Learning habitat models for the diatom community in Lake Prespa

Habitat suitability modelling studies the influence of abiotic factors on the abundance or diversity of a given taxonomic group of organisms. In this work, we investigate the effect of the environmental conditions of Lake Prespa (Republic of Macedonia) on diatom communities. The data contain measurements of physical and chemical properties of the environment as well as the relative abundances of 116 diatom taxa. In addition, we create a separate dataset that contains information only about the top 10 most abundant diatoms. We use two machine learning techniques to model the data: regression trees and multi-target regression trees. We learn a regression tree for each taxon separately (from the top 10 most abundant) to identify the environmental conditions that influence the abundance of the given diatom taxon. We learn two multi-target regression trees: one for modelling the complete community and the other for the top 10 most abundant diatoms. The multi-target regression trees approach is able to detect the conditions that affect the structure of a diatom community (as compared to other approaches that can model only a single target variable). We interpret and compare the obtained models. The models present knowledge about the influence of metallic ions and nutrients on the structure of the diatom community, which is consistent with, but further extends existing expert knowledge.     

用改进的TRAP法测定树木端粒酶活性

TRAP法是一种常用的测定端粒酶活性的方法,但并不太适合测定木本植物的端粒酶活性.因此以油松针叶为实验材料,对TRAP法进行改进.参照前人的研究通过对比实验证明,在端粒酶提取过程中将PEG8000加入上清液,可获得高效的端粒酶.在此基础上,对PCR先导引选择TS、模板浓度选择100 ng,最终获得油松针叶高质量的端粒酶PCR产物.应用SYBR Green I替代银染液对电泳凝胶进行染色,获得条带清晰、重复性好的电泳结果.通过对油松针叶、银杏叶片、胡杨愈伤组织、沙冬青悬浮细胞等4种木本植物实验材料进行测定,证明该改进的技术体系可能是适合于木本植物端粒酶活性测定的稳定的、灵敏度高的可行方法.图5表1参17     

古树名木保护地方立法评析与建议

对我国出台的15部古树名木保护地方性法规和规章出台时间、主要内容进行了归纳分析。结果发现:法规和规章中存在着管理体制不顺、权责利不对等、处罚标准不合理等问题。在研究基础上,提出完善古树名木保护立法的建议:加快推进古树名木保护国家立法,逐步完善地方立法,进一步理顺保护管理体制,建立古树名木保护补偿制度,加强科学研究与技术推广等。     

Removal of atmospheric particles by leaves and twigs of urban trees: Some preliminary observations and assessment of research needs

This paper reviews the various lines of evidence that support the hypothesis that above-ground plant parts remove particulates from the atmosphere. Some scanning electron microscope observations of the particulate burden on leaves of London planetree are discussed. The authors present an outline of the kinds of research required to support or reject the hypothesis that urban woody plants are important air filters.     

路面预防性养护时机确定方法探讨

介绍了路面预防性养护时机的确定方法 :应用行驶质量指数或破坏指数、基于时间或路况、效益费用评估、生命周期费用分析、决策树或决策矩阵、评分排序方法进行路面预防性养护时机的确定 ;挖掘了目前路面预防性养护时机选取方法中存在的不足。根据路面破坏的复杂性以及目前路面预防性养护时机选取方法的不足 ,提出应对措施 ,路面预防性养护时机研究应该在一个多标准、基于路面性能的基础上进行 ;在路面结构性能良好的情况下 ,基于预防性养护的路面功能性能衰变是进行路面预防性养护时机研究的关键     

北京不同古树类型和级别对土壤物理性质的影响

以北京的代表性古树白皮松、侧柏、油松和国槐为研究对象,分析不同树种类型和不同级别古树土壤理化特性以及土壤理化特性之间的关系,以期为古树土壤健康评价和复壮管理提供科学的依据。研究结果表明:研究区土壤含水量为10.62%,容重为1.20 g/cm3,紧实度为3.94 kg/m2,土壤孔隙度、毛管孔隙度和非毛管孔隙度分别为20.72%、11.77%和8.96%,各指标都呈中等变异;在6个物理指标中,土壤紧实度、土壤含水量和土壤容重与其他几个物理指标相关性较高;不同树种类型和不同古树级别对古树土壤物理特性影响并不显著。     

Impact of fertilization on chestnut growth, N and P concentrations in runo water on degraded slope land in South China

Growing fruit trees on the slopes of rolling hills in South China was causing serious environmental problems because of heavy application of chemical fertilizers and soil erosion. Suitable sources of fertilizers and proper rates of applications were of key importance to both crop yields and environmental protection. In this article, the impact of four fertilizers, i.e., inorganic compound fertilizer, organic compound fertilizer, pig manure compost, and peanut cake （peanut oil pressing residue）, on chestnut （Castanea mollissima Blume） growth on a slope in South China, and on the total N and total P concentrations in runoff waters have been investigated during two years of study, with an orthogonal experimental design. Results show that the organic compound fertilizer and peanut cake promote the heights of young chestnut trees compared to the control. In addition, peanut cake increases single-fruit weights and organic compound fertilizer raises single-seed weights. All the fertilizers increased the concentrations of total N and total P in runoff waters, except for organic compound fertilizer, in the first year experiment. The observed mean concentrations of total N varied from 1.6 mg/L to 3.2 mg/L and P from 0.12 mg/L to 0.22 mg/L, which were increased with the amount of fertilizer applications, with no pattern of direct proportion. On the basis of these experiment results, organic compound fertilizer at 2 kg/tree and peanut cake at 1 kg/tree are recommended to maximize chestnut growth and minimize water pollution.     

A method for determining critical events during large disasters of production platforms

This article presents a calculation-based methodology to determine the dominant event class in each of the phases of disasters being analysed, and to address the question of whether different disasters have similarities at crucial times in each phase of the disaster. Our approach is based on event network analysis. Disasters can be modelled using block diagrams and multiphase process trees. We propose trees in this article can be used as a tool for modelling phases of a disaster. The starting point for developing these models was fault tree analysis used for modelling the reliability structure of complex systems. This study demonstrates the possibility of using dual fault trees to describe the process as opposed to the structure. In our analyses, we examined four major disasters of production platforms that occurred in the last 50 years: Ixtoc I, Piper Alpha, Petrobras 36 and Deep Water Horizon. The course of each of these disasters has been described, the basic events of these disasters have been isolated, and assigned to event classes. The hierarchical importance of events was determined using the Birnbaum reliability measure, Birnbaum structural measure, Fussell-Vesely measure, criticality measure and improvement potential. For each phase of the analysed disasters, event importance is ranked, and the most important events that contributed to the phase are identified. General principles on the analysed disasters and the methodology used are also discussed.     

Predicting tree distributions in an East African biodiversity hotspot: model selection, data bias and envelope uncertainty

The Eastern Arc Mountains (EAMs) of Tanzania and Kenya support some of the most ancient tropical rainforest on Earth. The forests are a global priority for biodiversity conservation and provide vital resources to the Tanzanian population. Here, we make a first attempt to predict the spatial distribution of 40 EAM tree species, using generalised additive models, plot data and environmental predictor maps at sub 1 km resolution. The results of three modelling experiments are presented, investigating predictions obtained by (1) two different procedures for the stepwise selection of predictors, (2) down-weighting absence data, and (3) incorporating an autocovariate term to describe fine-scale spatial aggregation. In response to recent concerns regarding the extrapolation of model predictions beyond the restricted environmental range of training data, we also demonstrate a novel graphical tool for quantifying envelope uncertainty in restricted range niche-based models (envelope uncertainty maps). We find that even for species with very few documented occurrences useful estimates of distribution can be achieved. Initiating selection with a null model is found to be useful for explanatory purposes, while beginning with a full predictor set can over-fit the data. We show that a simple multimodel average of these two best-model predictions yields a superior compromise between generality and precision (parsimony). Down-weighting absences shifts the balance of errors in favour of higher sensitivity, reducing the number of serious mistakes (i.e., falsely predicted absences); however, response functions are more complex, exacerbating uncertainty in larger models. Spatial autocovariates help describe fine-scale patterns of occurrence and significantly improve explained deviance, though if important environmental constraints are omitted then model stability and explanatory power can be compromised. We conclude that the best modelling practice is contingent both on the intentions of the analyst (explanation or prediction) and on the quality of distribution data; generalised additive models have potential to provide valuable information for conservation in the EAMs, but methods must be carefully considered, particularly if occurrence data are scarce. Full results and details of all species models are supplied in an online Appendix.     

基于游客支付意愿的古树名木资源保护经济价值评估——以安徽省九华山风景区为例

运用条件价值评估法中支付卡式(PC)和二分式(DC)两种问卷,对九华山风景区游客保护古树名木的支付意愿进行研究,并分析了其影响因素。结果表明：838%的游客认为应该对古树名木进行保护,仅有302%对保护现状满意。支付卡式问卷调查结果为808元/(人·月),二分式问卷调查结果为954元/(人·月);按2010年游客接待量401万人次计算,2010年游客对九华山风景区古树名木保护的总支付意愿分别为1500×108元和4589×108元。影响支付卡式问卷支付意愿值的主要指标是年龄、个人年收入、文化程度和职业的相关性;影响二分式问卷支付意愿的主要指标是个人年收入。支付卡式问卷和二分式问卷支付意愿均与第一次调查结果无显著差异,PC1和PC2、DC1和DC2支付意愿值相差分别为062和173元,两次结果重现性良好,对本次研究结果的可靠性给予了保证