台州市主要生物防火林带特点分析与发展对策

在分析台州市森林火灾成因和现有主要生物防火林带特点的基础上,根据台州市的区位特点和森林资源分布现状,提出了适合台州市的17种防火林建设树种和四大类15种生物防火林带建设模式。     

北京高职教师职业幸福感调查与提升策略分析

高职院校教师职业幸福感对高职教育发展意义重大。通过对186名教师开展问卷调查及45名教师进行深度访谈,发现北京地区高职教师职业幸福感具有职业安全感降低、对工作过程体验满意度中等偏上、对家庭生活满意感中等偏上和幸福感与性别、年龄、职称等因素无显著相关关系的特点,课堂教学是高职教师感受快乐最多的工作内容。高职院校可以通过完善管理制度、加强学生管理、为教师提供多种展示能力的平台、加强人文关怀等措施提升教师的职业幸福感。     

生鲜农产品社区社群电商特征及实施策略分析

分享经济为电商的发展与创新提供了新的契机,社区社群电商应运而生。研究社区社群电商产生的背景及内涵,有助于理解生鲜农产品的特点以及社区社群电商相较于传统电商的区别与优势。通过探讨建立专业团队、保持生鲜农产品的三个稳定、找准目标群体、设计营销方案让顾客深度参与、高效低成本的仓配方案等方法与途径,提出了有效开展社区社群生鲜农产品电商的策略,从而为生鲜农产品社区社群电商的发展提供参考。     

气候变化视角下上海黄浦江滨水区洪涝风险评估与分区分策

为进一步降低河口城市滨水区因气候变化引起的洪涝灾害风险,提高城市抗洪能力,基于政府间气候变化专门委员会（IPCC）关于风险的定义,按照危险性、脆弱性、暴露度构建洪水风险指数评估模型,选取11个评价指标,采用场景模拟与GIS空间叠加的方法计算洪水风险指数。选取上海市黄浦江滨水空间为研究区,并分别以2030年、2050年及2100年为时间节点进行情景模拟,进一步按照人口密度单因子进行叠加评价,通过情景模拟识别黄浦江滨水空间景观,更新“三区三策”。结果显示：根据黄浦江滨水区气候变化目标下洪水风险的空间格局,显示风险度等级逐年提高;在2050及2100年的场景模拟中,黄浦江上、下游两部分均显示了高洪涝风险段。采取抵抗（抗洪）策略的岸线逐年增长,对城市高密度人口区等区域威胁日益增大;采取疏散策略的岸线逐年增长,水岸的宜居性降低;采取共处（承洪）策略的岸线逐年减少,需要采取更多抵抗策略与疏散策略。根据气候变化视角下黄浦江滨水区洪涝风险分区分策,泛洪区位于宝山区以东及浦东新区西北角,黄浦江滨水空间需要采取后退疏散策略,实施人口疏散,规划“河口保护计划”,以及在中游松江区内进行生态湿地建设;抗洪区位于中心城区,滨水空间需要继续采取抵抗洪水策略,且风险日益扩大;承洪区位于大部分黄浦江滨水空间,可采取与洪共处策略,但潜力日益缩小。     

Fungal colonization patterns in necrotic rootstocks and stem bases of dieback‐affected Fraxinus excelsior L.

European ash (Fraxinus excelsior) trees currently face the major threat of ash dieback caused by an invasive fungus, Hymenoscyphus fraxineus. Collar rots in F. excelsior have been increasingly associated with infections by this pathogen. However, the aetiology of the collar rots is still unclear and remains heavily debated. In contrast to most studies of this kind, entire rootstocks of four diseased ash trees were dug out to examine necrotic tissues in these rootstocks and stem bases in detail and to sample necrotic wood for fungal isolation. With the aid of morphological and molecular identification techniques, five to twelve fungal taxa were detected per tree. Members of the Nectriaceae family and Botryosphaeria stevensii, the causal agent of stem and branch cankers on many tree species, were frequently isolated from outer xylem. In contrast, H. fraxineus was the dominating species in interior wood layers. Microsatellite genotyping of 77 H. fraxineus isolates helped to identify up to six different genotypes per tree. The role of H. fraxineus and other isolated fungi in the aetiology of ash collar rots are discussed.     

城市绿地植物群落优化配置方法初探

植物群落是城市绿地的基本组成单元,群落结构的合理性是影响城市绿地健康稳定发展的关键。针对城市绿地群落结构中存在的树种选择违背适地适树原则、多样性不足,初植密度过大,植物配置跟风、结构不合理等问题;从优化植物群落配置的角度出发,分别从"树种选择—种植密度—配置模式—组合评价体系"等角度总结出当前国内对于城市绿地植物群落优化调控的方法和先进经验,提出了从物种选择、密度指标和格局设计等方面进行源头控制,加强群落结构动态发展管理和控制配置比例,根据评价体系不断升级城市绿地群落结构等优化策略。     

松材线虫病的发生原因、危害症状及防治策略

松材线虫病能够引起大面积松树出现枯死现象,对松树林产生毁灭性伤害,属于世界性病害。为了有效促进我国林业发展,需要对松材线虫病加强防治。而目前我国在防治松材线虫病过程中难度相对较大,防治技术也比较滞后,资金不足等问题导致难以高效控制松材线虫病。基于此,深入探究松材线虫病的发生原因、危害症状,并提出了有效的防治策略。     

Susceptibility of Eucalyptus grandis and Acacia mearnsii seedlings to five Phytophthora species common in South African plantations

Eucalyptus grandis and its hybrids, as well as Acacia mearnsii, are important non‐native trees commonly propagated for forestry purposes in South Africa. In this study, we conducted pathogenicity trials to assess the relative importance of five commonly isolated Phytophthora spp. (Phytophthora alticola, P. cinnamomi, P. frigida, P. multivora and P. nicotianae) from the plantation environment on E. grandis and A. mearnsii seedlings. Overall E. grandis was more susceptible to the tested Phytophthora spp. than A. mearnsii. Phytophthora cinnamomi was the only pathogen that had a significant negative effect on both the host tree species, leading to a reduction in root and shoot weight as well as to death in the case of E. grandis. Phytophthora alticola and P. nicotianae exclusively affected E. grandis and A. mearnsii, respectively. This study updated the current knowledge on the pathogenicity of Phytophthora spp. on two important non‐native commercially propagated tree species from South Africa.     

Effects of defoliation on whole‐plant maize characteristics as forage and energy crop

Hail affects yield and quality of maize crops, and consequences also depend on the growth stage at which the injury occurred. Whole‐plant maize (WPM) silage is often used within the same farm for cattle feeding and biogas production. The present study aimed to verify the effects of hail damage, simulated by artificial defoliation, on yield and chemical and nutritional features, as well as on biochemical methane potential (BMP) of maize forage. In a randomized block design with three replicates, four defoliation levels (0%, 33%, 66% and 100% of leaf area removal respectively) have been applied at either the V12 (12th leaf), R1 (silking) or R3 (milk) stages for two consecutive years. WPM yield, chemical and nutritional features, and BMP were measured. Dry‐matter (DM) yield per hectare was progressively reduced (p < 0.001) with increasing levels of defoliation and with application at V12 in comparison with R1 or R3 (1.26 vs. 1.39 and 1.46 kg ha^?1 for V12 vs. R1 and R3; p < 0.003). Nutritive value and BMP per unit of product were less altered than dry‐matter yield per hectare by defoliation. Anticipating defoliation reduced net energy for lactation (5.26 vs. 5.46 MJ kg^?1 DM for V12 and R3 respectively; p = 0.02). Total defoliation resulted in an accumulation of nitrates (NO₃) compared to the other treatments (3.98 vs. 1.53 g NO₃ kg^?1 DM; p < 0.001). BMP was mainly reduced by early and complete defoliation. Equations were developed to estimate the effects of defoliation on yield, composition, and nutritive and energetic values of WPM.     

Post‐grazing cutting management in tall fescue affects the sward structure,forage and liveweight production

Tall fescue is the main perennial grass of the pastures of the temperate region of Argentina. However, after flowering in spring, tall fescue loses productivity and quality. Based on this, the objective of this work was to evaluate the effects of different post‐grazing mechanical cutting managements on the forage mass, leaf proportion, stocking rate, liveweight gain and liveweight production of tall fescue pastures. The treatments were post‐grazing mechanical cutting at anthesis (FC), post‐grazing mechanical cutting throughout spring and summer (SSC), and no post‐grazing mechanical cutting (NC). The experiment was performed from 2011 to 2014 in Argentina. The greatest and lowest forage mass were determined in September–November and May–September respectively. The leaf proportion of the SSC treatment was greater than that of the NC treatment, except in September–November. NC had higher stocking rate and lower liveweight gain than SSC, and neither NC nor SSC differed from FC. The liveweight production of the treatments was characterized by a trade‐off between stocking rate and liveweight gain. We conclude that FC is an attractive management because, with a single post‐grazing cutting, swards remain productive and leafy.