西南边疆地区粮食安全问题研究

在介绍粮食安全概念的基础上,分析了西南边疆粮食安全的重要性和制约西南边疆粮食安全的因素,提出了保障西南边疆粮食安全的路径。     

兰州市高校校园绿地群落物种组成及多样性分析

初步尝试采用天然群落样带调查法对兰州市几所具有代表性高校校园绿地群落进行调查,分析其物种组成、重要值及多样性等特征,为城市生态学研究及校园绿化建设提供理论根据。调查结果表明:5所院校绿化树种中被子植物种类数量均占绝对优势,裸子植物偏少,以蔷薇科、杨柳科、蝶形花科植物为主,显示出北方地域植被的特点;除甘肃农业大学外,其它4所院校绿化树种中的乡土种比例均高于栽培和外来种;甘肃省委党校校园物种种类丰富,均匀度指数较大,多样性较高;其它4所院校绿地群落多样性水平均不高。5所院校校园乔木层、灌木层Shannon-Weiner指数(H’)和Simpon指数的统计结果基本一致。     

关于创新农业科研院所新闻外宣工作的思考

文章阐述了农业科研院所新闻外宣工作的重要性,分析了农业科研院所新闻外宣工作中的"短板",如新闻外宣意识不强、科技人员外宣观念落后、宣传队伍亟待建设等,并针对新闻外宣工作中的"短板"提出了转变观念、协同创新、队伍建设、遵循利用新闻规律等创新外宣工作机制的对策。     

基于新形势下农民健身活动引发的再思考

在新形势下,开展农民健身活动是社会可持续发展和落实科学发展观的需要,是我国国情的需要。分析了开展农民健身活动存在的问题及其有利因素,提出要坚持具体问题具体分析,以点带面,统筹兼顾。     

Forest structure, composition, and tree diversity response to a gradient of regeneration harvests in the mid-Cumberland Plateau escarpment region, USA

Upland hardwood stands on mesic, escarpment-oriented sites on the Cumberland Plateau region of northeastern Alabama provide a myriad management opportunities. Stands are primarily managed for Quercus, but the high species diversity allows for management that targets multiple species. Stand composition is unique in that dominant species include shade tolerant species such as Acer saccharum, intermediate tolerant Quercus spp. and Carya spp., and intolerant Liriodendron tulipifera. Three replications of five levels of disturbance were created to assess species compositional changes; disturbances included three levels of harvest intensity, a mid-story herbicide treatment, and a control. After eight growing seasons, there were no discernable differences in species richness, diversity or evenness. Importance values based on relative basal area and relative density also changed little, except for clearcuts where L. tulipifera greatly increased. An initial gradient in basal area, canopy cover, and light created by harvesting or thinning dissipated following five growing seasons. Options exist for future stand management, including promoting two-aged or uneven-aged systems. Maintenance of Quercus will require additional tending.     

浅议房地产景观

在景观融入房地产的过程中,地产景观作为一种新兴事物在房地产发展过程中不断的发展与完善。地产景观在房地产项目中所扮演的角色越来越重要,也越来越受到人们的关注与议论。地产景观的营造与发展成为了当今的一个重要话题,地产景观在争议中不断的成长发展壮大。本文笔者从园林的自然风貌、园林特点、人文景观、历史沉淀等多方面的特点为出发点探讨地产景观的多样性、自然性等特点。     

载畜率对荒漠草原植物群落影响的研究

对不同载畜率下短花针茅荒漠草原植物群落特征进行比较,结果表明:不同植物种群的盖度对载畜率的响应不同,无芒隐子草盖度在轻度放牧区最大,栉叶蒿盖度在7月份、8月份分别以中度放牧区和轻度放牧区最大;短花针茅、冷蒿、阿氏旋花、细叶葱、木地肤随载畜率增大高度下降明显,猪毛菜高度在四个载畜率下差异均不显著;随着载畜率的增大,植物群落生物量呈下降趋势,且重度放牧与不放牧、轻度放牧有显著差异;随着载畜率的增大,建群种、优势种地位改变不明显,但一年生的猪毛菜重要值增大,在重度放牧区达到最大并占据优势地位;Shannon-wiener指数、Simpson指数、Pielou均匀度指数均以轻度放牧区最大,Shannon-wiener指数、Simpson指数均为轻度放牧>中度放牧>重度放牧>不放牧,且不放牧与轻度放牧差异显著。     

Depth-specific distribution and importance of nitrite-dependent anaerobic ammonium and methane-oxidising bacteria in an urban wetland

Anaerobic ammonium oxidation (anammox) and nitrite-dependent anaerobic methane oxidation (n-damo) are two recently discovered processes in the nitrogen cycle that are catalysed by anammox bacteria and n-damo bacteria, respectively. Here, the depth-specific distribution and importance of anammox bacteria and n-damo bacteria were studied in an urban wetland, Xixi Wetland, Zhejiang Province (China). Anammox bacteria related to Candidatus Brocadia, Candidatus Kuenenia and Candidatus Anammoxoglobus, and n-damo bacteria related to “Candidatus Methylomirabilis oxyfera” were present in the collected soil samples. The abundance of anammox bacteria (2.6–8.6 × 10⁶ copies g⁻¹ dry soil) in the shallow soils (0–10 cm and 20–30 cm) was higher than that (2.5–9.8 × 10⁵ copies g⁻¹ dry soil) in the deep soils, whereas the abundance of n-damo bacteria (0.6–1.3 × 10⁷ copies g⁻¹ dry soil) in the deep soils (50–60 cm and 90–100 cm) was higher than that (3.4–4.5 × 10⁶ copies g⁻¹ dry soil) in the shallow soils. Anammox activity was detected at all depths, and higher potential rates (12.1–21.4 nmol N₂ g⁻¹ dry soil d⁻¹) were observed at depths of 0–10 cm and 20–30 cm compared with the rates (3.5–8.7 nmol N₂ g⁻¹ dry soil d⁻¹) measured at depths of 50–60 and 90–100 cm. In contrast, n-damo was mainly occurred at depths of 50–60 cm and 90–100 cm with potential rates of 0.7–5.0 nmol CO₂ g⁻¹ dry soil d⁻¹. This study suggested the niche segregation of the anammox bacteria and n-damo bacteria in wetland soils, with anammox bacteria being active primarily in deep soils and n-damo bacteria being active primarily in shallow soils.     

海淀公园木本植物多样性分析

[目的]了解海淀公园木本植物多样性。[方法]采用随机样方分析法,对北京海淀公园120个样方中的树木种类、数量和规格等进行统计。[结果]共调查了21科34属42种1 097棵木本植物,木本植物群落处于发展的中前期阶段,其树龄分布基本呈金字塔类型。木本植物的常绿与落叶种类之比约1∶6,数量之比约1∶3,同种常绿树种的使用重复度较高。乔木层的树种优势度相对灌木显著。乔木的物种多样性整体优于灌木,分布上乔木和灌木的均匀性基本类似。[结论]调查结果为城市植物多样性的相关研究和实践工作提供了参考。