Opportunity Costs of Emissions Caused by Land-Use Changes

Amid the euphoria of Reducing Emissions from Deforestation and Forest Degradation (REDD) and REDD+ discussions, the expectations of large financial gains raise the interest of all. A country, however, will only enjoy REDD benefits if the cost of REDD is lower than the benefit. The opportunity cost analysis is an effective tool for assessing the feasibility of REDD+ since the largest portion of costs associated with REDD+ and can help to identify fair compensation for those who change their land use. The opportunity cost analysis has been exercised in Tanjung Jabung Barat (Tanjabar) district-Indonesia to examine the economic-feasibility of carbon emission reduction under different type carbon price scenarios. This study reveals a sharp decline of land-use systems with high carbon-stock and low profitability is obvious. On mineral soil, low carbon-stock and high profitability (mostly oil palm) has increased rapidly, especially in the period 2000-2009. It has become the dominant land-use system. The low-to-medium carbon stock and medium profitability land-use category increased from 1990 to 2005 but declined from 2005 to 2009. The low carbon-stock and low profitability category was constant and the proportion of the area was below 15%. The ex-ante analysis in predicting the potential for future emissions reduction in Tanjabar through REDD+ approaches shows that the cumulative emission of Tanjabar in 2020 is estimated at 61.91 Mg CO2-eq/Ha.Year, while the reduced emission by excluding all land use conversion below $5 threshold is estimated at 51.71 Mg CO2-eq/Ha.Year. This means that there is a potential for 16% emission reduction using $5/ton CO2-eq incentive. Another important finding in this study is that if the price of carbon increases by double to $10, the amount of reduced emission does not change much. This can use as a basis for determining the right amount of incentive for trade-off between economic profitability and climate change mitigation effort in Tanjabar using REDD+ scheme both at seller and buyer perspectives.

The ecological cost of land reclamation and its enlightenment to coast sustainable development in the northwestern Bohai Bay,China

Land has been widely reclaimed in large area in coastal zones all over the world to relieve the pressure of land shortage,promoting social development and economic growth.Asia has become a focus of land reclamation with the rapid industrialization and urbanization.From the Binhai New Area of Tianjin to the Caofeidian New Area of Tangshan,the undergoing project of land reclamation on the northwest coast of Bohai Bay,China,is the largest in the world.To clarify the environmental issues and benefit sustainable development of the coastal zone,we conducted both retrospective and predictive assessments of the ecological cost caused by land reclamation on the northwest coast of Bohai Bay,China.We calculated the ecological costs of ten aspects of the four ecosystem services,i.e.,supply,regulation,support and culture,with the monetary estimate approach.The results indicate that the ecological cost of the new land reclamation is US$971.9 million from 2000 to 2010 and that the cost will be US$702.1 million from 2010 to 2020.The costs of gas regulation and marine food supply account for the greatest parts of the total value.Suggestions for land reclamation oriented to sustainable development in the study area are put forward,including a rational planning based on the comprehensive evaluation,reducing the amount of land reclamation area,optimizing the structure of the reclaimed land,reclaiming land with the concept of ＂low impact development＂ and implementing ecological compensation mechanisms,etc.

Impacts of the Rising Opportunity Cost of Farm Labor on Agricultural Land Use Structure: Theory and Empirical Evidences

Nowadays the rising of opportunity cost of farm labor comes to the forefront of attention in China. In order to understand its impact on agricultural land-use structure, a theoretical framework of household economics is formulated drawn on Low's model. Under the theoretical framework, the impact of the rising opportunity cost of on-farm on cropping structure is deduced in theory. And then, using statistic and survey data, taking mountain area of southern Ningxia as an example, the theoretical assumes are verified. The results show that the rise of opportunity cost of farm labor leads to less diversified cropping structure.

Cost analysis of sand barriers in desertified regions based on the land grid division model

Sand barriers are the most widely used mechanical implements for wind-blown sand control and desertification prevention.However,there is no standard quantitative cost analysis of the sizes and materials required for sand barriers.In this study,based on the original land grid division model for optimal resource utilization,we calculated the total side lengths of square and regular hexagonal sand barriers with the sizes of 1.0 m×1.0 m,2.0 m×2.0 m,and 3.0 m×3.0 m in a desertified region of the Shapotou area on the southeastern edge of the Tengger Desert,China.Then,through literature review and social survey,we obtained the material cost and material utilization amount of sand barriers with different materials and sizes.Finally,we calculated the costs of square and regular hexagonal sand barriers comprised of wheat straw,corn stalk,Salix mongolica,poly lactic acid,magnesium cement,and high-density polyethylene,with the sizes of 1.0 m×1.0 m,2.0 m×2.0 m,and 3.0 m×3.0 m.The results show that the material cost of regular hexagonal corn stalk sand barriers with the size of 3.0 m×3.0 m is the lowest,while the material cost of square magnesium cement sand barriers with the size of 1.0 m×1.0 m is the highest.When using the same material,the cost of regular hexagonal sand barriers is lower than that of square sand barriers with the same size.When using the same size,the cost of sand barriers with corn stalk material is lower than that of sand barriers with other materials.Based on the above analysis,we can conclude that the economic benefits of regular hexagonal sand barriers are greater than those of square sand barriers.This study provides a theoretical basis for accurately calculating the material cost of sand barriers,particularly for the estimated cost of mechanized sand barrier engineering projects.

Cassava Groundnut Intercropping: A Sustainable Land Management Practice for Increasing Crop Productivity and Organic Carbon Stock on Smallholder Farms

Cassava-groundnut intercropping is not a common practice among smallholder farmers in Sierra Leone even though both crops are well suited for intercropping. On-farm trials were conducted in three locations (Bai Largor, Bassah, and Njala Kanima) in the Moyamba district during the 2021 cropping season to investigate the efficacy of cassava-groundnut intercropping for increasing crop productivity and soil organic carbon stock on smallholder farms in the Moyamba district, Southern Sierra Leone. The experimental design was a randomized complete block design in three replications with treatments of sole groundnut, sole cassava and cassava-groundnut intercropping. Data on the yield and yield components of cassava and groundnut were analysed using the PROC MIXED procedure of SAS 9.4 and means were compared using the standard error of difference (SED). The above-ground biomass, number of roots per plant, and fresh root yield of cassava were not significantly (p > 0.05) affected by the cassava-based cropping system. Averaged across locations, intercropping cassava with groundnut decreased the above-ground biomass, the number of roots per plant, and fresh root yield of cassava by 17%, 11%, and 17%, respectively. The above-ground biomass, number of pods per plant and fresh pod yield of groundnut were significantly (p 1), the highest net revenue and benefit-cost ratio. The benefit-cost ratio was also favourable for the sole cassava (BCR > 1) but not favourable for the sole groundnut (BCR < 1). Averaged across locations, intercropping cassava with groundnut increased the benefit-cost ratio by 121% and 13% when compared to the sole groundnut and sole cassava. In the event of a 40% yield loss for the cassava and groundnut, the benefit-cost ratio was favourable (1.12) only for the cassava groundnut intercropping system. The net soil organic carbon stock was favourable only for the cassava-groundnut intercrop. Averaged across locations, the net soil organic carbon for the cassava-groundnut intercropping increased by 3.4% when compared to the baseline within one cropping cycle of the cassava (12 months). The results confirm that cassava-groundnut intercropping is a sustainable land management practice that could enhance crop productivity and soil organic carbon stock on smallholder farms.

农地确权的政策效果“事与愿违”吗?——基于农户异质性的因果效应评估

农地确权的政策效果及其对农户生计决策与福祉的影响,已有的实证研究看法不一。已有研究的一般假设是政策干预与农户对政策的响应是随机的,而我国的农地确权试点区域与试点时间均具有非随机的政策选择性,因而农户的应对决策并非随机。因此,已有研究的随机性假设需要加以检视。使用非参数匹配因果推断,全面估计农地确权对农户六类资源配置决策和福祉的影响,并分别从政策设计与实施的供给侧角度和农户面对政策变化调整其决策的需求侧角度,揭示已有实证研究结果不一致的原因。研究发现,在农业生产资料投入、劳动力向非农部门转移和获得正式贷款方面,确权政策的“顶层设计”与农户决策相匹配,有助于农户据此进行专业化分工与生产,政策效果虽然边际递减,但没有出现不一致现象。在土地流转方面,政策供给侧的选择偏差使农户流转土地的谈判交易成本上升33.3%,时间交易成本上升1.45倍;政策需求侧的农户应对行为使流转土地的谈判交易成本上升3.1倍,时间交易成本上升27.8%。供给侧与需求侧的双向偏差,加上确权的赋权增量非常有限,使政策效果与政策预期不一致,但这并不意味着确权是可有可无的,而是说明人们对确权效果的预期存在一定偏误。

甜菜生产大幅波动的原因探究——基于199份农户调查问卷

2022/2023年榨季我国甜菜糖产量108万t,约占食糖产量的12%,比上年增长25%。甜菜作为我国重要的糖料作物,近几年种植面积和产量的大幅波动非常引人瞩目。为此,基于199份甜菜农户的调查问卷,探究甜菜种植面积和产量的影响因素就尤为重要,主要得出以下结论:(1)2022年受甜菜价格上涨提振,甜菜种植面积增加明显。其中,内蒙古受到轮作土地和成本限制,种植积极性不如新疆地区。2023年因缺乏轮作土地和成本上涨,甜菜扩种热情削减。从区域异质性来看,内蒙古受政策和轮作土地影响较大,新疆受成本和作物竞争影响较大。(2)甜菜收购价格是影响种植面积的最主要因素,其次是甜菜单产,甜菜成本变动对种植面积也产生较大影响。(3)影响甜菜成本的主要因素是地租和生产资料,生产资料成本主要受化肥和农药价格变动的影响。(4)竞争作物和粮食补贴对甜菜种植面积也带来明显影响。(5)甜菜单产主要受甜菜品种、化肥施用、轮作倒茬的影响。(6)从现存的问题来看,生产成本上涨过快最受关注,作物竞争和气候异常的影响也比较严峻。此外,甜菜户均生产规模明显提升,2022年户均甜菜规模41.67 hm2,较2018—2020年提升128.08%;机械化程度总体较高,仅育苗移栽机械化程度略低。规模经营提升和机械化程度较高使得甜菜农户种植行为更为理性,对甜菜比较收益的反应更为敏感。

基于粒子群的旧工业建筑再利用空间优化算法

为了解决土地资源紧张的问题,优化旧工业建筑空间,提高建筑利用空间紧密度,实现空间再利用,提出基于粒子群的旧工业建筑再利用空间优化算法。将土地利用适宜性最大化、用地紧凑度最大化和转化成本最小化作为优化目标,构建空间优化模型,建立旧工业建筑再利用空间优化目标函数,在相关条件的约束下采用粒子群算法求解上述目标函数,实现旧工业建筑再利用空间的优化。仿真结果表明,所提方法的地类转换成本低,总适宜度、生态协调性和社会效益高,空间紧凑度高,优化效率高。

非粮化土地流转对粮食生产土地成本的实证分析

粮食生产土地成本持续走高成为既定事实,且土地快速流转与土地成本上涨呈相同趋势。基于粮食品种层面的885个宏观数据,将土地流转分为粮食化土地流转和非粮化土地流转,实证分析非粮化土地流转对粮食生产土地成本(流转地租金和自营地折租)的影响。研究表明,非粮化土地流转显著负向影响粮食生产的土地成本、流转地租金和自营地折租,而粮食化土地流转则显著正向影响粮食生产的土地成本和流转地租金,对自营地折租的影响不显著。机制分析表明,非粮化土地流转分别提高了土地流转中采用股份合作方式的比重及土地流转中土地流入合作社的比重,从而降低了粮食生产的土地成本。因此,需适当调控两类土地流转的比重,土地流转的种植结构不能“一刀切”;同时,支持各地区通过组织创新推进股份合作方式的土地流转,并发挥好新型农业经营主体中合作社的作用。结论为有效降低粮食生产土地成本提供实证依据。

陆基圆桶养殖大口黑鲈经济效益分析

陆基圆桶循环水养殖是一种新型高效的水产养殖模式,本研究旨在通过分析陆基圆桶循环水养殖大口黑鲈的经济效益,为促进该养殖模式的进一步推广应用提供参考。本文调查了安徽省3个县区的陆基圆桶大口黑鲈养殖企业,并对其大口黑鲈养殖的投入、产量、产值和经济效益进行分析。结果表明,投饲成本是养殖成本的第一大投入要素;通过成本与收益比较分析,投放密度、苗种来源、固定资产投入和销售时间均是影响养殖经济效益的重要因素。生产上建议养殖企业开展养殖技术研发,调整养殖模式,充分发挥陆基圆桶养殖潜力,适当延长养殖周期,提高商品鱼规格,错开销售高峰期等方式,以获得更高的经济效益。

基于复合标志的四旋翼无人机自主降落系统

四旋翼无人机能否快速、精确地降落在地面充电装置或回收装置上是实现空地机器人协同的关键步骤之一。提出了一种基于视觉的四旋翼无人机在静止平台上自主降落的模型化框架,设计了基于AprilTag的复合标签着陆标志,将视觉测量与无人机自驾仪提供的状态信息利用卡尔曼滤波器进行融合,提高无人机位姿估计精度。利用PID控制器计算无人机的期望加速度,并将其转化为无人机的姿态指令,使得无人机飞行到期望位置。在专用模拟器下,对提出的无人机自主降落系统进行了多次仿真,仿真结果表明,无人机的平均降落误差小于5cm,验证了无人机自主降落系统的有效性和精确性。

国土空间规划背景下存量工业用地评价与转型升级策略

国土空间规划背景下存量用地挖潜成为县市级政府获取建设空间的重要来源。工业用地在增量时代扩张较为迅速、粗放,也为更新转型带来挑战。目前,存量工业用地存在评价体系单一、更新规划过程静态化、退出机制缺乏等问题,文章从发展动力和土地绩效双维度,构建存量工业用地评价体系;以动态更新式思维,提供分类型、分时序的引导策略,构建存量工业用地动态开发“一张图”;以新制度经济学为解题范式,提供存量更新的倒逼机制、激励机制和责任机制。

Nature-based Natural-hazard Preparedness:A Cross Section of Categorized Examples

Despite prevailing interests,no rigorous research has been conducted to examine the role of nature in natural-hazard preparedness.This systematic review aimed to describe how nature can reduce the impacts of natural hazards during the preparedness stage.The study focuses on the land,water,and air systems and on three types of stakeholders:international organizations,developed countries,and developing countries.Further,it provides supplementary strategies,such as immediate actions,local engagement,and research and development,that the stakeholders should apply to enhance their nature-based natural-hazard preparedness.We suggest integrating costs and benefits analysis,local culture,societal challenges,and environmental justice into the implementation of nature-based solutions.Finally,this review outlines the framework of nature-based natural-hazard preparedness by discussing the relationship between nature and society.

Study on the Landscaping Technologies for Coastal Saline-Alkali Land in Tanghai County of Tangshan City

Tanghai County is one of the counties in Tangshan City with the highest saline-alkali degree, with 80% of its land being covered by saline-alkali soils. Through studying landscaping technologies for coastal saline-alkali land in Tanghai County, 3 dominant modes for landscaping engineering in such land were summarized as shallow underground pipe desalination technology, banding soil replacement technology and hole membrane soil replacement technology, which are different in application scope and also in cost (respectively 260, 210 and 170 yuan). 3 landscaping measures were also proposed, including promotion of suitable plant cultivation technologies, application of saline-alkali tolerant plants and biological improvement of soils. To explore economic and practical planting patterns for saline-alkali land, low-cost landscaping tests were conducted from the perspectives of improving landscaping engineering mode and optimizing landscaping measures, and the results showed that it was practical to apply low-cost landscaping patterns, and comprehensive ecological measures should be adopted to realize the sustained utilization of soil.

基于最小成本路径和线密度法的常州市主城区通风廊道研究

通风廊道的构建有利于改善城市的通风环境。文章综合考虑城市形态和地表温度的影响,使用最小成本路径和线密度法,基于多种权重设置情景进行城市通风廊道的识别,并结合开敞空间分布特征分析识别结果的建设可行性,以期为常州市主城区风环境优化建设提供参考。结果表明:基于最小成本路径和线密度法,能够较好地识别城市通风廊道的位置。东北偏东风、东风和东南偏东风3种盛行风向下共识别得到18条通风廊道,主要依托现有河流、公园、道路、耕地林地等引导空气流动。现阶段廊道的建设可行性均值东北偏东风和东南偏东风略优于东风,空间分布呈现南部和中部高、北部低的特征。

上海新一轮城市更新中的风貌保护难点分析与对策探讨

以2017年国务院批准实施《上海市城市总体规划(2017—2035年)》为标志,上海进入以存量土地再开发为特征的城市更新时代。首先简要分析上海近年来开展的城市更新和风貌保护工作,是由政府组织、规划引领、功能性企业主导,由多方共同参与运作的创新实践。其次分析上海风貌保护中的土地开发成本、资本和开发逻辑、存量转型政策、房屋产权和开发使用、历史建筑保护法律等方面的难点。最后提出风貌保护的对策思路,包括降低建设用地基准地价,优化城市更新资本和开发逻辑,探索“先租后让”的土地供应方式和历史建筑所有权、使用权分离管理模式,适时修订地方法规等。

交易费用视角下村委会行为对农地流转和契约选择的影响

农地规模化流转是农村土地规模化经营的前提。基于交易费用理论通过案例分析和完全信息静态博弈方法研究了村委会行为对农地流转中交易费用、风险性、契约选择的影响。研究发现,当村委会配合参与农地流转时,有助于降低交易费用、增强书面契约的使用率和执行力,同时减少违约风险,稳定交易双方总收益的最大化,有利于实现农业适度规模化经营和规模效益;当村委会不作为或过度参与时,会因利用职权谋求自身利益,造成交易费用和失地风险增加,导致书面契约执行困难,阻碍农地规模化流转和农业规模化经营。

储备土地资产价值实现机制探索

自然资源资产管理体制背景下,建立健全储备土地资产价值实现机制,是完善储备土地资产管理体制的重要内容,也是贯彻“两统一”职责定位,落实自然资源产权制度改革的关键举措。储备土地资产价值是经济价值、社会价值和生态价值的统一体,研究通过分析储备土地资产价值体系构成和价值实现内涵,尝试从“价值发现—价值创造—价值评估—价值实现—价值保护”链条构建储备土地资产价值实现机制,为土地储备政策制定、土地储备规划和计划编制工作、土地储备业务管理工作提供思路和方法。

偏向性用地政策如何强化了“隐性担保”预期——来自城投债市场的证据

针对我国地方债务超常规增长的现象,本文捕捉到导致“隐性担保”的更外生的制度性因素。2003年以来,中央将大量建设用地指标向中西部省份倾斜,而逐步收缩东部地区土地供应。本文从理论上说明偏向性用地政策强化了东部地区的“救助能力”以及中西部地区的“救助预期”,从而干扰了债券市场的定价机制。基于2009—2020年省级面板数据,利用固定效应估计发现:东部地区土地供给偏向程度每减少1单位,城投债发行信用利差下降1.03单位;中西部地区土地供给偏向程度每增加1单位,城投债发行信用利差下降0.63单位。偏向性用地指标稳定性每增加1个单位,偏向性用地政策对区域间城投债融资成本的干扰程度提高约4~5倍。研究结论表明中央政府更应注重政策间的协调配合,更加符合人口规模的用地指标调整可能间接提高债券市场资源配置效率,将中国地方债的违约风险治理研究从传统的财政金融视角拓展到土地要素空间配置之间的相互作用,可能是防范和化解地方隐性债务风险的有效途径。

基于复杂用地条件的地下式污水处理厂精细化设计

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