Runoff and sediment losses from 27 upland catchments in Southeast Asia: Impact of rapid land use changes and conservation practices

Rapid changes in upland farming systems in Southeast Asia generated predominantly by increased population pressure and ‘market forces’ have resulted in widespread land degradation that has been well documented at the plot scale. Yet, the links between agricultural activities in the uplands and downstream off-site effects remain largely unknown because of the difficulties in transferring results from plots to a larger scale. Many authors have thus pointed out the need for long-term catchment studies. The objective of this paper is to summarize the results obtained by the Management of Soil Erosion Consortium (MSEC) over the last 5 years from 27 catchments in five countries (Indonesia, Laos, Philippines, Thailand, and Vietnam). The purpose of the study was to assess the impacts of cultivation practices on annual runoff and erosion rates. Initial surveys in each catchment included topography, soils and land use. Monitoring included climatic, hydrologic and erosion (total sediment yield including bed load and suspended sediment load) data, land use and crop yields, and farmers’ income. In addition, new land management options were introduced through consultations with farmers and evaluated in terms of runoff and erosion. These included tree plantations, fruit trees, improved fallow with legumes, maize intercropped with legumes, planted fodder, native grass strips and agro-ecological practices (direct sowing and mulch-based conservation agriculture). Regressions analyses showed that runoff during the rainy season, and normalized runoff flow coefficient based on erosive rainfall during the rainy season (rainfall with intensity exceeding 25 mm h⁻¹) increase with the percentage of the catchment covered by maize. Both variables decrease with increasing soil depth, standard deviation of catchment slope (that reflects terrain roughness), and the percentages of the catchment covered by fallow (regular and improved), tree plantations and planted fodder. The best predictors of sediment yield were the surface percentages of maize, Job's tears, cassava and footpaths. The main conclusions generated from this study were: (i) soil erosion is predominantly influenced by land use rather than environmental characteristics not only at the plot scale but also at the catchment scale; (ii) slash-and-burn shifting cultivation with sufficiently long rotations (1 year of cultivation, 8 years of fallow) is too often unjustly blamed for degradation; (iii) in its place, continuous cropping of maize and cassava promotes high rates of soil erosion at the catchment scale; (iv) conservation technologies are efficient in reducing runoff and total sediment yield at the catchment scale; (v) the adoption of improved soil management technologies by upland farmers is not a function of the degree of intensification of their farming system and/or of their incomes. The results suggest that if expansion of maize and cassava into already degraded upland systems were to occur due to increased demand for biofuels, there is a risk of higher runoff and sediment generation. A failure to adopt appropriate land use management strategies will result in further rapid resource degradation with negative impacts to downstream communities.     

农牧民参与政府主导生态建设工程的初始行为响应——以江西山江湖和青海三江源为例

使用参与式农村评估方法对江西山江湖4县(市)的508户农民和青海三江源玛多县151户牧民进行住户访谈,使用生态时限法和EXCEL统计方法理解他们对初始参与生态建设工程的响应差异。结果表明:①山江湖农民参与生态建设的直接行为体现为投工投劳参与完成政府主导的山场造林,而三江源牧民的初始直接参与则体现为以少畜或无畜牧户为主的生态移民。对农牧民被动参与生态建设的调整上,山江湖仅需要进行产权明确,让农户自行参与和收益,而三江源的牧民行为调整并不仅仅是提高安置补偿费用和年限的问题,而更多地要考虑牧民宗教习俗的变迁;②山江湖农户的间接参与是在外来力量胁迫或冲击下自身利益最大化和产生有助于山场恢复的响应,主要受制于劳动力务农机会成本提升、养殖风险增大等的驱动,而不是农户的自觉行为,而三江源牧民的间接参与主要是在政府引导下传统牧业行为发生变迁的结果,"禁牧-围栏-减畜"是适宜于草场压力减轻和不完全改变传统牧业行为的牧民间接参与的首选响应;③山江湖农民转产具有较大的主动性,是农民综合权衡农业和非农收入差距的基础上作出的理性选择,转产后的生态效应展现出山场压力的长效减轻,反弹风险降低,而三江源牧民转产则显示出很大的被动性,是政府和牧民在对"清贫富饶"博弈后,由政府主导为牧民提供培训、就业、教育等机会和优惠政策下牧民被动参与的结果。转产后草场生态好转的反弹风险较大。该研究结果有助于为集中型生态重建和减压型生态恢复的生态建设工程中农牧民参与提供更为有效的数据和思路支撑。     

退耕还林还草对土地利用变化影响程度研究——以延安生态建设示范区为例

文章在分析延安生态建设示范区2000-2003年间各土地利用类型的数量变化和空间特征的基础上,引入退耕指数、退耕影响系数等指标研究退耕还林草对示范区土地利用结构变化的影响。结果显示,示范区已退耕坡耕地36.07%,平均每年退耕12.02%,全区的退耕影响系数高达4.76,该结果表明大规模的退耕还林草活动对区域土地利用变化的影响很大,它推动了土地利用结构的优化。分乡镇的研究显示,退耕对示范区各乡镇土地利用变化的影响存在一定的差异,除2个乡镇的退耕影响系数远远低于全区平均水平外,其他7个乡镇都高于全区平均水平。     

Runoff and soil erosion in arable Britain: changes in perception and policy since 1945

The realisation that runoff and soil erosion was a problem came late to Britain and policies to tackle the problem have evolved slowly and may well have a taken a different route to that in other countries. The perception of soil erosion and runoff in Britain by three interest groups (researchers, policy makers and farmers) has changed over time since the 1940s. Prior to 1970 none of the groups considered erosion and runoff were problems. From then to 1985 researchers found that erosion was widespread. Between 1985 and 2005 researchers not only confirmed that erosion was a problem, but that runoff and its impacts (muddy floods and pollution of water courses by sediment, phosphate and pesticides) were also problems. These widespread and costly economic and environmental impacts led policy makers to tackle the problems of erosion and runoff. From 2005 farmers have had to keep their land in ‘Good Agricultural and Environmental Condition’ by, amongst other things, attempting to curtail erosion and runoff, to comply with regulation in order to receive subsidy. Policy change was also stimulated by changes in the European Union's Common Agricultural Policy and the passing by the EU of the ‘Water Framework Directive’. Policy, if it is to be evidence based, will always lag behind research. There is a continuing need for field-based monitoring to assess if regulation is working, to ensure compliance, and as a basis for future policy.     

Brazilian biofuels and social exclusion: established and concentrated ethanol versus emerging and dispersed biodiesel

Increasing interest in biofuels trade between developed and developing countries has spurred worldwide discussions on issues such as subsidies and the ‘food for fuel’ crisis. One issue missing in recent discourse is the pressure exerted on developing countries to adopt large-scale mechanized farming practices to increase economic efficiencies. Such approaches often exclude small-scale farmers from participating in the emerging biofuels market, thus exacerbating poverty and social exclusion. Drawing on both qualitative and technical data, we discuss such pressures using Brazilian ethanol and biodiesel production. Pressure from international markets to become more economically efficient may contribute towards the erosion of recent schemes to encourage social benefits for small farmers in biodiesel production. We conclude with trade and policy implications.     

Agricultural adaptation to climate change: insights from a farming community in Sri Lanka

The vulnerability of smallholder farmers to climate change and variability is increasingly rising. As agriculture is the only source of income for most of them, agricultural adaptation with respect to climate change is vital for their sustenance and to ensure food security. In order to develop appropriate strategies and institutional responses, it is necessary to have a clear understanding of the farmers’ perception of climate change, actual adaptations at farm-level and what factors drive and constrain their decision to adapt. Thus, this study investigates the farm-level adaptation to climate change based on the case of a farming community in Sri Lanka. The findings revealed that farmers’ perceived the ongoing climate change based on their experiences. Majority of them adopted measures to address climate change and variability. These adaptation measures can be categorised into five groups, such as crop management, land management, irrigation management, income diversification, and rituals. The results showed that management of non-climatic factors was an important strategy to enhance farmers’ adaptation, particularly in a resource-constrained smallholder farming context. The results of regression analysis indicated that human cognition was an important determinant of climate change adaptation. Social networks were also found to significantly influence adaptation. The study also revealed that social barriers, such as cognitive and normative factors, are equally important as other economic barriers to adaptation. While formulating and implementing the adaptation strategies, this study underscored the importance of understanding socio-economic, cognitive and normative aspects of the local communities.     

上海市废弃电器电子产品产生预测与回收处理能力研究

本文应用“专家估计”模型预测了上海市废弃电器电子产品的产生量,分析了家电“以旧换新”政策实施下废弃电器电子产品的回收处理特点以及上海市拆解处理能力现状,发现上海市目前的拆解处理能力无法满足2015年废弃电器电子产品回收处理量的需求,提出相应的解决对策。     

黑河流域草地承载力研究

应用RS和GIS技术,从研究区植被类型、土壤侵蚀、坡度、距水源距离、生物多样性和生态系统保护等方面,确定了黑河流域不适合和适合放牧的区域。在适合放牧的区域,根据草地类型估测产草量。在牧草分配方面,从避免土壤侵蚀和遭遇干旱时保证植被群落弹性和再生的需要以及满足昆虫和土壤无脊椎动物及野生动物需要两个方面考虑了满足生态需要的牧草生物量。在确定放牧强度时,从坡度和距离水源远近两个方面考虑了载畜量的减少比例。在此基础上,计算出满足生态保护需要的草地承载力。研究结果表明,黑河流域适合放牧的区域仅占总面积的17.693%,在适合放牧的区域,天然草地的承载力为0.009～2.055只羊单位/hm²。     

Multi-scale scenarios of spatial-temporal dynamics in the European livestock sector

The European livestock sector has changed rapidly in the recent past and further changes are expected in the near future due to reforms in the European Common Agricultural Policy (CAP), increasing environmental concerns and changing consumer awareness. We developed a multi-scale modeling approach for exploring spatial and temporal dynamics of livestock distribution by accounting for drivers at different spatial scales. Such approach can provide a basis for environmental impact assessments of livestock farming at broad spatial scales. Assessment of change in both quantity and location was made for six livestock types. Four contrasting scenarios were applied ranging from globalization to regionalization, as well as from low regulation levels and dominance of market forces towards a higher degree of governmental regulation. National level livestock numbers as calculated by a macro-economic model were spatially distributed at the landscape scale according to the scenario assumptions considering biophysical, socio-economic, and political forces. Results indicate for most of the old European Union (EU) member countries a decrease in livestock numbers. In the new EU member countries sheep, goats and pigs are expected to decline while beef cattle and poultry are expected to grow. Livestock densities are expected to increase both within and outside current livestock hotspot regions in absence of environmental legislations. Environmental pressure as result of high livestock densities may, however, also remain in regulated scenarios where environmental policies are implemented and income support remains stable over time due to path dependencies in the livestock sector. But contrary to the non-regulated scenario it is less likely that new areas with high risk of negative environmental impacts due to livestock farming will develop.     

Streamwater phosphorus and nitrogen across a gradient in rural–agricultural land use intensity

This paper provides an overview of the impacts of rural land use on lowland streamwater phosphorus (P) and nitrogen (N) concentrations and P loads and sources in lowland streams. Based on weekly water quality monitoring, the impacts of agriculture on streamwater P and N hydrochemistry were examined along a gradient of rural–agricultural land use, by monitoring three sets of ‘paired’ (near-adjacent) rural headwater streams, draining catchments which are representative of the major geology, soil types and rural/agricultural land use types of large areas of lowland Britain. The magnitude and timing of P and N inputs were assessed and the load apportionment model (LAM) was applied to quantify ‘continuous’ (point) source and ‘flow-dependent’ (diffuse) source contributions of P to these headwater streams. The results show that intensive arable farming had only a comparatively small impact on streamwater total phosphorus (TP loads), with highly consistent stream diffuse-source TP yields of ca. 0.5 kg-P ha^?1 year^?1 for the predominantly arable catchments with both clay and loam soils, compared with 0.4 kg-P ha^?1 year^?1 for low agricultural intensity grassland/woodland on similar soil types. In contrast, intensive livestock farming on heavy clay soils resulted in dramatically higher stream diffuse-source TP yields of 2 kg-P ha^?1 year^?1. The streamwater hydrochemistry of the livestock-dominated catchment was characterised by high concentrations of organic P, C and N fractions, associated with manure and slurry sources. Across the study sites, the impacts of human settlement were clearly identifiable with effluent inputs from septic tanks and sewage treatment works resulting in large-scale increases in soluble reactive phosphorus (SRP) loads and concentrations. At sites heavily impacted by rural settlements, SRP concentrations under baseflow conditions reached several hundred μg-P L^?1. Load apportionment modelling demonstrated significant ‘point-source’ P inputs to the streams even where there were no sewage treatment works within the upstream catchment. This indicates that, even in sparsely populated rural headwater catchments, small settlements and even isolated groups of houses are sufficient to cause significant nutrient pollution and that septic tank systems serving these rural communities are actually operating as multiple point sources, rather than a diffuse input.     

青藏高原土地开发潜力与对策

青藏高原土地辽阔 ,地势高寒 ,农林牧各类土地资源的质量与数量很不平衡 ,开发潜力不一。提高现有耕地的单产水平 ;加强草场建设 ,提高畜产商品率 ;禁伐和保护天然林,积极发展经济果木与林下资源的生产 ,乃是高原土地合理开发 ,农业持续发展的重要对策     

Reconnecting crop and cattle farming to reduce nitrogen losses to river water of an intensive agricultural catchment (Seine basin,France): past,present and future

Nitrate and pesticide contamination of surface and groundwater has become a major problem in intensive farming regions in Europe, with nitrate concentrations reaching values above the standard defined in 2000 by the European Water Framework Directive. In the Seine basin, a major issue is the closure and abandonment of drinking-water wells, which force water managers and drinking-water producers to explore solutions for water resource protection. Organic farming has appeared as a credible alternative to conventional farming, and this study explores the potential of organic farming to reconcile agricultural production and water quality. On the basis of agricultural statistics, survey questionnaires and experimental data, the nitrogen soil surface balance (N-SSB) has been established at the scale of a small 104-km² catchment (The Orgeval sub-basin), representative of the intensive cash crop farming in the Seine basin. The N-surplus for arable land in specialized organic cash crop systems has been found to be half that of current conventional systems (15 kg N ha⁻¹ yr⁻¹ versus 30 kg N ha⁻¹ yr⁻¹, respectively). The N-yield in organic systems is 21% lower than in conventional systems, but total fertilization (mostly symbiotic N fixation) is also 26% lower. Whereas 2–3 years of forage legume (e.g., alfalfa) as a starter crop of the typical 7- to 10-year diversified rotation builds up N soil fertility and helps prevent weeds without pesticides, the existence of an outlet for this fodder production is a limiting factor for the economic sustainability and the environmental benefits of these farming systems. Therefore, we explored the possibility of a reconnection of livestock and crop farming systems in the Orgeval catchment, a traditional dairy farming and Brie cheese production region. We calculated the N-SSB for this type of a reconnected livestock and cropping system and found a value very close to the specialized organic cash crop system with full utilization of fodder production, leading to profitable animal production, essentially as milk in this farm design. This reconnected system is compared with the estimated situation in 1955 before separation of plant and livestock production. Furthermore, the N-SSB values were converted into infiltrating sub-root concentrations and used as a boundary condition to a biogeochemical model. Organic cropping and organic reconnected livestock cropping systems result in a 50% reduction of surface water nitrate concentrations, a surface water quality 20% better than that reconstructed for 1955, with an overall higher protein production.     

青海省塔拉滩草原利用方向探讨

青海省共和县塔拉滩是一个平坦开阔的大草原，近４０多年来一直有宜农与宜牧之争。本文就此，从３个方面作了重点论述：垦滩种粮的后果严重；超载过牧也有潜在生态危机；最佳出路是将根治沙源与合理利用草原结合起来，发展季节畜牧业，走一条治用结合、滩谷互补、农牧业相互促进的道路，建设一个新型草原。     

The new assessment of soil loss by water erosion in Europe. Panagos P. et al., 2015 Environmental Science & Policy 54, 438–447—A response

We respond to an article by Panagos et al.—‘The new assessment of soil loss by water erosion in Europe’ in Environ. Sci. Policy, 2015, 54, 438–447. It is aimed at helping policy makers make better decisions. The assessment uses a Geographical Information Systems approach based on the Revised Universal Soil Loss Equation. RUSLE is based on data gained from plot experiments. The authors assume RUSLE is the only way to assess erosion and ignore critiques of erosion models and other ways of assessing erosion. A different way of assessing water erosion, based on collecting information on extent, frequency and rates, mainly from farmers’ fields but also grazed uplands, has been carried out over recent decades in Britain. The two ways of assessing erosion, one largely theoretical, the other based on reality, evolved in response to particular situations. However, they should relate well to each other. We show that the model is inappropriate to assess soil loss by water erosion in Britain, not only for agricultural land but also for uncultivated land. Predicted high rates of erosion do not relate well to where erosion actually occurs and are too high, and the model takes no account of the spatial extent of erosion on the ground. In other words, the model does not reflect reality. Policy decisions should not be taken based on such a model. Erosion must be assessed in a better way with a large field-based element.     

规模化畜禽养殖小区替代分散养殖模式污染物减排核算及建议

规模化畜禽养殖小区采用生态工程处理养殖废水和粪便,是一种新出现的环保型养殖模式,与传统的分散养殖方式相比,具有集约型、减量化的特点.本文通过实地调查,监测某规模化畜禽养殖小区及其替代同等规模分散养殖户的主要污染物排放浓度和排放总量,为核算污染物初始排放量、削减量及外排量提供基础数据,以研究和核定实施集约化养殖后污染物减排成效.结果表明,规模化畜禽养殖替代散户养殖,能大幅度减少规模养殖区域养殖废水及污染物外排量,减少幅度为:废水量41.6％,COD 93.5％,NH3-N 99.9％,TP 99.4％,SS 90.5％.养殖小区通过源头减排,提高末端治理效率,并配套农牧结合的有效实施,可使替代养殖户的排污量削减全额认定,实现污染物“零排放”.     

Modelling interactions and feedback mechanisms between land use change and landscape processes

Land use changes and landscape processes are interrelated and influenced by multiple bio-physical and socio-economic driving factors, resulting in a complex, multi-scale system. Consequently in landscapes with active landscape processes such as erosion, land use changes should not be analysed in isolation without accounting for both on-site and off-site effects on landscape processes. To investigate the interactions between land use, land use change and landscape processes, a case study for the Álora region in southern Spain is carried out, coupling a land use change model (CLUE) and a landscape process model simulating water and tillage erosion and sedimentation (LAPSUS). First, both models are run independently for a baseline scenario of land use change. Secondly, different feedbacks are added to the coupled model framework as ‘interaction scenarios’. Firstly effects of land use change on landscape processes are introduced by means of a ‘changed erodibility feedback’. Secondly effects of landscape processes on land use are introduced stepwise: (i) an ‘observed erosion feedback’ where reallocation of land use results from farmers’ perception of erosion features, and (ii) a ‘reduced productivity feedback’ whereby changes in soil depth result in a land use relocation. Quantities and spatial patterns of both land use change and soil redistribution are compared with the baseline scenario to assess the cumulative effect of including each of the interaction mechanisms in the modelling framework.Overall, total quantities of land use change (areas) and soil redistribution do not differ much for the different interaction scenarios. However, there are important differences in the spatial patterns of both land use and soil redistribution. In addition, by incorporating the perception and bio-physical feedback mechanisms, land use types with stable or increasing acreages are increasingly relocated from their original positions, suggesting a current location on landscape positions prone to soil erosion and sedimentation. Implementing the ‘reduced productivity feedback’ causes most of these effects. Another important outcome is that on-site land use changes trigger major off-site soil redistribution dynamics. These off-site effects are attributed to down slope or downstream changes in sediment transport rates and/or discharge caused by changes in land surface characteristics.The results of this study provide insight into the interactions between different processes occurring within landscapes and the influence of feedbacks on the development of the landscape. The interaction between processes goes across various spatial and temporal scales, leading to difficulties in linked model representation and calibration and validation of the coupled modelling system.     

三工河流域油料作物的农户种植意愿影响因素分析——基于Logistic模型和240户农户微观调查数据

论文以新疆三工河流域27个行政村(连队)240户农户的调查数据为基础,通过建立农户种植油料作物意愿和各自变量的Logistic回归计量模型,从家庭特征因素、 资源禀赋因素、 家庭经济因素和其他因素四大方面分析了农户对油料作物种植意愿的影响因素。研究表明:家庭总人口、 对农业技术服务的态度与农户的种植意愿呈正相关关系,且对农业技术服务的态度标准化系数更大,影响更显著;常年从事农业劳动人数、 户主文化水平和地块位置与之呈反相关关系,且户主文化水平的标准化系数更大,影响更显著。但是反映土地投入、 种地收入以及人均收入没有通过检验,不能得出这几个变量与农户种植油料作物意愿之间的关系。文章最后探讨了兵地差异对农户种植意愿的影响及研究展望。     

Quantification and control of microbial pollution from agriculture: a new policy challenge?

Faecal indicator organisms (FIOs) are commonly used to quantify pollution of public health significance. Health protection, as indexed by FIO control, is a central aim of new ‘catchment-scale’ water quality management required in the USA by the Clean Water Act and in the European Union (EU) by the Water Framework Directive (WFD). Experience of the former, after a decade of implementation, suggests that the most significant reason for water quality ‘impairment’ is elevated FIO concentrations, mainly in recreational and shellfish harvesting waters. This provides an early warning of possible problems which the EU regulatory authorities are likely to face. To date, however, a surprising lack of EU attention has been given to prediction and control of catchment fluxes of this key parameter. This is likely to prove embarrassing if the experience of the US regulatory community is not acted upon with some urgency. There is a growing, though still partial, body of empirical science to form the ‘evidence-base’ for good regulatory practice. However, adoption of ‘best management practices’ (BMPs) to effect remediation of impacted waters will require close integration of water policy with policies on financial support for the farming community. This is likely to require enhanced communication and integration within the discrete policy communities addressing the agricultural sector through the Common Agricultural Policy and water regulation through the Water Framework Directive.     

禁牧政策及其效应解析

近年来,各地对脆弱生态环境的改善手段逐步从生态建设为主转向建设和保护并重的方向。禁牧政策便是影响重大的保护措施之一。通过对实施禁牧政策较早的、位于农牧交错带的内蒙古伊金霍洛旗的实地调查和分析发现,全年禁牧政策对保护和恢复面积广大的林草地生态环境很有效,但它与当地农牧户畜牧业生产的现实矛盾较大,执行率只有52.98％。因此,提出改变限制性禁牧政策为引导性禁牧政策的观点,实行有弹性的禁牧政策,以及农牧户改变畜牧业生产方式和调整畜种结构等政策调适建议。     

Relationships between diversity of grassland vegetation, field characteristics and land use management practices assessed at the farm level

In order to assess the impact of policies to encourage extensification in less favoured areas and improve our knowledge of extensive livestock systems, we analyzed relationships between the diversity of grassland vegetation and land use management practices and field characteristics. This study, conducted on a mountainous area in the centre of France, was based on 149 fields, mainly of natural grasslands belonging to 7 farmers. Regression analyses were performed to analyze the relations between the grassland vegetation types (five types established from the list of dominant species), management practices (cutting versus grazing and fertilization) and the topographic (altitude and aspect) and topologic (slope, distance and surface area) characteristics of the fields. The land use management rules used by the farmers were studied by specifying the grazing management rules of the herd (dairy cows), as well as those for conserved forage (mainly hay or silage) and were identified from observations mentioned on the “grazing schedules”, as well as from interviews at the beginning, in the middle and at the end of the study period. The statistical analysis showed that neither the topographic characteristics of the fields nor the distance from the cowshed or surface area were correlated with the grassland vegetation types. It was the management practices used, largely determined by the field slope, which determined the grassland vegetation type. On the other hand, farmers’ statements showed that the grazing and cutting management rules were mostly determined by the slope of the fields and the distance from the cowshed and, to a lesser extent, by the altitude and aspect. These results showed that the farmers take into consideration environmental differences when choosing fields to allocate for grazing and cutting at different seasons, particularly when they are constrained by these features. Nevertheless, when the constraints were minimal, a wide diversity of grassland vegetation types was also observed. This diversity was a result of attributing different functions to the fields which led to different management practices (defoliation methods and fertilization) and, thus, to different grassland vegetation types. Consequently, for farms where animal feed requirements vary according to the time of the year and the type of animal, we suggest that diversity in the grassland vegetation types is a sound component of these livestock systems.