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.     

A test for interaction between brown trout (Salmo trutta) and inanga (Galaxias maculatus) in an artificial stream

Abstract –  The interaction between brown trout ( Salmo trutta ; fork length (FL) range 255–390 mm) and inanga ( Galaxias maculatus ; FL range 55–115 mm) was tested during summer through autumn in an artificial stream consisting of a single run-riffle-pool sequence with a natural food supply. Each experimental trial lasted for 15 days, and consisted of two brown trout and 50 inanga collected fresh from a nearby stream, with each species given prior residence in four replicate tests, totalling eight trials in all. In addition, two control trials (each 10 days), with 50 inanga in each, were run. Brown trout almost exclusively occupied the pool, whereas inanga occupied all habitat types, although in different proportions, when tested with and without brown trout. The proportion of inanga in the pool was appreciably lower in the experimental trials with brown trout than in the control trials with no brown trout; prior residence had no significant effect on inanga habitat use. Mortality of inanga attributable to predation by brown trout ranged from 0 to 40% with a mean of 14.5 ± 4.7%. The results suggest that habitat use and survival of inanga populations in small streams can be adversely affected by brown trout.     

府谷县兽用抗菌药减量化实施经验总结

为深入贯彻落实习近平总书记关于食品药品安全“四个最严”要求,全面提升畜禽绿色健康养殖水平,府谷县以《全国兽用抗菌药使用减量化行动方案（2021—2025年）》为契机,与西北农林科技大学畜禽无抗养殖技术团队合作,签订“府谷县畜禽减抗替抗养殖技术示范推广”项目合作协议,在府谷县全面开展抗生素减量化示范推广,得到了府谷县委县政府和榆林市科技局的大力支持,从饲料端禁抗、养殖端减抗替抗和粪污端无抗三个方面遏制抗菌药的使用,经过2年的技术示范推广,取得了一定的经验和成果。     

调亏灌溉和氮处理对小桐子生长及水分利用的影响

为了研究阶段水分亏缺(亏水+不亏水W_LW_H、不亏水+亏水W_HW_L、亏水+亏水W_LW_L、不亏水+不亏水W_HW_H)和不同施氮量(N_Z:0,N_L:0.2 g/kg,N_H:0.4 g/kg)对小桐子生长、生理指标和灌溉水利用效率的影响,通过盆栽试验,发现W_LW_H的生长和灌溉水利用效率均显著高于W_HW_L;作物的灌溉水利用效率随施氮量的增大而呈现先增大后减小的趋势,在N_L水平下达到最大值;与高水高氮的处理N_HW_HW_H相比,中水低氮处理N_LW_LW_H节约灌溉水27%,节约氮肥使用量50%,小桐子株高减少31%、总干物质量减少35%,灌溉水利用效率减少13%,但茎粗增加13%,根冠比增加20%.可见小桐子在第一阶段处理(40~90 d)幼树期对水分的需求量较小,适度的亏缺灌溉可提高灌溉水利用效率;小桐子在第二阶段处理(90~140 d)处于旺长期,对水分的需求量较大,增大灌水量可大幅度促进小桐子生长及其干物质量的积累.全生育期实施亏缺灌溉,可提高小桐子自身适应外界环境能力,抗干旱胁迫能力也逐渐增强,但W_LW_L水平下的小桐子生长缓慢.经综合分析,认为处理N_LW_LW_H可作为干旱地区条件下的小桐子灌溉和施氮制度.     

寡糖及其在饲料生产中的应用

本文综述了寡糖的概念、种类、作用机理及其在畜牧生产中的应用。结合当前人们逐渐增强的绿色环保意识，提出了开发天然饲料添加剂。     

The multiple land degradation effects caused by land-use intensification in tropical steeplands: A catchment study from northern Thailand

The strongly incised mountain landscape of northern Thailand has changed dramatically during the last few decades due to increased population pressure, agricultural commercialization, limitation to use old fallows and reforestation of upper catchments. The traditional shifting cultivation with fallow periods of 7 years and longer was gradually replaced by 1 to 4 year fallow periods. As a result, in high population areas the landscape became dominated by fields planted to rainfed upland crops, wetland rice terraces, fallow vegetation, and patches of secondary forest. This new land-use system seems to have triggered new land degradation processes that are easy to observe when travelling through this landscape.     

校园土地利用结构和空间布局变化与优化建议——以湖南农业大学为例

以湖南农业大学为研究区,根据2005和2010年两期土地利用分类图,利用土地利用类型转移矩阵,结合GIS的空间分析方法,对土地利用结构和空间布局演变进行分析.结果表明,近一半的其他用地按面积比例从大到小依次转变为绿地、道路、娱乐、生活及教学用地.新增教学和娱乐用地分别集中在以修业广场为中心的400m和以老校门为圆心的300 m缓冲区内,新增生活用地呈现南北分化的趋势,新增道路虽较分散但与其余的用地类型毗邻度较高,水域基本不变,而新增绿地面积较大的一片集中在中西部,其余与生活用地的空间演变规律一致.总体来看,土地开发的重点在北部、中部及靠近浏阳河的沿线南端,呈正“S”形格局.未来的校园建设应遵循“科学、生态、人文”的理念,兼顾系统性、关联性和坚持弹性规划的原则对用地布局进行优化.     

控释氮肥和尿素配比对不同品种夏玉米氮素累积、转移及其利用效率的影响

在黄淮海夏玉米生产区,不同控释氮肥和尿素的配比下,研究不同氮效率玉米品种的产量及其花前花后干物质和氮素累积分配规律,以及相应的氮素利用效率与经济效益,为该区域夏玉米氮肥高效施用提供理论与技术依据.试验采用裂区设计,周期为两年,以施氮处理为主区,设置0、180、300 kg·hm-23个施氮水平,并在180 kg·hm-...     

Assessing the impacts of domesticated versus wild ungulates on terrestrial small mammal assemblages at Telperion Nature Reserve,South Africa

Grazing by large mammals alters vegetation physiognomy, consequently changing habitat suitability for small mammal communities. We investigated the response of terrestrial small mammals to grazing by wild and domesticated ungulates at the boundary of a protected area (Telperion Nature Reserve) and surrounding cattle ranches in Mpumalanga, South Africa over two seasons. Fifteen paired grids were set on either side of the boundary fence at which small mammals were trapped in Sherman live traps placed flat on the ground. A total of 11 760 trap nights resulted in the capture of 187 animals belonging to 14 species (11 rodents, two shrews and one elephant shrew). The small mammal communities in grasslands grazed by domesticated or wild ungulates were similar in abundance, species richness, diversity and demographic parameters, likely due to the fact that vegetation structure of the two grazing systems was also similar. We used generalised linear models to show that rock and grass cover were plausible predictors of small mammal abundance in this system. Rock cover showed a positive relationship with small mammal abundance whilst grass cover showed a negative relationship. Our observations suggest that at the scale of our study and with the current stocking densities, wild and domesticated ungulates have similar impacts on the small mammal community.     

西藏东南部原始森林夏-秋季节鸡类的栖息地利用

本文报道了1995年夏-秋季节西藏东南部原始森林鸡类栖息地的利用方式.记录有7个物种,这些物种大多喜欢在阳坡环境,而回避相对潮湿的阴坡环境.在这一鸡类群落中,白马鸡(Crossoptilon crossoptilon)与藏马鸡(C.harmani)的杂交类型在数量上是最丰富的,其次是血雉(Ithaginis cruentus)和斑尾榛鸡(Bonasa sewerzowi).随后于2001年的调查表明,由于地处偏僻,这些鸡类依然没有遭受人类狩猎和栖息地干扰的影响.