沙漠化地区两种生态治理政策交易成本的比较研究

本文将交易成本分析引入沙漠化地区生态治理政策分析过程,构建生态治理政策交易成本分析框架,确定交易成本计算方法,估算内蒙古乌审旗退耕还林政策执行期间的交易成本为每年4 931.92元·hm-2。其中,政府直接支付占交易成本的50.06%,农户支付占交易成本的46.86%,政府直接支付是退耕还林机会成本的118.75%。草原休牧政策执行期间的交易成本为每年906.07元·hm-2,政府直接支付占交易成本的12.86%,农户支付占交易成本的80.35%,政府直接支付是草原休牧机会成本的23.30%。退耕还林政策的政府支付与退耕还林的机会成本大致相同,因此该政策执行效果良好,并且实现了退耕还林地区的全面禁牧。草原休牧政策的政府支付达不到休牧机会成本的1/4,牧民利益受到损失,牧民偷牧率达到100%,致使草原休牧流于形式。生态治理政策的交易成本分析,将为不同生态治理政策的比较和绩效评价提供一个新的角度,具有重要意义。     

沙质草地放牧和封育下物种丰富度和生物量关系的季节变化

研究了科尔沁沙质草地放牧和封育下植被盖度、密度、丰富度与地上生物量关系的季节变化。结果表明:放牧和封育草地4月的植被盖度、丰富度和生物量均低于生长旺季8月,而4月植物密度要高于8月;封育草地生长季盖度高于放牧草地,6月和8月生物量高于放牧草地, 4月和6月植物密度则低于放牧草地。封育草地8月物种丰富度与生物量呈极显著的负线性关系（p<0.01）;放牧草地植物密度与生物量4月表现出极显著的正线性关系（p<0.01）、8月为极显著的负线性关系（p<0.01）。放牧草地优势植物糙隐子草4月的密度和生物量呈极显著的正线性关系（p<0.01）、8月为极显著的负线性关系（p<0.01）;黄蒿和狗尾草8月的密度和生物量均呈极显著的负线性关系（p<0.01）;猪毛菜4月和6月的密度和生物量呈极显著的正线性关系（p<0.01）。封育草地达乌里胡枝子、猪毛菜8月的植物密度和生物量呈极显著的正线性关系（p<0.01）。持续放牧和季节变化及其二者的交互作用对植被盖度、密度和生物量均有重要的影响（p<0.05）;放牧通过影响草地生长季中的优势植物密度变化和生物量积累,引起了草地植物密度和生物量关系的季节变化,也导致生长季物种丰富度和生物量无显著关系;封育草地植物的竞争导致了物种丰富度和生物量关系的季节变化。     

“数字辐射沙脊群”资源与环境信息管理平台设计与关键技术

针对江苏中部岸外辐射沙脊群海洋资源与环境数据的综合管理和信息辅助决策需求,基于Client/Server(C/S)和Browser/Server(B/S)混合架构完成了"数字辐射沙脊群"资源与环境信息管理平台的研制。平台采用组件式模块化方法开发,实现了基本的海洋信息管理、查询、分析与共享发布功能以及面向海洋深层次应用的数据挖掘、专题图自动生成、数据产品制作、海洋二维动力场可视化及浅海三维地形可视化模拟功能,为辐射沙脊群资源的合理开发利用提供了技术支撑。论文详细介绍了平台的设计思路,并对建设过程中采用的关键技术进行了深入探讨,目的为实现我国"数字海洋"的一体化建设提供参考。     

Sediment mobility and bed armoring in the St Clair River: insights from hydrodynamic modeling

The lake levels in Lake Michigan‐Huron have recently fallen to near historical lows, as has the elevation difference between Lake Michigan‐Huron compared to Lake Erie. This decline in lake levels has the potential to cause detrimental impacts on the lake ecosystems, together with social and economic impacts on communities in the entire Great Lakes region. Results from past work suggest that morphological changes in the St Clair River, which is the only natural outlet for Lake Michigan‐Huron, could be an appreciable factor in the recent trends of lake level decline. A key research question is whether bed erosion within the river has caused an increase in water conveyance, therefore, contributed to the falling lake level. In this paper, a numerical modeling approach with field data is used to investigate the possibility of sediment movement in the St Clair River and assess the likelihood of morphological change under the current flow regime. A two‐dimensional numerical model was used to study flow structure, bed shear stress, and sediment mobility/armoring over a range of flow discharges. Boundary conditions for the numerical model were provided by detailed field measurements that included high‐resolution bathymetry and three‐dimensional flow velocities. The results indicate that, without considering other effects, under the current range of flow conditions, the shear stresses produced by the river flow are too low to transport most of the coarse bed sediment within the reach and are too low to cause substantial bed erosion or bed scour. However, the detailed maps of the bed show mobile bedforms in the upper St Clair River that are indicative of sediment transport. Relatively high shear stresses near a constriction at the upstream end of the river and at channel bends could cause local scour and deposition. Ship‐induced propeller wake erosion also is a likely cause of sediment movement in the entire reach. Other factors that may promote sediment movement, such as ice cover and dredging in the lower river, require further investigation. Copyright © 2012 John Wiley & Sons, Ltd.     

Through‐water terrestrial laser scanning of gravel beds at the patch scale

Acquiring high resolution topographic data of natural gravel surfaces is technically demanding in locations where the bed is not exposed at low water stages. Often the most geomorphologically active surfaces are permanently submerged. Gravel beds are spatially variable and measurement of their detailed structure and particle sizes is essential for understanding the interaction of bed roughness with near‐bed flow hydraulics, sediment entrainment, transport and deposition processes, as well as providing insights into the ecological responses to these processes. This paper presents patch‐scale laboratory and field experiments to demonstrate that through‐water terrestrial laser scanning (TLS) has the potential to provide high resolution digital elevation models of submerged gravel beds with enough detail to depict individual grains and small‐scale forms. The resulting point cloud data requires correction for refraction before registration. Preliminary validation shows that patch‐scale TLS through 200 mm of water introduces a mean error of less than 5 mm under ideal conditions. Point precision is not adversely affected by the water column. The resulting DEMs can be embedded seamlessly within larger sub‐aerial reach‐scale surveys and can be acquired alongside flow measurements to examine the effects of three‐dimensional surface geometry on turbulent flow fields and their interaction with instream ecology dynamics. Copyright © 2011 John Wiley & Sons, Ltd.     

白彦砾岩的形成时代及砾石组构特征分析

通过对白彦砾岩中孢粉取样鉴定及其砾石组构的统计研究,孢粉组合特征显示其形成时代为中侏罗世,并非通常认为的古近纪。砾石组构特征显示为湖滨相或海滨相成因,砾岩中金刚石特征显示出与蒙阴常马金刚石原生矿的相似性。综合分析认为,白彦砾岩形成于中侏罗世鲁西地区单断拉分盆地诞生之前,应为三台组沉积之前的沉积物。白彦砾岩沉积时代的确定,对恢复该区岩相古地理、确定金刚石原生矿的剥蚀与搬运等都具有重要意义。     

砂田不同覆盖方式对土壤微生物组成的影响

为研究砂田(GSMF)表面覆盖的砾石层对土壤微生物组成的影响,于2004年春布设试验,分别为砾石覆盖厚度试验、覆盖砾石粒径试验和不同粒径砾石按不同比例混合覆盖试验。于2009年5月对未经扰动的土壤细菌、真菌、放线菌组成和土壤含水量进行研究,土壤剖面深度分别为0~1 cm、1~2 cm、2~4 cm和4~20 cm。结果表明,砾石覆盖可以增加土壤含水量和土壤微生物数量,当土壤表面覆盖的砾石粒径越小或者组成覆盖层的砾石以小粒径为主时,有利于土壤水分的积累和细菌的生长,反之则利于放线菌的生长,粒径范围在1~8 cm时,较利于真菌生长,在砾石覆盖厚度试验中观察到有超过50%的真菌分布在0~1 cm深的土壤剖面中这一特有现象。砾石层覆盖厚度为7~9 cm时,最适宜微生物生长。     

科尔沁沙地夏秋(6—9月)季不同类型沙丘土壤呼吸对气温变化的响应

 通过测定分析了科尔沁沙地6—9月不同生境（固定、半固定和流动沙丘）土壤呼吸速率的日动态、月际动态及其对气温变化的响应。结果表明：测定期平均土壤呼吸速率在各生境间存在显著差异,其大小为固定沙丘（2.35 μmolCO₂·m^-2·s^-1）＞半固定沙丘（1.67 μmolCO₂·m^-2·s^-1）＞流动沙丘（1.06 μmolCO₂·m^-2·s^-1）;指数模型能够较好地揭示不同生境土壤呼吸对气温变化的响应,但土壤呼吸的月际动态与气温变化不完全同步;各生境土壤在高温环境下的Q10值(土壤呼吸对温度敏感程度)普遍低于低温环境下的Q₁₀值;固定、半固定和流动沙丘基于气温月际变化的Q₁₀值分别为2.34、1.99和1.31,表明不同的植被状况和土壤性质会影响到土壤呼吸对温度变化的敏感程度。     

Weathering, mineralogical evolution and soil organic matter along a Holocene soil toposequence developed on carbonate-rich materials

A toposequence of Holocene soils located between 1100–2400 m asl in the Italian Alps served as the basis for the following analyses: the weathering of limestone and dolomite, the calculation of mass balances, understanding the formation of pedogenic Fe and Al, the determination of soil mineral and clay mineral reactions and transformation and the measurement of accumulation and stabilisation mechanisms of soil organic matter. Leaching of carbonates is most intense at the lower elevations, although calcite and dolomite have a higher solubility at low temperatures. The pCO₂ in the soil is higher at lower elevations and weathering is driven mainly by carbonic acids. At higher elevations, organic acids appear to determine the mineral transformations and weathering reactions to a greater extent. This suggests that two very different weathering regimes (carbonic and organic acid weathering) exist along the toposequence. The transformation of mica into vermiculite is the main process in both the clay and fine-earth fraction. Weathering of silicate minerals started even before the carbonates had been completely removed from the soils. The transformation mechanisms of silicate minerals in the A and O horizon at higher elevations was at least as intensive as that at the climatically warmer sites. The neoformation of pedogenetic clays at climatically cooler sites was slightly greater than that at the warmer sites. However, the formation rate of secondary Fe and Al phases was more pronounced at lower elevation, which means that this process seemed to be driven dominantly by carbonic acid (weathering of primary minerals). Soil organic matter (SOM) abundance in the mineral soil is nearly 15 kg/m² at all sites and, surprisingly, no climate-driven effect could be detected. In general, the preservation and stabilisation of SOM was due to poorly crystalline Al and Fe phases and vermiculite, regardless of some variations in the composition of the parent material (varying calcite/dolomite ratio).