特困地区自然灾害脆弱性及其致贫效应的调查分析

为揭示市场化反贫困进程中农户的自然灾害脆弱性及其致贫效应,厘清精准扶贫工作优先序,本文采用滇桂黔石漠化地区和秦巴山区连片特困地区的农户调查数据,对农户灾害风险的感知情况进行分析,并通过熵值法和Probit模型评估农户的自然灾害脆弱性和市场风险脆弱性。通过对二者致贫效应进行对比研究后发现,相较于市场风险,自然灾害尤其旱涝等气象灾害是农户面临的主要威胁。农户自然灾害脆弱性程度更高,说明与市场风险相比,自然灾害对其造成损失的可能性更大。自然灾害脆弱性程度提高会显著增加农户陷入贫困的可能性,其致贫效应强于市场风险脆弱性,但两者致贫效应存在着统计意义上的此消彼长关系。可见,自然灾害致贫问题仍然不容忽视,应将提高特困地区农村抗灾减灾能力摆在首要位置,并促进小农户与大市场的有效对接,惟此方可实现特困地区农户精准脱贫和稳定发展。     

水土保持生态自然修复适宜性研究综述

 根据我国的地域特点和水土保持生态建设的实施情况,进行适宜性研究至关重要。在介绍生态自然修复主要基础理论的基础上,分析了自然因素和人为因素对生态自然修复的影响作用。从区域定性、定量分析,地带性分区到GIS技术应用,以及适宜人为促进修复的作用和措施等方面探讨了水土保持生态自然修复适宜性研究的方法和内容。生态自然修复适宜性研究正向前迈进,在地理空间分析技术的引领下,生态自然修复适宜性评价在方法上会有新的发展。     

A methodology for the selection of aquatic natural areas

A methodology is presented for selection of aquatic natural areas based on numerical ranking of sites. Non-weighted points are assigned to 24 physical and biological characteristics of the aquatic and terrestrial components of a proposed natural area. Cumulative score reflects both natural diversity and occurrence of unusual species or conditions. A systematic selection procedure is described which can be utilised by land managers or natural area organisations to arrive at and support objective decisions involving natural area selection.     

干旱荒漠区植物骆驼刺的耗水规律

天然植物的耗水量是其生态需水量的一部分，也是确定其生态需水量的基础。额济纳旗位于黑河的下游，属于干旱荒漠区，全区域只在河流沿岸依靠地下水形成天然绿洲，骆驼刺是天然绿洲上的一种常见多年生天然矮灌木，具有额济纳旗天然植物根系生物量比地上部分生物量大的多且侧根十分发育的共有特点。因此搞清骆驼刺的耗水规律及耗水量将为认识额济纳旗区域内其它天然植物的耗水量及其耗水规律提供科学的基础。同时也将为维持额济纳旗现有天然生态不再恶化提供科学的依据。为此本文利用由土壤含水量及根系有效长度得到的折算因子与可能蒸散量的积成功地确定了骆驼刺实际蒸散量即其耗水量。得出额济纳旗天然矮灌木骆驼刺林地的年耗水量为132．00mm。并得出额济纳旗矮灌木骆驼刺的耗水量主要来源于潜水蒸发量与土壤贮水量。     

农业可持续发展模式设计的自然资源评价方法初探

在农业可持续发展模式设计中通过进行以经济价值为表征的自然资源持续性评价,有利于变自然资源的无偿使用为有偿使用,保持农业自然资源的生产能力。对资源经济价值评价理论与方法进行了集中分析,并以资源折旧法对拜泉县试验小区数据进行了运算分析,证实了该方法的有效性。     

Investigation,evaluation, and priority ranking of natural areas

Texas experience suggests that amateur naturalists will be heavily involved in preliminary ecological surveys of natural areas, hence a simple key for identification of community-types is presented. Line intercept transects are suggested for amateur use in providing standardised quantitative data on the physiognomy of natural areas. A scheme for the evaluation of each area utilises the weighted values of climax condition, educational suitability, species significance, community representation, and human impact through multiplicative scoring to give a natural area score. With the weighted values-multiplicative scoring scheme, natural areas are clearly distinguished in priority for acquisition.     

天然植物提取物在果蔬保鲜中应用研究进展

农产品采后保鲜始终是关系到农业可持续发展的重要问题，采用天然植物提取物对果蔬进行保鲜可以减少化学合成杀菌剂对人类健康的不良影响，并有效防止植物病原菌的抗药性。能够应用到果蔬贮藏保鲜中的天然植物提取物主要是天然香辛料和部分中草药, 其提取物对果蔬贮藏保鲜过程中的主要病原菌具有较强的抑制作用。天然防腐保鲜剂的活性成分大多是挥发性精油，主要通过作用于微生物的细胞膜或者能量代谢途径达到抗菌效果。天然植物提取物在果蔬保鲜中的主要应用方式有浸蘸、熏蒸、喷洒或与保鲜纸及涂膜剂等载体相结合，但目前尚缺乏成熟的产业化应用技术。发展植物源果蔬保鲜剂的未来研究应集中于确定植物提取物的活性成分与构效关系，以及产业化应用的系统工程技术。     

关于水土保持生态修复工程中几个问题的思考

 生态修复是近年来水土保持生态建设的新思路,但目前对其概念的界定尚不统一。为了探讨水土保持生态修复工程的理论,加速生态修复实践的进一步深入,讨论了生态修复的定义、水土保持与生态修复的关系,提出了实施生态修复的思路。     

Dose Response Models with Natural Mortality and Random Effects

When fitting dose–response models to entomological data it is often necessary to take account of natural mortality and/or overdispersion. The standard approach to handle natural mortality is to use Abbott’s formula, which allows for a constant underlying mortality rate. Commonly used overdispersion models include the beta-binomial model, logistic-normal, and discrete mixtures. Here we extend the standard natural mortality model by including a random effect to account for overdispersion. Parameter estimation is based on a combined EM Newton–Raphson algorithm, which provides a simple framework for maximum likelihood estimation of the natural mortality model. We consider the application of this model to data from an experiment on the use of a virus (PhopGV) for the biological control of worm larvae (Phthorimaea operculella) in potatoes. For this natural mortality model with a random effect we introduce the likelihood ratio test, effective dose, and the use of a simulated residual envelope for model checking. Comparisons are made with an equivalent beta-binomial model. The procedures are implemented in the R system.     

The use of natural areas to establish environmental baselines

In order that wise decisions can be made in environmental management, an understanding is needed of ecosystem functioning and reaction to change. To obtain this information we must have continuing knowledge of the undisturbed ecosystem as a baseline against which to measure the effects of modifications. It is proposed that relatively undisturbed natural areas form the basic research tool for the establishment of such baselines. Thus, there is a need for a comprehensive natural area system to preserve, manage, and catalogue for use, the full range of natural area types. This, together with a network of environmental monitoring stations, should lead to the long-term continuation of the many baseline measurements required for necessary ecosystems analysis programmes. It is expected that such a system of natural area/baseline programmes will lead away from the narrow focus on pollution and towards an integrated approach to environmental quality and management.     

川南天然常绿阔叶林人工更新后枯落物层持水特性研究

对川南林区天然常绿阔叶林及其人工更新成檫木林、柳杉林和水杉林后林下枯落物层蓄积量、自然含水量和持水过程进行研究。结果表明：枯落物层蓄积量天然常绿阔叶林（25．68t／hm^2）〉水杉林（18．14t／hm^2）〉檫木林（9．95t／hm^2）〉柳杉林（1．13t／hm^2）。天然常绿阔叶林枯落物层自然含水量分别是檫木林、柳杉林和水杉林的3．18倍、41．33倍和1.53倍。在整个持水过程中．前2h内各林分枯落物层持水作用较强。林下枯落物层持水量与浸泡时间之间的关系式为Q=alnt＋b．吸水速率与浸水时间之间的关系式为V=kt＂。枯落物层最大持水量、最大拦蓄量和有效拦蓄量均是天然常绿阔叶林〉水杉林〉檫木林〉柳杉林。因此，保护天然常绿阔叶林及其选择适宜的树种进行更新对于提高林下地表枯落物层水文生态功能具有重要的作用和意义。     

自然灾害的风险特征及风险管理模型的探讨

随着人口的增加和城市化的发展,自然灾害问题将更加严峻,理解自然灾害的风险特征比以往任何时期都显得更加重要.在认识自然灾害风险的特点和风险概念的基础上,本着科学与实用,通用与开放的原则,构建一个由风险鉴别、风险分析、风险评估和风险处理四个模块组成自然灾害风险管理模式,该模型具有灾害风险管理的基本思路和系统方法,能够为灾害风险管理提供行动指南.     

定西黄土丘陵沟壑区不同土地利用类型水土流失研究

以坡耕地作为对照,通过自然降水条件下径流小区连续14年的观测资料,分析了人工乔、灌、草植被和自然草地的水土流失差异,揭示了不同土地利用类型小区的减水减沙效果:不同土地利用类型小区具有不同的产流、产沙量,年产流值具有显著性差异,坡耕地、牧草地和乔木林地间年产流没有显著性差异,自然草地与灌木林地间年产流也没有显著性差异;各类径流小区年产沙量具有显著性差异,牧草地与乔木林地、自然草地与灌木林地间的产沙量无显著性差异,坡耕地、牧草地和乔木林地的产沙量明显大于自然草地和灌木林地;乔木林地比自然草地、灌木林地有更高的土壤侵蚀强度及频率。在定西黄土丘陵沟壑区,控制水土流失的基本措施是保护好现有的自然植被,实行坡耕地退耕还林还草,建设人工植被应实行"灌木为主,草灌优先,草灌乔相结合"。     

Tin streaming and channel changes some preliminary observations from Dartmoor, England

The valley floor of the North Teign River on Dartmoor has been much modified by tin streaming activity, particularly during the nineteenth century. Field measurements of channel size at sample sites along the river were collected, to asses whether the tin streamed reaches had undergone observable channel changes. Close similarities in the relationships between channel size and drainage area for both natural and streamed sites suggest that no real channel changes are apparent at the present time, but differences in the relationships between channel size and total stream length for the natural and streamed sites show that the uppermost natural sites are considerably larger than the streamed sites at similar locations. Integration of the relationships between channel size and total stream length allows a comparison of estimated total network volumes for the streamed and natural sites, and the estimated volume for the streamed river is about 18 % smaller than that of the natural channel over the same reach. Channel change is believed to be related to changes in the size composition of sediment load in the stream, occasioned by the modified distribution of valley floor sediments brought about by the streaming activities.     

Natural product chemistry meets genetics: when is a genotype a chemotype?

The chemotype of a microbial or plant species has traditionally been defined as its profile of natural products, and the genotype has been defined as its genetic constitution or DNA sequence. The purpose of this perspective is to discuss applications of DNA genotyping, particularly by polymerase chain reaction (PCR)-amplification methods, to predicting natural product chemotypes of fungi and plants of importance in food and agriculture. Development of PCR genotyping for predicting chemotypes will require collaboration between molecular biologists and natural product chemists, as well as community standards for reporting data. PCR genotyping should be validated by chemical analysis of individuals that represent the allelic diversity of the target gene in the population. To avoid misinterpretation, it is critical to differentiate data obtained by genotyping from data obtained by chemical analysis. The obvious and appropriate solution is to retain the established meanings of genotype and chemotype, both of which have been in use for half a century in the fields of genetics and natural product chemistry.     

宁夏六盘山不同森林类型林地的贮水量

 为评价宁夏六盘山不同森林类型的水源涵养生态功能,对宁夏六盘山地区华北落叶松人工纯林、辽东栎天然纯林、白桦+山杨天然混交林和华山松+红桦+白桦天然混交林4种林地枯落物和土壤的贮水特征进行研究。采用样方法和浸泡法测定枯落物不同层次的最大持水量和持水特性,采用环刀法和浸泡法测定土壤水分物理性质和贮水量。结果表明:林地枯落物层饱和贮水量为华山松+红桦+白桦天然混交林最大,华北落叶松人工纯林次之,辽东栎天然纯林其次,白桦+山杨天然混交林最小;除华北落叶松人工纯林枯落物未分解层和华山松+红桦+白桦天然混交林半分解层在浸泡6h时达到最大持水量外,其他森林类型各层次均在浸泡3h时达到最大持水量;土壤饱和贮水量为华山松+红桦+白桦天然混交林最大,辽东栎天然纯林次之,华北落叶松人工纯林其次,白桦+山杨天然混交林最小。     

Data-SSI与图论聚类结合识别果树固有频率

果树的固有频率是林果振动采收机械设计的重要依据之一。为有效识别果树的固有频率,该研究提出了基于数据驱动随机子空间Data-SSI（Data-driven Stochastic Subspace Identification）法与图论聚类稳定图相结合、仅以果树的输出响应信号对果树进行固有频率识别的方法,以尽量减少人为主观因素的影响。将该方法用于一棵室内小型银杏树和一棵室外较大银杏树固有频率的识别并与冲击力锤频谱测试结果进行对比分析。结果表明,室内小型果树在随机激励下本文方法识别结果与频谱试验结果相对误差小于4.17%;室外大型果树在环境激励下所提方法识别结果与频谱试验结果平均相对误差为2.88%,最大相对误差为6.02%。本文方法对仅基于输出响应信号的果树固有频率识别具有一定可行性,可为果树智能化共振采收时快速准确确定共振频率提供参考。     

Principles of selecting reference soils for the Red Data Book of Russian Soils

The meaning of the term “etalon” (reference, standard) in natural sciences and, particularly, in soil science is discussed. The need to preserve natural landscapes and soils as reference objects for comparison with their anthropogenically transformed analogues and as a basis for sustaining the natural diversity of plants and animals is demonstrated. The principles and criteria for the choice of reference soils for the Red Data Book of Russian Soils are suggested. The choice of reference soils should be made with due account for the provinces of the soil-geographical (or soil-ecological) zonation as territories characterized by similar environmental conditions and typical soil cover patterns.     

北京市八达岭林区生态修复对植被多样性的影响

通过比较封山育林、抚育和更新措施3种样地与对照样地（未采取措施）植被多样性的差异,分析了八达岭林区不同水土保持生态修复措施在植被恢复中的作用。结果表明,总体上采取措施的样地植被多样性大于对照样地;对于灌木而言,对照样地与其它3种采取措施的样地存在显著差异,多样性指数小于采取措施样地,而封山育林、抚育和更新三者之间无显著差异;对于草本而言,对照样地与其它3种之间无显著差异;均匀度变化与多样性指数基本一致,生态优势度变化与其几乎相反。实施水土保持生态修复,植被多样性增加。     

青海省大通县退耕还林生态功能综合评价

根据生态经济学原理,采用层次分析法（AHP）,建立了黄河上游退耕还林还草综合生态效益评价指标体系和数学模型。以青海大通县为例,对天然云杉林、退耕林地、天然荒草地、天然灌丛等植被类型进行综合生态效益评价,与农田生态系统进行对比研究。评价结果表明：天然云杉林、退耕林地、天然灌丛等类型的生态效益指数均大于农田生态系统,其综合生态效益指数排列顺序为,天然云杉林＞退耕林地＞天然灌丛＞农地＞天然荒草地。这一研究结果可为黄河上游退耕还林生态工程建设提供参考。