DSSAT作物模型的统计和图形校验方法

本文以玉米, 大豆, 马铃薯和冬小麦试验为例, 详细讨论了DSSAT模型的统计校验和图形校验方法及其支持软件EasyGrapher的应用。结果指出: R2 不是理想的模型校验统计,因为它是测量线性回归y = + x + 的拟合度, 其随机误差建立在正态性、 相互独立和方差同质的假设之上。模型校验主要是检验残差di = yi-xi（y 为测量值, x为模拟值）,不是估计回归系数、 。RMSE、 E、 EF 和 d 都是比较好的校验模型残差的统计量, 它们不需要遵循回归模型的基本假设, 统计量的物理意义明确, 大样本容量下统计校验更为可靠。图形校验是模型校验必不可少的辅助工具,当有测量数据时,时间序列和残差校验图形是两种最基本的图形校验方法; 没有测量数据, 模拟图形仍然能够检验模型输出之间或与时间的动态关系, 辨析模拟误差或者错误。应用EasyGrapher 软件可以快速进行DSSAT模型的图形校验和统计校验。     

最新侵蚀模型的应用前景

本文介绍了USLE与RUSLE的主要区别,从分析比较可知,RUSLE比USLE有较大的改进,更符合模拟侵蚀过程的要求。目前推出RUSLE不是等待更完善的高级侵蚀预测模型(如WEPP)问世,而是基于USLE已有一定的侵蚀过程概念基础,其新的模型具有更复杂的结构和需要充分的试验数据的支持。RUSLE仍在发展中,它将以国际单位制出现,以便将使用的方法(RUSLE模型软件包)奉献于用户。对RUSLE模型的应用前景以及今后有希望应用的模型如WEPP,欧洲流失方程以及新近立项的MEDALUS模型的发展前景作了展望和比较分析。     

济离子在电场中的实际模型初探

本文提出泋离子在电场中的实际模型,既不是水化直径9的(H_9O_4)~+离子,也不是裸质子,而是(H_3O)~+离子,是直径约为2的三棱锥形结构的水合离子。用这一模型可以比较合理地解释泋离子在电场中的行为,如含泋离子的电解质对溶胶的聚沉能力、土壤负胶的阳离子交换规律以及泋离子的特殊的离子电导等等。     

面向控制的温室系统小气候环境模型要求与现状

以往的温室作物生长和小气候环境模型,主要是从面向研究而不是面向实际生产的温室获得的,这二者的最大不同是:面向研究的模型主要考虑的是得到作物生长高产所需的"最优"的温室内部气候环境参数设定值,而较少考虑温室内控制设备的能力（控制动态过程）、生产过程中温室外气候变化情况和达到"最优"所需付出的能量等代价;而后者在面向实际生产的自动化控制的温室系统模型中是必不可少的。当前温室系统自动化控制面临的一个最大困难,就是缺乏一个这样的可靠的温室系统模型,而只能采用面向研究的温室系统模型去进行实际生产的温室系统控制,这种忽视实际生产条件下的温室系统模型与理想条件下的模型之间差异的"纸上谈兵"的做法,必然导致温室控制技术水平低、达不到预期效果。该文介绍了温室系统的整个控制过程,对一个实际生产的温室系统中各种变量和参数作了简要描述,并概括了面向实际的温室生产控制要求的温室系统模型的基本结构,对温室环境模型、作物生长模型和能耗及CO₂消耗模型的研究现状作了详细的回顾。从满足控制需求出发对现有的温室系统模型所存在的问题进行了分析,并指出了其中的不足和局限性。探讨了未来温室系统的建模方法和需要解决的关键问题,提出了面向控制需求的温室系统建模要满足的要求,为温室系统的建模研究提供了一种新的思路和方向。     

Soil and Water Conservation Implications on Soil Security and Civilizations Decline-Commented by José Luis Rubio, An International Famous Expert of Soil and Water Conservation Research

水土资源的不当管理或滥用是影响土壤安全,进而导致人类文明衰落甚至毁灭的一个重要因素.本文系根据大量文献归纳而成的综述文章,旨在从世界历史上人与肥沃土壤的关系角度分析水土保持对土壤安全及文明衰落的影响.有关结论目前还主要是基于逻辑推理,而不是已知的事实.但是我们认为其基本的观点都是成立的,结论也合理正确.     

基于多源数据AnnAGNPS西枝江流域的污染模拟研究

以西枝江流域为研究对象,结合GIS技术,建立了AnnAGNPS模型数据库,对流域内非点源污染主要影响因素的特征以及非点源污染的时空分布特征进行了分析。结果表明:流域内降雨侵蚀力、径流深、土壤侵蚀和沉积负荷的年际间变化很大,降雨侵蚀力月间分布极不均匀,季节变化十分明显,后三者的变化趋势都与平均降水量表现出较好的对应关系,但是又并不完全一致;流域内的径流深空间分布极不均匀,而土壤侵蚀、沉积负荷空间变化相对不是十分明显,三者都有沿河道向两边逐渐递减的趋势,在人口密集地区及河塘密集地区,径流相对其他区域比较大。本文为西枝江流域的非点源污染模拟研究提供了基础数据平台,也为该模型在整个东江流域的合理应用奠定了科学基础。     

林网网格总体效应的研究——兼论林网与林带防护效益的差异

近年来,我国平原地区正在建设以农田林网为主体的综合防护林体系。为了从总体上阐明农田林网防护效益,而不是一两条林带的防护效益,我们参照中国株科院林研所防护林室的研究方法,并结合我们测点的实际情况,加以改进,于1980年5—6月在江苏省丰县宋楼公社渠坑大队进行了林网网格总体效应的观测,现将结果整理如下:     

植物物候模型研究

植物物候模型是基于植物对环境因子的响应机理而建立的可模拟植物生长发育的数学方程。本文介绍了树木物候模型和作物物候模型,根据对植物休眠解除过程的不同理解,树木物候模型主要有7种不同的类型;根据作物发育规律而建立的作物物候模型也大体相同。同时,还阐述和探讨了研究植物物候模型的意义、研究中存在的问题及其发展趋势。     

小麦-玉米轮作制中氮肥效应模型的选择──经济和环境效益分析

从经济和环境效益两个方面对描述冬小麦、夏玉米轮作制中作物产量对氮肥反应的四个施肥模型（二次型,平方根,二次型＋平台,线性＋平台）进行了比较研究,结果表明,不同模型的拟合程度都较高,且拟合程度和计算的最佳产量均无显著差异,但线性＋平台和二次型＋平台模型推荐的最佳施肥量大大低于二次型模型,因而经济效益较高,研究还表明,与二次型模型相比,采用线性＋平台和二次型＋平台模型推荐和最佳施肥量,有利于维持土壤无机氮的基本平衡（而不是显著上升！）平台和二次型＋平台模型推荐的最佳施肥量,有利于维持土壤无机氮的基本平衡（而不显著上升！）,提高氮肥利用率,并使小麦、玉米茎秆含氮量降低,表现出较佳的环境效应。     

硫酸盐如何遮蔽正午的阳光

<正> 据一个国际性的气象学家小组报道,过去40年间,在美国、中国和前苏联经历过的大多数气候变暖的原因是温和的夜晚而不是炎热的白天.加州Lawrence Livermore国家图书馆的Michael Maccracken说,温室效应的标准模型根本没有预言到这一点.     

Thematic Evolutionary Analysis of Core Agricultural and Natural Resource Academic Journals in Iran

ABSTRACT

For a core journal to be developed, fruitful research articles, diversity, and continuity of research topics are essential. The main goal of this study was to trace the thematic evolution (historical development) of agricultural and natural resource academic journals (ANAJs) published by public academic institutions in Iran. To this end, the study analyzed 2,961 articles published from 1905–2003 in all publicly-funded ANAJs in all contributing agricultural and natural resource academic majors (subfields), examining the scientific domain, research subject, research method, citations, impacts, and the aggregation level of journals on academic majors and academic majors on journals. Less than 5% of the articles were qualitative and cited theoretical frameworks. Over 95% were quantitative articles as their publications progressed. Thematically, agronomy and plant breeding, with 31.68%, had the highest aggregation level among academic majors; whereas, agricultural extension and education, with 2.08%, had the lowest.     

基于环境库兹涅茨曲线的福建省水土流失状况分析

随着生态环境领域研究的不断发展,水土流失状况与区域经济发展之间的相关关系已成为学术界研究的新热点。运用环境库兹涅茨曲线（EKC）理论和回归分析模型,对1995—2008年福建省水土流失面积与人均GDP进行了分析。研究结果表明,福建省水土流失状况与经济增长之间具有环境库兹涅茨曲线特征。当前该区的经济发展所处阶段可有效减少水土流失面积,对水土保持具有积极的促进作用。     

基于霍尔三维结构的土地整治信息组织模式

为揭示土地整治信息体系的特征,指导土地整治信息处理和交换,促进土地整治信息化建设,该文在对土地整治信息分类现状、要素构成和分类对象分析的基础上,考虑到土地整治信息来源多样、结构复杂等特点,分别从霍尔三维结构理论、项目管理理论和信息生态原理等角度探讨了土地整治信息的组织模式。按照稳定性、系统性、可扩延性、实用性原则,对3种组织模式下涵盖的信息进行了梳理,确定了用于分类的信息要素,结合信息要素的性质,建立了从属性维、信息维和时空维3个维度构建土地整治信息分类体系,并以土地整治规划为例进行了方法论证。研究表明该分类体系能够较为全面、系统地反映土地整治的信息全貌,揭示土地整治信息的层次与特征,对促进土地整治信息技术进步和管理方式转型,提高信息资源共享度和利用深度等具有参考和借鉴意义。     

中国土壤侵蚀研究重大成就及未来关键领域

[目的] 回顾中国土壤侵蚀研究的发展历程,总结该领域的重大研究成果,分析其现阶段存在的问题及未来关键研究领域,旨在为中国水土保持及区域生态建设与绿色高质量发展提供参考。[方法] 基于多年的土壤侵蚀研究野外调查和学术研究工作经验,对中国土壤侵蚀的有关重大问题进行了长期思考。经过多次学术研讨,并与同行权威专家进行了交流和探讨。[结果] 中国土壤侵蚀研究领域近百年来取得了一系列重大研究成果,也存在着一些不足和问题。中国土壤侵蚀研究未来应从土壤侵蚀预报模型完善推广及精度评价,坡面径流计算方法及模型构建,人工模拟降雨试验和水槽试验结果的代表性及真实性评价等方面开展重点研究,并关注土壤侵蚀过程机理、模型应用、技术方法、响应评价、瓶颈问题等议题的研究。[结论] 近百年来的研究实践证明,中国土壤侵蚀研究只有立足于国情,根据中国土壤侵蚀特点、研究现状及社会需求的变化确定和调整研究方向,才有可能取得标志性成果。同时,在国家大力推行生态文明建设的新时代,土壤侵蚀研究也要调整思路和研究重点。此外,水土保持工作还应与国家乡村振兴和生态建设相结合,以先预防,少扰动为主,改变过去先破坏再治理的模式。     

大渡河上游河谷与半山区耕地利用集约度及影响因素的对比分析

集约度变化是土地利用变化研究的核心问题,而目前对西部地区耕地利用集约度特征及原因解释的研究较少。该文采取参与式农村评估法（participatory rural appraisal,PRA）,以大渡河上游典型河谷与半山区为例,共调查农户357户,通过Tobit和OLS估计方法,定量对比分析了河谷与半山区耕地利用集约度及其影响因素。研究表明：河谷区和半山区在耕地利用集约度上存在显著差异。无论是资本集约度还是劳动集约度,河谷区均高于半山区。影响河谷与半山区耕地利用集约度差异的因素有承包耕地面积、人均实际耕地面积、家庭固定资产、离集镇的距离、二三产业收入、农业劳动力、年需换工数量、人情往来支出等。耕地资源禀赋和农业劳动力数量是导致集约度差异的关键因素,农业生产条件或环境和家庭收入水平对其有重要影响。     

Enhanced Degradation of Atrazine by Soil Microbial Fuel Cells and Analysis of Bacterial Community Structure

Atrazine degradation in soil microbial fuel cells (MFCs) under different anode depths and initial concentrations is investigated for different redox soil conditions, and the microbial communities in the anode and different layers are evaluated. Atrazine degradation is fastest in the upper layer (aerobiotic), followed by the lower layer (anaerobic). A removal efficiency and a half-life of 91.69% and 40 days, respectively, are reported for an anode depth of 4 cm. The degradation rate is found to be dependent on current generation in the soil MFCs rather than on electrode spacing. Furthermore, the degradation rate is inhibited when the initial atrazine concentration is increased from 100 to 750 mg/kg. Meanwhile, the exoelectrogenic bacteria, Deltaproteobacteria and Geobacter, are enriched on the anode and the lower layer in the soil MFCs, while atrazine-degrading Pseudomonas is only observed in very low proportions. In particular, the relative abundances of Deltaproteobacteria and Geobacter are higher for lower initial atrazine concentrations. These results demonstrate that the mechanism of atrazine degradation in soil MFCs is dependent on bioelectrochemistry rather than on microbial degradation.     

Taking stock of the assisted migration debate

Assisted migration was proposed several decades ago as a means of addressing the impacts of climate change on species populations. While its risks and benefits have been debated, and suggestions for planning and management given, there is little consensus within the academic literature over whether to adopt it as a policy. We evaluated the main features of the assisted migration literature including the study methods, taxonomic groups, geographic regions and disciplines involved. We further assessed the debate about the use of assisted migration, the main barriers to consensus, and the range of recommendations put forth in the literature for policy, planning or implementation. Commentaries and secondary literature reviews were as prevalent as first-hand scientific research and attention focussed on a global rather than regional level. There was little evidence of knowledge transfer outside of the natural sciences, despite the obvious policy relevance. Scholarly debate on this topic has intensified during the last 3 years. We present a conceptual framework for evaluating arguments in the debate, distinguishing among the direct risks and benefits to species, ecosystems and society on the one hand, and other arguments regarding scientific justification, evidence-base and feasibility on the other. We also identify recommendations with potential to advance the debate, including careful evaluation of risks, benefits and trade-offs, involvement of relevant stakeholders and consideration of the complementarity among assisted migration and less risk-tolerant strategies. We conclude, however, that none of these will solve the fundamental, often values-based, challenges in the debate. Solutions are likely to be complex, context-dependent and multi-faceted, emerging from further research, discussion and experience.     

基于CiteSpace可视化分析有机肥料研究进展

从Wo S数据库核心合集中检索出1900—2019年相关文献4473篇,运用CiteSpace知识图谱分析工具,对合著国家、机构、作者、学科领域、关键词、文献共被引网络等进行可视化分析,对有机肥料的研究进展及演变趋势进行图谱解读与分析:①有机肥料对改善土壤理化性状、抑制土传病害、提高作物产量品质的作用及其机理依然是研究重点;②最新的基因测序等分子生物学技术在有机肥料研究中将得到更加广泛应用;③添加天然沸石、生物质炭等物质制造有机类肥料是未来有机肥料加工的重要方向;④有机肥料研究具有很强的学科交叉性,涉及农业、化学、环境生态学、环境科学、工程学等众多学科领域;⑤中国有机肥料研究发展迅速,国际上合作发表有机肥料学术论文数量前三的研究机构分别是中国科学院、南京农业大学、中国农科院,具有重要的学术影响力。     

Religion, social support, fat intake and physical activity

OBJECTIVE: Most research on diet and exercise has focused on these health behaviours as proximate causes of disease, rather than examine the context of how diet and exercise are developed and maintained. This study examined religion and social support in relationship to fat intake and physical activity. DESIGN, SETTING AND SUBJECTS: Data from surveys of 546 adults aged 17-91 years, residing in one upstate New York county, were analysed. RESULTS: Most relationships between the multiple facets of religion, fat intake and physical activity were not statistically significant. After controlling for demographics and social support, Conservative Protestant women and women specifying an "Other" religious affiliation reported higher fat intakes than did Catholic women. There were no relationships between religion and fat intake in men. In women, religious commitment was associated with greater moderate and vigorous physical activity, whereas in men, divine social support was associated with greater moderate physical activity. Social support did not substantially change the magnitude of the relationships between religion, diet and physical activity. CONCLUSION: Overall, there were few relationships between religion, fat intake and physical activity, suggesting that in contemporary US society religion may play a small role in the context of how diet and exercise are developed and maintained. The limited range of religiosity in the sample, however, may have underestimated the role of religion. Significant relationships between religion and physical activity in women suggest that further research is needed to more clearly delineate religion's relationship with health behaviours.     

Palatability of microfungi to soil arthropods in relation to the functioning of arbuscular mycorrhizae

We investigated the feeding preferences of six species of mites and collembolans for three fungi commonly associated with roots of Acer saccharum (Glomus macrocarpum, Alternaria alternata and Trichoderma harzianum), from a maple-forest soil in southern Ontario, Canada. Experiments were also conducted in vitro to determine animal feeding responses to (1) increasing quantities of hyphal biomass, (2) the presence of root vs. litter fungal substrates, and (3) hyphae of different widths of Glomus macrocarpum. The results indicate that arthropods prefer to graze in the litter region rather than in the deeper soil layers. Under ideal moisture/temperature conditions, animals are forced to the lower regions by interspecific interactions. They prefer to graze on hyphae of conidial fungi rather than on those of arbuscular mycorrhizal fungi. When arbuscular mycorrhizal fungal hyphae are grazed, there is a clear preference for the narrower hyphae, which are those further away from the root. The thicker hyphal segments, commonly found connecting absorptive hyphal fans to roots, were less preferred. These data are not consistent with the hypothesis that microarthropods are detrimental to arbuscular mycorrhizal associations, and suggest that Glomalean fungi may have evolved mechanisms to deter grazing by microarthropods.