基于RS与GIS的麻地沟土壤侵蚀及其生态环境效应研究

以GIS、RS和修正的土壤流失方程(RUSLE)为基础,结合遥感影像解译数据、地形图及降雨资料等,对麻地沟的土壤侵蚀进行了定量分析,并根据土壤侵蚀定量计算结果,结合景观生态学的方法,分析土壤侵蚀引起生态环境效应的因子,包括植被指数和景观指数等,对麻地沟地区的生态环境效应进行了分析。结果表明:研究区土壤侵蚀状况正在逐步好转,坡耕地和坡荒地是发生土壤侵蚀面积相对较高的两种土地利用类型,在保证当地居民所需坡耕地的情况下,修造梯田和植树造林是控制土壤侵蚀最有效的方式。     

天山托木尔峰国家级自然保护区垂直自然带景观特征分析

根据实地考察和相关参考资料,运用历史文献和统计分析的方法,对托木尔峰国家级自然保护区垂直自然带景观特征进行分析,结果显示：对托木尔峰自然保护区垂直自然带的形成,地形地貌因素起着主导作用,纬度起着次要作用,受地形地貌因素制约的水热条件是形成各垂直自然带景观特征的最重要的物质和能量来源,随着水热条件的垂直变化,从低山带至高山带有规律的出现暖温带荒漠带、温带荒漠草原带、山地草原带、亚高山草甸带、高山草甸带、高山垫状植被带和高山冰雪带.东西走向的天山山脉,南北向深切的冰川和流水地貌,对来自北大西洋和北冰洋的湿润气流起了显著地屏障作用,致使托木尔峰南、北坡具有不同的气候特点,南坡形成了暖温带半干旱和干旱气候.自然景观以温带荒漠、荒漠草原和草原为主,植物种类贫乏,具有耐旱特点,随着海拔高度的增加,植物的荒漠成分逐渐减少,草原和草甸成分逐渐增加,土壤的有机质含量提高,碳酸盐的淋溶作用增强.     

Improved simulation of river water and groundwater exchange in an alluvial plain using the SWAT model

Hydrological interaction between surface and subsurface water systems has a significant impact on water quality, ecosystems and biogeochemistry cycling of both systems. Distributed models have been developed to simulate this function, but they require detailed spatial inputs and extensive computation time. The soil and water assessment tool (SWAT) model is a semi‐distributed model that has been successfully applied around the world. However, it has not been able to simulate the two‐way exchanges between surface water and groundwater. In this study, the SWAT‐landscape unit (LU) model – based on a catena method that routes flow across three LUs (the divide, the hillslope and the valley) – was modified and applied in the floodplain of the Garonne River. The modified model was called SWAT‐LUD. Darcy's equation was applied to simulate groundwater flow. The algorithm for surface water‐level simulation during flooding periods was modified, and the influence of flooding on groundwater levels was added to the model. Chloride was chosen as a conservative tracer to test simulated water exchanges. The simulated water exchange quantity from SWAT‐LUD was compared with the output of a two‐dimensional distributed model, surface–subsurface water exchange model. The results showed that simulated groundwater levels in the LU adjoining the river matched the observed data very well. Additionally, SWAT‐LUD model was able to reflect the actual water exchange between the river and the aquifer. It showed that river water discharge has a significant influence on the surface–groundwater exchanges. The main water flow direction in the river/groundwater interface was from groundwater to river; water that flowed in this direction accounted for 65% of the total exchanged water volume. The water mixing occurs mainly during high hydraulic periods. Flooded water was important for the surface–subsurface water exchange process; it accounted for 69% of total water that flowed from the river to the aquifer. The new module also provides the option of simulating pollution transfer occurring at the river/groundwater interface at the catchment scale. Copyright © 2015 John Wiley & Sons, Ltd.     

The estimation of estuary dimensions using a simplified form model and the exogenous controls

The most common definition of an equilibrium condition for estuaries and inlets makes use of the well documented relationship between tidal prism and the cross‐sectional area of the channel. However, the tidal prism is itself a function of the morphology of the tidal basin. It would therefore be useful to be able to define the key dimensions of estuaries and inlets based on properties that are external to the estuary itself. This would then provide a more rigorous basis for understanding how systems are being ‘perturbed’ by developments, or other influences such as climate change. An idealized representation of the three–dimensional (3D) form of an estuary has been proposed and is here applied to a wide range of UK estuaries to explore its ability to predict the gross properties of a range of different estuary types. When considering just tidal flow, the model was found to provide an adequate representation, however, the inclusion of wave action was found to significantly improve the predictive power of the model. The exogenous parameters therefore provide a basis for determining the estuary dimensions and how they are likely to change over time. This in turn provokes a broader definition of an estuary than those commonly cited. Copyright © 2012 John Wiley & Sons, Ltd.     

Did tillage erosion play a role in millennial scale landscape development?

Landscape evolution models (LEMs) quantitatively simulate processes of sedimentation and erosion on millennial timescales. An important aspect of human impact on erosion is sediment redistribution due to agriculture, referred to herein as tillage erosion. In this study we aim to analyse the potential contribution of tillage erosion to landscape development using LEM LAPSUS. The model is calibrated separately for a water erosion process (i) without tillage and (ii) with tillage. The model is applied to the ~250 km² Torrealvilla case study catchment, SE Spain. We were able to simulate alternating sequences of incision and aggradation, that are important on longer (millennial) timescales. Generally, model results show that tillage erosion adds to deposition in the lower floodplain area, but neither water erosion alone nor water with tillage erosion together could exactly reproduce the observed amounts of erosion and sedimentation for the case study area. In addition, scale effects are apparent. On hillslopes, tillage may contribute importantly to erosion and may fill local depressions. If assessed on the catchment scale, sediments from tillage erosion eventually reach the lower floodplain area where they contribute to deposition. However, water erosion was observed in the model simulations to be the most important process on the catchment scale. This is the first time that tillage erosion has been explicitly included in a landscape evolution model at a millennial timescale and large catchment scale. Copyright © 2012 John Wiley & Sons, Ltd.     

Construction of cDNA library from intestine, mesentery and coelomocyte of Apostichopus japonicus Selenka infected with Vibrio sp. and a preliminary analysis of immunity-related genes

The aquaculture of sea cucumber Apostichopus japonicus (Echinodermata, Holothuroidea) has grown rapidly during recent years and has become an important sector of the marine industry in Northern China. However, with the rapid growth of the industry and the use of non-standard culture techniques, epidemic diseases of A. japonicus now pose increasing problems to the industry. To screen the genes with stress response to bacterial infection in sea cucumber at a genome wide level, we constructed a cDNA library from A. japonicus Selenka (Aspidochirotida: Stichopodidae) after infecting them with Vibrio sp. for 48 h. Total RNA was extracted from the intestine, mesentery and coelomocyte of infected sea cucumber using Trizol and mRNA was isolated by Oligotex mRNA Kits. The ligated cDNAs were transformed into DH5α, and a library of 3.24×105 clones (3.24×105 cfu mL-1) was obtained with the sizes of inserted fragments ranging from 0.8 to 2.5 kb. Sequencing the cDNA clones resulted in a total of 1106 ESTs that passed the quality control. BlastX and BlastN searches have identified 168 (31.5%) ESTs sharing significant homology with known sequences in NCBI protein or nucleotide databases. Among a panel of 25 putative immunity-related genes, serum lectin isoform, complement component 3, complement component 3-like genes were further studied by real-time PCR and they all increased more than 5 fold in response to Vibrio sp. challenge. Our library provides a valuable molecular tool for future study of invertebrate immunity against bacterial infection and our gene expression data indicates the importance of the immune system in the evolution and development of sea cucumber.     

中国城镇书法景观空间分异及其地方意义——以城镇商业街区为例

书法景观作为文化符号是中国传统文化景观的典型代表,是城镇文化景观的重要组成部分,其空间分布特征及其在全球化城市景观更新背景下的演化特征规律,是文化地理研究的重要问题。通过设计书法景观指数对北京、江苏、安徽、香港、四川等19个案例地典型地段的12种案例类型的书法景观调查统计,揭示了中国城镇书法景观存在多种明显的空间分异现象,即书法景观的空间分异存在于不同属性的城镇之间、城镇内部不同文化和功能属性的街区之间、以及同一街区的核心区与外围区之间。本文分析了影响中国城镇书法景观空间分异的基本因素-现代化和全球化、文化认同、城市更新、商业驱动,并构建了一个相应的机制模型。研究表明,中国人潜意识地将书法作为一种传统景观标志和传统文化象征符号,使得书法景观具备了空间地方界定和定义的功能,并促成了城镇中文化象征空间和地方感的形成以及书法景观的空间分异。书法景观研究对全球化和城市化过程中我国传统文化景观的保护具有一定的现实意义。     

Spatial Process of Green Infrastructure Changes Associated with Rapid Urbanization in Shenzhen,China

Through a case study of Shenzhen City,China,this study focused on a quantitative method for analyzing the spatial processes involved in green infrastructure changes associated with rapid urbanization.Based on RS,GIS and SPSS statistics software,the approach includes selection of the square analysis units and representative landscape metrics,quantification of the change types of landscape metrics in all analysis units through two indices and hierarchical cluster analysis of the above analysis units with different landscape metric change types(i.e.spatial attributes).The analyses verify that there is a significant sequence of continuous changes in green infrastructure in Shenzhen.They are the perforation,the segmentation,the fragmentation,the evanescence and the filling-in processes,which have a good spatio-temporal correspondence with urbanization and reflect the synthetic influence of urban planning,government policies and landforms.Compared with other studies on quantifying the spatial pattern,this study provides an alternative probe into linking the spatial pattern to spatial processes and the corresponding ecological processes in the future.These spatio-temporal processes offer many opportunities for identifying,protecting and restoring key elements in an urban green infrastructure network for areas in the early stages of urbanization or for non-urbanized areas.     

景观连通性理论在城市土地适宜性评价与优化方法中的应用

针对传统的土地适宜性分析方法忽略景观水平生态过程的问题,本文将景观连通性理论应用于土地适宜性评价方法的不同阶段,以达到优化城市生态系统的目标。首先选择影响生物水平流动的主要要素作为评价因子,应用于长沙市望城区滨江片区,确定案例区的土地适宜性评价结果,建构城市土地景观过程阻力评价体系。通过水文连通性分析方法及分布式水文模型确定案例区的潜在雨水生态廊道,将之与土地适宜性评价结果进行加权叠加,根据评估结果,提出案例城市土地适宜性评价的优化方案。结果表明:景观连通性方法适用于传统城市土地适宜性评价方法的改进以及评价结果的优化。     

“美国2050”空间战略规划及启示

“美国2050”空间战略规划是美国第一个综合性的全国国土空间战略规划,由联邦政府提议,旨在研究和构建美国未来40-50年空间发展的基本框架,以应对21世纪面临的各种挑战。在分析“美国2050”空间战略规划制订的背景的基础上,文章从基础设施规划、巨型都市区域规划、发展滞后地区规划、和大型景观保护规划四个方面系统介绍了“美国2050”空间战略规划的核心内容。归纳总结了“美国2050”空间战略规划的特点,探讨了“美国2050”空间战略规划在理念、方法、机制等方面对中国国土空间规划的启示。