中国城市土地财政扩张及对经济效率影响路径

土地财政对经济效率的影响过程具有系统性、复杂性特征。本文考虑效率提升的结构性特征,从规模经济效应、技术抑制效应等方面构建土地财政对全要素生产率影响机制,进而从投资挤占效应、成本拉动效应探索其传导路径,并基于2005—2015年中国285座地级以上城市面板数据集,运用固定效应模型对其影响过程机理与区域分异特征进行实证检验。结果表明：① 2005—2015年间,中国城市土地财政规模持续扩张,并由沿海城市向内陆城市扩散,但城市全要素生产率增长率却出现波动下降趋势。② 整体上,土地财政对城市全要素生产率产生显著的负向影响,且对西部、中部、东北等地区以及中小城市、Ⅰ型大城市、Ⅱ型大城市的影响依次增强,而东部地区与超特大城市并不显著。③ 土地财政对经济效率影响的技术抑制效应显著大于规模经济效应,中部地区、Ⅰ型、Ⅱ型及超特大城市尤其严重。④ 具体传导路径为,土地财政扩张主要通过房地产开发带来的投资挤占效应影响城市全要素生产率,其次是房价上涨的成本拉动效应,而工资水平上升主要在东部地区、Ⅰ型及以下规模城市发挥作用。以上结论在一系列稳健性检验后依然成立。最后提出明确土地出让收支范围、产业梯度转移与升级、宏观调控与因城施策并行等政策建议。     

Assessing the sensitivity of site index models developed using bi-temporal airborne laser scanning data to different top height estimates and grid cell sizes

Site productivity and forest growth are critical inputs into projecting wood volume and biomass accumulation over time. Site productivity, which is determined most commonly using site index models is also the primary criterion to consider many forest management decisions. Most of the previous research utilizing the remote sensing data for assessment of site index with forest height are based on the existing site index models developed with traditional dendrometric methods. However, these traditional methods are both time-consuming and expensive. This study demonstrates how bi-temporal airborne laser scanning (ALS) data collected within the 8-year period can be used for the development of site index models for Scots pine. The accuracy of ALS-derived models was assessed by comparison to the reference site index model developed based on data from stem analysis of 174 felled Scots pine trees. We evaluated the effect of different height metrics and grid cell size on the trajectory of site index models developed from ALS-derived measurements. Four methods of estimating top height from ALS point clouds were evaluated: 95th, 99th and 100th percentiles of point clouds and an individual tree detection approach (ITD). The models were created for a range of grid cell sizes: 10 × 10 m, 30 × 30 m, and 50 × 50 m. The results indicate that bitemporal ALS data could substitute traditional methods that have been applied to date for stand growth modelling. It was found that top height increment can be estimated by using both ITD approach and the 100th percentile of point cloud giving an appropriate top height (TH) increment estimation. Observed growth curves of reference trees agreed best with the trajectories that were obtained based on TH calculated using ITD method (R² = 0.892) and 100th percentile (R² = 0.797). In case of TH obtained from 99th and 95th percentiles only weak correlation was found: R² = 0.358 and R² = 0.213, accordingly. The height growth models developed with 95th and 99th percentiles of point cloud were not compatible with the reference model. We also found that grid cell size did not affect the model height growth trajectories. Irrespective of the grid cell size, the obtained model trajectories for the given method of TH estimation are nearly identical for cells 10 × 10, 30 × 30 and 50 × 50 m.     

拼接镜面主动控制系统的定标

对拼接主镜进行主动控制是拼接镜技术的难点之一,8 m环形拼接太阳望远镜主动光学的控制性能主要取决于倾斜探测的精度与控制模型建立的准确程度。在研制主动控制系统时,需要对倾斜探测精度定标以及建立较为准确的控制模型,即对主动控制系统定标。实验系统中搭建了用于实时探测拼接子镜倾斜的夏克-哈特曼波前传感器,并对其重复测量精度进行了定标,精度达到0.014 arcsec,接近8 m环形太阳望远镜面形控制的要求。然后利用边缘传感器和夏克-哈特曼波前传感器测量了两镜主动控制系统的控制矩阵,建立较为准确的控制模型。     

中国近海鲐鱼资源时空分布与海洋净初级生产力的关系研究

海洋净初级生产力影响了浮游动植物的空间分布和丰度,因此决定了海洋渔业的潜在产量。本文根据2006-2015年7-9月中国远洋渔业数据中心提供的中国近海鲐鱼捕捞数据和海洋净初级生产力遥感数据,以单位捕捞努力量渔获量（CPUE）表征资源丰度,以经度和纬度重心表征空间分布,分析研究了鲐鱼资源丰度和空间分布与海洋净初级生产力的关系。研究结果表明,2006-2015年鲐鱼产量、CPUE、经度和纬度重心呈现明显的月份和年际变化,7-9月渔场内净初级生产力空间分布模式不同。频率分布结果表明7-9月鲐鱼对应的适宜净初级生产力浓度范围分别为300~500 mg/（m2·d）（以碳计,下同）,300~400 mg/（m2·d）,300~400 mg/（m2·d）。相关分析结果表明,鲐鱼资源丰度与适宜净初级生产力海域范围比例呈显著正相关,且鲐鱼纬度重心与适宜净初级生产力海域平均纬度呈显著正相关关系,这表明渔场内的净初级生产力大小和分布模式显著影响鲐鱼的资源丰度和渔场重心位置。在鲐鱼主要分布海域25°~30°N,120°~130°E范围内,鲐鱼资源丰度与净初级生产力大小呈显著负相关关系。此外,不同气候条件下鲐鱼渔场净初级生产力大小变化不同,2007年和2010年强拉尼娜年份以及2009年中强厄尔尼诺年份鲐鱼渔场范围海洋净初级生产力降低,但适宜的海洋净初级生产力范围增大,导致鲐鱼资源丰度上升;而2015年超强厄尔尼诺年份鲐鱼渔场范围内海洋净初级生产力上升,但适宜的海洋净初级生产力范围显著减小,因此鲐鱼资源丰度相对降低。研究表明,中国近海鲐鱼资源时空分布与海洋净初级生产力具有显著关联。     

基于初级生产力的海洋生物资源承载力评估

资源环境承载力研究亟待突破承载阈值界定与关键参数率定的技术瓶颈,并建立一套标准化的定量评价关键技术。本研究基于“资源量?消费量”模型,通过调查与实验分析获取特定海区的初级生产力、浮游植物有机碳含量、鱼类营养级等关键参数值,采用营养动态模型和Tait沿岸海域能流模型来估算海洋生物资源总量,然后根据年人均水产品摄入量或年人均蛋白质摄入量来计算该海区海洋生物资源承载力的阈值。根据2016年对日照辖区海域的生态环境状况调查,该海域年平均初级生产力(以C计)为428.22 mg/(m2·d),浮游植物年生产量为918.51万t,鱼类、虾蟹类和头足类的平均营养级分别为3.85、3.92和3.90,利用营养动态模型计算海域渔业资源(鱼类、虾蟹类和头足类)的年生产量为3.89万t;根据Tait沿岸海域能流模型计算日照10 m等深线以内浅海的除去壳重的贝类资源量为5.50万t。按照年人均水产品摄入量为21 kg,计算出日照辖区海域的海洋生物资源承载力总和为192.86万人;按照年人均摄入蛋白质量为30 kg,计算出日照辖区海域的海洋生物资源承载力总和为16.87万人。本文建立了一项具有广泛适用性的海洋生物资源承载力定量评价技术,对科学地开发利用海洋生物资源和建立陆海统筹的资源环境承载力的监测预警机制起到积极的促进作用。     

胶州湾水温和营养盐硅限制初级生产力的时空变化

根据作者近年来对胶州湾水域的主要研究结果,分析和探讨了营养盐硅和水温对浮游植物生长的变化和其集群结构的改变影响,研究了胶州湾初级生产力的年变化过程是如何受到营养盐硅和水温的限制和提高,其时间阶段和空间区域又如何划分,营养盐硅和水温如何控制不同阶段和不同区域的初级生产力。同时,揭示了营养盐硅或水温在时间和空间的尺度上如何控制浮游植物生长的变化过程,而且在时空的变化中,2种因子营养盐硅和水温在时间和空间的尺度上又如何有顺序的控制,产生出各种类型的生产力。研究结果展示了在初级生产力的时间和空间的变化过程中,营养盐硅和水温控制初级生产力的不同时间阶段,尤其用增殖能力展示了水温对浮游植物生长的控制时间阶段;营养盐硅控制初级生产力的不同空间区域。从而阐明了营养盐硅和水温控制初级生产力的变化过程。从陆地到海洋界面的硅输送量决定了初级生产力的时间变化过程;硅的生物地球化学过程决定了初级生产力的空间变化过程。因而,营养盐硅和水温是浮游植物生长的“发动机”,营养盐硅是主要的,而水温是次要的。     

渤海生态动力过程的模型研究Ⅰ.模型描述

建立了一个NPZD类型的生物化学模型,并将其与原始方程海流模型(POM)、太阳辐射模型和河流输入模型耦合再现渤海的生态动力过程.模拟的初级生产力与实测值吻合较好;此外,该文还首次全方位地检验了渤海f-ratio的特征,通过与莱州湾的实测值比较,模拟结果也显示了相当的准确度.另外,该文在分析f-ratio变化特征的基础上还揭示硝酸盐和铵盐对渤海浮游植物生长的相对贡献率.     

Predicting and assessing changes in NPP based on multi-scenario land use and cover simulations on the Loess Plateau

Land use/cover change(LUCC)is a major factor affecting net primary production(NPP).According to the LUCC of the Loess Plateau from 2005 to 2015,the LUCC patterns in 2025 in three scenarios were predicted by using the Future Land Use Simulation(FLUS)model.Furthermore,taking the average NPP of various land use/cover types in 16 years as the reference scale,the changes in NPP in multi-scenario simulations are predicted and an-alyzed,and the impact of different land use/cover transfers on NPP is quantified.The results are as follows:(1)The land use/cover changes greatly in the baseline and fast development scenarios,and changes relatively little in the ecological protection scenarios.(2)The changes in NPP in different scenarios reflected the significant difference in the ecological protection effect.All the three scenarios promote an NPP increase,but the ecological protection sce-nario can promote NPP increases the most.(3)The changes in NPP caused by LUCC in the three scenarios reflected the significant difference in the various land use/cover types pro-tection effect.Analyzing and predicting NPP changes in multi-scenario LUCC simulations in the future can provide a theoretical basis for decision makers to judge the future changes in ecological environments and ecological protection effects against different policy back-grounds.     

Phases of Environmental Evolution Indicated by Primary Chemical Elements and Paleontological Records in the Upper Pleistocene-Holocene Series for the Salawusu River Valley, China

Studies of lithology, sedimentary facies and the distribution regularity of SiO2 and Al2O3 contents and Al2O3/SiO2 ratio allow us to divide the Upper Pleistocene-Holocene Series represented by the MUanggouwan section in China＇s Salawnsu River valley into six segments： MGS1, MGS2, MGS3, MGS4, MGS5 and MGS6. The boundary ages for MGS1 （the Dishaogouwan and Dagouwan Formations）, MGS2 （the upper Chengchuan Formation）, MGS3 （the middle Chengchuan Formation）, MGS4 （the lower Chengchuan Formation）, MGS5 （most strata of the Salawusu Formation） and MGS6 （the bottom of the Salawusu Formation and the top of the Lishi Formation） correspond to those of MIS1, MIS2, MIS3, MIS4, MISS and MIS6, respectively, from deep sea sediments or continental glaciers. MGS5 can be subdivided into five subsegments （MGS5a, MGS5b, MGS5c, MGS5d and MGS5e） and the boundary ages of these subsegments correspond to those of MISSa, MISSb, MIS5c, MIS5d and MIS5e, respectively. Based on the paleoenvironment and paleoecology indicated by the primary chemical elements, fossil vertebrates, mollusks and pollen grains, we hypothesize that MGS1, MGS2, MGS3, MGS4, MGS5 and MGS6 and the subsegments of MGS5 match the corresponding stages for oxygen isotopes in the deep sea sediments and continental glaciers, and the substages of MIS5 in terms of climatic characters, further explaining the phenomena that determined the formation of the late Quaternary strata and the paleontology of the Salawusu River valley. These phenomena relate to fluctuations in the global climate （and particularly in the East Asian monsoon） during the glacial and interglacial periods.     

褶皱带橄榄岩-榴辉岩杂岩和稳定地块含金刚石岩筒的成因特征

金刚石母岩可以是榴辉岩、辉石岩、橄榄岩等多种岩石,它们与金刚石都是在地幔深处形成的,并上侵最终固结于地壳中。母岩中的金刚石等矿物在地壳中又发生准稳定生长。地壳中金伯利岩和钾镁煌斑岩岩浆作用对金刚石母岩侵入体进行改造,使原生金刚石发生破碎、溶解、再生长等一系列变化,并形成巨晶、劣质金刚石和黑金刚石等新类型,这些现象不是在金刚石母岩形成之初发生的。