关键词： Farmland   climate change   spillovers   spatial econometrics  

摘要： This paper estimates a Ricardian model of farmland value across the counties of the semiarid Southwestern United States. Compared to previous contributions, we focus on one climate zone and include the presence of extreme weather events and of farm subsidies in our analysis. We also control for heterogeneity and for various types of spillover effects. Once calibrated, the model is used to project changes due to future climate conditions. We find that the probability of a decrease is great in highland counties while an increase or decrease is equally probable in lowland counties where climate impacts farmland value less.

关键词： 气候变化   农业生产   人口分布   中原地区  

摘要： 农业的形成和发展是古代文明兴起的最重要的前提条件之一，世界上的文明古国无一不是建立在农业高度发展的基础之上，中国亦不例外。中国是粟作农业和稻作农业的重要起源地，两个农业体系相互交流与融合，共同推进了中国古代文明的诞生和演进。黄河流域的华夏文明是中国古代文明的核心，而其兴起和发展的摇篮则在中原地区，这与中原地区农业的起源和发展密不可分。因此，揭示中原地区古代农业的基本面貌和发展过程，对深入认识中华文明和社会发展的来龙去脉具有重要意义。目前，基于炭化植物遗存分析，中原地区古代农业发展的宏观图景已初步形成，但是早期阶段，即裴李岗-仰韶时期的农业结构特点、演变过程、不同类型遗址农作物种植的差异等问题尚不清楚。原因在于早期炭化植物遗存易溶蚀、难保存，以及区域系统植物考古研究的缺乏。在中原关键区域，如嵩山周边地区，选择不同类型遗址进行系统采样，利用多种植物考古方法提取植物遗存证据，是中原早期农业研究的重要途径。\n 目前在北方旱作农业的研究中，有关粟、黍比例的问题，存在同一遗址或区域，植硅体和炭化植物遗存分析结果相矛盾的现象，从而影响了对旱作农业结构的判断。粟、黍种子在炭化过程中保存下来的概率是否存在不同，进而导致植物考古统计分析出现误差，是解释上述矛盾的关键。利用炭化模拟实验复原粟、黍种子的炭化条件对解决这一问题具有重要意义。然而，目前的炭化模拟实验更多关注的是炭化过程中粟、黍颗粒形态、大小和结构特征的变化，粟、黍炭化的温度条件有无差别尚不清楚，还需要更多细致的工作和数据加以揭示。\n 农业的形成也是人类植物利用历史上的重大变革。旧石器时代晚期以来，人类植物生计从采集到农业生产的转变过程以及随后的农业发展情况，已在西亚地区得到了清晰的记录。近年来，随着植物考古数据的大量积累，为描绘中国古代农业形成过程中植物利用方式的演变进程提供了机会。收集已有植物考古数据，并进行定量化分析，是重建这一进程的主要方法。\n 农业的兴衰、环境的变化与人类文化变迁关系密切。目前，史前人类活动与气候变化关系的研究受到了极大关注，而随着考古碳十四概率密度方法的运用，国际学界已在重建史前人口规模及其与气候变化关系上取得许多进展。然而，这一方法很少用到中国的史前人口研究中，气候变化是否影响中国史前人口的发展也是不清楚的。建立集成性的中国考古碳十四数据库，利用概率密度方法对数据进行分析，并与气候曲线对比，是探讨人口变化及其与气候变化关系的重要方式。\n 本文在中原核心区—嵩山腹地的郑州地区选择位于不同地貌部位、不同规模的13处裴李岗-仰韶文化遗址进行系统采样，通过考古学文化和AMS14C测定确立年代框架，并以植硅体分析为主，结合炭化植物遗存分析，揭示了中原地区裴李岗-仰韶时期农业结构特点以及不同类型遗址农作物种植的差异，并且结合环境资料，探讨了气候变化与中原早期农业格局形成和发展之间的关系。通过设计不同的加热温度、时间和氧气条件，对现代粟和黍种子进行了炭化模拟实验，确定了粟和黍种子炭化的温度区间，探讨了炭化粟、黍形成条件的差异及原因。编汇了中国旧石器时代晚期到新石器时代中期的植物考古数据库，通过对数据的定量分析重建了史前植物利用的宏观发展进程。编录了我国考古遗址14C年代数据库，利用14C数据的总和概率密度分布，重建了区域至全国人口的长时间尺度变化，并探讨了人口变化与最近5万年气候变化的关联。得到以下几点结果与认识:\n 1、中原地区早期农业是在中国北方对禾草类尤其是黍族植物集约利用的宏观图景下发展起来的，而距今1万年前后对黍和粟两种小米的耕作和驯化奠定了中原地区早期农业的基础。\n 2、中原地区在裴李岗-仰韶文化时期(c.8000～5000a BP)均属于以黍为主的黍、粟、稻混作农业;相较于裴李岗时期，仰韶时期粟和稻的比例显著提高，标志着仰韶时期农作物多样化程度的加深以及农业种植结构的优化;裴李岗时期的农业生产属于采集经济之外辅助性的生产活动，到仰韶时期农业生产取代了野生植物采集成为主要的经济活动。\n 3、不同地貌单元和规模等级的遗址具有不同的农业格局:裴李岗时期，在平原地带和大型聚落为旱稻混耕，在台塬沟谷区和中小聚落为黍粟农业;仰韶时期，台塬沟谷区和中小聚落更侧重于黍的种植，平原地区和大型聚落中粟和稻的比例相对较高，但水稻耕作开始向中小聚落及沟谷地区扩散。这种差异可能与土壤、水分、耕作技术等因素有关。\n 4、中原地区裴李岗时期以黍为主的旱作农业，可能与北方早全新世相对较干的气候状况有关;距今8，000年前后，在全新世适宜期气候转暖变湿的背景下，稻作北传至中原旱作区，形成了最早的旱稻混耕模式，农业的扩展伴随着文化的融合。\n 5、根据目前的植硅体鉴定标准，中原地区裴李岗和仰韶时期发现的水稻植硅体均为驯化类型，

关键词： 农业生产   气候要素   变化特征   宝鸡市  

摘要： 为了研究陕西宝鸡市近50 a气候变化对农业生产的影响,选用宝鸡市11个气象站1961-2010年气温、降水量等气候要素资料统计分析,结果表明,宝鸡市年平均气温以0.238℃·10 a^(-1)气候倾向率上升,冬、春季平均气温上升趋势最快;年降水量以31.187 mm·10 a^(-1)的倾向率波动减少,春季和秋季降水量减少趋势最大。农业界限温度的初日明显提前,终日推迟,持续日数明显增多,积温显著增加,以日平均气温≥0℃和≥10℃的指标变化较明显。气候变暖使农业生产的不稳定性增加,产量波动加大。

关键词： 多哥   气候变化   农业经济   李嘉图模型  

摘要： 气候变化对农业的影响会极大地增加对粮食自给自足和减少贫穷目标的发展挑战。多哥，在其配置中，农业人口占总人口数的70％，产出占GDP总量的40％，但其农业严重依赖于天气条件。气候变化会使人口数目和经济状况更加脆弱。多哥农业部门的经济状况受气候变化的影响到何种程度。\n 本研究的目的是通过李嘉图模型来评估气候变化对多哥粮食农作物生产的影响和程度。借以可行的广义最小二乘方法(FGLS)和2000年到2011年期间的33个多哥自治州的面板数据，本研究使用辅助数据和变量，其中变量为生产、线性和二次气候变量（温度、降水）和生产领域。在Stata11分析后，研究表明，在多哥，气候条件的变化对农业生产有显著的影响。该模型首先建立了农业生产与气候变量（温度、降水）之间的关系。其次，分析了粮食农作物生产对这些气候变量的灵敏度。研究结果表明，降雨量增加1毫米将会导致粮食农作物产量增加122吨。然而，温度增加1℃将会导致产量减少30969吨（其他条件不变）。为了适应气候变化和增加粮食农作物的生产力，本研究提出了一些相关建议。

关键词： 气候变化   粮食安全   性别平等  

摘要： 气候环境变化使得不确定性因素在农业生产中频繁出现,为了达到农业生产目标,当前在发展中国家中流行采用基于参与国际贸易的方式来克服粮食短缺问题。文章研究目的是探讨农业生产者如何影响粮食安全,对往年文献中应对气候变化和粮食安全关系的研究提出不同意见,并引用农业推广项目方法来应对这些挑战。针对有关农业产量增长、粮食安全和气候变化影响因素的描述,文章还涉及与农业产量增长息息相关的贫困和性别平等问题。贫困地区的农业生产者只能通过必要机制才能享受到全球农业贸易给他们带来的收益所得,针对性别平等问题的农业推广项目可以帮助他们应对气候环境变化带来的挑战。

关键词： Climate change   Adaptation policy   Eastern Africa   Agricultural production  

摘要： We estimate the production function for agricultural output in Eastern Africa incorporating climate variables disaggregated into growing and non-growing seasons. We find a substantial negative effect of within growing season variance of precipitation. We simulate predicted climate change for the region and find a resulting output reduction of between 1.2% and 4.5%. Our simulation also demonstrates substantial potential for economic benefits from mitigating the effects of within growing season precipitation variability through conventional technologies such as flexible planting and rainwater harvesting on the same scale as the potential loss from predicted climate change. (C) 2015 Elsevier B.V. All rights reserved.

关键词： Water supply   Agriculture -- Arizona   Climate change   Management of groundwater -- Law & legislation   Rivers -- Arizona  

摘要： The article offers the author's insights on the state of agriculture, rural needs and climate change in Arizona. Topics discussed include the effort of the state's population toward sustainable water supplies, reliance to various sources of water such as the Salt and Verde River system, the Colorado River and groundwater reserves, and the Groundwater Management Act of 1980 (GMA).

关键词： agriculture   United States   fast-switching  

摘要： Agricultural conservation practices on managed lands provide many environmental and societal benefits, such as improved water quality, improved habitat for wildlife, and retention of water for attenuation of flood and drought risks, in addition to sustaining agricultural production. Here, Hyberg et al talk about the rapidly changing climate which can have profound consequences on agriculture and rural communities.

关键词： Climate change adaptation   Decision making   Hydro-economic modeling   Multi-criteria analysis   Social network mapping   Spain's agriculture  

摘要： Climate change is already affecting many natural systems and human environments worldwide, like the semiarid Guadiana Basin in Spain. This paper illustrates a systematic analysis of climate change adaptation in the Guadiana irrigation farming region. The study applies a solution-oriented diagnostic framework structured along a series of sequential analytical steps. An initial stage integrates economic and hydrologic modeling to evaluate the effects of climate change on the agriculture and water sectors. Next, adaptation measures are identified and prioritized through a stakeholder-based multi-criteria analysis. Finally, a social network analysis identifies key actors and their relationships in climate change adaptation. The study shows that under a severe climate change scenario, water availability could be substantially decreased and drought occurrence will augment. In consequence, farmers will adapt their crops to a lesser amount of water and income gains will diminish, particularly for smallholder farms. Among the various adaptation measures considered, those related to private farming (new crop varieties and modern irrigation technologies) are ranked highest, whereas public-funded hard measures (reservoirs) are lowest and public soft measures (insurance) are ranked middle. In addition, stakeholders highlighted that the most relevant criteria for selecting adaptation plans are environmental protection, financial feasibility and employment creation. Nonetheless, the social network analysis evidenced the need to strengthen the links among the different stakeholder groups to facilitate the implementation of adaptation processes. In sum, the diagnostic framework applied in this research can be considered a valuable tool for guiding and supporting decision making in climate change adaptation and communicating scientific results.

关键词： Autonomous and planned adaptation   Rural development plan   eParticipation   Multinomial probit model  

摘要： There is an increasing call for agricultural water management to adapt to climate change, yet efforts in this direction often consider only the policy dimension, or planned adaptation perspective. However, it is crucial to include an assessment of farmers' autonomous adaptation into the design and evaluation of rural policy measures. Amongst others, this helps avoid doubling efforts and ensure the effectiveness of the policies proposed. Moreover, farmers are the primary receivers of climate-proofing agricultural policies. Hence, to maximise a policy's success, it is fundamental to include farmers in its design phases. Farmers autonomously react to changes and policies should build on ongoing efforts. This work, carried out in the Veneto Region of Italy, proved the advantages of approaching adaptation as a continuum between autonomous and planned, rather than addressing the two separately. We first collected farmers' perceptions of and adaptations to change through an online questionnaire. We then identified the major determinants of their choice to adapt through a multinomial probit model. We analysed farmers' expectations of effectiveness of five different adaptation options for water conservation, via an ad-hoc online decision support system tool, mDSSweb. Our work provided policy makers with information on how different typologies of farmers are (not) adapting their practices to climate change. We clearly identified which groups of farmers the policies should target first and with what type of support. Both policy makers and farmers reacted positively to our approach and expressed interest in up-scaling it to become more inclusive.