5 results
Search Results
2. Mechanical Behavior of a Granite from Wuyi Mountain: Insights from Strain-Based Approaches.
- Author
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Xiong, Liangfeng, Wu, Shunchuan, and Zhang, Shihuai
- Subjects
CYCLIC loads ,GRANITE ,ROCK mechanics ,FRACTURE mechanics - Abstract
A series of monotonic and cyclic loading tests were conducted on granite samples from Wuyi Mountain to investigate the mechanical behavior under different confinements and damage states. The irreversible axial and radial strains were computed to characterize the development of the damage state, and three characteristic stages were detected according to the average gain rate. The evolution of the apparent deformation parameters with the deviator stress level was investigated to determine the linear elastic stage, but no substantial progress was achieved. In addition, two typical approaches (transitional region and same gradient region of hysteresis) were also found to be unsuitable for determining the elastic parameters to complete the cyclic loading test. Therefore, a secant approach was proposed based on volumetric strain to identify the lower bound of the nominal linear elastic stage with the upper bound established by linear regression. The results indicated that both elastic parameters and stress thresholds showed positive correlations with confinement. With the accumulation of the damage state, the peak stress and crack initiation threshold decreased, crack damage threshold and elastic parameters first increased and then decreased, and the crack closure threshold showed a tendency to decrease-increase-decrease. In addition, the strain softening stage showed a higher slope and minor stress drop value under larger confinement, and a transition from plastic compaction to plastic dilatancy was also detected. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
3. Historical data for conservation: reconstructing range changes of Chinese pangolin (Manis pentadactyla) in eastern China (1970-2016).
- Author
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Minhao Chen, Chao Zhang, Zhaomin Huo, Xiaofeng Luan, Li Yang, Challender, Daniel W. S., Waterman, Carly, and Hongwei Liu
- Subjects
MANIS ,PANGOLINS ,CONSERVATION biology ,ANTHROPOGENIC effects on nature - Abstract
The Chinese pangolin (Manis pentadactyla) has long suffered from intense exploitation driven by consumer demand for medicinal use and food. Effective conservation management is hampered by insufficient data on pangolin status and distribution. We integrated ecological niche modelling with long-term ecological records at the local scale (e.g. from local historical documents, grey and published literature and interviews) to estimate the magnitude of potential distribution change of the Chinese pangolin in eastern China (Fujian, Jiangxi and Zhejiang provinces) over time. Our results suggest that the range of the species decreased by 52.20% between the 1970s and early 2000s and that the population is now mainly confined to the Wuyi Mountains. This reduction in potential distribution range is attributable to anthropogenic pressures. According to our conservation prioritization analysis, the priority conservation area for the Chinese pangolin in eastern China is 51 268.4 km², 5.62% of which is covered by nature reserves. There are 18 nature reserves and 46 prefectures which are priority areas for conservation in China. The priority-level nature reserves and prefectures in eastern China are mainly located in the centre of the Wuyi Mountains, and areas declared important tend to be around the Wuyi Mountains. We propose several actions to improve the conservation status of this species: establish or enlarge nature reserves, ensure local governments at the prefecture level prioritize conservation management and encourage local communities to participate in pangolin conservation. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
4. Association of Soil Aggregation with the Distribution and Quality of Organic Carbon in Soil along an Elevation Gradient on Wuyi Mountain in China.
- Author
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Li, Liguang, Vogel, Jason, He, Zhenli, Zou, Xiaoming, Ruan, Honghua, Huang, Wei, Wang, Jiashe, and Bianchi, Thomas S.
- Subjects
SOIL structure ,CARBON in soils ,SOIL quality ,FOREST soils ,CARBON sequestration ,GLOBAL warming & the environment - Abstract
Forest soils play a critical role in the sequestration of atmospheric CO
2 and subsequent attenuation of global warming. The nature and properties of organic matter in soils have an influence on the sequestration of carbon. In this study, soils were collected from representative forestlands, including a subtropical evergreen broad-leaved forest (EBF), a coniferous forest (CF), a subalpine dwarf forest (DF), and alpine meadow (AM) along an elevation gradient on Wuyi Mountain, which is located in a subtropical area of southeastern China. These soil samples were analyzed in the laboratory to examine the distribution and speciation of organic carbon (OC) within different size fractions of water-stable soil aggregates, and subsequently to determine effects on carbon sequestration. Soil aggregation rate increased with increasing elevation. Soil aggregation rate, rather than soil temperature, moisture or clay content, showed the strongest correlation with OC in bulk soil, indicating soil structure was the critical factor in carbon sequestration of Wuyi Mountain. The content of coarse particulate organic matter fraction, rather than the silt and clay particles, represented OC stock in bulk soil and different soil aggregate fractions. With increasing soil aggregation rate, more carbon was accumulated within the macroaggregates, particularly within the coarse particulate organic matter fraction (250–2000 μm), rather than within the microaggregates (53–250μm) or silt and clay particles (< 53μm). In consideration of the high instability of macroaggregates and the liability of SOC within them, further research is needed to verify whether highly-aggregated soils at higher altitudes are more likely to lose SOC under warmer conditions. [ABSTRACT FROM AUTHOR]- Published
- 2016
- Full Text
- View/download PDF
5. Geochronology of the Granitoids Above Nappe Structure in Nanling Scientific Drilling.
- Author
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GUO, Naxin, Xiaoqiang, LÜ, ZHAO, Zheng, FANG, Guicong, CHEN, Yuchuan, and WANG, Denghong
- Subjects
NAPPES (Geology) ,GEOLOGICAL time scales ,DRILLING & boring ,PORPHYRY ,GRANITE ,GRANODIORITE ,RHYOLITE - Abstract
The article discusses the geochronology of the granitoids above nappe structure in Nanling Scientific Drilling-1 (NSLD-1), which is a subproject of the Sinoprobe Program titled as "Deep Exploration Technology and Experimentation," located at Yinkeng ore field in metallogenic belts of Wuyi Mountains and Nanling, China. It states that three types of granitoids were exposed above the nappe structure in NSLD-1 including rhyolite porphyry, granite porphyry and granodiorite porphyry.
- Published
- 2014
- Full Text
- View/download PDF
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