食物消费结构升级对农业碳排放的动态影响机制研究

[目的]探寻主要食物消费结构与农业碳排放之间的动态关联机制。[方法]基于1990—2015年面板数据,通过VAR模型进行研究。[结果]结果显示食物消费结构升级与农业碳排放确实有着一定的关联性,且存在一定的滞后性,但其影响程度和方向因食物种类而异。[结论](1)从影响方向看,农业碳排放对肉禽类、奶类等动物性食物消费和粮食、蔬菜、食用植物油等植物性食物消费变动的冲击响应方向基本相反,这主要是由动物性食物和植物性食物的替代性导致;农业碳排放对食物消费变化冲击的响应方向呈正负交替变化,且随着时间的推移而趋于平缓,主要是由于农产品供求的收敛型"蛛网"变动特点引起。(2)从响应时间看,农业碳排放变动对植物性食物消费冲击响应更为迅速,主要是由于动物类食物调整生产周期明显长于植物类食物产品;以植物性食物消费代替动物性食物消费的方式在短期内(3～4年以内)确实可以一定程度上降低碳排放,但是长期看来效果并不明显;所有食物消费变动对农业碳排放的冲击效应在8～9期以后均逐渐消失,说明食物消费结构的变动对农业碳排放的影响持久,农业碳减排任务不可能在短期内一蹴而就,而需要长期而持续的努力。(3)从影响程度看,方差分解结果表明,对农业碳排放变动的影响贡献最大的是其自身,说明农业碳排放基数庞大,减排工作任务艰巨,尽管肉禽类食物消费导致的碳排放量比重较大,但研究期间农业碳排放变动的并不是主要由这类食物消费的变化导致,而是由植物性食物消费变化导致。研究结果为在满足居民食物消费需求的前提下降低农业碳排放、发展低碳农业提供一定的依据。     

The Sexual Economy,Gender Relations and Narratives of Infant Death on a Tomato Farm in Northern South Africa

Based on an extended case study of a large‐scale tomato farm in northern Limpopo province, the paper examines how the restructuring of agriculture transforms the sexual economy through shifts in the composition of labour and management practices on farms in this area. The employment of Zimbabwean migrants, rather than relatively permanent Venda families, suggests a potentially greater variety of people participating in the sexual economy. While families as units of employment have declined, black supervisors increasingly serve as a primary locus of coercion on the farm and in the sexual economy. The monetization of erstwhile paternalistic services places pressure on women to earn income however they can, including transactional sex. Contested interpretations over the causes of infant deaths on the farm, in the form of hygiene, blood‐mixing and infanticide, provide an ethnographic framework for a deeper analysis of the sexual economy and its social effects. While the sexual economy presents opportunities for women to increase their income, it also exposes them to the risks of HIV/AIDS and unwanted pregnancies, resulting in contradictory implications for the status of women on farms.     

新常态下生态农业的发展前景与对策———以河南省为例

农业是我国国民经济的基础,农业可持续发展直接关系到作为国家战略核心的粮食与食品安全问题。在经济社会发展步入新常态形势下,河南省作为我国农业大省在产业发展与结构调整方面坚持以增量带动结构优化、以创新促进产业升级,增量调整与存量优化并举。文章从新常态下生态农业问题入手,分析了人口压力、农业人口素质、劳动力转移风险及科技水平等方面所面临的挑战;并结合河南省当前农业发展的整体态势与发展生态农业的前景,指出在经济发展放缓与农业改革转型压力增强情况下河南省应通过发展生态农业来进一步加快农业现代化步伐,将发展生态农业作为农业工作的重要指标来全盘考虑;提出培育资源节约与环境友好型农业、培育高素质的职业农民、培育贯穿农业生产全过程的社会化服务体系、推进产业融合及发展特色农产品等建议。     

山西省新型农业经营体系构建问题研究

党的十八大报告明确提出,要坚持和完善农村基本经营制度,培育新型经营主体,发展多种形式的规模经营,构建新型农业经营体系,这为创新农业经营组织指明了方向。山西省作为农业大省,正处于加快现代农业发展的关键期,也要积极构建新型农业经营体系,明确战略定位和发展思路,走出一条具有山西特色的新型农业经营体系的路。实践证明山西省新型农业经营体系构建取得了一定的成绩,但发展过程中也暴露出了一些问题,即新型农业经营类型比例不均衡、土地流转制度不健全、生产效率不高等。究其原因,主要是几个因素的叠加影响,包括政策支持力度不到位、农业劳动者科学文化水平不高及农业经营的科技化水平不强等,因此山西省应从加强政策引导与资金投入、建立完善的农民技能培训及提高农业生产经营的科技化与机械化水平等方面积极入手,进一步促进新型农业经营体系的持续稳定发展。     

Evolving splines and seasonal unit roots in weekly agricultural prices

The univariate statistical properties of agricultural price series need to be examined as a first step in the analysis of price transmission mechanisms. However, in the case of weekly price series, increasingly available, the testing procedures usually applied in this step are not suitable to deal with evolving seasonal effects. In this study, a method of testing for seasonal unit roots in weekly series of agricultural prices is described. When the deterministic seasonal component does not remain constant over time, the restricted evolving spline model (RESM) is shown to be a useful parametric formulation to capture the deterministic seasonal pattern. Therefore, the RESM model should be included as a deterministic component in auxiliary regression for unit root tests at seasonal frequencies. This proposal is applied to three weekly series of Canary Islands banana prices. From the standard seasonal unit root tests, the null hypothesis is failed to be rejected at the 5% or 10% significance level at some seasonal frequencies for each one of the series. Once critical values are obtained by simulation exercises when the RESM model is included, the hypotheses of unit root are rejected at each one of the seasonal frequencies for all of the three series.     

白音查干矿井涌水量预计

矿井涌水量计算是矿床水文地质勘查中一项重要而复杂的工作,也是矿床水文地质勘查中的根本任务之一。运用大井法和廊道法对首采区、首采工作面和开切眼涌水量进行了预计,认为大井法计算的涌水量成果较为可靠,矿井最大涌水量为296.80m3/h,为今后的矿井安全生产提供了理论依据。     

Identifying terms of trade shocks in a developing country using a sign restrictions approach

Using annual data for Botswana from 1960 to 2012, we examine the responses of macroeconomic variables to four generalized positive terms of trade shocks – global demand, globalizing, sector-specific and global supply. A sign-restricted structural vector autoregression model with a penalty function is estimated to identify the four possible shocks. While positive global demand and globalization shocks are both expansionary, they have opposite effects on inflation. A positive commodity market specific shock dampens real GDP growth and is inflationary, suggesting a possible Dutch disease response. A negative global supply shock suppresses both output growth and inflation. All but the last shock leads to a significant declining interest rate. Monetary policy contraction is recommended for the first shock and expansion for the others.     

基于能量分析的农业生态可持续发展指数方法研究

[目的]农业可持续发展的研究首先面临的一个问题是如何对其进行有效评价,农业可持续发展评价一般采用多指标评价法,然而过多的指标给实际操作带来很多困难。文章从可持续发展评价理论创新和方法创新的需求出发,寻求建立一个简便易行的综合性指标——农业可持续发展指数(ASDI),以提高农业可持续发展评价的有效应和准确性。[方法]该文基于能量投入产出方法,利用Logistic曲线构建了ASDI,并以贵州省印江县为实证研究案例,对其农业生态的可持续性行进行评价分析。[结果]通过研究发现印江县的ASDI具有很大波动性,由于2002~2007年农业投入增加,印江县的ASDI呈现下降趋势,其中2007年因为投入过多而出现了负效应指数。[结论](1)利用一个简单的综合指标来评价农业可持续发展在理论和实践上是可行的;(2)ASDI作为农业可持续发展的研究,或将为生态安全预警提供了一个可供参考的指标。     

共生视角下村域生产空间重构路径设计——以重庆市合川区大柱村为例

研究目的:从多元农业经营主体这一本源入手,运用共生理论,构建"以人为本、互利互惠"的生产空间重构路径,旨为其开展重构提供一新思路。研究方法:参与式农户调查,共生理论量化方法。研究结果:2010-2015年大柱村形成三对稳定的农业经营共生体,其共生关系均处于非对称互惠共生阶段;共生界面是影响农业经营主体共生关系变化的关键因素,其中劳动力、农业基础设施、惠农政策是大柱村主要共生界面阻尼介质。研究结论:多元农业经营主体是生产空间重构的本源,共生界面是关键,共生效益是目标,构建"强化主体共生能力—夯实共生界面—保障共生利益"的生产空间重构路径,能确保村域内"资源共享、义务共担、环境共建"的实现。