中国土地利用变化生态环境效应的空间分异性与形成机理   总被引：8，自引：1，他引：7  

陈万旭  李江风  曾杰  冉端  杨斌 《地理研究》2019,38(9):2173-2187

中国复杂的自然要素、社会经济要素、区域发展战略和政策调控形成了当前中国不均衡的经济发展空间格局、土地利用空间格局和生态环境质量空间格局。厘清中国生态环境质量的空间格局及形成机理对中国土地资源的可持续利用和生态环境的有效保护具有重要的实践意义和价值。以往研究缺乏对中国县域尺度土地利用/土地覆被变化生态环境效应的空间分异性及形成机理的相关研究,本研究基于1995—2015年间中国土地利用现状遥感监测数据,尝试采用生态环境质量指数方法测度中国土地利用变化的生态环境效应,并且综合运用重心分析、热点分析工具（Getis-Ord G_i*）和地理探测器等研究方法,分析1995—2015年中国生态环境质量时空演变特征及形成机理。研究结果如下：① 东部季风区生态环境质量指数高于青藏高寒区和西北干旱区,东部季风区生态环境质量低值区主要分布在人口和经济集聚的城市群以及省会城市周边地区。研究期间中国生态环境质量重心持续向西北方向迁移;② 1995—2015年间中国生态环境质量变化的热点区域主要分布在西藏地区、新疆、重庆、贵州以及位于黄土高原的省份（青海、甘肃、宁夏、内蒙古、山西、陕西以及河南）境内,冷点区域主要分布在长江经济带沿线地区省份以及东南部沿海地区省份;③ 土地利用程度对于生态环境质量影响力显著强于其他因子,东部季风区的社会经济和交通区位因子对生态环境质量影响力强于青藏高寒区、西北干旱区和生态大区过渡带;④ 影响因子之间相互作用主要包括非线性增强作用和双因子增强作用两种类型,以非线性增强作用为主。  相似文献   

国际极地研究进展的文献计量分析     

崔尚公  李雪  杨益  王少朋  秦雪  李红军 《海洋科学》2021,45(7):137-146

本文基于WoS和CNKI数据库,通过文献计量方法对2013—2018年中国和国际极地科研情况从发文量、被引量、机构、学科分布、合作关系、来源期刊、高被引论文等方面进行统计分析,并结合中西方传统学科优势和自然地理位置的差异,总结了当前极地领域的研究热点,得出以下结论：（1）“极地冰盖不稳定性和海平面变化”“极地生态系统的敏感性与脆弱性”“北极海-冰-气相互作用及其气候效应”是当前世界各国共同关注的研究重点;（2）“‘冰上丝绸之路’倡议下的国家战略与合作”等政治环境研究已成为我国特有的极地战略课题。同时,从加大政策支持、构建合作体系和优化战略布局等三个方面提出了启示与建议。  相似文献   

Spatial and temporal characterization of nutrient net uptake in a vegetated urban stream: Stream bank features leading to net uptake hotspots          下载免费PDF全文

Ana Catarina Singh  Carolyn Oldham 《水文研究》2017,31(17):3003-3016

Urban stream features can be used to promote nutrient retention; however, their interactions with different hydrological regimes impact nutrient cycling, decrease their retention capacity, and inhibit stream ecosystem functioning. This study analysed the temporal and spatial dynamics of the uptake of three nutrients (nitrate, ammonium, and phosphorus) in an urban drainage stream during high flows. In particular, we studied variations in net uptake along the right margin (with native vegetation and a roots mat) comparatively to the left margin (a non‐rooted grassy bank). Applying the spiralling approach within each subreach on either side, we determined nutrient subreach (sr) retention metrics: uptake rate coefficients , mass transfer rates , and areal uptake rates . Our results showed nitrate (NO₃) and ammonium (NH₄) net uptakes on the right side were higher and more frequent along subreaches where the root mat was more abundant ( [μg m^?2 s^?1] = 22.80 ± 1.13 for NO₃ and 10.50 ± 0.81 for NH₄), whereas on the left side both nutrients showed patchy and inconsistent net uptake patterns despite the homogeneous grass distribution. Net uptake for filtered reactive phosphorus (FRP) was not observed on either side at any flow rate. The impact of hydrological factors such as discharge, travel time, water depth, and concentration, on uptake metrics was studied. Despite increases in travel time as the flow decreased, there was a reduction in net uptake rates, and , on either side. This was attributed to a reduction in water level with declining flows, which decreased hydrologic connectivity with the stream banks, combined with a decrease in water velocity and a reduction in nutrient concentrations. We concluded the rooted bank acted as an effective retention area by systematically promoting net uptake resulting in a twofold increased dissolved inorganic nitrogen (DIN) retention relative to the non‐rooted side where net uptake was spatially localized and highly dynamic. Overall, this work emphasized the importance of strategically sampling close to biologically active surfaces to more accurately determine areas where gross uptake surpasses release process.  相似文献   

A Maastrichtian palaeomagnetic pole for the Pacific plate from a skewness analysis of marine magnetic anomaly 32     

Katerina E. Petronotis  & Richard G. Gordon 《Geophysical Journal International》1999,139(1):227-247

The asymmetry (skewness) of marine magnetic anomaly 32 (72.1–73.3  Ma) on the Pacific plate has been analysed in order to estimate a new palaeomagnetic pole. Apparent effective remanent inclinations of the seafloor magnetization were calculated from skewness estimates of 108 crossings of anomaly 32 distributed over the entire Pacific plate and spanning a great-circle distance of ~12  000  km. The data were inverted to obtain a palaeomagnetic pole at 72.1°N, 26.8°E with a 95 per cent confidence ellipse having a 4.0° major semi-axis oriented 98° clockwise of north and a 1.8° minor semi-axis; the anomalous skewness is 14.2° ± 3.7°. The possible dependence of anomalous skewness on spreading rate was investigated with two empirical models and found to have a negligible effect on our palaeopole analysis over the range of relevant spreading half-rates, ~25 to ~90  mm  yr⁻¹ . The new pole is consistent with the northward motion for the Pacific plate indicated by coeval palaeocolatitude and palaeoequatorial data, but differs significantly from, and lies to the northeast of, coeval seamount poles. We attribute the difference to unmodelled errors in the seamount poles, mainly in the declinations. Comparison with the northward motion inferred from dated volcanoes along the Hawaiian–Emperor seamount chain indicates 13° of southward motion of the Hawaiian hotspot since 73  Ma. When the pole is reconstructed with the Pacific plate relative to the Pacific hotspots, it differs by 14°–18° from the position of the pole relative to the Indo–Atlantic hotspots. This has several possible explanations including bias in one or more of the palaeomagnetic poles, motion between the Pacific and Indo–Atlantic hotspots, and errors in plate reconstructions relative to the hotspots.  相似文献   

区域弹性研究热点与前沿的可视化     

韩增林  朱文超  李博 《热带地理》2021,41(1):206-215

基于Web of science核心数据库中1991—2019年收录主题为"regional resilience"的文献数据,利用CiteSpace5.0软件,采取关键词共现网络分析、共被引文献聚类分析、社会网络共现分析等方法对区域弹性研究现状进行知识图谱可视化.结果发现:1)区域弹性相关研究文献发表数量总体呈上升趋...  相似文献   

Holographic measurements of surface topography in laboratory models of mantle hotspots   总被引：1，自引：0，他引：1  

R. W. Griffiths  Michael Gurnis  Georg Eitelberg† 《Geophysical Journal International》1989,96(3):477-495

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How robust are global conservation priorities to climate change?     

Takuya Iwamura  Antoine Guisan  Kerrie A. Wilson  Hugh P. Possingham 《Global Environmental Change》2013,23(5):1277-1284

International conservation organisations have identified priority areas for biodiversity conservation. These global-scale prioritisations affect the distribution of funds for conservation interventions. As each organisation has a different focus, each prioritisation scheme is determined by different decision criteria and the resultant priority areas vary considerably. However, little is known about how the priority areas will respond to the impacts of climate change. In this paper, we examined the robustness of eight global-scale prioritisations to climate change under various climate predictions from seven global circulation models. We developed a novel metric of the climate stability for 803 ecoregions based on a recently introduced method to estimate the overlap of climate envelopes. The relationships between the decision criteria and the robustness of the global prioritisation schemes were statistically examined. We found that decision criteria related to level of endemism and landscape fragmentation were strongly correlated with areas predicted to be robust to a changing climate. Hence, policies that prioritise intact areas due to the likely cost efficiency, and assumptions related to the potential to mitigate the impacts of climate change, require further examination. Our findings will help determine where additional management is required to enable biodiversity to adapt to the impacts of climate change.  相似文献   

基于ESDA的辽宁省县际经济差异时空分析   总被引：16，自引：3，他引：13  

关伟  朱海飞 《地理研究》2011,30(11):2008-2016

以县域（含县、县级市、市辖区）为研究单元,采用人均GDP为测度指标,运用ES—DA的方法对2000-2009年辽宁省县际经济差异的时空格局进行分析,认为辽宁省县际经济具有显著的空间自相关,区县经济差异呈现先扩大后缩小的趋势。在局部差异方面,“高-高”类型的区县主要集中在沈阳、大连地区并有向沿海地区扩散的趋势,“低-低”...  相似文献   

社会感知视角下基于“头尾划分”的游憩热点识别新方法     

师浩辰  赵渺希  林思仪 《地理与地理信息科学》2022,38(1):23-30

作为游憩空间的核心研究对象,游憩热点在研判居民游憩偏好、落实城市游憩规划等方面具有重要作用。该文从“社会感知”视角,结合“头尾划分”理论,提出基于时空轨迹数据识别城市游憩热点的新方法。首先基于个人轨迹数据识别停留点,然后基于“头尾划分”理论划定游憩停留点簇群,最后整合停留点簇群并赋值于邻近道路形成游憩热点;以广州市老城区为例进行实证分析,并与两种既有点数据聚类方法进行对比。结果显示:1)广州市老城区的游憩热点整体集中于中、西部,热点类型可分为蓝绿空间、历史风貌、商业街区、批发市场和新兴网红场所5类;2)相比DBSCAN和CFSFDP算法,该文方法在识别游憩热点数量、捕捉游憩热点核心、明确游憩热点边界和运行简洁程度等方面表现更好,有利于后续游憩热点的深度分析与整合。研究成果可为城市游憩热点的识别提供新思路,也可为国土空间规划语境下游憩系统的重塑与提升提供重要分析基础。  相似文献   

基于PI算法的青藏块体强震回溯性研究     

余娜  张晓清  袁伏全  赵燕杰 《地震地磁观测与研究》2021,42(1):35-41

利用中国地震台网中心提供的1970—2019年8月全国地震目录,在分析青藏块体最小完备震级的基础上,应用PI算法,选取空间网格尺度0.2°×0.2°,截止震级为M_L3.0,目标震级≥M_S6.0,预测时间窗设定为10 a、5 a、3 a不同时间尺度进行回溯性研究,并对预测结果进行ROC检验。结果表明,预测时间窗内的强震基本发生在PI算法所得异常区域附近,且预测结果明显优于随机概率法;PI算法对青藏块体中长时间尺度的强震具有一定的预测效能,而且将预测时间窗设定为3 a时,预测效能较好。此外,定性分析了活动块体边界带“目标”地震与地震热点丛集间的关系,发现青藏块体M_S≥6.0地震与活动块体边界带地震热点间的对应关系较好。在实际应用中,将PI算法计算结果与活动块体边界带结合起来考虑强震相对危险区域时,该研究结果具有一定的参考价值。  相似文献