How to characterize ‘good’ and ‘greening’ in the EU Common Agricultural Policy (CAP): the case of clay soils in the Netherlands

The change in the Common Agricultural Policy (CAP) of the European Union from product to producer support, including requirements for ‘good agricultural and environmental conditions’ and ‘greening’, is excellent. However, these requirements are now defined in rather general terms. Questions can be raised about suitable indicators, and there is a recognized need for effective management recommendations to support farmers in achieving the required ‘good’ conditions. These recommendations are bound to be quite different for different soils in different countries. A study of Dutch clay soils was based on a storyline describing current problems and management options for improvement, which were quantified using a soil–water–crop simulation model. Indicators were defined for agricultural conditions and suggestions made for the use of the model in a predictive mode to help farmers improve their soil management. Environmental conditions were judged by current environmental guidelines for water and air. When modelling, implicit assumptions that soils are homogeneous were shown to be unrealistic for these clay soils, requiring development of innovative methods and procedures, presenting a challenge for soil research.     

TOPMODEL在水阳江流域的应用及模型对DEM昀敏感性检验

将TOPMODEL模型应用到安徽水阳江流域，检验其在湿润地区的径流模拟能力，得到了较好的模拟结果。同时，利用安徽水阳江流域不同分辨率的DEM数据，进行了DEM分辨率对TOPMODEL模型的模拟结果的敏感性实验分析，结果袁明，随着流域DEM数据分辨率的降低，模型的确定性系数也随之降低，模型对流域的DEM数据是敏感的。     

地貌发育阶段判识方法研究——以泥河沟流域和枣子沟流域为例

为更加准确判识小流域地貌发育阶段,以黄土高原综合治理小流域——陕西省淳化县泥河沟流域和乾县枣子沟流域为例,分别应用盒分维方法和Horton分维方法进行水系分维值的计算,并利用面积高程积分和地貌信息熵进行验证。结果表明,泥河沟和枣子沟流域水系盒分维值分别为1.886和1.827。根据Strahler曲线积分值和地貌信息熵方法验证结果表明,盒分维方法计算的水系分维值对流域地貌发育阶段的判识更加准确、可靠;这2个流域地貌处于侵蚀发育阶段的壮龄期,其生态敏感性整体上处于较低水平,生态环境抗干扰能力增强并趋于更加稳定的状态。     

Effects of 17/0 circle hooks and bait on fish catches in a Southern Atlantic swordfish longline fishery

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Influence of regional-scale soil heterogeneity and land use on water discharge formation in the “Stettiner Haff” catchment in North-East Germany

Abstract

The influence of regional soil distribution and land use on discharge formation in the “Stettiner Haff” catchment (8,456 km²) was investigated. The model ABIMO was used to calculate mean discharge for a long period (1961 – 1990) in consideration of regional differences in hydrological site conditions and soil heterogeneity. The highest discharge was found on settlement areas (276 mm a^?1), on devastated plots (319 mm a^?1) and on the non-hydromorphic agriculturally used sandy soils (214 mm a^?1). Due to their small size these sub-areas were found to influence regional discharge for a limited extent only. On loam and clay soils only about 100 mm a^?1 of discharge was formed. However, this share proved to be most important for the height of regional discharge because of the high area proportion in the region. Mineral soils of comparable parent material produce lower discharge under hydromorphic conditions than under non-hydromorphic conditions. With increasing clay content of the soils these differences decreased. The agriculturally used areas were found to be most important for the region's water discharge. They accounted for 83% of the discharge, i.e. they originated 119 mm a^?1 on average. At forest sites, the discharge height was about 52 mm a^?1. Sites close to groundwater table (groundwater level <1 m) proved to act as depletive areas.     

植物根系对土壤水力参数影响的定量研究综述

植物根系是土壤结构以及土壤水力参数变化的重要影响要素。目前不仅缺乏定量描述“根-孔隙-土壤水力参数”相互作用的研究方法,在更大尺度上根系作用的客观表达也尚不明确,由此导致降雨入渗、径流和蒸发等流域水文过程的精细刻画与模拟预测具有很大的不确定性。基于文献检索,本文对国内外相关研究进行了回顾与梳理,量化了植物根系对土壤水力参数的改变和影响,并提出其与植被、土壤类型的响应方式,总结了植物根系动态性生长下的土壤水力参数定量表述及其预测模型进展。同时分析了在定量研究根-土复合系统中存在的问题及未来研究的发展方向,指出目前根系影响土壤水力参数的研究主要集中在小尺度控制实验方面,忽略了大尺度下土壤空间异质性及外部环境因素的干扰,强调大尺度根系作用和根系参数纳入土壤结构的重要性和实际意义,进一步与水文模型的深度耦合逐渐成为未来研究的热点。     

Sedimentary characterization of Tagus estuarine beaches (Portugal)

Background, Aim and Scope  The distribution of sediments in estuarine beaches is controlled by the interactions between sediment supply, hydrodynamic processes and human intervention. The main purpose of this study is to characterize the sediments of Tagus estuarine beaches in order to understand their origin and to contribute to a better knowledge of the Tagus estuary sediment budget. Methods  Surface sediment samples were collected across beach profiles and sand grain size analysis was performed by dry sieving. Grain size statistics for the median (d₅₀) and standard deviation (SDM) were obtained using the Moment method. This study was complemented by a qualitative evaluation of the sediment composition. Cross-shore topographic surveys were conducted for selected sampling sites. Results  Tagus estuarine beach sediments are mainly composed of quartz sand particles which are fine-grained and well sorted near the mouth of the estuary and medium to coarse-grained and moderately sorted in the inner domain. Compositional results show evidence of active anthropogenic sediment sources, especially in the coarser fractions. Discussion  The analysis of the textural and compositional characteristics of beach sediments in the inner estuarine domain is compatible with local sedimentary sources, while a marine signature is present at the mouth and inlet channel sediments. In the inner domain, differences in the sedimentary processes are represented by the textural characteristics of the sediments, such as the sorting degree and the gravel content. Sediment characteristics also reflect human intervention in the system, with the introduction of anthropogenic and allochthonous particles and the mixture of sediments from different sources. Conclusions  The sediments of the inner Tagus estuarine beaches are derived from local Plio-Pleistocene outcrops while inlet and outer estuary beaches reveal a dominant marine source. Beach textural variability observed in the inner domain is not related to wave forcing gradients, but mainly to variations in the sedimentary processes along the estuarine margins and to human intervention. Results show that the Tagus estuarine beaches depended, almost exclusively, on sediment input from local sources until the last century. With increasing human occupation, sediment transfers became dominated by anthropogenically related activities mainly connected with the occupation of estuarine margins and dredging. Recommendations and Perspectives  Further studies should extend the present level of knowledge in what concerns sand transport patterns through additional compositional and geochemical analysis, and the development of new techniques in order to allow the quantitative evaluation of the impact of human activities on the sediment budget.     

流域侵蚀产沙的尺度变异规律研究

 侵蚀产沙的尺度变异规律,是当今土壤侵蚀研究的前沿,它涉及的研究范围广泛,小到土壤颗粒,大到全球气候变化与碳循环过程。特别是不同尺度流域之间侵蚀产沙和输移,究竟有什么样的内在联系,小流域所获得的研究成果是否能推广应用到大中流域,已成为迫切需要解决的重要科学问题。有关流域侵蚀产沙与输移过程随流域尺度复杂变化的研究,国际上刚刚开始,国内有关流域尺度研究主要涉及于水文学领域的一些尺度研究,关于流域侵蚀产沙与输移过程随流域尺度复杂变化的研究不多。作者对国外当前土壤侵蚀模型的最新进展进行了综述,并对侵蚀产沙的尺度变异规律进行了分析。由于具有GIS强大的空间数据管理和分析能力,它将在流域侵蚀产沙尺度变异这一侵蚀产沙的问题研究中发挥重要作用。     

黄土高原土壤风蚀区玉米起垄覆盖集水效应

为了选择黄土高原土壤风蚀区玉米种植最佳集水技术,采用5种不同处理方法（秸秆覆盖、起垄覆膜膜侧种植、起垄无膜、无垄覆膜和常规耕作）对土壤蓄水量和玉米的生理特性进行分析。结果表明：不同处理间土壤蓄水量、叶片叶绿素含量、净光合速率（Pn）、蒸腾速率（Tr）、水分利用效率（WUE）以及产量性状等指标均存在差异,以起垄覆膜膜侧种植为最优种植模式,其耕作层土壤蓄水量在抽雄期（8月9日）比对照高72.3%;整个生育期叶片的叶绿素含量、净光合速率和蒸腾速率分别比对照平均高16.95%、9.77%和16.21%,籽粒产量比对照提高27.28%。表明各种起垄覆盖集水模式对黄土高原土壤风蚀区玉米种植均具有增产效果,其中起垄覆膜膜侧种植集水效应最好,增产效果最优,是该区大面积推广的最佳耕作模式。     

基于遥感和CASA模型的西江流域NPP时空分布特征研究

基于EOS/MODIS遥感资料,采用CASA模型分析西江流域陆地植被净第一性生产力（NPP）的时空变化特征。结果表明:西江流域平均植被NPP为400～500 gC/（m²·a）,上游地区偏低,为200～300 gC/（m²·a）,中下游地区较高,平均500～600 gC/（m²·a）,部分地区可达到800 gC/（m²·a）以上;植被NPP季节变化显著,夏季最高,春、秋季节次之,冬季最低小;西江流域植被NPP的空间差异明显,在5-10月,上游地区植被NPP较低,中下游地区较高;在1-3月,上游地区尤其是南盘江流域的植被NPP较高,中下游地区尤其是中游地区明显较少。西江流域植被NPP的空间特征还表现在汛期空间差异大,枯水期空间差别小。