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901.
In order to investigate the feasibility of reintroducing the South China tiger (Panthera tigris amoyensis) in the Jiangxi Matoushan National Nature Reserve, field surveys were conducted to assess prey distribution in the reserve. Twelve permanent transects were set in three distinct functional zones from February to April 2012 and May to July 2013. A total of 112 ungulate signs were recorded on these transects. In addition, 20 camera traps were used to survey ungulates and predators in 2012, while the following year we extended the survey site by using 30 cameras. Overall, 6641 capture events on 2930 camera days were obtained, presenting a variety of ungulate species: muntjak (Muntiacus muntjak), tufted deer (Elaphodus cephalophus), serow (Capricornis sumatraensis) and wild boar (Sus scrofa). Population structure and composition of ungulates was compared in different functional zones using a single factor of variance analysis in SPSS software. Significant differences in the distribution of ungulates were recognized between the core zone and experimental zone, but not in other zones due to differences in habitat types and management practices of the nature reserve. Using ArcGIS analysis and Salford Predictive Modeler software, we ran several predictive models to understand which areas are most suitable for ungulates. We conclude that muntjac and wild boar are mainly distributed in the experimental zone, serow are more common in the core zone, while tufted deer are located evenly in the three functional zones. Finally, suggestions for effective and feasible management strategies and techniques for Matoushan National Nature Reserve were recommended based on the results and analysis in this study.  相似文献   
902.
早三叠世海水的碳同位素组成与演化是二叠纪-三叠纪生物群体灭绝事件之后全球生态萧条与重建时期地球碳循环的重要记录,为地学界长期高度关注。文中测试了四川盆地宣汉渡口和重庆北碚下三叠统及相邻地层258个海相碳酸盐样品的碳、氧同位素组成,以便探讨早三叠世海水的碳同位素组成与演化。这些样品对海水碳同位素组成具有不同的保存性,飞仙关组及嘉陵江组第一、三段保存较好,而嘉陵江组第二、四段保存较差。基于氧同位素可以更为敏感地反映海相碳酸盐成岩蚀变性的原理,在碳、氧同位素相关性分析的基础上,以δ18O<-7.5‰为剔除标准,筛选出近200个有效数据建立了碳同位素演化曲线,该曲线与前人在贵州建立的同期曲线具有很好的可对比性。曲线显示出海水碳同位素组成的巨大波动,变化幅度达8.55‰,包括2个完整的上升-下降旋回,第1个旋回由飞仙关组和嘉陵江组第一段组成,第2个旋回由嘉陵江组第二段、第三段和部分第四段组成,同时还包括若干短周期的次级旋回。利用曲线形态与前人建立的同期曲线进行了岩石地层与年代地层单位的对比,飞仙关组可大致与Induan阶对应,嘉一段可大致与Smithian亚阶对应,嘉二段、嘉三段和嘉四段下部可大致Spathian亚阶对应;绿豆岩作为下-中三叠统界线其位置可能偏高,下-中三叠统界线应该位于绿豆岩之下的嘉四段内部。早三叠世海水碳同位素组成高频率大幅度的波动指示了生物大灭绝后环境的不稳定性,其中菌藻类等微生物灾后过度繁盛,可能导致了有机碳在短时间内的快速埋藏和海水碳同位素的正漂移;而碳同位素大规模的负漂移可能与甲烷水合物释放带来的轻碳有关。研究认为,白云岩所在的地层段往往具有更高的δ13C值,这可能说明微生物活动、白云岩形成和海水δ13C值升高之间的有机联系。下三叠统的白云岩、尤其是嘉二段和嘉四段的白云岩可能是微生物成因的,嘉陵江组有机碳的生产和埋藏可能主要是与白云岩形成有关的微生物的贡献,具最高δ13C值的嘉二段的烃类在一定程度上可能具有自生自储的特点。  相似文献   
903.
Based on the simulation with the Ocean-Atmosphere Coupled Model CCSM and Ocean Model POP under the greenhouse gas emission scenario of the IPCC SRES A2 (IPCC, 2001), and on the earth crust subsidence and glacier melting data, the relative sea level change is obtained along the coast of China in the 21st century. Using the SRTM elevation data the submergence of coastal low land is calculated under the extreme water level with a 100-year return period. The total flooding areas are 98.3×103 and 104.9×103 km2 for 2050 and 2080, respectively. For the three regions most vulnerable to extreme sea level rise, i.e., the coast of Bohai Bay, the Yangtze River Delta together with neighboring Jiangsu Province and northern Zhejiang Province, and the Pearl River Delta, the flooded areas are 5.0×103, 64.1×103 and 15.3×103 km2 in 2050 and 5.2×103, 67.8×103 and 17.2×103 km2 in 2080, respectively.  相似文献   
904.
A households′production behavior directly influences the quality of the environment and determines the successful development of nature reserves.Meanwhile,the households′production behaviors are complicated by interrelated factors,such as protection attitudes,resource endowment,and family wealth.This research evaluated households near the Crested Ibis National Nature Reserve in Shaanxi Province,acquiring data from 436 households around Yang County and Ningshan County in the south slope of Qinling Mountains,China.Based on the collected data,we developed a structural equation model to evaluate the coupling relationships among households′ protection attitudes,production behaviors,resource endowment,and family wealth.The results showed that:1) households with great resource endowment had more negative attitudes,probably due to their greater protection costs;2) the households with higher education levels had worse protection attitudes;3) the households with more family wealth were likely to use fewer fertilizers,pesticides,and firewood;4) the households with more resource endowment showed less production and management behaviors;5) the enhancement of households’ attitudes improved production behaviors to protection the environment,but the effects were not statistically significant.Our results provide a basis for the government’s protection policy making,exploring the effective management measures that are beneficial for both nature reserve management and community development.  相似文献   
905.
The Magnuson-Stevens Fishery Conservation and Management Act (1976), opened a new era of federal fishery management in the United States. It was enacted primarily to establish a system for conserving and managing fisheries in the new 200-mile (EEZ). The US assumed exclusive authority for managing all fisheries within the EEZ, except for highly migratory species such as tunas and billfishes. Within the framework of the Act, eight Regional Fishery Management Councils (Regional Councils) were created, which are responsible for preparing Fisheries Management Plans (FMPs) in federal waters under their jurisdiction. Each FMP must meet a series of National Standards (NSs) for conservation and management. The Act was reauthorized in 1996 with the passage of the Sustainable Fisheries Act (SFA), which aimed at fine tuning the fishery regulatory apparatus that was established under the original Act. This "fine tuning" involved increased attention to biological concerns, and removal of ambiguities within it. The Act was reauthorized again in 2007, mainly to provide for more clear directives and regulations to end overfishing. After more than thirty years since the Act was passed into law, the debate among conservationists, commercial and recreational fishery representatives, and politicians on the effectiveness of the Act in achieving its purported goals it still continues. Is the Act delivering on its promises? Do NSs reflect the most important priorities for the US fishery resources, conservation and sustainable exploitation? Do the Regional Councils represent all parties that should be involved in the fisheries resources management? The aim of this paper is to provide a critical analysis to answer these questions. This paper begins with a review of the Act and its background, followed by discussion and analysis of the Act's benefits and flaws. Finally, suggestions for the implementation of its structure and future directions in fishery management strategies are made.  相似文献   
906.
A cross-system analysis of bulk sediment composition, total organic carbon (TOC), atomic C/N ratio, and carbon isotope composition (δ13C) in 82 surface sediment samples from natural and planted mangrove forests, bank and bottom of tidal creeks, tidal flat, and the subtidal habitat was conducted to examine the roles of mangroves in sedimentation and organic carbon (OC) accumulation processes, and to characterize sources of sedimentary OC of the mangrove ecosystem of Xuan Thuy National Park, Vietnam. Sediment grain sizes varied widely from 5.4 to 170.2 μm (mean 71.5 μm), with the fine sediment grain size fraction (< 63 μm) ranging from 11 to 99.3% (mean 72.5%). Bulk sediment composition suggested that mangroves play an important role in trapping fine sediments from river outflows and tidal water by the mechanisms of tidal current attenuation by vegetation and the ability of fine roots to bind sediments. The TOC content ranged from 0.08 to 2.18% (mean 0.78%), and was higher within mangrove forests compared to those of banks and bottoms of tidal creeks, tidal flat, and subtidal sediments. The sedimentary δ13C ranged from − 27.7 to − 20.4‰ (mean − 24.1‰), and mirrored the trend observed in TOC variation. The TOC and δ13C relationship showed that the factors of microbial remineralization and OC sources controlled the TOC pool of mangrove sediments. The comparison of δ13C and C/N ratio of sedimentary OC with those of mangrove and marine phytoplankton sources indicated that the sedimentary OC within mangrove forests and the subtidal habitat was mainly composed of mangrove and marine phytoplankton sources, respectively. The application of a simple mixing model showed that the mangrove contribution to sedimentary OC decreased as follows: natural mangrove forest > planted mangrove forest > tidal flat > creek bank > creek bottom > subtidal habitat.  相似文献   
907.
Concentrations of ten metals were measured in waters and sediments at 14 sites during four sampling periods (1996–1997). These sites include various marine ecosystems that are highly influenced by industry, tourism and river discharges, nine of which are within the Morrocoy National Park. Spatially, metal concentrations in water were homogenous, whereas in sediments their distributions were related to grain size. Maximum concentrations of cadmium (Cd) and mean concentrations of copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn) in water were above the guideline values proposed by NOAA, indicating the potential of these metals for producing chronic effects in marine biota. Sheltered sites showed the highest metal concentrations in sediments; with Cd and Zn above these guidelines. Enrichment factors and geo-accumulation indexes suggested that metals in sediments were largely of natural origin except for Pb, Cd and vanadium (V), which were apparently associated with industrial effluents. A disruption of the spatial distribution of metals after heavy rainfall, when exposed sites reached concentrations as high as those in sheltered sites, showed the influence of nearby rivers. The potential increase of such climatic events could represent additional stress for natural protected areas in the Caribbean.  相似文献   
908.
This laboratory study seeks to investigate the effect of surface irregularities on the motion characteristics of a falling rock. The irregularly-shaped surfaces of greywacke with a range of joint roughness coefficient (JRC) from 2 to 18 were used in an experimental setup where a falling rock was dropped from a height of 110 cm. A high-speed camera was utilised to capture the trajectory of the falling rock upon its impact with the rock surface. The data from 287 tests were statistically analysed to determine the dominant type of motion and to establish relationships between JRC and the coefficient of restitution (CoR). The effect of surface roughness was seen in different modes of motion of the falling rock with more irregular surfaces often produced ‘sliding’ or ‘rolling’ instead of ‘bouncing’. The obtained data indicated that the rock surface roughness did not seem to have a significant effect on CoR; however, it affected the rebound angle of the falling rock.  相似文献   
909.
Titanite: A potential solidus barometer for granitic magma systems   总被引:1,自引:1,他引:0  
Constraining crystallization pressure and thus intrusion depth of granites in various geodynamic settings remains challenging, yet important to further our understanding of magma system and crustal evolution. We propose that titanite, which is a common accessory in metaluminous and weakly peraluminous granites, can be used as a barometer if it crystallized in magmatic, near-solidus conditions and in equilibrium with amphibole, plagioclase, K-feldspar, quartz, biotite, and magnetite ± ilmenite. Titanite Al2O3 increases with pressure (P) according to: P (in MPa) = 101.66 × Al2O3 in titanite (in wt%) + 59.013 (R2 = 0.83) with estimated uncertainties of ~±60 to ~±100 MPa for crystallization between ~150 and 400 MPa. We highlight that the current calibration dataset is limited, and that systematic experimental studies are needed to rigorously quantify the relation. The most important use of this empirical barometer will be for rocks in which amphibole is present but significantly altered, or in combination with amphibole barometry, as titanite can be easily dated by LA-ICP-MS.  相似文献   
910.
Mayflies are very rare in the British fossil record. The first nymph to be found, Schistonotorum wallisi gen. et sp. nov., is described from the non-marine Lower Cretaceous of southeast England. This Early Barremian find is from the Upper Weald Clay Formation at Smokejacks brickworks, Surrey. It is preserved as an adpression in concretionary sideritic ironstone from the upper insect bed exposed in the northeast face of the pit. The palaeoecological significance of this record is discussed.  相似文献   
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