Dispersal of invasive Phytolacca americana seeds by birds in an urban garden in China

Although seed dispersal is a key process determining the regeneration and spread of invasive plant populations, few studies have explicitly addressed the link between dispersal vector behavior and seedling recruitment to gain insight into the invasion process within an urban garden context. We evaluated the role of bird vectors in the dispersal of pokeweed (Phytolacca americana), a North American herb that is invasive in urban gardens in China. Fruiting P. americana attracted both generalist and specialist bird species that fed on and dispersed its seeds. The generalist species Pycnonotus sinensis and Urocissa erythrorhyncha were the most frequent dispersers. Seedling numbers of P. americana were strongly associated with the perching behavior of frugivorous birds. If newly recruited bird species use seedling‐safe perching sites, the P. americana will regenerate faster, which would enhance its invasive potential. Based on our observations, we conclude that the 2 main bird vectors, P. sinensis and U. erythrorhyncha, provide potential effective dispersal agents for P. americana. Our results highlight the role of native birds in seed dispersal of invasive plants in urban gardens.     

郑州商品交易所棉花期货价格与现货价格关系的实证分析

采用ADF单位根检验、协整检验、Granger因果检验对我国郑州商品交易所棉花期、现货价格之间的关系进行实证分析。结果表明,棉花期、现货价格之间有高度的相关性,二者之间存在协整关系,棉花期货的价格发现功能已经得到了有效发挥,运行状况良好。     

河北北戴河区农田生态系统服务功能价值测算研究

农田生态系统是支撑与维持地球生命支持系统的重要组成部分,既具有直接供给农产品功能,又具有调节、支持、文化服务等间接功能。研究选取河北省北戴河区农田生态系统为研究对象,以生态系统服务功能为切入点,运用生态经济学方法,综合测算研究区农田生态系统服务功能价值。研究表明,2014年研究区农田生态系统服务功能所产生的间接价值为直接价值的1.09倍,说明农田生态系统不仅具有高效的、直接的生产功能,而且具有极其重要的生态环境支撑功能。鉴于此在北戴河区农业结构调整过程中,要对其生态系统服务功能给予足够的重视。农田生态系统服务功能的各项指标价值量由大到小排序为农田生产供给价值休闲旅游价值固碳释氧价值废弃物处理价值涵养水源价值社会保障价值土壤形成与保护价值秸秆还田价值净化大气价值。因此,研究认为:北戴河区在加快现代农业园区建设过程中,要大力发展生态休闲农业,全力推进农作物秸秆综合利用,积极发展生态循环农业,合理调整农田利用方式,应注重提高调节、支持、文化服务功能价值,使农田生态系统服务功能价值达到最优化。通过对北戴河区农田生态系统服务功能价值测算,为北戴河区有效保护和永续利用农田生态系统提供决策基础和科学支撑。     

森林粗木质物残体贮量及功能研究综述

粗木质物残体(CWD)在森林生态系统能量流动、物质循环以及维护森林生态系统的完整性和稳定性方面发挥着重要作用, 科学有效地对其贮量进行定量化研究, 对进一步了解CWD在生物地球化学循环过程中和全球碳循环与碳平衡中的地位与作用具有重要意义。文中论述了CWD的贮量、CWD的分解、CWD在碳贮量与碳循环中的重要作用以及影响CWD贮量和分解的原因, 系统阐明了CWD在促进森林生产力、维持生物多样性以及促成森林更新等方面的功能, 展望了CWD贮量定量化研究以及结构与功能研究的发展方向。     

基于6PS理论的复合型观光农业开发——以四川省为例

基于市场营销理论中对于6PS的开发,针对观光农业的特性,分析得出观光农业的6PS,即产品、价格、渠道、促销、权力与公共关系需要关注的问题,需要政府、农民、社会、科研机构一起努力共同实现农村闲置土地的合理流转,最终实现四川地区劳动力外出务工促进经济发展和土地资源得到合理利用的双赢局面。     

Severe hail damage to mangroves at Port Curtis, Australia

A hailstorm in October 1994 was found to have moderately or severely impacted on 5.3% of the mangrove forests in Port Curtis. All mangrove species showed evidence of hail damage, including the three most common species (Rhizophora stylosa, Ceriops tagal and Avicennia marina). Physical effects of hail damage included stripping of leaves from plants, holes punched through leaves, bruising to bark, divots removed from bark, branch and plant death. Speciesspecific differences in vulnerability to the effects of hail were observed with C.tagal experiencing relatively higher mortality rates than the other two common mangrove species. A delayed pattern of mortality was observed in two species _ C.tagal and A.marina. Alterations to mangrove community structure included: (1) reductions in stem density, stem diameter and basal area, (2) reductions in canopy cover (based on a photographic index of foliage projective cover) and (3) changes in relative abundance of species in mangrove zones. Recovery was observed in some stands but others had not recovered to prehail levels of canopy cover two years after the hailstorm. Recovery had occurred by regeneration of fresh leaves but no recruitment of young plants had been observed during the study. The forests in the impact area were dominated by either Ceriops tagal or Rhizophora stylosa with Avicennia marinaas a subdominant in places. C.tagal dominated forests within the impact area were relatively more severely affected (41.8% in the severe category) than R.stylosa dominated communities (only 17.4% in the severe category). This indicated that C.tagal dominated forests were more vulnerable to the effects of hail damage than R.stylosa dominated forests. In addition, hailimpacted C.tagal dominated forests represented a relatively high percentage of the area of C.tagal dominated forests in Port Curtis (44.3%). This percentage was much higher than hailimpacted R.stylosa dominated forests in Port Curtis (2.7%). These two factors – relatively severe impact on C.tagal communities and a relatively higher percentage affected within the Port Curtis area – illustrate that hailstorms, as a form of natural disturbance, are an important influence on the forest ecology of mangrove ecosystems in this region.     

奎屯河流域土地利用/覆被及生态系统服务功能变化

[目的]分析25年来奎屯河流域土地利用/覆被与生态系统服务功能的变化,以期为该区域资源管理和生态经济协调发展提供理论基础.[方法]在3S技术的支持下,以1975年和2000年的TM 图像解译数据为基础,采用谢高地的评价方法分析了25年来奎屯河流域土地利用/覆被与生态系统服务功能的变化特征.[结果]1975～2000年,奎屯河流域耕地、城乡建设用地、盐碱地和沙地有所增加,其他林地、草地、水域和沼泽的面积均减少;区域生态系统服务功能从1975年的3 108.68×106元减少到2000年的2 953.91×106元,减少量为154.77×106元,减少率为4.98;;[结论]生态系统服务价值降低说明该区域生态环境趋于恶化,将来区域发展必须加强生态环境保护力度.     

基于理性选择理论的农户农产品安全生产意向研究——以湖北省农村水稻生产为例

调查从农产品生产者的角度出发,通过对湖北省武汉、荆州、枣阳三市288个水稻生产农户的问卷调查和个案访谈,基于理性选择理论视角,在描述农户农产品生产特征与当前农产品安全生产的现状及问题的基础上,从农户的生存理性、社会理性和制度理性三个层面探讨了影响农户安全生产意向的因素。研究表明,农业生产收入、病虫害频率、是否受他人影响、社会身份、政府监管力度等因素与农户安全生产意向相关。据此,研究指出,政府应该通过加大宣传教育、加强农田监督与管理、保障农户生产经济利益等措施,进一步增强农户安全生产的选择意向,从而促进农产品的安全生产。     

利用灰色系统理论对早熟桃果实经济性状的综合评判

利用灰色系统理论对在浙江省金华地区栽培的22个早熟桃果实单果重、可溶性固形物含量、果实硬度、成熟期等8个经济性状进行模糊综合评价。结果显示,春雪、超红桃综合评分为0.634和0.623,综合性状优良,可重点推广;超丽春、海峡佳丽、春蜜、秀玉、金硕、砂红综合性状较优,适合推广;极早518、千年红、早凤王、早霞露、双喜红综合评分中等;以上13个品种综合评判结果均优于金华大白桃(CK1)、大观1号(CK2)。     

社会心理学在耕地保护中应用的探讨

耕地保护必须以人为本,因此有必要根据农民的社会心理,充分调动农民保护耕地的主动性和积极性.本文探讨应用社会心理学的基本思想进行耕地保护,并提出社会科学和自然科学相结合解决耕地保护问题的新思路.