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Recent studies have identified poverty reduction near parks and protected areas, findings that challenge an extensive literature on the social burdens associated with protected areas. These studies move the discussion on the social dynamics of conservation forward, however, they do not offer insight into the underlying mechanisms that shape household-level outcomes such as income and wealth. By focusing on protected areas as centers of uncertainty, upheaval, and disturbance, this study examines the character and incidence of livelihood diversification within communities near Tarangire National Park in northern Tanzania compared to communities far from the park. Livelihood diversification is well understood as a coping and/or risk mitigation strategy pursued in response to various types of shocks, and uncertainty more generally. This study draws on mixed methodologies to construct multivariate statistical models to estimate the effect of proximity to the park on measures of livelihood diversification. The results indicate that proximity to park is strongly correlated with livelihood diversification, suggesting that households near the park are adapting to opportunities and constraints and may be seeking to reduce variance in income and wealth in response to disturbances and uncertainty associated with the park. 相似文献
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Timothy M. Shanahan Jonathan T. Overpeck W. E. Sharp Christopher A. Scholz Justice A. Arko 《水文研究》2007,21(13):1678-1691
Historical changes in the level of Lake Bosumtwi, Ghana, have been simulated using a catchment‐scale hydrological model in order to assess the importance of changes in climate and land use on lake water balance on a monthly basis for the period 1939–2004. Several commonly used models for computing evaporation in data‐sparse regions are compared, including the Penman, the energy budget, and the Priestley–Taylor methods. Based on a comparison with recorded lake level variations, the model with the energy‐budget evaporation model subcomponent is most effective at reproducing observed lake level variations using regional climate records. A sensitivity analysis using this model indicates that Lake Bosumtwi is highly sensitive to changes in precipitation, cloudiness and temperature. However, the model is also sensitive to changes in runoff related to vegetation, and this factor needs to be considered in simulating lake level variations. Both interannual and longer‐term changes in lake level over the last 65 years appear to have been caused primarily by changes in precipitation, though the model also suggests that the drop in lake level over the last few decades has been moderated by changes in cloudiness and temperature over that time. Based on its effectiveness at simulating the magnitude and rate of lake level response to changing climate over the historical record, this model offers a potential future opportunity to examine the palaeoclimatic factors causing past lake level fluctuations preserved in the geological record at Lake Bosumtwi. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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Limonitic oncoliths from the Bajocian of Europe, widely known as ‘snuff-boxes’, grew by accretion of bundles of laminae on one side, followed by overturning and accretion of laminae on the other side. A diverse hard-substrate encrusting fauna grew interleaved with the ferruginous laminations. The palaeoecological preferences of this fauna indicate that its growth, and hence the accumulation of the laminations, took place on the gloomy undersides of the oncoliths. This upsidedown growth is supported by characteristics of the lamination bundles themselves, and by the predominant present-day orientations of the snuff-boxes. The abundance of the associated fauna and the lack of carbonate-dissolving macroborers cutting the laminae suggest an original ferric composition. Precipitation was probably under the control of non-photosynthetic microorganisms that inhabited the microenvironments represented by the oncoliths' lower surfaces. 相似文献
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Albedos and diameters of three Mars Trojan asteroids 总被引:1,自引:1,他引:0
David E. Trilling Andrew S. Rivkin John A. Stansberry Timothy B. Spahr Richard A. Crudo John K. Davies 《Icarus》2007,192(2):442-447
We observed the Mars Trojan Asteroids (5261) Eureka and (101429) 1998 VF31 and the candidate Mars Trojan 2001 FR127 at 11.2 and 18.1 microns using Michelle on the Gemini North telescope. We derive diameters of 1.28, 0.78, and <0.52 km, respectively, with corresponding geometric visible albedos of 0.39, 0.32, and >0.14. The albedos for Eureka and 1998 VF31 are consistent with the taxonomic classes and compositions (S(I)/angritic and S(VII)/achondritic, respectively) and implied histories presented in a companion paper by Rivkin et al. Eureka's surface likely has a relatively high thermal inertia, implying a thin regolith that is consistent with predictions and the small size that we derive. 相似文献
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Petrology and geochemistry of feldspathic impact‐melt breccia Abar al' Uj 012, the first lunar meteorite from Saudi Arabia 下载免费PDF全文
Marianna Mészáros Beda A. Hofmann Pierre Lanari Randy L. Korotev Edwin Gnos Nicolas D. Greber Ingo Leya Richard C. Greenwood A. J. Timothy Jull Khalid Al‐Wagdani Ayman Mahjoub Abdulaziz A. Al‐Solami Siddiq N. Habibullah 《Meteoritics & planetary science》2016,51(10):1830-1848
Abar al' Uj (AaU) 012 is a clast‐rich, vesicular impact‐melt (IM) breccia, composed of lithic and mineral clasts set in a very fine‐grained and well‐crystallized matrix. It is a typical feldspathic lunar meteorite, most likely originating from the lunar farside. Bulk composition (31.0 wt% Al2O3, 3.85 wt% FeO) is close to the mean of feldspathic lunar meteorites and Apollo FAN‐suite rocks. The low concentration of incompatible trace elements (0.39 ppm Th, 0.13 ppm U) reflects the absence of a significant KREEP component. Plagioclase is highly anorthitic with a mean of An96.9Ab3.0Or0.1. Bulk rock Mg# is 63 and molar FeO/MnO is 76. The terrestrial age of the meteorite is 33.4 ± 5.2 kyr. AaU 012 contains a ~1.4 × 1.5 mm2 exotic clast different from the lithic clast population which is dominated by clasts of anorthosite breccias. Bulk composition and presence of relatively large vesicles indicate that the clast was most probably formed by an impact into a precursor having nonmare igneous origin most likely related to the rare alkali‐suite rocks. The IM clast is mainly composed of clinopyroxenes, contains a significant amount of cristobalite (9.0 vol%), and has a microcrystalline mesostasis. Although the clast shows similarities in texture and modal mineral abundances with some Apollo pigeonite basalts, it has lower FeO and higher SiO2 than any mare basalt. It also has higher FeO and lower Al2O3 than rocks from the FAN‐ or Mg‐suite. Its lower Mg# (59) compared to Mg‐suite rocks also excludes a relationship with these types of lunar material. 相似文献
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