鹤山龙口村边次生常绿阔叶林群落分析

鹤山龙口村边次生常绿阔叶林属季风常绿阔叶林类型, 其种类组成复杂多样而富于热带性, 据１２００ ｍ２ 的样方统计, 有维管束植物６２ 种, 分属于３２ 科、５４ 属, 其中, 属热带分布的有３２ 种, 属热带－ 亚热带分布的有２１ 种, 属亚热带分布的只有７ 种, 其余２ 种为世界分布。本群落的外貌终年常绿, 层次结构复杂而不明显, 样地内高于１－５ｍ 的立木有５２ 种１８５７ 株, 灌木层种类和株数尚多, １００ ｍ２ 内有１８５株, 草本层以乔灌木幼苗为主, 草本植物较少。群落组成结构与地带性常绿阔叶林相似, 乔、灌、草各层的物种多样性指数在４ 左右, 群落均匀度为０－７ ～０－９ , 生态优势度为０－０７ ～０－１０ , 但群落明显具有次生性, 大部分优势种群呈集群分布。若能减少人为干扰破坏, 本群落将向地带性典型植被类型演替。     

基于贝叶斯网络的水源涵养服务空间格局优化

以渭河流域关中—天水经济区段（简称“渭河流域关天段”）为研究区,基于贝叶斯网络和水量平衡原理建立了水源涵养服务网络模型;将CA-Marcov模型与贝叶斯网络模型相结合,预测了2050年不同土地利用情景及其水源涵养服务分布概率;提出了关键变量关键状态子集方法,对研究区水源涵养服务空间格局进行优化。结果表明：① 保护情景下,林地面积增长了18.12%,其主要来源为耕地;草地和城市面积增长缓慢,分别增加了0.73%和0.38%;水体和未利用地分别减少了5.08%和0.92%,该情景下的水源涵养量值偏高的概率在3种情景中最大,保护情景的设计对未来的土地利用政策制定具有一定参考价值。② 水源涵养服务的关键影响因子是降水、蒸散发和土地利用,水源涵养量最高状态对应的关键变量关键状态子集是：﹛降水= 1,蒸散发= 2,土地利用= 2﹜,该子集主要分布在年平均降雨量和蒸散发量较大,植被覆盖率高的地区。③ 研究区适宜优化水源涵养的区域主要分布在天水市麦积区南部、宝鸡市陇县西南部和渭滨区南部、咸阳市旬邑县东北部和永寿县西北部,以及铜川市耀州区西部。结合贝叶斯网络模型研究水源涵养服务的优化区域,不仅有助于提升对生态系统水源涵养服务过程的直观认识,而且增加了情景设计和格局优化的合理性。在此基础上提出的关键状态关键因子方法,对研究区水源涵养生态环境建设和政策制定都具有重要的意义。     

甘肃“5·5"黑风暴小波分析

用小波变换理论对１９９３年春季甘肃省河西走廊地区一场特大黑风暴进行了分析。结果表明，小波分析能比较客观地将时间序列中不同时间尺度的振动分离开，使我们能清楚地看到黑风暴中的中尺度扰动。     

非均质地基中平面应变隧道开挖面稳定上限分析

非均质是软黏土地基中比较普遍的现象,而目前隧道开挖面稳定研究中比较成熟的理论主要是针对均质土体。因此,从塑性极限分析上限法的基本原理出发,采用平面应变隧道刚体平动破坏模式(多块体上限法),考虑软黏土地基的非均质性,推导了平面应变隧道极限支护压力关于隧道埋深、土体重度及土体强度的上限公式。通过与其他方法的比较分析,证明了极限分析方法在隧道开挖面稳定性方面的可行性;利用该方法的计算结果详细探讨了隧道开挖面稳定的影响因素;而且由计算结果可知,地基土的非均质性在影响隧道开挖面极限支护压力的同时,也影响着隧道开挖破坏面的位置和形状,为工程实践提供重要的理论依据。     

Traffic accessibility and the coupling degree of ecosystem services supply and demand in the middle reaches of the Yangtze River urban agglomeration,China

Journal of Geographical Sciences - The spatial relationships between traffic accessibility and supply and demand (S&D) of ecosystem services (ESs) are essential for the formulation of...     

关联演化视角下地理学区域韧性分析的新思考

区域韧性是一个区域应对发展进程中短期冲击与长期变化、积极进行自我调适与转型的能力,表征了区域的适应性、创新性与可持续性,作为新兴理念反映了地理学可持续发展与区域研究的新需求。本研究综述了区域韧性研究进展,基于关联演化视角,探索构建区域韧性认知框架,将情境分析与过程分析并重,思考并总结区域韧性分析的方法论,尝试建立区域韧性评估方程,从经济、社会、环境及制度四个维度进行区域韧性评估,将区域韧性应用于中国地理学研究,分析中国区域韧性研究的一般性与特殊性,将区域韧性研究对接中国实际问题,以期对区域韧性研究做出理论贡献,助推地理学区域发展研究及相关认知领域的跨学科讨论、知识集成与学术交流,为国家制定相关区域政策提供参考,并为国家及区域可持续发展提供科学指引。     

沈阳市资源环境与GDP增长的脱钩态势分析

基于资源环境压力与经济发展的相互耦合关系视角,基于脱钩理论构建了资源环境与经济增长的脱钩状态评价指标体系,引入生态足迹法并结合改进的弹性脱钩分析方法,探讨了沈阳市2002～2009年资源环境与经济发展的脱钩程度、时序演变及其综合脱钩程度等.研究结果表明：2002 ～ 2005年研究区经济增长导致资源环境压力逐渐增大,2005～2009年资源环境压力趋缓;整个时段内研究区资源环境与经济发展脱钩状态以相对脱钩为主,呈“相对脱钩4—强耦合—相对脱钩4—相对脱钩1”的演变趋势.     

Parallelization of the flow-path network model using a particle-set strategy

High-performance simulation of flow dynamics remains a major challenge in the use of physical-based, fully distributed hydrologic models. Parallel computing has been widely used to overcome efficiency limitation by partitioning a basin into sub-basins and executing calculations among multiple processors. However, existing partition-based parallelization strategies are still hampered by the dependency between inter-connected sub-basins. This study proposed a particle-set strategy to parallelize the flow-path network (FPN) model for achieving higher performance in the simulation of flow dynamics. The FPN model replaced the hydrological calculations on sub-basins with the movements of water packages along the upstream and downstream flow paths. Unlike previous partition-based task decomposition approaches, the proposed particle-set strategy decomposes the computational workload by randomly allocating runoff particles to concurrent computing processors. Simulation experiments of the flow routing process were undertaken to validate the developed particle-set FPN model. The outcomes of hourly outlet discharges were compared with field gauged records, and up to 128 computing processors were tested to explore its speedup capability in parallel computing. The experimental results showed that the proposed framework can achieve similar prediction accuracy and parallel efficiency to that of the Triangulated Irregular Network (TIN)-based Real-Time Integrated Basin Simulator (tRIBS).     

Cluster analysis on summer precipitation field over Qinghai–Tibet Plateau from 1961 to 2004

The summer day-by-day precipitation data of 97 meteorological stations on the Qinghai–Tibet Plateau from 1961 to 2004 were selected to analyze the temporal-spatial dis-tribution through accumulated variance, correlation analysis, regression analysis, empirical orthogonal function, power spectrum function and spatial analysis tools of GIS. The result showed that summer precipitation occupied a relatively high proportion in the area with less annual precipitation on the Plateau and the correlation between summer precipitation and annual precipitation was strong. The altitude of these stations and summer precipitation ten-dency presented stronger positive correlation below 2000 m, with correlation value up to 0.604 (α=0.01). The subtracting tendency values between 1961–1983 and 1984–2004 at five altitude ranges (2000–2500 m, 2500–3000 m, 3500–4000 m, 4000–4500 m and above 4500 m) were above zero and accounted for 71.4% of the total. Using empirical orthogonal function, summer precipitation could be roughly divided into three precipitation pattern fields: the Southeast Plateau Pattern Field, the Northeast Plateau Pattern field and the Three Rivers' Headstream Regions Pattern Field. The former two ones had a reverse value from the north to the south and opposite line was along 35°N. The potential cycles of the three pattern fields were 5.33a, 21.33a and 2.17a respectively, tested by the confidence probability of 90%. The station altitudes and summer precipitation potential cycles presented strong negative corre-lation in the stations above 4500 m, with correlation value of –0.626 (α=0.01). In Three Rivers Headstream Regions summer precipitation cycle decreased as the altitude rose in the sta-tions above 3500 m and increased as the altitude rose in those below 3500 m. The empirical orthogonal function analysis in June precipitation, July precipitation and August precipitation showed that the June precipitation pattern field was similar to the July’s, in which southern Plateau was positive and northern Plateau negative. But positive value area in July precipita-tion pattern field was obviously less than June’s. The August pattern field was totally opposite to June’s and July’s. The positive area in August pattern field jumped from the southern Pla-teau to the northern Plateau.