Potential of woody biomass production for motivating widespread natural resource management under climate change

In this study we assessed the potential of woody biomass (short-rotation Mallee Eucalypts) for renewable energy generation as an economically viable way of motivating widespread natural resource management under climate change in the 11.9 million ha Lower Murray agricultural region in southern Australia. The spatial distribution of productivity of agricultural crops and pasture, and biomass was modelled. Average annual economic returns were calculated under historical mean (baseline) climate and three climate change scenarios. Economically viable areas of biomass production were identified where the profitability of biomass is greater than the profitability of agriculture under each scenario for three factory gate biomass prices. The benefits of biomass production for dryland salinisation, wind erosion, and carbon emissions reduction through biomass-based renewable energy production were also modelled. Depending on climate scenario, at the median price assessed ($40/tonne) biomass production can generate $51.4–$88 M in annual net economic returns, address 41,226–165,577 ha at high risk of dryland salinisation and 228,000–1.4 million ha at high risk of wind erosion, and mitigate 10.4–12 million tonnes of carbon (CO₂^−e) emissions annually. Economically viable areas for biomass production expanded under climatic warming and drying especially in more marginal agricultural land. Under the baseline, the area at high risk of dryland salinisation was more than double that at high risk of wind erosion. However, under climatic warming and drying the relative importance of these two natural resource management objectives switched with the area at high risk of wind erosion becoming much larger. As biomass production can achieve multiple natural resource management objectives, it may provide a land use policy option that is adaptable to changing priorities and economically resilient given climatic uncertainties. For such a significant and enduring land use change policy it is prudent to assess both the economic and environmental potential under climate change.     

The dynamics of phase farming in dryland salinity abatement

In Australia, soil salinisation has become a major concern. One way to deal with the problem is for farmers to plant trees or regenerate native bush. However, doing so raises several questions which involve optimal switching times, when switching involves a cost in the form of up-front investments. Optimality conditions are derived for the three-stage problem, and applied to dryland salinity control in Western Australia. Optimal management practices are found to be very sensitive to farmers' discount rates and to the speed at which the watertable rises or falls.     

The Amenity Value of Agricultural Landscape and Rural–Urban Land Allocation

We analyse rural–urban land allocation in the light of the increasing environmental role of agricultural landscapes. The landscape amenity value of farmland varies across crops and as a result affects the optimal crop mix in addition to its effect on rural–urban land allocation. Investigating the effects of population and income growth processes, we find that, contrary to market outcomes, the socially optimal allocation may call for more farmland preservation under both processes. In an empirical application to a region in Israel, we find that the extent of market under‐supply of farmland is substantial and that population growth calls for more farmland preservation at the expense of urban land.     

Motivations to grow energy crops: the role of crop and contract attributes

Perennial energy crops are a promising source of bioenergy whose production involves production risks, long‐term commitment of land and need for crop‐specific investments without the coverage of crop insurance potentially available for conventional crops. We conduct a choice experiment in five states in the Midwestern and South‐central regions of the U.S. to examine the effect of crop‐contract attributes on the joint discrete‐continuous choice decisions to adopt an energy crop and convert acres to it from a status quo use, while controlling for the effect of various farmers’ risk and time preferences, sociodemographic characteristics, and availability of crop insurance for conventional crops. We find robust evidence that high discount rates, high upfront establishment costs and need for crop‐specific investments create disincentives for adoption and allocation of land to energy crop production. The effects of riskiness of returns and risk aversion are less robust across specifications. The effect of conventional crop insurance on the energy crop adoption decision differs across types of insurance; in particular, farmers with revenue insurance are statistically significantly less likely to adopt an energy crop. Our results have implications for the design of effective contracts and policy incentives to induce the production of energy crops.     

Risk aversion and land allocation between annual and perennial crops in semisubsistence farming: a stochastic optimization approach

This article analyzes the effect of production uncertainty on farmland allocation decisions between perennial and annual crops, focusing on a representative farmer's attitude toward risk. A dynamic stochastic optimization model that considers net planting—the difference between new plantings and removals of perennial crops that achieve full production cycle—is used. The effect of uncertainty on the representative farmer's decisions to increase or decrease perennial crops’ acreage, on the optimal path, is examined. Our results reveal that the response of optimal path of net planting to uncertainty related to perennial crop production is highly affected by the farmer's attitude toward risk. A risk‐averse or a low‐risk loving farmer tends to reduce land allocation to perennial crops under uncertainty, while a high‐risk loving farmer will do exactly the opposite. Also, due to disutility of farming, the farmer tends to reduce land allocation to perennial crops when prices are high enough for him to attain a desired income level expectation. One implication of this research is the need for mechanization—in sub‐Saharan countries in particular—that increases per‐acreage yield and output in semisubsistence agriculture.     

Spatial optimization of nutrient reduction measures on agricultural land to improve water quality: A coupled modeling approach

The objective of this study is to identify the optimal spatial distribution of Best Management Practices (BMPs) to reduce total phosphorus (TP) runoff from agricultural land in the largest Canadian watershed draining into Lake Erie, the Great Lake most vulnerable to eutrophication. BMP measures include reduced fertilizer application, cover crops, buffer strips, and the restoration of wetlands. Environmental SWAT model results feed into a spatial optimization procedure using two separate objective functions to distinguish between public BMP program implementation costs (PIC) on the one hand and farmers’ private pollution abatement costs (PAC) on the other hand. The latter account for the opportunity costs of land retirement and changing land productivity. PAC are initially lower than PIC but exceed the latter after 30% of the annual TP baseline load is eliminated. This suggests that under optimal conditions existing grant and incentive payments cover the economic costs farmers face up to a maximum of 30% of the baseline load reduction. Imposing further reductions of up to 40% results in a cost to farmers of almost $52 million per year. This is 45% higher than the optimal solution based on PIC and therefore not deemed incentive-compatible under the watershed's existing cost-sharing scheme.     

Designing afforestation subsidies that account for the benefits of carbon sequestration: A case study using data from China's Loess Plateau

This paper presents a method for determining the subsidy required to motivate farmers to participate in timber afforestation programs designed to maximize social well-being. The method incorporates a carbon sequestration benefit function into the land expected value model in order to quantify the social benefit arising from carbon sequestration by the planted trees. This is used to calculate the optimal rotation age for newly planted forests that maximizes social utility. The minimum subsidy required to motivate farmers to participate in the afforestation program was calculated using a modified decision model that accounts for the subsidy's impact. The maximum subsidy offered by the government was taken to be the NPV of the carbon sequestration achieved by afforestation. Data on Robinia pseudoacacia L. trees planted on the Loess Plateau were used in an empirical test of the model, which in this case predicts an optimal subsidy of 254.38 yuan/ha over 40 years. This would guarantee the maintenance of forest on land designated for afforestation until they reached the socially optimal rotation age. The method presented herein offers a new framework for designing afforestation subsidy programs that account for the environmental service (specially, the carbon sequestration) provided by forests.     

Greenhouse gas and groundwater recharge abatement benefits of tree crops in south-western Australian farming systems

The indirect benefits of a commercial tree crop for greenhouse gas and groundwater recharge abatement are analysed. Oil mallees are introduced into a whole-farm linear programming model as a source of income, an offset to greenhouse gas emissions from the mixed sheep and cropping enterprises and as a source of groundwater recharge abatement. The profitability of oil mallees is found to be very sensitive to the discount rate, yield and price assumptions and the relative profitability of other farm enterprises (especially the wool enterprise). Under standard assumptions where oil mallees are profitable, the trees significantly reduced greenhouse gas emissions and groundwater recharge and the farm remains profitable. If farm-level policies are introduced for greenhouse gas abatement, without tree crops or some other technological change, the current farming systems would fail and be replaced by alternative land uses.     

Towards productive landscapes: Trade-offs in tree-cover and income across a matrix of smallholder agricultural land-use systems

One of the main causes of tropical forest loss is conversion to agriculture, which is constantly increasing as a dominant land cover in the tropics. The loss of forests greatly affects biodiversity and ecosystem services. This paper assesses the economic return from increasing tree cover in agricultural landscapes in two tropical locations, West Java, Indonesia and eastern Bangladesh. Agroforestry systems are compared with subsistence seasonal food-crop-based agricultural systems. Data were collected through rapid rural appraisal, field observation, focus groups and semi-structured interviews of farm households. The inclusion of agroforestry tree crops in seasonal agriculture improved the systems’ overall economic performance (net present value), even when it reduced understorey crop production. However, seasonal agriculture has higher income per unit of land area used for crop cultivation compared with the tree establishment and development phase of agroforestry farms. Thus, there is a trade-off between short-term loss of agricultural income and longer-term economic gain from planting trees in farmland. For resource-poor farmers to implement this change, institutional support is needed to improve their knowledge and skills with this unfamiliar form of land management, sufficient capital for the initial investment, and an increase in the security of land tenure.     

The influence of land-use change paradigm on Romania’s agro-food trade competitiveness—An overview

The current transformations of the Romanian agricultural sector have imposed new paradigms in using the land resources. The objective of this study is to assess Romanian agro-food products competitiveness on world market, in terms of land use changing paradigms. The research question is whether the land is cultivated with crops which are competitive on world market. For assessing agro-food competitiveness, Balassa index is calculated. The findings show relative performance for barley, maize, triticale, wheat, poultry meat, oilseeds, and tobacco. But the areas cultivated with barley and wheat decreased in the period under analysis, although these products have highest relative performance of exports. The paper also proposes structural changes of land use needed for encouraging those crops and products which have high revealed comparative advantages on world markets.     

Dynamic Supply Response and Welfare Effects of Technological Change on Perennial Crops: The Case of Cocoa in Malaysia

Modern biotechnology will generate crops with higher yields and enhanced resistance to pests and diseases. In the case of perennial crops, the age composition of the present stand, the farmers' willingness to invest, and the yield profiles of old and new trees determine the speed of adoption of the new technology and the timing of the effects on supply and demand conditions. We adapt conventional welfare measures to account for these factors in the Assessment of research induced supply shifts. The application to cocoa in Malaysia shows that consumers and adopting producers gain and non-adopters lose. Overall, 72% of the welfare gains go to the consumers.     

Evidence of climate change impacts on crop comparative advantage and land use

Relative agricultural productivity shocks emerging from climate change will alter regional cropland use. Land allocations are sensitive to crop profits that in turn depend on yield effects induced by changes in climate and technology. We develop and apply an integrated framework to assess the impact of climate change on agricultural productivity and land use for the U.S. Northern Great Plains. Crop-specific yield–weather models reveal crop comparative advantage due to differential yield impacts of weather across the region's major crops, that is, alfalfa, wheat, soybeans, and maize. We define crop profits as a function of the weather-driven yields, which are then used to model land use allocation decisions. This ultimately allows us to simulate the impact of climate change under the RCP4.5 emissions scenario on land allocated to the region's major crops as well as to grass/pasture. Upon removing the trends effects in yields, climate change is projected to lower yields by 33–64% over 2031–2055 relative to 1981–2005, with soybean being the least and alfalfa the most affected crops. Yield projections applied to the land use model at present-day input costs and output prices reveals that Dakotas’ grass acreage will increase by up to 23%, displacing croplands. Wheat acreage is expected to increase by up to 54% in select southeastern counties of North Dakota and South Dakota, where maize/soy acreage had increased by up to 58% during 1995–2016.     

Assessing CAP Reform: Sensitivity of Modelling Decoupled Policies

The European Union reformed farm policy in June 2003 towards the decoupling of farm income support instruments. Available impact studies find that this reform reduces production incentives substantially for beef and to a lesser extent for arable crops. However, these studies assume that the previous reform, under Agenda 2000, already decoupled arable crop direct payments to a considerable extent, while beef premiums were linked more closely to production. Our main objective in this paper is to test the sensitivity of these results to this questionable modelling of Agenda 2000 direct payments, which neglects eligibility rules and land market imperfections. Our analysis reveals that the effects of the reform on both arable crop and beef production are always negative, however the Agenda 2000 direct payments are modelled. On the other hand, we show that, when the eligibility rules and land market imperfections are acknowledged, the production reducing effects may be much larger for arable crops than for beef. Policy implications of these results are noted.     

Analyzing the drivers of tree planting in Yunnan,China, with Bayesian networks

Strict enforcement of forest protection and massive afforestation campaigns have contributed to a significant increase in China's forest cover during the last 20 years. At the same time, demographic changes in rural areas due to changes in reproduction patterns and the emigration of younger population segments have affected land-use strategies. We identified proximate causes and underlying drivers that influence the decisions of farm households to plant trees on former cropland with Bayesian networks (BNs). BNs allow the incorporation of causal relationships in data analysis and can combine qualitative stakeholder knowledge with quantitative data. We defined the structure of the network with expert knowledge and in-depth discussions with land users. The network was calibrated and validated with data from a survey of 509 rural households in two upland areas of Yunnan Province in Southwest China. The results substantiate the influence of land endowments, labor availability and forest policies for switching from cropland to tree planting. State forest policies have constituted the main underlying driver to the forest transition in the past, but private afforestation activities increasingly dominate the expansion of tree cover. Farmers plant trees on private incentives mainly to cash in on the improved economic opportunities provided by tree crops, but tree planting also constitutes an important strategy to adjust to growing labor scarcities.     

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.     

Land Invasions,Insecure Property Rights and Production Decisions

This paper investigates empirically the effect of land invasions on farm production decisions. The main hypothesis is that more invasions in a region are associated with lower investment, and in particular a bias towards annual crops as opposed to long‐term crops. We use a county‐level dataset for the state of Paraná, Brazil, from 2003 to 2007, with 1,995 observations. The panel data structure allows us to control for fixed effects, such as the formalisation of land titles and land concentration, which might be correlated with the intensity of invasions. An instrumental variable fixed effects model was estimated to avoid other sources of bias. Our main finding is that land invasions are associated with lower long‐term crop production and a higher percentage of annual crops, which could accelerate land degradation, and undermine environmental sustainability.     

耕地征收最优规模的理论与实证研究 ——基于边际理论视角

研究目的：针对当前盲目征收耕地的现象,探讨耕地征收最优规模测算方法,为科学调控耕地征收提供参考依 据。研究方法：生产函数模型与面板计量方法。研究结果：2005—2010年耕地征收实际规模从过度征收逐步趋近于最优规模;“十二五”期间需新增耕地规模为153.27万hm2。研究结论：（1）基于边际理论视角测算耕地征收最优规模的方法具有科学性和可操作性,可为各地合理确定耕地征收规模和土地利用总体规划修编提供参考;（2）保障粮食安全前提下的耕地效益最大化是确定当前最优征收规模的标准;（3）提升耕地的边际效益是解决当前耕地保护与建设用地扩张矛盾的关键。     

中国耕地保护生态治理内涵及实现路径

研究目的：厘清耕地保护生态治理内涵并明确实现路径，为丰富生态文明背景下的耕地保护与治理提供理论支 撑。研究方法：文献综述法、归纳法、推理法等。研究结果：（1）中国耕地存在空间适宜性差、作土垂直关系紊乱、生产 生态功能失衡等问题。（2）聚焦耕地保护新要求，中国耕地保护生态治理核心内涵包括“耕地空间适宜性、作土垂直关 系匹配性、耕地生产生态功能协调性”等三个方面。（3）实现路径包括科学技术领域突破、部门形成合力、政策对接融 合转型、区域之间协同共进等。（4）保护与治理工具包括通过国土空间规划、全域土地综合整治以提升耕地空间适宜 性；调整粮食生产布局、确定合理复种指数等强化作土垂直关系的匹配性；对耕地生产空间进行严格的用途管制，减 少化肥、农药施用量和灌溉投入强度，优化耕地功能的协调性；建立耕地生态保护补偿机制，推动实现三性协同。研究 结论：中国耕地保护从单独侧重数量、质量保护进入到保护与生态治理相结合的新阶段，要建立起源头控制、过程监管 和末端治理的全流程治理新机制。     

Landowner willingness to supply marginal land for bioenergy production

This study elicits willingness to supply marginal land for biomass cultivation in Southern Lower Michigan. Most of the surveyed landowners are not interested in renting land for bioenergy crop production. Those who are interested offer relatively little land for bioenergy crops, even at rental rates three times current levels. Willing landowners would prefer to grow a significant portion of these crops on cropland rather than non-crop, marginal land. Hence, the area of marginal land that owners are willing to supply for bioenergy crop production falls far short of area estimates based on remote sensing that ignore landowner preferences.     

基于改进的农业生态区法的中国耕地粮食生产潜力评价

研究目的:发展适合于中国的农业生态区(AEZ)方法,并应用于全国耕地粮食生产潜力评价的实践.研究方法:农业生态区法.研究结果:在2000年投入水平下的全国耕地粮食生产潜力为食用粮58984.28万吨,油料3017.76万吨,糖料9744.46万吨.研究结论:AEZ是宏观尺度土地生产潜力评价的有效方法.受基础数据精度、评价参数适用性等影响,评价的结果仍然有待于进一步验证.