Gliricidia sepium Carbon Inputs and Soil Carbon Pools in a Costa Rican Alley Cropping System

Alternative land management practices, including agroforestry, help to maintain levels of soil organic matter (SOM) and can facilitate soil carbon (C) sequestration for mitigating atmospheric CO₂ emissions. This study quantified C inputs and determined the changes of the soil C pool in a 19-year-old Gliricidia sepium alley cropping system, studied at two fertiliser levels (tree prunings only [? N], and tree prunings plus chicken manure [+ N]), and was compared to a sole crop system. Carbon input from tree prunings ranged from 455 to 457 g C m^{? 2} y^{? 1}, whereas C inputs from crop residues were similar between alley- and sole crops ranging from 121 to 159 g C m^{? 2}y^{? 1}. The soil organic C (SOC) pool in the alley crop was 16–23% higher than the sole crop. In the 19th year of alley farming, SOC was significantly higher (p < 0.05) in the alley crop (3.2%) compared to the sole crop (2.4%), and was also greater compared to that at the time of establishment of the agroforestry system (2.8%). Gross SOC turnover to a 20-cm depth ranged from 12 to 14 years in the + N and ?N alley crops compared to 49 and 50 years in the + N and ?N treatments for the sole crops. Residue stabilisation efficiency in the alley crops was 39% and 55% in + N and ?N treatments respectively.     

对构建全国碳交易体系的几点思考

面对气候变化的机遇与挑战,中国政府已采取了一系列积极的政策和切实的行动,其中包括将于2017年启动全国性碳交易体系。研究首先对碳交易体系的国外研究作了简要概述,然后梳理了以欧盟碳交易体系为首的10个国外碳交易体系和中国7个省市的碳交易试点的实践。研究最后对全国碳交易体系的建立提出了几点思考,强调了数据的科学监测和林业碳汇在中国碳交易体系中的重要作用。     

Comparing the Profitability of a Greenhouse to a Vertical Farm in Quebec

Rapidly growing demand for year‐round fresh food, regardless of the weather or climate, is driving demand for controlled environment agriculture systems. Sales from greenhouses (GHs) are growing at 8.8%, while sales from vertical farms (VFs) are growing at 30%. It is commonly believed in industry circles that a VF cannot economically compete with a GH, due to the high cost of powering artificial lighting. Nonetheless, researchers have yet to analyze the economics underlying a VF, let alone compare the profitability of a VF to that of a GH. This research gap is particularly relevant to Canada, as it is uniquely positioned to be a leader in the VF market. Below, we report the results of a detailed simulation of the profitability of growing lettuce in a VF and in a GH located near Quebec City. Surprisingly, we find that the costs to both equip and run the two facilities are very similar, while the gross profit is slightly higher for the VF.     

土地供应规则的变化对北京市住宅用地市场的影响

研究目的:以2004年8月31日和2005年5月1日为界,将北京市住宅用地市场分为三个阶段,从土地供应量、地价、竞租曲线、土地—资本替代弹性等方面分析土地供应规则的变化对住宅用地招拍挂出让市场的影响。研究方法:定性分析,土地竞租曲线和土地—资本替代弹性分析。研究结论:(1)经营性项目用地招拍挂供应的政策对住宅用地市场的影响胜于“熟地”供应政策;(2)土地竞租曲线的变化反映土地市场在经过较大波动之后正在适应新的土地供应规则;(3)土地—资本替代弹性分析显示北京市住宅用地的市场效率仍然偏低。     

Computerized Delphi: An Application to Quota Value Determination in the Quebec Dairy Industry

In an effort to develop a substitute for the consensus panel, a Delphi experiment was conducted based on five simulated benchmark dairy farms in Quebec and communicated to an expert farmer panel by means of a microcomputer model. Farmers were asked to make decisions about quota purchase or sale at alternative quota prices given the detailed data base in the computer model. The results in terms of the convergence analysis, analysis of variance, estimation of fluid quota demand, supply and the equilibrium price are realistic. The method appears to be free from the danger of possible manipulation by individual panelists and hence a good way of generating unbiased information.
Pour essayer de développer un substitut pour le panneau à majorité simple, une expérience "Delphi" a été conduite à partir des données fournies par une simulation de cinq fermes laitierès typiques et communiquée à un panneau agricole au moyen d'un modéle micro-ordinateur. On a demandé aux fermiers de faire des décisions sur l'achat ou la vente d'un contingent à des prix alternatifs pour le contingent étant donnée la base detaillée des données contenue dans le modèle d'ordinateur. Les résultats quant à l'analyse par convergence, l'analyse des variations, l'évaluation de la demande des contingents de fluide, l'offre et l'équilibre des prix sont réalistes. La méthode semble être libre du danger de manipulation possible par un individu dans les panneaux et en conséquence est un bon moyen de produire de l'information objective.     

Boreal Forest Carbon Sequestration Strategies: A Case Study of the Little Red River Cree First Nation Land Tenures*

In this paper, creation of carbon offset and emission reduction credits are examined from the perspective of the Little Red River Cree Nation (LRRCN), a forest tenure holder in northern Alberta. Carbon credits are produced under three scenarios: (1) carbon uptake in forest ecosystems, with postharvest waste left on site; (2) carbon uptake in forests and products; and (3) carbon uptake in forests with harvested fiber used for energy production. A mathematical programming model is used to solve for the minimum prices that cause the LRRCN to include production of carbon credits in its forest management and post‐harvest processing strategies. If LRRCN is paid according to its costs of creating carbon credits, it will opt to use fiber for forest products as this provides the greatest earning potential. If LRRCN faces a fixed price for carbon credits, it will produce fiber for generating electricity in lieu of coal as this strategy has the lowest average cost. However, when costs of feedstock transportation and construction of a power plant are taken into account, carbon uptake in biomass and forest products turn out to be more competitive.     

Differentiation and Synergies in Rural Tourism: Estimation and Simulation of the Israeli Market

This article applies a discrete-choice equilibrium model with product differentiation to study the rural tourism industry in Israel and to jointly estimate the effect of lodging and farm characteristics on consumer preferences and firms' costs. The model accounts for heterogeneity in tastes and technologies and allows for unobservable product characteristics. We find evidence for technological synergy in the joint production of agricultural goods and rural tourism services, but none in the demand. The differentiation in the industry is the major contributor to the price-cost margin, which averages 62%. An additional minor cause is government regulations, which restrict supply. Simulation results demonstrate the growth potential of the industry and show that the government can play an important role in catalyzing growth via investment subsidization, deregulation of supply and information distribution.     

Using Limited Information to Support the Decision to Launch a New Product in the Fruit Juice Market: A Teaching Case Study

Fresh Juice Incorporated (FJI) is in the process of determining whether it should launch a new fruit juice, Genetically Enhanced (GE) Juice. The GE Juice meets consumers' demands for a tasty, nutritious product and it would be the first new juice product in the last fifteen years. Before FJI decides to launch GE Juice, it must analyze the uncertainty surrounding market size, market share, and price of GE Juice. Finally, if FJI decides to launch GE Juice, then they must decide if they will bottle the juice themselves or outsource this process. This case teaches students how to discuss the strategic implications of launching a new product and develop a net present value and financial feasibility simulation model given limited information.     

Choice of Rice Production Practices in Ghana: A Comparison of Willingness to Pay and Preference Space Estimates

Rice has been identified as an important food security crop in Ghana. However, there is a production deficit and new technologies to reduce the deficit are not widely adopted. Although poor adoption by farmers’ is often linked to constraints such as access to information, farmers’ perceptions of the technologies are also important. We apply an advanced discrete choice experiment to evaluate farmers’ preferences for rice production practices. Specifically, we generate willingness to pay (WTP) estimates using willingness to pay space (WS) and compare these with values from the indirect or preference space (PS) method. Our modelling also accounts for the effects on WTP estimates of farmers’ stated attribute importance (SAI) information. Empirical results from WS and PS models reveal that on average, farmers value higher yields and are negatively affected by higher risk of crop failure and labour requirements. Comparing the performance of the two models, we find the WS model provides a superior fit to our data and reduces the likelihood of producing implausible WTP estimates. Further, SAI inclusion did not produce much variation in our WTP estimates.     

The Influence of Commodity Programs on Acreage Response to Market Price: With an Illustration Concerning Rice Policy in the United States

Farm programs influence the parameters of typically estimated supply functions. We develop and apply an approach that uses detailed information about farm program incentives and constraints to identify underlying structural acreage response parameters when the data reflect behavior under complex government commodity programs. We illustrate the approach with data on rice acreage response to market price in the United States. For U.S. rice, estimates that fail to appropriately incorporate the program rules under which market data were generated are three to four times smaller than the structural parameters that are useful for most policy analysis or projections under alternative policies.     

市场整合过程中传统手工艺品的出路：一个贫困村的案例研究

中国在迈向市场经济的过程中，如何保护、发展并发扬光大传统的工艺品，是一个值得探讨的问题。本以中国西南彝族贫困村寨——九龙村手工艺品试点项目为个案，讨论了市场整合中贫困社区面临的挑战，并提出了市场经济条件下依靠 社区自身解决长期生存保障的办法。     

水价变化对灌区种植结构的影响--对辽宁丹东东港铁甲灌区的模拟分析

本文利用对辽宁丹东东港铁甲灌区的入户调查数据,运用线性规划方法模拟分析了水价变化对灌区种植结构的影响,并通过变换模型中的目标函数对模拟结果进行了扩展分析,最后将模拟结果与实际情况进行了对比分析。     

流域水资源分配市场经济宏观调控模型的探讨

本文以塔里木河流域为例,分析了流域各地区之间以及地区内部各用户群体之间在水资源分配上的博弈现状,利用对策理论建立了针对不同层面博弈问题的水资源分配模型,并进行了相应的比较和评价.在此基础上提出了通过宏观调控和市场经济等两种手段来对全流域的利益进行分配和调节,即基于水产权的初级分配和市场交易机制来促进水资源的有效配置,从而建立一个具有“激励相容”特征的实际管理运行机制,以实现水资源在全流域的优化配置,以及当地社会经济和生态环境的可持续发展.     

Empirically Testing the Law of One Price in an International Commodity Market: A Rational Expectations Application to the Natural Rubber Market

The Law of One Price (LOP) is an important ingredient in theories of international trade and exchange rate determination. An important shortcoming of the existing empirical literature is that parity is typically assumed to hold contemporaneously. This overlooks the fact that international commodity arbitrage takes place over time as well as across spatially separated markets. Recognizing this fact, we expect to see parity holding for expected prices. A model which incorporates the expectations of commodity arbitragers is constructed and used to test the LOP in the natural rubber market. Results indicate that the inclusion of expectations may be of value when considering the LOP.     

东北地区土壤活性有机碳对水热梯度变化的反映S152.4+2S153.6

基于样区20年气象资料统计结果和2006年土壤有机碳实测值,分析了东北样区内土壤活性有机碳各组分的空间分布格局及其与年均温(t)、降雨量(p)、有效积温和p/t(降雨量/年均温)之间的关系。结果表明:样区内土壤活性有机碳各组分沿纬度呈现出南低北高的分布趋势;活性有机碳各组分与土壤有机之间具有显著的正相关性;活性有机碳组分之间具有较强的相关性;活性有机碳各组分与气候因素之间存在良好的相关性。活性有机碳各组分与年均温之间的相关性大于活性有机碳各组分与降雨量之间的相关性。     

Estimating Market Power by Retailers in a Dynamic Framework: the Italian PDO Cheese Market

In this article, we evaluate the role of market power by retailers within the supply chain of Parmigiano Reggiano (PR) and Grana Padano (GP), the two most famous Italian quality cheeses. Market power is analysed in the context of a dynamic imperfect competition model of the supply chain, in which retailers are allowed to exert market power both downstream and upstream. We jointly estimate market‐power parameters together with supply and demand elasticities, by means of a structural system of demand, supply and price‐transmission equations, estimated using the generalised method of moments. We find evidence of downstream market power by retailers (toward final consumers) for PR and GP, but no evidence of upstream market power (toward processors/ripeners). These results may be explained by the structure of the supply chain and by the peculiar characteristics of the two cheeses.