The use of urban organic wastes in the control of erosion in a semiarid Mediterranean soil

Abstract. A two year field experiment was carried out in a semiarid Mediterranean area in order to evaluate, the effect on soil erosion of adding different urban organic wastes: a stabilized municipal waste (compost), an unstabilized municipal waste, and an aerobic sewage sludge. All the treatments significantly reduced soil erosion, compared to the control soil. The soil amended with compost was the most effective treatment, reducing soil loss by 94% and runoff by 54%.     

An evaluation of the pesera soil erosion model and its application to a case study in Zakynthos, Greece

Abstract. The Pan‐European Soil Erosion Risk Assessment (pesera ) model was evaluated using existing soil erosion data collected under various types of climate, vegetation, landscape and soil conditions. The data used represent a variety of typical Mediterranean land uses such as winter wheat, vines, olives and bare, stony land prevailing in hilly areas. Using this data, the model was calibrated for sediment transport by overland flow and results compared to measured soil erosion values from runoff plots and a watershed on a monthly basis. The performance of the model was assessed statistically, showing that it can be satisfactorily used for predicting soil erosion rates under the conditions included in the study. The overall model estimate including all the available experimental data was 0.69 t ha^?1 yr^?1 with a maximum error of 1.49 t ha^?1 yr^?1. After validation, the model was applied to a small watershed (60 ha) of great ecological importance for the sea turtle Caretta caretta. For this purpose, soil and vegetation maps were compiled from all the necessary data for applying the model. The model was run for three years using daily data from an existing nearby meteorological station. The predicted and measured soil erosion rates for a 7‐month period were 0.31 t and 0.18 t, respectively. Application of the model to each mapping unit showed the over‐riding importance of land use for sediment generation under the given climatic conditions. Bare land, occupying 5.5% of the watershed area, generated up to 69% of the total sediments estimated for the watershed. It is concluded that the pesera model can be used as a regional diagnostic tool under a range of soil, topographic and climatic conditions for identifying the best land use type and vegetation cover to protect hilly areas from soil erosion. The calculated overall root mean square error for the model is 0.06 t ha^?1 yr^?1, compared to a soil erosion rate of 0.04 t ha^?1 yr^?1, which can be tolerated for protecting the area for the sea turtle.     

气象因子对棉花产量和品级影响的灰色关联分析

采用灰色关联分析法，研究了气候因子对棉花产量和纤维品级的影响。结果在明，气象因素的变化曲线与皮棉单产和纤维品级的变化曲线相似。气象因子与皮棉产量之间的灰色关联度平均为０．６４２２．与纤维品级之间的灰色关联度为０．５５５８．对湖南棉花皮棉单产和纤维品红影响最大的气候因子是降雨日和日照时数，影响最小的是日平均温度。     

Re-defining tillage erosion: quantifying intensity–direction relationships for complex terrain

Abstract. Current tillage erosion models account for the influence of tillage direction in the magnitude of the soil (tillage) transport coefficient. It is argued here that this is counter-intuitive and causes significant problems in modelling tillage erosion in areas of complex terrain. This article examines whether a re-modelling of tillage erosion is possible that separates tillage direction (an interaction with the landform) from the soil transport coefficient (a measure of tillage intensity representing the combination of implement erosivity and soil erodibility). Experimental data for mouldboard ploughing upslope, downslope and cross-slope at Coombe Barton Farm, Devon are examined. Integration of data for all directions into a single relationship, which relates translocation in the direction of tillage to slope in the direction of tillage and translocation perpendicular to tillage to slope perpendicular to tillage, is not possible using previously published methods of analysis. However, when total translocation distance is regressed against the tangent of the slope at 45° to the tillage direction (bisecting the tillage direction and the direction of overturning) it is found that a single relationship can be used to describe tillage in all three directions. Therefore, this relationship is used to determine a single value of the soil transport coefficient ( k _fTa) for constant soil and implement conditions but different tillage directions. This redefinition of tillage is important both for true estimation of tillage erosion severity, the adirectional coefficient being 40% larger than the directional coefficient, and for modelling of tillage erosion in complex terrain. These improvements are vital when tillage erosion simulation is used to direct soil conservation strategies.     

陆地棉核雄性不育材料在山东不同地区的育性转变及应用研究

对在山东的济南、平度、莱西、烟台种植的几种陆地棉（Ｇｏｓｓｙｐｉｕｍ　ｈｉｒｓｕｔｕｍＬ．）核雄性不育材料的育性表现进行了研究,结果表明：洞Ａ不育系的衍生材料ＭＢ、ＭＡ在不同气候条件下有育性的变化。在济南高度不育,可作为不育系。在其他几个地区表现不同程度的可育。其中ＭＢ在平度有相当好的育性,能正常结铃。而双隐性核不育材料５９Ａ、６２Ａ未能观察到育性变化。本文就核不育材料在棉花杂交制种中的应用前景及需深入研究的问题作了探讨。     

Wind-mediated spread of Rice yellow mottle virus (RYMV) in irrigated rice crops

A study was carried out to demonstrate that Rice yellow mottle virus (RYMV), a virus known to be transmitted by beetles, can spread between rice plants by direct leaf contact caused by wind. Almost all healthy plants surrounding an infected plant became infected when exposed to a fan blowing for 15 min at a distance of 50 cm. Spread of RYMV by plant contact, mediated by wind, was also demonstrated in field experiments, the extent of spread depending on plant density. Infection was almost 10 times higher in plots with a density of 33 plants m⁻² than in plots with 16 plants m⁻². Less spread was observed in plots protected by 1·5 m high windscreens. It is suggested that wind-mediated spread of RYMV may result from abrasive contact between leaves of plants.     

灌木林对地表风况及空气动力学参数影响的野外调查研究——以丰宁满族自治县小坝子乡为例

通过野外实地调查和定位观测,系统研究了灌木林盖度和高度对地表风况及空气动力学参数的影响。结果表明:风速轮廓线受灌木林覆盖度和高度的影响显著;风蚀率随灌木林覆盖度的减少呈指数增加,灌木林高度对土壤风蚀影响相对较小。空气动力学粗糙度及零风速平面位移高度均与灌木林覆盖度之间呈幂函数关系。灌木林高度对空气动力学粗糙度的影响不明显。     

山东五莲无花果栽培气候条件分析

为在山区五莲引进推广无花果栽培,本研究依托山东五莲本地历年汇编气象资料及近年气象数据,结合无花果的生物学特性,开展山东五莲无花果栽培气候适宜性分析,并对常见气象灾害及其防御进行探讨,分析五莲主要气候条件对无花果生长的影响。结果表明,对气象灾害采取适当的防范和补救,五莲气候条件基本满足无花果的生长发育。研究为进一步推广五莲县无花果的栽培,防御气象灾害,振兴农村经济提供借鉴和参考。     

Dispersal of woody plants in forest edges and hedgerows in a Southern Swedish agricultural area: the role of site and landscape structure

The distribution of woody vegetation was studied in forest edges and hedgerows in a 28 km² southern Swedish agricultural area, characterised by species-rich edge zones. The occurrence of 21 selected woody species (taxa) was related to differences in both edge structure and landscape structure. All the species studied were represented in both edge types, but a higher frequency of animal-dispersed species was found in hedgerows.Animal dispersed species were more affected by edge width and density than wind dispersed species. A higher number of wind-dispersed species were more frequent in forest edges, in hedgerows near to forest, or with a high proportion of forest within 500 m. A clear relationship was found between the number of physically connected elements in hedgerow networks and increasing frequency of occurrence for Corylus avellana, Crataegus spp., Euonymus europaeus, and Quercus robur; which indicate the ecological significance of connectedness for certain animal dispersed species. The study supports the general principle that woody species distribution and landscape structure are linked in a positive feedback loop. The results match findings from studies in other countries and are interpreted in the context of landscape processes and the ecological characteristics of woody plant species. We emphasise the importance of understanding dispersal mechanisms of woody species for the design and improvement of edge habitats in agricultural landscapes.     

Effects of wind turbines and other physical elements on field utilization by pink-footed geese (Anser brachyrhynchus): A landscape perspective

The effects of wind turbines and other physical landscape elements on field utilization by wintering pink-footed geese (Anser brachyrhynchus) were studied in a Danish farmland landscape. Within the study area geese were feeding on pastures, which together with cereals were the main crop types. Apart from wind turbines a variety of potentially disturbing landscape elements was present, e.g., high-power lines, windbreaks, roads and settlements. Patterns of field use were assessed by measuring goose dropping densities along transects perpendicular to wind farms (with turbines in clusters and in lines) and other landscape elements. Local effects were expressed in terms of `avoidance distance', i.e., the distance from a given landscape element to the point at which 50% of maximal dropping density was reached. The spatial distribution of landscape elements within an eight km radius from the goose roost was determined from aerial photographs. The area occupied by various elements, together with the adjacent zones which were not available to geese due to their associated avoidance distances, were quantified using Geographic Information System (GIS).The avoidance distance of wind farms with turbines in lines and in clusters were ca 100 m and ca 200 m, respectively. Geese did not enter the area between turbines within the cluster. At the landscape level, the combined effect of physical elements other than wind turbines caused an effective loss of 68% of the total field area (40 km²). Wind turbines caused an additional loss of 4% of the field area. However, of the remaining area available to geese (13 km²), wind turbines caused a loss of 13% of the total area. The habitat loss per turbine was higher for the wind farm with turbines arranged in a large cluster than for wind farms with turbines in small clusters or lines. This difference was mainly due to the fact that wind farms in small clusters or with a linear layout were generally placed close to roads or other elements with existing associated avoidance zones, whereas the large cluster was placed in the open farmland area. The avoidance zones associated with physical elements in the landscape do not take into account possible synergistic effects and, hence, actual field areas affected are likely to be minimum estimates. Implications of these findings for planning of wind farms in areas of conservation interest to geese are discussed.