替代面法和推算法在淅川库区氨氮干沉降评估中的适用性分析

农业源氨氮沉降是水库型水源地水体收到的重要的外源氮之一,其沉降量评估与来源识别是水体氮污染防控的重要依据 .替代面法和推算法是大气氮素干沉降监测的两种常用方法 .采用替代面法和推算法,于 2019年 9月—2020年 8月对淅川库区周边设置的 5个大气监测点进行干沉降样品采集,测定了样品中氨氮浓度及其氮同位素,探讨了 2 种监测方法在氨氮干沉降通量估算及氨氮来源解析中的适用性 .结果表明：替代面法获得的氨氮干沉降通量为推算法的1.4～2.1倍,2种监测方法获得的氨氮干沉降通量在时空变化趋势上具有一致性;推算法获得的δ¹⁵N-NH₄⁺较替代面法偏负,季均相差为11.1‰,时空差异显著.替代面法在获得淅川库区氨氮干沉降通量方面具有优势,受氨氮分馏影响,直接获得的 δ¹⁵N-NH₄⁺值较初始源 δ¹⁵N-NH₃值存在较大偏差,影响溯源结果的准确性;推算法能够分别获得不同氨氮形态干沉降中的 δ¹⁵N...     

Participatory integrated assessment of adaptation to climate change in Alpine tourism and mountain agriculture

Winter tourism and mountain agriculture are the most important economic sectors in a major part of the Swiss Alps. Both are highly sensitive to changing climatic conditions. In the framework of the CLEAR project, results from climate impact research in the field of tourism and agricultural production were used to investigate the perception of climatic change by stakeholders and to assess possible adaptations. We used a participatory integrated assessment (PIA) to involve the knowledge, values and experiences of the various social actors in tourism and agriculture (e.g., skiers, tourism managers, farmers) in the research process. Whereas climate change may have various severe direct impacts on the tourism industry, depending on the region, agricultural production may generally benefit from changed climatic conditions. But because of the dependence of farmers on “off-farm” income, the loss due to declining winter tourism in specific areas may cause more important indirect effects. However, the two sectors may adapt actively by choosing from a variety of strategies, and the loss of income from the tourism industry may support the re-evaluation of the various functions agriculture plays in mountain regions, beyond the production of food. The study demonstrates the suitability of the PIA approach to elucidate the interactions between different stakeholders and their perception of the climate change phenomena. A similar participatory approach could be a useful tool to transfer research results and expert knowledge to the political process addressing adaptations to climate change. This revised version was published online in July 2006 with corrections to the Cover Date.     

典型脆弱生态区的稳定性与可持续农业发展

本文利用分形理论对脆弱生态区的稳定性进行了定量分析 ,并据此指出了脆弱生态区农业可持续发展的限制性因素。最后以内蒙古翁牛特旗为例 ,提出了其农业可持续发展的合理化建议。     

Water Planning and Hydro-Climatic Change in the Murray-Darling Basin,Australia

More than a third of humanity lives in regions with less than 1 million liters of fresh water per person per year. Population growth will increase water demand while climate change in arid and semi-arid areas may reduce water availability. The Murray-Darling Basin in Australia is a region where water reform and planning have been used to reduce consumptive extraction to better sustain river ecosystems under climate variability. Using actual data and previously published models that account for climate variability and climate change, the trade-off between water extractions and water essential to the long-term ecological function of river systems is analysed. The findings indicate that better water planning and a more complete understanding of the effects of irrigation on regional climate evapotranspiration could: (1) increase the overall benefits of consumptive and non-consumptive water use; (2) improve riparian environments under climate variability; and (3) be achieved with only small effects on the profits and gross value of food and fiber production.     

新型农业经营主体参与低碳农业发展的激励机制设计

新型农业经营主体在一定程度上使得我国农业呈现集约化发展,为低碳农业发展提供组织保障,但是其自身没有发展低碳农业的动力。本文基于多任务委托-代理模型,从低碳农业发展过程中政府和新型农业经营主体之间的委托—代理关系为视角,设计政府激励和约束新型农业经营主体参与低碳农业发展的激励机制,促使其兼顾经济效益、环境效益和社会效益。结果表明由于缺乏评价标准,政府对新型农业经营主体在固碳减排效益方面比经济效益方面的不确定性更加明显,而不确定性程度与新型农业经营主体努力结果的可观测性呈负相关关系,固碳减排效益的不确定因素无限大的时候,其激励强度趋于0;在政府的补贴过程中,成本系数越高、绝对风险率越高和不确定因素越多,则政府的激励契约对新型农业经营主体的激励强度就越低,需要强化对新型农业经营主体在固碳减排效益和社会服务效益方面的激励强度;政府对经济效益的最优激励因子与其绝对风险规避呈正向相关,因此政府在对处于高风险规避期的新型农业经营主体组织给予较高的激励,而对于风险规避率较低的处于成熟期的新型农业经营主体组织给予较低的激励。最后对结论进行整理,并作出实际的解释和提出针对性的对策建议。     

新世纪以来国内外生态农业综合评估研究进展

在梳理了新世纪以来国内外文献的基础上,对生态农业的概念进行了溯源与辨析,系统总结了国内外学者对生态农业综合评估指标选取和指标体系建立的主要思路,将现有评估体系归纳为EES框架及其拓展和PSR、DSR模型两类,对评估研究所采用的主要指标进行了频度统计、讨论和中外对比。概括了当前研究中采用的权重确定与综合评估的主要方法并进行了优缺点比较。从农业特征、空间尺度、时间跨度等角度对国内外已有的实证研究进行了分类与总结。研究比较发现,国内生态农业评估在实际指标的选取中,往往将数据易得性放在首要位置,而缺乏对指标之间内在逻辑联系和指标合理性、有效性的审视,指标体系构建缺乏代表性和概括性。此外,在对生态概念的理解上,现有评估体系对农业生产环节的生态影响挖掘的并不深刻,对石油消耗、电力消耗尤其是碳排放等重要的间接生态影响存在遗漏。最后,针对现有农业生态评估存在的问题,研究提出六方面的建议:1鉴于全球气候变化影响的广泛和深入,考察我国和各地区的生态农业需要具有全球视野,应当将农业碳汇/碳源的测度和评估纳入到生态农业综合评估体系中;2评估时应当把握好农业生产效率的提升与生态环境保护两者之间的关系;3重视对农业生态模式和类型的辨识;4以我国农业发展阶段特征作为指标体系设计的基石,避免直接移植国外文献中的指标体系;5注重综合评估的案例导向性,并结合多源异构数据的优势来提高评估准确度;6注重对生态农业发展和变迁情况的长期性、复杂性和综合性的考量,提高评估的空间尺度和时间跨度。     

Air concentrations of currently used herbicides and legacy compounds in the Canadian prairies,subarctic, and arctic

Passive air samplers were installed in the summers of 2005 and 2007 for 90 days at four locations in the agricultural region of the Canadian Prairies and at five locations in the Canadian Subarctic and Arctic. The presence and masses of ten currently used herbicides and three legacy compounds in the polyurethane foam disks were quantified. Herbicides 2,4-D, bromoxynil and MCPA were detected at all locations in the Canadian Prairies and in both years because these herbicides are widely applied to control broadleaf weeds in cereal crops that are an integral part of Prairie agricultural production systems. MCPA was also detected at one location in the Arctic in 2007. The detection of the other seven herbicides in the 2 years combined ranged from no detections (atrazine only) to five detections for the relatively volatile herbicides trifluralin and triallate. Triallate was the only other herbicide detected in the Arctic (2005). Legacy compounds were either not detected (alachlor) or at levels near their detection level (γ-HCH and α-HCH). γ-HCH and α-HCH were more frequently detected in 2005 than in 2007 indicating that their concentrations in Canadian air have decreased over time. γ-HCH, widely used as an insecticide in Prairie oilseed production until 2002, was detected at larger concentrations in the Canadian Prairies than in the Subarctic and Arctic. α-HCH, a manufacturing by-product in technical HCH prior to 1971 in Canada, was not detected in the Canadian Prairies but was at detectable levels in the Subarctic and Arctic as the Arctic Ocean is reported to be a major source of α-HCH to the atmosphere. We conclude that some of the most widely used herbicides in Canadian agriculture today are commonly present in the air in regions where they are applied and that a portion of these herbicides may be traveling as parent molecules to the Canadian Arctic. To the authors’ knowledge, this is the first evidence of the presence of MCPA and triallate in Arctic air samples, perhaps because previous research has seldomly monitored for currently used herbicides in this region.     

中国农业源碳汇估算及其与农业经济发展的耦合分析

农业作为重要的产业部门,在满足人们基本的物质需求的同时具有重要的生态保障和碳汇功能,充分发掘农业的碳汇潜力对于农业绿色化发展和农民增收具有重要意义。本文量化测算了我国1993—2011年的农业源碳汇潜力,并构建农业源浄碳汇与农业经济发展的耦合模型,结果发现农业源碳汇量由1993年的52 318.70万t波动增加到2011年的66 073.77万t,年均增加1.38%,但是农业源的浄碳汇量却呈现波动递减趋势,由1993年的36 691.72万t减少到34 815.67万t,其中粮食作物的CO2吸收总量占据主要部分,经济作物CO2吸收量在农业总的CO2吸收量所占的比重虽小,但是增速较快,年均增幅达到4.15%;从影响因素来看,农业源碳汇和耕地面积关联度不大,农作物单位产量和农业源碳汇呈正相关;农业源浄碳汇与农业经济发展之间处于强负耦合状态,耦合状态不理想,农业产值与农业净碳汇关联度不强,这主要是由高投入、高消耗的农业生产方式引发农业碳排放增加和农业总产出效益提升等原因造成的。最后,本文针对性地提出促进我国农业减排增汇的对策建议:强化政府引导,从农业的规划、生产、消费等多领域进行引导;加大农业减排增汇的技术、资金和人力支持,为农业的减排增汇做好保障;通过林地增汇、农田增汇、草地增汇、综合增汇等多种手段,提升农地的碳汇能力;加快碳市场交易体系建设,以市场杠杆推进农业的减排增汇。     

Linnaeus’ study of Swedish swidden cultivation: Pioneering ethnographic work on the ‘economy of nature’

Carl Linnaeus’ work on the ‘economy of nature’ was a major early development in what became the modern field of ecology. This analysis suggests that a key subject of this work that has been ignored or misunderstood for 250 years is the rural livelihoods, especially swidden (or slash-and-burn) agriculture, which Linnaeus studied during his expeditions through rural Sweden. Rereading his reports in the light of modern work on swiddens, political ecology, and the history of science affords a new appreciation of Linnaeus’ insights into traditional systems of resource exploitation. The logic of nutrient cycling in swidden agriculture and its utilization of natural dynamics to serve human ends exemplify the principles of the ‘economy of nature’, and gave Linnaeus a philosophical basis for understanding and defending this system of agriculture as well as other rural resource use systems in Sweden. This analysis sheds new light on Linnaeus’ ethnographic work, his view of folk environmental knowledge, and his often derided identification with Sweden’s ethnic peoples.     

Conservation agriculture and climate resilience

Agricultural productivity growth is vital for economic and food security outcomes which are threatened by climate change. In response, governments and development agencies are encouraging the adoption of ‘climate-smart’ agricultural technologies, such as conservation agriculture (CA). However, there is little rigorous evidence that demonstrates the effect of CA on production or climate resilience, and what evidence exists is hampered by selection bias. Using panel data from Zimbabwe, we test how CA performs during extreme rainfall events - both shortfalls and surpluses. We control for the endogenous adoption decision and find that use of CA in years of average rainfall results in no yield gains, and in some cases yield loses. However, CA is effective in mitigating the negative impacts of deviations in rainfall. We conclude that the lower yields during normal rainfall seasons may be a proximate factor in low uptake of CA. Policy should focus promotion of CA on these climate resilience benefits.