崀山丹霞地貌区植物群系特性研究

采用线路与标淮地调查相结合的方法,研究了崀山丹霞地貌区森林植物群系特性。结果为:峎山有10个植被型、72个植物群系,其植被主要是中国、日本共同的属和众多的中国特有属树种为组成特征的森林植被,也有一定比例东亚—北美成分,在结构组成上表现出中亚热带常绿阔叶林的特点;丹霞单体出現特异的群系分布格局和"植被孤岛效应",不同发育期丹霞地貌上分布着不同演替系列上的森林植被类型;发現分布于丹霞赤壁下部的1个新的植被型(藤本植被型)和2个丹霞赤壁面上由崀山特有物种为建群种组成的持有植物群系(新宁毛莨群系,崀山唇柱苣苔群系)。     

Dating fluvial processes from historical data and artifacts

Geographers have long used historical data and artifacts to reconstruct past landscapes. Many of the same data can provide powerful tools for dating stream processes over the past century or so but applications can range from months to millennia. Historical techniques are important not only to mainstream geomorphological investigations but also to fluvial applications in environmental management. The approach is useful for human-induced fluvial changes as well as for those occurring naturally. This paper is intended as an introduction to several of the primary techniques.     

Nikolay I. Makkaveev and the development of Fluvial Geomorphology in Russia and the former Soviet Union

2008 marks the centenary of the birth of Professor Nikolay Ivanovich Makkaveev (1908–1983), a former Professor in the Faculty of Geography at Moscow State University and the founder of the Laboratory of Soil Erosion and Fluvial Processes in the Faculty of Geography.     

Linking form and function: towards an eco‐hydromorphic approach to sustainable river restoration

• 1. River restoration is now widely undertaken and may be considered an increasingly important aspect of river management. Recent developments in European legislation (Habitats Directive and the Water Framework Directive) should give further impetus to river restoration across EU member states, as this legislation places greater emphasis on the processes that support river ecology.
• 2. Traditional river restoration approaches have been reach‐focused and opportunistic, capitalizing on flood defence works and the cooperation of sympathetic landowners.
• 3. Furthermore, many schemes have been species‐ or habitat‐driven and, thus, have sought to recreate channel forms believed to be favoured by particular species or associated with particular habitats. Such approaches have not always given due attention to the underlying geomorphological processes that create channel form and, consequently, the schemes have not been self‐sustaining, requiring continued management input.
• 4. Consistent with the ethos of the Water Framework Directive, an eco‐hydromorphic approach to river restoration is proposed here. This approach views spatial and temporal heterogeneity as fundamental characteristics of fluvial systems and advocates recreating a framework within which natural processes, such as sediment transport and nutrient dynamics, can occur.
• 5. Mesoscale habitat approaches are considered as one possible way to plan and achieve this framework, providing the potential to link the wide range of spatial and temporal scales that characterize river systems.
• 6. It is argued that river restoration will only be sustainable if it is undertaken within a process‐driven and strategic framework with inputs from a wide range of specialists. Such an approach needs to be reviewed constantly in light of appraisal and monitoring of previous river restoration schemes.

Copyright © 2003 John Wiley & Sons, Ltd.     

Soil development and fertility characteristics of inland valleys in the rain forest zone of Nigeria: Physicochemical properties and morphological features

Abstract

Inland valleys are a widespread topography in West Africa and have significant potential for agricultural development, especially wet rice cultivation. This study investigated the physicochemical and morphological properties of the soils of two inland valleys in Abakaliki and Bende, Southeast Nigeria, where the soils are derived from shale materials, and discusses their agricultural potential as well as the soil-forming process. Particle size analysis suggested that the soils at both sites were fine-silty, fine-loamy or clayey and, thus, would be able to retain a high amount of water. In contrast, the higher content of clay and silt in the Abakaliki soils would enhance much more water retention than the Bende soils. The soils in Abakaliki, except for some subsoil horizons, generally had acidic reactions, low contents of exchangeable bases (Ca, Mg, K and Na) and high amounts of exchangeable acidity (Al and H) for which leaching effects under high precipitation in the area would be implicated. Bray-1 P values in these soils were generally low under such acidic conditions, while organic C and total N were recorded at relatively high levels, in particular at the surface horizons, reflecting large biomass production under a humid climate. The Bende soils showed similar chemical properties to Abakaliki except for relative accumulation of exchangeable bases throughout the profile on the downslope possibly because of the rolling topography. This result suggested that geological fertilization (i.e. afflux of nutrients released during the soil formation in the upland into the lowland) was more beneficial in Bende than Abakaliki. From the findings of the present study, we concluded that soils in both Abakaliki and Bende had good texture for sawah development (leveled and bounded rice field with an inlet and an outlet for irrigation and drainage), but their poor chemical properties would be constraints for agricultural production.     

Spatial variation in drainage characteristics and geomorphic instantaneous unit hydrograph (GIUH); implications for watershed management—A case study of the Varada River basin,Northern Karnataka

Geomorphological characteristics can be treated as signatures of hydrological responses. Geomorphologic instantaneous unit hydrograph (GIUH) is of utmost use in planning watershed management programs on a broad scale in absence of hydrologic data. Fifth order basins from different agroclimatic zones in the Varada River basin were selected to understand the spatial variation in drainage characteristics. These sub-basins show significant differences in their morphometric properties such as basin area, drainage density, bifurcation ratio, circularity ratio, constant of channel maintenance etc. These differences reflect variation in the hydrological process and geomorphologic instantaneous unit hydrograph (GIUH) of different sub-basins and can be used to understand watershed management aspects. Fifth order sub-basin in the Southern Transition agroclimatic zone is potential for artificial recharge programs. Sub-basins in the Hilly non-forest zone on the north are ideal for surface water storage like tank development program while Forested Hilly zone on the north are environmentally sensitive and prone to erosion.     

农业资源与环境专业地质与地貌学课程教学改革探索与实践简

为了解决农业资源与环境专业地质与地貌学课程“内容多、课时少、难度大”的矛盾,培养适应社会需求的应用型专门人才,从更新优化教学内容、改革教学方法、注重实践教学等几方面,对地质与地貌学课程教学改革进行了探讨。实践证明,取得了良好的教学效果。     

河流生态系统结构功能模型研究

回顾了河流生态系统结构功能模型的研究进展，介绍了多种重要的概念和模型。在此基础上，提出了河流生态系统结构功能整体模型，它是由河流流态－生态结构功能４维连续体模型、水文情势－河流生态过程耦合模型、地貌景观空间异质性－生物群落多样性耦合模型３个子模型组成。整体模型建立了河流流态、水文情势和地貌景观这３大类生境因子与河流生态系统结构功能和生态过程的相关关系，基本上抽象概括了河流生态系统的主要特征。在模型中除了考虑自然力因素以外，还考虑了水利水电工程设施的干扰作用。     

天山北坡河流的数学地貌特征及河流产沙分析初探

本文应用数学地貌方法对天山北坡五条河流建立了流域地貌数学模型。通过区域地质地貌及河流水文资料的分析,确立了它们之间的内在联系,并对人们关心的河流产沙问题进行分析。本方法对于干旱内陆区地形变化大,岩性复杂的天山地区是适用的。河流的产沙与河流流域地貌数学特征及发育阶段相对应,又与地层岩性、降水量、植被等有关。穿过有大面积中生界和第三系地层出露地区的河流,其含沙量高,侵蚀模数大。另外在新构造运动强烈地区的流域地貌数学特征值:河流比降,地形高程曲线积分值大,河流侵蚀搬运力强。     

Control of C,N,P distribution in soils of riparian forests

It is now well accepted that riparian forests have an important role in regulating upstream/downstream flow of matter and energy in river ecosystems. Since geomorphic processes determine the structure of channels and floodplains, we have investigated whether different geomorphic features of riparian forests had any effects on the ability of their soils to retain nutrients and organic carbon. Willow riparian forests were chosen within the annual floodplain of the Garonne River, southwest France, to represent two different geomorphic types. Erosional types of riparian forests (E-type) were characterized by sand deposition on their soils because of high current velocity which hampered fine particle deposition. Depositional types of riparian forests (D-type) were characterized by slower overflow velocity; consequently silt and clay were dominant in their soils. Soil samples were taken at the end of the vegetation growth period, coinciding with low water levels prior to annual floods. Erosion and sedimentation processes affected the distribution of total C,N, and P contents in riparian forest soils, since they were significantly correlated with soil grain size. D-type riparian forest soils act as a sink for upstream/downstream nutrients and carbon flows during floods through accumulation of total C,N and P from year to year. In contrast, E-type riparian forests act as potential nutrient sources during high water periods, since they may release from their soils large amounts of easily available C, N and P into the river. These results demonstrate that nutrients and carbon retention ability of riparian forests soils should be analyzed through their geomorphic features rather than by their vegetation composition. Even if they belong to the same vegetation succession, riparian forests should not be considered as a homogeneous buffering system for upstream/downstream flows of nutrients and organic carbon.