fishes such as snapper, and indicate that the location‐specific context of that habitat is also likely important.  相似文献   

Climate change alters growing season flux dynamics in mesic grasslands     

Matt D. Petrie  Nathaniel A. Brunsell  Jesse B. Nippert 《Theoretical and Applied Climatology》2012,107(3-4):427-440

Changing climate could affect the functioning of grassland ecosystems through variation in climate forcings and by altering the interactions of forcings with ecological processes. Both the short and long-term effects of changing forcings and ecosystem interactions are a critical part of future impacts to ecosystem ecology and hydrology. To explore these interactions and identify possible characteristics of climate change impacts to mesic grasslands, we employ a low-dimensional modeling framework to assess the IPCC A1B scenario projections for the Central Plains of the United States; forcings include increased precipitation variability, increased potential evaporation, and earlier growing season onset. These forcings are also evaluated by simulations of vegetation photosynthetic capacity to explore the seasonal characteristics of the vegetation carbon assimilation response for species at the Konza Prairie in North Central Kansas, USA. The climate change simulations show decreases in mean annual soil moisture and and carbon assimilation and increased variation in water and carbon fluxes during the growing season. Simulations of the vegetation response show increased variation at the species-level instead of at a larger class scale, with important heterogeneity in how individual species respond to climate forcings. Understanding the drivers and relationships behind these ecosystem responses is important for understanding the likely scale of climate change impacts and for exploring the mechanisms shaping growing season dynamics in grassland ecosystems.  相似文献   

The heating duration and provenance age of rocks in the Salton Sea geothermal field, southern California     

Matthew T. Heizler  T.Mark Harrison 《Journal of Volcanology and Geothermal Research》1991,46(1-2)

⁴⁰Ar/³⁹Ar step heating of single K-feldspar crystals ( 500 μg) in a furnace with a low argon blank and accurate temperature control provide constraints on the thermal history of the Salton Sea geothermal field, southern California. Estimates of ⁴⁰Ar loss from detrital K-feldspars, coupled with kinetic information gleaned from laboratory degassing of ³⁹Ar, allow possible thermal histories to be evaluated. Samples from core and cuttings of sandstones from the State 2–14, Landers #1, Dearborn Farms #1, Magmamax #2, Elmore #3 and Sinclair #3 wells have been analyzed for this purpose. No recent ⁴⁰Ar^* loss is recognized in any of the 17 crystals measured, even for samples currently at temperatures greater than 275°C. This observation suggests that the present temperature distributions in these wells have not been maintained for greater than 1000 years. However, aggregates ( 100 mg) of two K-feldspar samples do reveal recent ⁴⁰Ar^* loss from the State 2–14 well, suggesting a time scale of 1000 to 5000 years for near-peak thermal conditions. These estimates of heating duration are broadly consistent with earlier results from thermal modelling, but do not support interpretations that paleotemperatures were once hotter than present.Provenance ages span the Tertiary through Middle Proterozoic but cluster at ages of 25, 70 and 1250 Ma. These age peaks are very common K-feldspar K-Ar ages in detachment terranes of southeastern California and southwestern Arizona, both drained by the Colorado River. This coincidence supports earlier suggestions that the sands of the Salton Trough were derived mainly from the Colorado River.Unrealistically low apparent activation energies (< 20 kcal/mol) for argon transport are observed for several single crystals which yield absurdly low calculated closure temperatures (e.g., -100°C). We infer that this anomalous behaviour results from a combination of the laboratory heating schedule and the distribution of diffusion domain sizes.  相似文献   

Combining biology,chemistry, and meteorology in modeling and measuring dry deposition     

B. B. Hicks  D. R. Matt 《Journal of Atmospheric Chemistry》1988,6(1-2):117-131

The range of chemical, biological, and meteorological processes contributing to the net exchange of trace chemical species between the atmosphere and the underlying surface is examined, in the context of a multiple-resistance exchange model. For those chemical species known to be always depositing, the resistance model provides a means to formulate appropriate deposition velocities in a convenient manner; however, extension to other situations is not straightforward. Field data indicate that the multiple-resistance approach is appropriate for application to assess the dry deposition of ozone and sulfur dioxide, but is not as appropriate for nitrogen dioxide. Data obtained over agricultural crops suggest that canopy factors frequently dominate the overall exchange process. A trial program of dry deposition measurement based on application of parameterized deposition velocities was initiated late in 1984, and has demonstrated shortcomings in under-standing concerning several factors, most importantly the roles of surface emissions and wetness, and the scaling-up of laboratory results to describe vegetative canopies.  相似文献   

Eddy fluxes of CO2, water vapor,and sensible heat over a deciduous forest   总被引：12，自引：0，他引：12  

Shashi B. Verma  Dennis D. Baldocchi  Dean E. Anderson  Detlef R. Matt  Robert J. Clement 《Boundary-Layer Meteorology》1986,36(1-2):71-91

Fluxes of CO₂, latent heat and sensible heat were measured above a fully-leafed deciduous forest in eastern Tennessee with the eddy correlation technique. These are among the first reported observations over such a surface. The influences of solar radiation, vapor pressure deficit and the aerodynamic and canopy resistances on these mass and energy exchanges are examined. Following a concept introduced by McNaughton and Jarvis (1983), examination of our data suggest that the water vapor exchange of a deciduous forest is not as strongly coupled with net radiation as is that of agricultural crops. The degree of decoupling is smaller than in the case of a coniferous forest. This difference may be attributable in part to the greater aerodynamic resistance to water vapor transfer in a deciduous forest. It appears that the concept of decoupling may be extended to the CO₂ exchange of a deciduous forest as well.Published as Paper No. 7832, Journal Series, Nebraska Agricultural Research Division. ATDD Contribution No. 85-17.  相似文献   

A micrometeorological investigation of surface exchange of O3, SO2 and NO2: A case study     

B. B. Hicks  D. R. Matt  R. T. McMillen 《Boundary-Layer Meteorology》1989,47(1-4):321-336

Data obtained in an intensive field study of the dry deposition of sulfur dioxide, ozone, and nitrogen dioxide, conducted in 1985 in central Pennsylvania, are used to illustrate the factors that must be considered to assure that high quality results are derived. In particular, the quality of the site must be such that flux measurements made above the surface are representative of surface values. For this purpose, tests involving momentum transfer and the surface energy budget are especially useful. In addition, conditions must not be changing rapidly, and the statistical uncertainty associated with flux measurement must be low. For the set of data presented here, conservative quality-assurance guidelines are used to reject potentially erroneous flux data. For ozone, most of the measured fluxes are of use in deriving surface resistances. For SO₂, far fewer data points are available. For NO₂, fluxes appear to lack the order of the O₃ and SO₂ fluxes, and do not enable surface resistances to be computed. The highest-quality SO₂ and O₃ data yield surface resistances in fair average agreement with model predictions for SO₂, but substantially higher than predictions for O₃.  相似文献   

GPS Solutions for the Verification and Resolution of GIS Coordinate Database     

Ramesh L. Shrestha  Jim Cameron  Matt Wilson 《GPS Solutions》1995,1(2):129-138

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Methane emissions from a landfill measured by eddy correlation using a fast response diode laser sensor     

D. C. Hovde  A. C. Stanton  T. P. Meyers  D. R. Matt 《Journal of Atmospheric Chemistry》1995,20(2):141-162

We describe a fast response methane sensor based on the absorption of radiation generated with a near-infrared InGaAsP diode laser. The sensor uses an open path absorption region 0.5 m long; multiple pass optics provide an optical path of 50 m. High frequency wavelength modulation methods give stable signals with detection sensitivity (S/N=1, 1 Hz bandwidth) for methane of 65 ppb at atmospheric pressure and room temperature. Improvements in the optical stability are expected to lower the current detection limit. We used the new sensor to measure, by eddy correlation, the CH₄ flux from a clay-capped sanitary landfill. Simultaneously we measured the flux of CO₂ and H₂O. From seven half-hourly periods of data collected after a rainstorm on November 23, 1991, the average flux of CH₄ was 17 mmol m^–2 hr^–1 (6400 mg CH₄ m^–2 d^–1) with a coefficient of variation of 25%. This measurement may underrepresent the flux by 15% due to roll-off of the sensor response at high frequency. The landfill was also a source of CO₂ with an average flux of 8.1 mmol m^–2 hr^–1 (8550 mg CO₂ m^–2 d^–1) and a coefficient of variation of 26%. A spectral analysis of the data collected from the CH₄, CO₂, and H₂O sensors showed a strong similarity in the turbulent transfer mechanisms.  相似文献