安徽省茶叶家庭农场适度规模问题调研

基于茶叶家庭农场的科学定义,本文采用数据包络分析法（DEA）模型,对安徽省六安市100个茶叶家庭农场的经营效率展开分析,并在此基础上利用层次分析法（AHP）构建、评价茶叶家庭农场适度规模的体系,对茶叶家庭农场的规模化问题进行讨论。研究结果表明,100个茶叶家庭农场中有16个处于规模有效阶段,其中2~2.667βhm²规模的综合效益大于0~0.667βhm²及6.667βhm²以上规模的综合效益,因此现阶段安徽省主要产茶区发展茶叶家庭农场的适度规模为2~2.667βhm²。在此基础上,作者提出完善土地流转制度、培育新型茶叶家庭农场主、开展多种形式的培训、完善农业社会化服务体系、完善扶持政策等相关建议。     

Precipitation and soil particle size co-determine spatial distribution of biological soil crusts in the Gurbantunggut Desert,China

Biological soil crusts(BSCs) are bio-sedimentary associations that play crucial ecological roles in arid and semi-arid regions. In the Gurbantunggut Desert of China, more than 27% of the land surface is characterized by a predominant cover of lichen-dominated BSCs that contribute to the stability of the desert. However, little is known about the major factors that limit the spatial distribution of BSCs at a macro scale. In this study, the cover of BSCs was investigated along a precipitation gradient from the margins to the center of the Gurbantunggut Desert. Environmental variables including precipitation, soil particle size, soil p H, electrical conductivity, soil organic carbon, total salt, total nitrogen, total phosphorus and total potassium were analyzed at a macro scale to determine their association with differing assemblages of BSCs(cyanobacteria crusts, lichen crusts and moss crusts) using constrained linear ordination redundancy analysis(RDA). A model of BSCs distribution correlated with environmental variables that dominated the first two axes of the RDA was constructed to clearly demonstrate the succession stages of BSCs. The study determined that soil particle size(represented by coarse sand content) and precipitation are the most significant drivers influencing the spatial distribution of BSCs at a macro scale in the Gurbantunggut Desert. The cover of lichen and moss crusts increased with increasing precipitation, while the cover of cyanobacteria crusts decreased with increasing precipitation. The cover of lichen and moss crusts was negatively associated with coarse sand content, whereas the cover of cyanobacteria crusts was positively correlated with coarse sand content. These findings highlight the need for both the availability of soil moisture and a relatively stable of soil matrix, not only for the growth of BSCs but more importantly, for the regeneration and rehabilitation of disturbed BSC communities in arid and semi-arid lands. Thereby, this study will provide a theory basis to effectively increase soil stability in desert regions.     

面向对象分类技术在开发建设项目水土保持监测中的应用

[目的]研究基于无人机低空遥感影像的面向对象分类技术在开发建设项目水土保持监测中的应用,为水土保持监测工作的信息化能力提升提供技术支撑。[方法]利用旋翼无人机获取水土保持监测目标区域的低空遥感影像,通过倾斜摄影技术构建数字表面模型,结合ESP分割尺度评价工具获取最优分割尺度参数,采用多元特征空间指标参与最邻近分类法的监督分类,并依据位置信息的评价方法和误差矩阵对分类解译精度进行验证。[结果]本研究的水土保持监测目标区域的地物分类总体精度达到了86.10%,Kappa系数为0.841,有较好的一致性,能够满足精度需求。[结论]利用无人机低空遥感影像的面向对象分类技术实现了开发建设项目水土保持监测区域地物的快速、精确识别和分类。     

结合SOM与动态度方法的土地利用及其时空演变研究

[目的]验证结合自组织神经网络(self-organizing map neural network,SOM)与动态度的方法在时间序列土地利用地类与结构的交互分析中的适用性,从多尺度展开土地利用地类及其结构演变分析,为城市土地资源可持续开发和利用提供参考。[方法]基于湖北省黄石市2005,2010,2015年土地利用数据,运用土地利用动态度,分析市域层面地类变化和转移特征,构建SOM模型实现乡镇层面结构空间表达,综合二次聚类和动态度分析整体土地利用演变规律。[结果](1)建设用地著增加,贡献者为耕地、林地、未利用地;耕地持续减少,转换为建设用地和采矿用地与裸地;未利用地大量减少。(2)乡镇级土地利用结构变化趋势以耕地型向城镇/耕地型过渡为主。(3)中部、西部及南部乡镇土地利用变化和缓,东北部乡镇土地利用变化活跃,土地利用结构类型也发生了变化。[结论]SOM与土地利用动态度结合的方法适用于多尺度长时间序列土地利用时空演变综合分析。     

内蒙古农牧交错带普通农户与种植大户耕地集约度及影响因素研究——以乌兰察布市为例

为研究规模化经营耕地集约度的特征及影响因素,运用熵值法及计量估计模型,以马铃薯为例,分析内蒙古农牧交错带普通农户与种植大户的耕地集约度及影响因素。结果表明:种植大户在耕地的投入水平、产出水平都显著高于普通农户,但在耕地的可持续利用水平上显著低于普通农户,总体耕地集约利用水平是后者的4.84倍。影响种植大户耕地集约度的生计因素主要有户主年龄(负相关)及家庭贷款金额(正相关)。影响普通农户耕地集约利用程度的因素主要有家庭年收入(正相关)、家庭畜牧业收入(负相关)、家庭贷款金额(正相关)。     

修文县猕猴桃园蚧壳虫种类调查及药剂防治

为掌握贵州省修文县猕猴桃果园蚧壳虫种类及其发生规律,采用五点取样法对修文县猕猴桃园内蚧壳虫种类进行系统调查。结合调查结果,采用4种药剂对蚧壳虫进行室内毒力测定和田间防效试验。结果表明:危害修文猕猴桃果树的蚧壳虫有三种,草履蚧、犁圆蚧、桑盾蚧,其中桑盾蚧占95%以上,对修文猕猴桃危害最为严重。4种药剂中,22.4%螺虫乙酯SC对草履蚧、犁圆蚧的毒力最强,其LC_(50)分别为2.306 mg/L、4.239 mg/L,而31%噻嗪酮·杀扑磷EC对桑盾蚧防治效果最好,LC_(50)为2.602 mg/L;田间试验和室内毒力测定的结果基本相符,不同药剂药后14 d对不同蚧壳虫的防治效果均在89%以上;其余药剂对猕猴桃蚧壳虫也有较好防治效果,均可用来防治猕猴桃蚧壳虫。     

雇工劳动对农户粮食生产技术效率的影响研究——基于三省水稻种植户的调查

随着我国现代农业与规模农业的不断推进,农业经营主体对雇工劳动力的需求日益增大。针对雇工中存在的道德风险问题,从雇工劳动视角分析其对粮食生产效率的影响对于进一步梳理粮食规模化经营中存在的瓶颈制约问题具有重要的现实意义。基于黑龙江、浙江、四川3省的调研数据,采用不同前沿面的超越对数随机前沿生产函数,分析农户粮食生产技术效率及其损失的影响因素,重点考察雇工劳动对农户粮食生产技术效率的影响。结果表明:雇工生产在粮食生产中成为一种普遍现象,44.7%的样本农户进行雇工生产,规模经营户的雇工需求尤为突出。农户粮食生产的平均技术效率为85.11%,存在显著的技术效率损失,但技术效率的省际差异并不明显;农业雇工投入比例与粮食生产技术效率呈现"倒U型"效应趋势,雇工投入比例在25%~50%区间内,农户的粮食生产技术效率最高。控制变量方面,户主受教育年限、人均纯收入和地块面积对生产技术效率均有显著的正向影响,种地规模、地块距离家的距离、地块受灾和差的土壤质量均对粮食生产技术效率有显著的负向影响。基于此,提出普及农业机械化生产与开拓新型经营方式、建立有效劳动监督激励机制与"农业CEO"管理机制、重视农业劳动力的人力资本积累等建议。     

Do habitat measurements in the vicinity of Atlantic salmon (Salmo salar) parr matter?

Atlantic salmon, Salmo salar L., parr habitat characterisation is usually performed by in situ measures of key environmental variables taken at the exact fish location if the fishing gear allows precise pinpointing of this location, or in large sampling sections covering a river reach or mesohabitat, often ignoring variability in the immediate vicinity around individual fish. These data may be critically important in the development and validation of habitat preference models. The influences of seven increasing distances of measures, the variation of the number of considered measures and the depth of velocity measurement (bottom or 0.6 of the depth) in the calculations of HSI (Habitat Suitability Index) from a multiple‐experts fuzzy model of Atlantic salmon parr habitat were tested. When a parr was present, six measures collected in a 50‐cm radius around the fish to provide an average measure as input data and velocity measured at 60% of the depth gave the highest HSI values. These results show some potential for the use of an intermediate study scale, between micro‐ and mesohabitat, and questions how fish habitat conditions are currently measured.     

Towards the identification of ecological management units: A multidisciplinary approach for the effective management of bottlenose dolphins in the southern Iberian Peninsula

相似文献