2000—2018年西辽河流域植被覆盖度时空变化特征及影响因素研究

目的 研究“退耕还林”“退牧还草”及“镰刀弯”等生态政策实施以来西辽河流域植被覆盖时空变化趋势及驱动因素,探究各类驱动因子对区域植被覆盖的影响,为区域生态建设和环境保护提供参考。方法 文章采用像元二分模型,估算西辽河流域植被覆盖度,归纳了植被覆盖变化的驱动因素,利用一元线性回归和Pearson相关系数等方法,定性定量分析2000—2018年西辽河流域植被覆盖时空变化趋势及其与气候、地形、农村居民点分布和土地利用变化等驱动因子的响应关系。结果 19年来,西辽河流域植被覆盖度呈波动增加趋势。分区看,农区植被覆盖度最高,其次是半农半牧区,牧区植被覆盖度最低。全区植被覆盖空间变化趋势较为稳定,96.63%面积植被覆盖无明显变化,2.07%面积植被覆盖极显著改善,1.30%面积植被覆盖显著改善,基本无退化区域。结论 （1）植被覆盖度与降水、气温因子正向相关,降水对植被覆盖度的影响高于气温。（2）高程、坡度和农村居民点密度均与植被覆盖度正向相关,其中农区人类农业种植活动正向促进作用要大于生产建设活动的负向抑制作用。（3）林地和作物种植面积长势的增加促进了全区植被覆盖的改善。“退耕还林”和“镰刀弯”生态实施促进了全区植被覆盖的改善,但“退牧还草”生态工程效益有待提高。应注重区域植被覆盖变化监测与预警,充分发挥生态政策的积极导向作用,优化生态工程实施结构,提高生态脆弱区抵御风险能力。     

Public preferences for controlling an invasive species in public and private spaces

Discrete choice experiments have been used in this case study to assess community benefits for the control of red imported fire ants, an aggressive ant species that were introduced by accident in 2001 to Brisbane, Australia. This invasive species could have substantial impacts on agricultural production, biodiversity, ecosystem services, infrastructure and communities. Values for avoiding impacts on three particular land uses have been assessed in this study with discrete choice experiments. The results indicated that on a per hectare basis, the value estimates to avoid infestation in public areas (schools and parks), were much higher than for private areas (housing) or natural bushland areas (protected native vegetation). There were high levels of support for eradication rather than containment strategies, despite the additional costs involved. The use of both random parameters logit and latent class models demonstrates that there is a significant heterogeneity in preferences and values for controlling or eradicating the invasive species, indicating that it may be challenging to gain and maintain political support for management options, particularly if these involve large costs or inconvenience to households.     

Editorial - Decision rules, government rules, and the costs of vegetation protection in New South Wales

Governments regularly spend public funds to purchase environmental amenities. They might purchase land to add to the public estate, pay to fence stock out of endangered native forest, or offer stewardship payments as incentives to conservation. Governments also regularly introduce policies to achieve environmental goals, even though these policies impose costs on firms, households or farms. The basic decision rule, to maximise environmental benefits from a given budget, in all these cases is received wisdom within the economics profession. In the case of purchase of land to add to the public estate:Maximise environmental benefits by purchasing land in descending order of the ratio of benefit to cost until the budget is exhausted.More generally, funds should be allocated to individual activities within a programme in order of the decreasing ratio of benefits to costs until the budget is exhausted. This rule can be applied when benefits can be measured in any monetary or non-monetary quantitative index. In the case of conservation of vegetation, it can be applied relatively simply in the field when vegetation types and land values can be mapped jointly through GIS techniques.This simple decision rule is not always followed by government agencies that manage environmental programmes. Consider the protection of native vegetation, which is defined to include native forest, native woodland and native grassland. To meet international obligations to protect this kind of environment, most countries must involve private landholders in conservation because there are insufficient government reserves to meet the international commitments. Indeed, most countries have already introduced many policies to encourage private landholders to protect native vegetation on their forests and farms.The New South Wales state government, in Australia, has introduced the Native Vegetation Conservation Act (1998) to ensure that private landholders protect vegetation. The Act constrains farmers to retain all the native forest, native woodland, and native grassland, on their land irrespective of the costs to them. Farmers can then apply for consent to clear and crop this land, but consent is rarely granted in full and often not at all. The Act is consistent with a decision rule of “maximise-benefits-only” - protect all vegetation irrespective of the costs to those who have to conserve it.Constraints of this kind will inevitably lead to a loss of income and land value when they restrict the farm enterprises, and so will impose opportunity costs on the farmer. There is already ample published evidence on the sizes of these costs - from publications of the relevant state agency itself, consultants' reports, farmer submissions and independent research. For example, in a large region in the northwest of New South Wales, where land could be cropped very productively:- some farmers bear only small losses (a quarter lose less than five per cent of their potential income),- some farmers bear very large losses (another quarter lose more than half of their potential income),- the overall losses of income per farm are high (an average loss of almost 30 per cent of potential income across the region), and- the losses are highest for those who have already conserved most woodland.Consider now the problem of reducing these costs by applying the benefit-cost rule as opposed to the maximise-benefits-only rule that has led to this position. There are three economic decision rules that might be used to rank projects or activities.The benefit-cost rule: Impose the constraint on the farm with the highest ratio of environmental benefit per dollar of opportunity cost first, then on the farm with the next highest ratio, etc., until the environmental goal is met. And so maximise the ratio of benefits to opportunity costs.The benefit-only rule: Impose the constraint on the farm with the highest environmental benefits first, then on the farm with the next highest benefits, etc., until the environmental goal is met. And so maximise benefits.The cost-only rule: Impose the constraint on the farm with the lowest opportunity costs first, then the next lowest cost, etc, until the environmental goal is met. And so minimise opportunity costs.But do these rules normally lead to different outcomes? If the “budget” or willingness to impose opportunity costs were large enough, all three would lead to the same outcome because constraints would be imposed on all suitable land. Otherwise the outcomes differ - that is the different rules lead to different levels of environmental benefit from the imposition of a given level of opportunity cost (or from the expenditure of a given budget).Both the benefit-only and cost-only rules lead to inefficiencies (see Babcock et al (1997) and Wu et al (2000) for a discussion of the associated statistical issues). Benefit-only targeting leads to the retirement of highly-productive land from agricultural uses - which is a major reason why opportunity costs are often high when native vegetation is conserved under the Act in New South Wales. The cost-only rule can lead to the reservation or purchase of land with few environmental benefits, even though expenditure or opportunity cost is minimised.A comparison of the benefit-cost rule and the benefit-only rule in the northwest of New South Wales illustrates the problem. The region is potentially highly-productive crop land but large areas of it are presently covered by native forest and woodland which cannot now be cleared. Much of this vegetation is under various degrees of threat even though it is not rare or endangered. The farm is the unit of assessment under the Act, so is used in the example. Benefits are measured as the percentages of species that are saved on each farm when its vegetation is protected rather than cleared to crops. The total benefit is the aggregate of percentage species saved across the farms - again following the present administration of the Act. The opportunity costs are measured as the losses in land value because land cannot now be cleared due to the Act.The comparison of the two rules indicates substantial savings with the benefit-cost rule. For example, 90 per cent of the total benefits can be obtained by imposing 93 per cent of the total opportunity costs with the benefit-only rule, and by imposing only 54 per cent of the total opportunity costs with the benefit-cost rule. The benefit-cost rule saves 39 per cent of the total costs at this level of benefits. Again, 80 cent of the total benefits can be obtained by imposing 86 per cent of the total opportunity costs with the benefit-only rule, but by imposing only 46 per cent of the total opportunity costs with the benefit-cost rule. The benefit-cost rule saves 40 per cent of costs at this level of benefits.While such results can only be indicative of the magnitudes, they do serve to highlight the inefficiencies of decision rules used by government agencies. In New South Wales, the Native Vegetation Conservation Act imposes high opportunity costs on farmers, partly because it is implemented through a high-cost decision rule. Now that suitable GIS technology, vegetation maps, and spatial land value data, are becoming available, these costs can be lowered with a more rational decision rule to guide choices in the field.The environmental goal is not at issue, but the cost of achieving it is. We can identify who bears the opportunity costs of environmental conservation, and often value the magnitude of these costs. Now we can also reduce the levels of these costs with the use of the benefit-cost decision rule.Jack SindenAgricultural and Resource EconomicsUniversity of New EnglandArmidale, New South WalesReferencesBabcock Bruce A, Lackshminarayan PG, Wu JunJie and Silberman D (1997) “Targeting Tools for the Purchase of Environmental Amenities”, Land Economics, 73, 325-339.Wu JunJie, Adams Richard M., Zilberman David, and Bruce Babcock (2000) “Targeting Resource Conservation Expenditures”, Choices, Second Quarter, 2000, 3-8.     

TREE REMOVALS AND SALINE SEEPAGE IN VICTORIAN CATCHMENTS: SOME HYDROLOGIC AND ECONOMIC RESULTS*

Average salt concentrations in a number of Victorian streams are related statistically to the proportions of their catchments cleared of trees for agriculture and to other catchment variables. A causal relationship is assumed, so that an economic evaluation of one of the external benefits of tree retention in a given catchment can be estimated. This is done by using the model to predict stream salinity increases that would occur with further clearing, and estimating the costs of such increases by either the costs experienced by water users, or the costs of restoring stream salinity to the original level. The methods are illustrated by application to a representative catchment.     

Investigating distance effects on environmental values: a choice modelling approach*

Analysis of the relationship between distance and willingness to pay (WTP) is important for estimation and transfer of environmental benefits. Several contingent valuation (CV) studies have investigated this topic, but results are mixed. This paper describes a choice modelling (CM) application that estimates distance effects on parameters of three environmental attributes. Combinations of these attributes create different management policies for native vegetation. The CM study is based on a sampling procedure that provides a geographically balanced sample and statistical tests to choose the best specification of the distance–WTP relationship. Welfare analysis shows that disregarding distance causes under‐estimation of individual and aggregated benefits and losses, seriously misdirecting resource allocation.     

Use of Public Perceptions of Groundwater Quality Benefits in Developing Livestock Management Options

In this study, a dichotomous choice model is used to determine the compensating welfare measure for water quality improvements stemming from livestock waste management in the Abbotsford region of southwestern British Columbia. The benefits of improving water quality are compared with the net costs of composting manure on a large scale, the option for handling livestock wastes preferred by the provincial government. The results indicate that the costs of composting manure exceed the revenue from selling manure (compost) plus the off-site damages avoided.     

Optimal conservation investment for a biodiversity‐rich agricultural landscape*

This study develops a theoretical and empirical framework for optimal conservation planning using satellite land cover data and economic data from a farm survey. A case study is presented for a region within the South‐west Australia Biodiversity Hotspot (Nature 403, 853). This Biodiversity Hotspot is a focus for conservation investment as it combines a relatively high level of biodiversity with severe threat to the biodiversity from agriculture. The conservation planning model developed determines the optimal set of bush fragments for conservation. This model can also be used to assess the trade‐off between the budget and a vegetation species metric. Results from the case study show that, without an effective conservation scheme that at least fences fragments, significant plant biodiversity losses will occur in the North East Wheatbelt Regional Organisation of Councils region of the WA wheatbelt over a 10‐year period. A perfect price discriminating auction scheme could reduce the costs of conservation by around 17 per cent relative to a fixed‐payment scheme; however, a fixed payment on outcome (measured as change in the species metric) scheme represents a viable second‐best alternative, to a conservation auction, where conservation spending is spatially targeted.     

Investigating Preferences for the Local Delivery of Agri‐environment Benefits

Since 2005, Environmental Stewardship (ES) has been the principal agri‐environment scheme for England and is the key instrument for the delivery of increased environmental benefits from agricultural landscapes. The main objective of this study is to investigate the hypothesis that individuals have greater relative preferences for the environmental benefits associated with agri‐environment schemes when they are delivered within those landscapes closest to where they live. A choice experiment approach based on a national survey provides the data and a mixed logit approach is used to model relative preferences for the environmental benefits of ES across five generic landscape types. Results show that most respondents have a preference for benefits delivered in those areas closest and most accessible to where they live.     

A MODEL OF JOB CHOICE FOR THE ANALYSIS OF GOVERNMENT INTERVENTION IN STRUCTURAL ADJUSTMENT*

The paper presents a model of choice between alternative available jobs in which each job has an uncertain multi-period income prospect. Imperfectly informed expectations as well as job preferences and attitudes to risk determine the choice. The model is used to locate and discuss some problems of designing government programs which are intended to increase job mobility. The main conclusion is that government interventions may impose costs on the economy which are greater than the benefits because the information needed to assess costs and benefits is not generally available and political pressures may distort the expenditures.     

Evaluation of a dairy agri-environmental programme for restoring woody green infrastructure

Pastoral landscape woody vegetation provides ecosystem services, but potentially competes for space, light and nutrients that could provide additional farm production. A questionnaire determined the values and behaviours of New Zealand dairy farmers to evaluate voluntary agri-environmental programmes for restoring woody vegetation. Findings indicate the area is increasing, while the composition and configuration of networks are changing and redistributing. Farms with little are losing more, and those with more are gaining. Farmers are planting new areas to increase their public ecosystem services, but may not provide these services through planting and management. Barriers include insufficient private woody vegetation ecosystem services, and low rates of growth of native plants. Government incentive programmes are ineffective in overcoming barriers. Farmers may be motivated by stronger evidence of valued ecosystem services, information about their benefits and drawbacks and how to support services through planting and management. However, a targeted environmental stewardship scheme is required to overcome barriers to planting, with government and the dairy industry working together to develop and maintain a landscape-scaled woody vegetation network on private and public land. Such networks would build sustainability and resilience into dairy farming, leading to an equitably sharing of benefits and costs of their public ecosystem services.     

黄土高原土地利用变化特征及其环境效应

研究目的:基于黄土高原近30余年来土地利用/植被覆盖变化(LUCC),分析该地区LUCC及其环境效应,为区域生态环境与社会经济的可持续发展政策提供科学依据。研究方法:地统计和趋势分析等。研究结果:(1)黄土高原土地利用结构整体上未发生变化,仍以草地、耕地和林地为主,但植被覆盖度提升显著;(2)黄土高原LUCC受气候变化和人类活动共同影响,影响程度存在区域性差异,其中黄土高原中部丘陵沟壑区主要由人类活动导致;(3)黄土高原LUCC对地表径流、土壤侵蚀、土壤水分及碳循环等生态环境过程将产生长期的影响,植被恢复在发挥生态效益的同时对区域生态环境产生消极的作用。研究结论:黄土高原植被生产力已接近水资源承载力阈值,提升人工植被稳定性、促进水资源平衡仍为现阶段促进黄土高原可持续发展的主要课题。     

Assessing the trade‐offs of increased mining activity in the Surat Basin,Queensland: preferences of Brisbane residents using nonmarket valuation techniques

The mining boom in Australia since 2003 has produced significant economic benefits for regional, State and National economies, creating new job opportunities and revenue flows. Despite the contribution of the resources sector to economic growth, questions are frequently raised about the concomitant negative social, economic and environmental impacts. The Surat Basin in southern Queensland is a traditional agricultural region with a small but growing coal mining sector and a rapidly developing liquefied natural gas industry (mainly associated with extracting coal seam gas). In this paper, the preferences of residents in Brisbane, the State capital, are explored in relation to the relative importance of social, economic and environmental impacts of the resource boom in the Surat Basin. A choice modelling experiment was conducted to assess the trade‐offs Brisbane residents would make (in monetary terms) between the economic benefits and the associated costs of increased mining activity on local communities. The results identify the strength of concerns about community and environmental impacts and can potentially be used to help evaluate the net benefits of resource development.     

基于AHP的山东省农业适度规模效益测度

[目的]通过总结山东省农业适度规模经营模式及其实施区域分布概况,并研究其产生的经济、社会和生态效益,以期为山东省农业适度规模经营的可持续发展提供借鉴。[方法]文章采用层次分析法(AHP),构建山东省农业适度规模经营效益指标评价体系,并确定指标权重。然后根据农业规模经营从业者和当地农民根据实际情况对各指标的评分值与权重值加权计算各区域的经营效益指数并分析。[结果]鲁南和半岛地区的农业适度规模经营效益明显好于其他4个区域;农业适度规模经营所带来的经济效益要远大于社会效益和生态效益,尤其是农业土地利用率和农业产出值的增加较为明显,农民人均纯收入也得到较大提高。[结论]山东省农业适度规模经营模式多样化发展,规模经营效益区域差异明显,鲁南和半岛地区的效益最好。农业适度规模经营经济效益较为突出,显著提高了农业土地利用率和产出值。农业适度规模经营是一种在新形势下可以有效改变传统农业发展模式并能带来巨大经济效益的农业发展新模式,值得在更大的区域推广和实施。     

Duck Hunting and Wetland Conservation: Compromise or Synergy?

Duck hunting is an issue — often controversial — that generates both benefits and costs to society. Hunters enjoy benefits from engaging in their sport, while those who have ethical concerns regarding the shooting of ducks endure costs. Some in the community fear that duck hunting puts pressure on the continued ecological viability of the hunted species, while others argue that the demand for hunting provides sufficient economic incentive for wetland conservation. Whether society as a whole should permit or restrict duck hunting is to some extent an empirical question: Are the costs to society of allowing duck hunting greater or less than the benefits it generates? Evidence presented in this paper addresses this question. The benefits enjoyed by people who hunt ducks in the upper south east of South Australia are estimated using the travel cost method. The ethical costs borne by the general community because of duck hunting are estimated using the choice modeling technique. Finally a threshold value analysis is used to assess the activities of Wetlands and Wildlife, a not‐for‐profit organization that manages wetlands in part for hunting.     

AN APPROACH TO LINKING AN ECOLOGICAL VEGETATION MODEL TO AN AGRICULTURAL ECONOMIC MODEL

Agricultural policy measures are directed increasingly towards encouraging production systems that are deemed to be favourable for ecologically valued plant communities and species. This paper presents an approach to linking an ecological model of vegetation with a regional economic model of agricultural production to provide a means of estimating the costs of achieving a given area of a desired vegetation type. This is demonstrated by an empirical study of heather and hay meadow conservation in the River Tyne catchment in northern England. The results show that policy measures need to take account both of spatial linkages within agriculture and temporal links between ecological processes and agricultural productivity.     

A latent class approach to investigating demand for genetically modified banana in Uganda

This study explores consumer acceptance and valuation of a genetically modified (GM) staple food crop in a developing country prior to its commercialization. We focus on the hypothetical introduction of a disease‐resistant GM banana variety in Uganda, where bananas are among the most important staple crops. A choice experiment is used to investigate consumer preferences for various attributes related to the banana (such as bunch size, technology, producer benefit, and price) and examine their opinions on GM foodstuff. Choice data come from 421 banana‐consuming households randomly selected from three regions of Uganda. A latent class model is used to investigate the heterogeneity in consumers’ preferences for selected attributes related to the banana and to profile consumers who are more or less likely to accept GM bananas. Our results reveal that there is significant heterogeneity in consumer preferences across our sample. GM bananas are valued the most by poorer households located in the rural areas of the Eastern region. These food‐insecure households would experience the highest benefits (i.e., welfare gains) from the commercial release of GM bananas. In contrast, urban consumers are less accepting of GM bananas, and they would experience significant welfare losses if GM banana is released. According to our welfare estimates, both the total welfare benefits acquired by the gainers and the total welfare losses borne by the losers of this technology are significant and large. These results suggest the need for further investigation of the overall welfare effects of the introduction of GM bananas on the Ugandan society as a whole.     

Using Geographically Weighted Choice Models to Account for the Spatial Heterogeneity of Preferences

In this paper, we investigate the use of geographically weighted choice models for modelling spatially clustered preferences. We argue that this is a useful way of generating highly‐detailed spatial maps of willingness to pay for environmental conservation, given the costs of collecting data. The data used in this study come from a discrete choice experiment survey of public preferences for the implementation of a new national forest management and protection programme in Poland. We combine these with high‐resolution spatial data related to local forest characteristics. Using locally estimated discrete choice models we obtain location‐specific estimates of willingness to pay (WTP). Variation in these estimates is explained by characteristics of the forests close to where respondents live. These results are compared with those obtained from a more typical, two stage procedure which uses Bayesian posterior means of the mixed logit model random parameters to calculate location‐specific estimates of WTP. We find that there are indeed strong spatial patterns to the benefits of changes to the management to national forests. People living in areas with more species‐rich forests and those living nearer bigger areas of mixed forests have significantly different WTP values than those living in other locations. This kind of information potentially enables a better distributional analysis of the gains and losses from changes to natural resource management, and better targeting of investments in forest quality.     

Modelling socially optimal land allocations for sugar cane growing in North Queensland: a linked mathematical programming and choice modelling study

A modelling framework is developed to determine the joint economic and environmental net benefits of alternative land allocation strategies. Estimates of community preferences for preservation of natural land, derived from a choice modelling study, are used as input to a model of agricultural production in an optimisation framework. The trade-offs between agricultural production and environmental protection are analysed using the sugar industry of the Herbert River district of north Queensland as an example. Spatially-differentiated resource attributes and the opportunity costs of natural land determine the optimal trade-offs between production and conservation for a range of sugar prices.     

Effect of yield and price risk on conversion from conventional to organic farming*

Although the benefits of organic farming are already well known, the conversion to organic farming does not proceed as the Dutch government expected. In order to investigate the conversion decisions of Dutch arable farms, a discrete stochastic dynamic utility‐efficient programming (DUEP) model is developed with special attention for yield and price risk of conventional, conversion and organic crops. The model maximizes the expected utility of the farmer depending on the farmer’s risk attitude. The DUEP model is an extension of a dynamic linear programming model that maximized the labour income of conversion from conventional to organic farming over a 10 year planning horizon. The DUEP model was used to model a typical farm for the central clay region in the Netherlands. The results show that for a risk‐neutral farmer it is optimal to convert to organic farming. However, for a more risk‐averse farmer it is only optimal to fully convert if policy incentives are applied such as taxes on pesticides or subsidies on conversion, or if the market for the organic products becomes more stable.     

Imperfect competition,functional forms,and the size and distribution of research benefits

The effects of functional forms for supply and demand on the size and distribution of the returns to research are examined under a range of forms of competition. Under perfect competition, the choice of functional form is relatively unimportant for the estimation of research benefits. Under imperfect competition, the combination of the choice of functional forms for supply and demand and the nature of the research-induced supply shift can have profound implications for the results. Functional form plays a much more important role than in the competitive model. The most important contrast is between the constant elasticity model and the linear model (along with various cases of a generalized linear model). These findings are illustrated using a combination of analytical results and numerical simulations.