Multi-objective Programming and Social Welfare Analysis of Rural-urban Land Conversion Decision-making

Rural-urban land conversion is an inevitable phenomenon in urbanization and industrialization. And the decision-making issue about this conversion is multi-objective because the social decision maker (the whole of central government and local authority) has to integrate the requirements of different interest groups (rural collective economic organizations, peasants, urban land users and the ones affected indirectly) and harmonize the sub-objects (economic, social and ecological outcomes) of this land allocation process. This paper established a multi-objective programming model for rural-urban land conversion decision-making and made some social welfare analysis correspondingly. Result shows that the general object of rural-urban land conversion decision-making is to reach the optimal level of social welfare in a certain state of resources allocation, while the preference of social decision makers and the value judgment of interest groups are two crucial factors which determine the realization of the rural-urban land conversion decision-making objects.     

农户宅基地流转意愿的影响因素分析——基于湖北二县市的农户调查研究

通过对湖北省二县市农户宅基地流转意愿的抽样调查,采用Logistic回归模型,分析农户宅基地流转意愿与区位条件、农户家庭属性特征及经济发展水平等的关系,找出影响农户宅基地流转意愿的主要因素。研究结果表明：目前愿意将自家宅基地进行流转的农户所占比例略高于50%。按作用程度排序,影响农户宅基地流转意愿的因素依次为非农收入占总收入的比重、距县城距离、对政策了解程度、户主年龄、户主学龄;其中,距县城距离和户主年龄的影响方向为负,其它因素的作用方向为正。从区域角度来看,经济较发达地区农户非农收入已占据主导地位,农户的流动性较强,愿意流转的农户所占比例高于社会经济欠发达地区的比例;影响农户宅基地流转意愿的因素及其作用程度也存在一定的区域差异。     

转型期中国耕地非农化与土地退化的实证分析

改革开放以来．伴随着国民经济的快速发展．中国的耕地非农化速度也在不断加快。并由此产生了大量的社会和环境问题。本文从人类土地利用行为变化的角度提出了分析耕地非农化对土地退化影响的基本思路：然后基于这一思路．并结合对全国层面统计数据的计量分析．深入探讨了转型期中国的耕地非农化对土地退化的影响：研究表明由耕地非农化所引致的耕地开垦、耕地集约利用以及非农建设用地扩张等人们土地利用行为的变化会最终引起土地资源的退化：包括水土流失和土地沙化的加剧、土壤质量的退化以及土地污染的加剧等。     

Mutual Conversion of Land Use between Urban and Rural Area in the Process of Urbanization: A Case Study of Shandong Province

Abstract

Urbanization is one of the driving forces for the land use change in type and structure, and its prominent effect is to convert rural land to urban land. This paper takes Shandong Province as an example to analyze the current situation of the mutual conversion between the urban and rural areas from the aspects of the structure of land use, the decreasing tendency of the cultivated land, the changes of land use in urban and rural residential areas. It points out that cultivated land is converted to residential area land, industrial and/or mining area land. The relationship between the urban area land and the cultivated land is more direct; meanwhile, the changes of rural residential area lag behind obviously. The decrease of the cultivated land and the decline of soil quality will be the two difficult problems in the process of urbanization.     

Welfare Balance of Different Interest Groups During Rural-urban Land Conversion

Rural-urban land conversion is currently a common social economic phenomenon during the process of economic development and rural urbanization in China. Rural-urban land conversion is positively effective as far as social and economic benefits are concerned （Yang, 2002）, but its negative effect is also evident, resulting in such problems as low efficiency of rural land configuration and loss of social welfare. Consequently, farmers should also have an equal chance to enjoy the social welfare enhanced by land conversion. Based on the theories of welfare economy, this paper puts forward policy suggestions by discussing the welfare changes of various interest groups, builds the model of welfare distribution, and analyzes the conditions of maximizing social welfare. The absolute and opposite value of social welfare is closely related with the speed of rural-urban land conversion, and governments should give farmers and collectives fair compensation to make up for the utility loss caused by land expropriation, which are conclusions drawn from this paper. This study aims to provide a theoretical basis for regulating targets and evaluation criteria, realizing the mechanism and implementation of public polices during rural-urban land conversion.     

Impact of urbanization trends on production of key staple crops

Urbanization has appropriated millions of hectares of cropland, and this trend will persist as cities continue to expand. We estimate the impact of this conversion as the amount of land needed elsewhere to give the same yield potential as determined by differences in climate and soil properties. Robust spatial upscaling techniques, well-validated crop simulation models, and soil, climate, and cropping system databases are employed with a focus on populous countries with high rates of land conversion. We find that converted cropland is 30–40% more productive than new cropland, which means that projection of food production potential must account for expected cropland loss to urbanization. Policies that protect existing farmland from urbanization would help relieve pressure on expansion of agriculture into natural ecosystems.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-021-01674-z.     

两相厌氧系统中产甲烷相有机酸转化规律

研究了两相厌氧系统产甲烷相中有机酸转化规律.以产酸相、产甲烷相COD负荷分别为41.5 kg/(m³·d)、6.05kg/(m³·d)的连续流试验装置培养种泥,运行稳定后,进行静态试验采用气相色谱仪(GC-122型)分析有机酸组成及含量结果表明,反应器相同位置的微生物降解转化有机酸速率快慢依次为:乙酸＞乙醇＞丁酸＞丙酸;利用乙醇产乙酸的微生物与产甲烷菌所需最佳pH值范围相近;乙醇型发酵是充分发挥两相厌氧系统功能的最佳发酵类型;在产甲烷反应器中,大部分挥发酸的最终降解都要经历乙酸降解途径才能完成,造成乙酸的降解转化相对缓慢,成为厌氧工艺中的限速步骤.     

SOIL-MOISTURE EFFECTS OF CONVERSION OF SAGEBRUSH COVER TO BUNCHGRASS COVER1

Precipitation, soil moisture, runoff, and vegetation were measured on two, 5- to 10-acre, big sagebrush (Artemisia tridentata) watersheds and two, equally small, beardless bluebunch wheatgrass (Agrophron inerme) watersheds that were converted from big sagebrush in 1967. The watersheds are located near Wolcott, Colorado, at an elevation of 7,200 feet, and are mantled with 2 to 3 feet of silty clay soils. Annual precipitation was about 13.5 inches; about 9 inches occurred as rain or snow from April through October and about 4.5 inches accumulated as a snowpack from November through March. Evapotranspiration was about 2 inches greater in 1968 and 1 inch greater in 1969 from the sagebrush watersheds than from the grass watersheds. With a mature stand of grass in 1970 and 1971 the differences in evapotranspiration were within the range of differences measured during the 3-year calibration period when all four watersheds were sagebrush. Water use was similar in the top 1 foot of soil but slightly more water was used by the grass in the 1- to 2-foot zone and more water being used by the sagebrush below 2 feet. Soil-water potential data indicated that only the big sagebrush used a small amount of water from the fractured shale at depths below 40 inches. Sagebrush used more water in August and September than the grass.     

资源型城市刚性产业结构的问题与对策--以大庆市为例

资源型城市在中国经济发展过程中起着重要作用,但近年来随着资源的过度开发,资源型城市的发展面临着一系列问题.以大庆市为例,通过对大庆问题的分析,得出影响大庆发展的根本性问题是刚性产业结构,阐述了其带来的诸如经济发展缓慢、失业、政府能力低下等严重影响.在大庆自身优势的基础上,围绕解决刚性结构提出了发展措施.     

Financial viability of reforesting reclaimed surface mined lands, the burden of site conversion costs, and carbon payments as reforestation incentives

US Federal law mandates that mined land be returned by mine operators to a condition capable of supporting its pre-mining use or a higher use. Previously forested lands have commonly been reclaimed to hayland/pasture or wildlife habitat, and most of these lands have been abandoned from management and rendered non-productive. This situation has left landowners in the position of converting these reclaimed mined lands to forests at a later date, if they choose to make them economically productive. Such land-use conversion, however, comes with a substantial up-front cost to the landowner, which makes the financial viability of such a conversion questionable. We examine the financial viability of reforestation of these previously reclaimed mine lands by calculating land expectation value (LEV) under a range of conditions that include forest type, site quality, and reforestation intensity. We find that conversion to white pine is viable on higher quality sites under low to moderate interest rates with low or high timber prices, but conversion to mixed hardwoods is only profitable under the high price scenario with low interest rates, and only on higher quality sites. We also consider the implications of a shift in reforestation burden from the landowner to the mine operator, and results suggest that including costs of reforestation as part of the mining operation creates a financially viable forest enterprise for landowners under all scenarios for both white pine and mixed hardwoods. Two forms of carbon payments that could encourage reforestation of previously reclaimed mined lands also are examined: an annual payment based upon the total accumulated carbon found on-site in a given year, and an annual payment based on only the increment of carbon storage each year. Our carbon payment results indicate that annual values of up to $5.17 per ton of carbon stored in hardwoods and $9.39 per ton of carbon stored in pines would be required to make reforestation profitable under the poorest conditions (high interest rates, low prices, and poor quality site) when the payment is based on accumulated on-site carbon, although lower values are required under more favorable scenarios. Payments that are based upon the annual increment of carbon must fall in the range of $8.66–$71.88 per ton of carbon stored in hardwoods and $0–$83.29 per ton of carbon stored in pines to make reforestation financially viable.