基于生态足迹模型的湖北省农业资源开发评估

[目的]农业资源是人类生存发展的重要物质基础,对维持社会经济的可持续发展具有主导作用。评估湖北省农业资源的开发利用状况,为今后统筹资源利用和社会经济协调提供理论依据,以期提出可行性建议。[方法]采用生态足迹模型,计算了2009—2015年湖北省的人均生态足迹和人均生态容量及生态赤字,分析了该省各土地利用类型的人均生态足迹组分变化和各项农业生物资源和能源资源的开发状况,对资源开发总体形势展开了评价。[结果] 2009—2013年湖北省人均生态足迹逐年递增,2014和2015年明显降低,但人均生态足迹远高于人均生态容量。能源用地、建筑用地和草地构成了湖北省人均生态足迹的主体,且开发强度呈上升趋势。其中,玉米、小麦、稻谷、蔬菜以及各类畜产品和水产品,部分能源资源的开发强度增强。[结论]湖北省对农业资源的开发已超过生态系统的供给能力,严重威胁到生态系统的稳态,土地资源的承载力面临较大压力。全省需要从改变消费和生产方式,调整产业结构,优化土地利用类型,合理布局土地利用规划,发展高效农业资源利用模式等方面入手,提高农业资源的开发效率,降低人均生态足迹,维持生态容量。保证全省休闲农业与乡村生态旅游事业健康发展。     

新旧动能转换的理论探索与实践研判

新旧动能转换是实现创新驱动、推动经济由高速度增长向高质量发展的重大战略举措。从世界范围看，新旧动能转换不仅是世界经济演进的客观规律，也是新技术革命持续发展的必然要求。从国内发展看，新旧动能转换是中国迈向全球价值链中高端、进入经济发展新时代的根本出路。本文通过考察新旧动能转换的内涵和模式，进而从技术效率和技术进步二维视角分析新旧动能转换的动态演进。新旧动能转换包含要素、企业、产业和社会四个层面的着力点。新旧动能转换存在从政府主导走向政府引导、从经济领域走向社会领域、从重点示范走向全面推进、从要素驱动走向创新驱动、从渐进式革新走向颠覆性创新等多条发展路径。     

我国丘陵山区农机化水平影响因素及区划研究*——基于全国丘陵山区238个县（市）的调研数据

[目的]通过对全国丘陵山区县(市)与农机化有关的社会、经济和自然条件等因素进行调研所获取的238个有效样本进行分析,研究影响我国丘陵山区农机化水平的因素及其贡献,进而对我国丘陵山区进行区域划分。[方法]运用线性回归法对影响丘陵山区农机化水平的影响因素进行分析,进而对农机化水平产生显著影响的因素进行聚类分析。[结果]国内生产总值、农业劳动力数量对农机化水平产生极显著影响,耕地禀赋条件、务工工资、耕地规模、农机合作社数量和农机推广人员数量对农机化水平产生显著影响。对我国丘陵山区农机化水平呈正相关关系的因素有国内生产总值、务工工资、耕地规模、农机合作社数量,呈负相关的因素有耕地禀赋条件、农业劳动力数量、农机推广人员数量和农机化水平。[结论]我国可丘陵山区划分为中西、东南部地区,北部地区和东部沿海地区3大类地区。     

土地整治对中国粮食产出稳定性的贡献

研究目的:研究土地整治对粮食产出稳定性的贡献,为制定合理高效的土地整治政策,促进粮食增产稳产提供依据。研究方法:采用H-P滤波法实证分析中国粮食产量的波动性及增长趋势,然后基于C-D生产函数,分别建立趋势产量和波动强度面板回归模型,分析土地整治对粮食产出稳定性的影响。研究结果:(1)粮食作物播种面积、农业机械总动力、农用化肥施用量均对粮食长期趋势产生不同程度促进作用;农业劳动力对主产区粮食长期趋势影响显著为负,对非主产区却有正向影响。(2)土地整治面积和单位面积投资额均降低了全国及主产区粮食产量的波动程度,土地整治规模在全国和主产区的影响系数分别为-1.4162和-2.2215;单位土地整治面积投资额在全国和主产区的影响系数分别为-0.7589和-1.3509。(3)土地整治新增耕地面积对全国和主产区的粮食产量波动强度影响为正,影响系数分别为0.8018和1.3931。可能是通过土地整治新增的耕地质量较低,产出不高,导致了粮食产量波动。土地整治投入在非主产区均表现为不显著。研究结论:应继续推进尤其是主产区的土地整治项目实施,加大土地整治投资强度,建立长期稳定的投入机制,合理使用整治资金,注重提高新增耕地质量和综合生产能力,同时将土地整治投入和管理机制与农业生产系统运行机制、自然因素等有效结合,并制定差别化区域政策,以保障粮食增产稳产和区域协调发展。     

How government-led land consolidation efforts achieve grain production stability? An empirical analysis in Hubei Province,China

China has been conducting massive land consolidation (LC) projects since the late 1990s to ensure national food security which has been one of the common issues in the world. How the implementation of LC projects affects grain production stability is a question should be answered. Basing on an empirical analysis at the county level in Hubei Province, China, this paper separates the trend component and the fluctuation component from a time series of grain production over 1991-2016 using the H-P filtering method. Then we estimate the impacts of LC projects and climate change on the trend and fluctuation rate of grain production for the entire Hubei Province. Moreover, the effects on the production of different major crops for the central, eastern, southwestern, northwestern and northern areas are also examined, respectively. The results show that: (1) the production trends for five subareas and the whole area all have followed a trajectory of “increase-decrease-increase” from 1991 to 2016. The magnitude of fluctuation rate was large but became smaller in recent years. (2) The contribution of LC to the long-term trends of grain production for the entire samples in Hubei Province mainly benefits from the growth in the cultivated land area through LC; more LC investment and newly-added arable land area promote the sudden increase in grain production above the long-term trends, while the impacts of LC area are negative. (3) The impacts of LC on the major crop production vary across areas. LC exerts significant impacts on the production of major crops in the central and eastern Hubei, and this effect persists to the following year. Similarly, this influence also exists in the southwestern and northern area, while becomes insignificant in the following year. No significant effect of LC variables is found in the northwestern area. These findings may provide reference for the government to address LC inefficiency and food security problems, and an effective and innovative mechanism combining the agricultural production, land consolidation and meteorological factors needs to be established to ensure food security and long-term and stable agricultural production. In addition, the regional difference in natural conditions and LC orientations should also be considered.     

Economic impacts of smallholder farmers’ adoption of drought-tolerant maize varieties

Drought and high temperatures are major threats to sustainable food production and consequently the livelihoods of the majority of Africans who depend on fragile agricultural systems. As a response to these threats, climate-smart agricultural technologies, such as drought-tolerant maize (DTM) varieties, have been developed and promoted on the continent. It is well-known that the adoption of improved technologies generally impacts positively on the wellbeing of adopters. Nevertheless, the magnitude of the impact of any technology or intervention is always an empirical question. Therefore, this study sought to determine the factors that influence the adoption of DTM and subsequently estimate how yield, commercialization intensity, and farm income are affected by adoption. To establish causation, we relied on observations from 200 farm households in the Northern Region of Ghana and estimated an instrumental variable regression. Consistent with findings reported in the literature, we found that DTM adoption is primarily driven by access to seed, extension service, labor availability, and location of farm households. In addition, we found that DTM adoption positively impacts on yield and commercialization intensity. The magnitude of impact is not trivial. For example, the yield of farm households increased by more than 150% (936 kg/ha) following DTM adoption. These results imply that policy-makers and development practitioners must support research and promotion of climate-smart agriculture to improve adoption and welfare indicators, such as yield and commercialization.     

江苏茶叶生产成本、规模及问题分析

对茶叶生产问题的研究有利于茶叶产业的发展与转型升级,通过运用2008—2017年间茶叶生产相关统计数据,论文以生产成本和生产规模为切入点,详细阐明江苏苏南和苏北地区的茶叶生产成本和规模的差异,深入剖析江苏茶叶生产中所出现的宏观问题,并据此提出对策与建议:加大扶持力度、培育龙头企业、提升茶农专业知识水平和开发茶文化旅游,以此助推乡村振兴政策的进一步实施和茶产业发展再上新台阶。     

苏北地区农业完全成本水价农户承受力调查——基于水源地生态补偿的视角

南水北调东线一期工程江苏段的主要目标是向苏北供水,缓解该地区的农业用水短缺问题。但现行农业水价未考虑水源区的机会成本损失,不利于调动水源区环境保护积极性。论文设计单边界CVM引导技术,估算了苏北农户以提高农业水价的方式对水源区生态补偿的支付意愿。研究发现,苏北农户生态补偿支付意愿为7.63元/亩,但在不同作物种植结构和不同城市存在较大异质性。未来3年内,苏北农业用水每年所提供的生态补偿资金总额在1.526~1.679亿元之间。在发达地区探索构建绿色导向的农业水价体系有利于为其他地区提供先行示范效应。     

Inference for large financial systems

We treat the parameter estimation problem for mean‐field models of large interacting financial systems such as the banking system and a pool of assets held by an institution or backing a security. We develop an asymptotic inference approach that addresses the scale and complexity of such systems. Harnessing the weak convergence results developed for mean‐field financial systems in the literature, we construct an approximate likelihood for large systems. The approximate likelihood has a conditionally Gaussian structure, enabling us to design an efficient numerical method for its evaluation. We provide a representation of the corresponding approximate estimator in terms of a weighted least‐squares estimator, and use it to analyze the large‐system and large‐sample behavior of the estimator. Numerical results for a mean‐field model of systemic financial risk highlight the efficiency and accuracy of our estimator.     

审计质量、产权性质对上市公司投资效率的影响研究

审计质量作为第三方会计师事务所为公司提供的服务,可以独立于公司之外对上市公司投资活动进行监督。根据产权理论,产权性质不同的经济组织从事的经济活动不同,审计质量对不同产权性质的上市公司投资效率的影响也不相同。本文以2014—2018年沪深两市上市公司作为样本,实证检验了审计质量、产权性质与公司投资效率间的关系。研究发现,审计质量与上市公司投资过度显著负相关,与投资不足负相关但作用并不明显;在国有上市公司中审计质量对投资过度行为的抑制作用更明显,在非国有上市公司中审计质量可以在一定程度上防止投资不足行为的发生但作用并不显著。研究结论有利于启示各不同产权性质公司的利益相关方,客观认识审计师的作用功能及其局限性,有针对性、有效率地利用好审计服务,改善公司投资效率。