Soil properties and the macrofauna community in abandoned irrigated rice fields of northeastern Argentina

This study compared soil physical, chemical, and biological characteristics between natural grassland and recently abandoned rice fields in order to identify those variables that might explain the observed increase of Camponotus punctulatus anthills in abandoned rice paddy fields from Northern Argentina. Mainly due to a reduction of macropores and mesopores, overall porosity decreased by around 6% and bulk density was about 7% greater, in the 0- to 10- and 10- to 20-cm layers of the abandoned rice fields. Carbon and nitrogen content from organic matter increased (29% and 41% respectively for the 0- to 20-cm horizon) during cultivation but decreased (38% and 24%) 2 years after the last rice harvest. Forty percent of natural grassland-organic matter and 30% of abandoned rice-organic matter mineralized in less than 2 years. There was a different community structure between the abandoned rice fields and the undisturbed natural grassland and only a 20.6% (i.e. only 19 species from a total of 92) overlap in species composition. The abundance of macrofauna was greater in abandoned rice fields (2,208 individuals m^–2) in comparison to natural grasslands (288 ind m^–2) due to higher densities of small earthworms and Camponotus punctulatus ants; however, the Shannon index showed lower values in comparison to natural grasslands. Earthworms and C. punctulatus in the abandoned rice fields showed a change in their ¹³C signature indicating a switch in diet from natural grassland organic matter (C4) to organic matter from rice (C3). Our results indicate that the effects of rice cultivation practices did not seem to produce any physical or trophic limitations to recolonization by the macrofauna. It seems that changes in overall soil conditions have favored a change in the construction behavior of C. punctulatus which, in combination with population increases, could explain the explosion in number of anthills.     

A review of management impacts on the soil productivity of South African commercial forestry plantations and the implications for multiple-rotation productivity

An overview of southern African research that has investigated the impact of management practices that can potentially affect the long-term site productivity of plantations is presented, with an emphasis of these impacts on soil productivity and with the implications for multiple-rotation site productivity. Activities that are most likely to cause long-term changes in soil productivity are identified as those causing high site disturbance during the inter-rotation period, notably ground-based mechanised operations and harvest residue management (including complete biomass removal) and, under some conditions, fertilisation. The impacts of these practices on soil and stand productivity are discussed from a southern African perspective. Knowledge gaps are identified and it is suggested that the immediate research priority is to identify meaningful indicators that are sensitive to change and that can be linked to stand production. Other key research focus areas are proposed and the need for a permanent long-term monitoring network is highlighted.     

江西省造林再造林碳汇项目发展潜力的评价指标探讨

文章对江西省清洁发展机制造林再造林碳汇项目发展潜力的评价进行分析研究,通过对土地资源、林木生长率、生物多样性、造林成本、农民收入等有关评价指标的分析,表明江西省实施CDM-AR项目具有明显的优势和巨大的潜力。     

基于雷达图分析法初步评价稻米食昧品质的研究

本研究建立了一种基于雷达图分析稻米食味评价的新方法.该方法选择胶稠度、碱消值、粒型、直链淀粉含量和蛋白质含量等5个对稻米食味品质影响较大的理化指标作为雷达图分析的评价指标.各个评价指标经无量纲化处理后用于绘制雷达图.为消除指标排列顺序不同引起的差异,本文采用雷达图的平均周长和平均面积作为特征向量构建评价参数,并对10个参试样品的食味品质进行综合评价.结果表明,采用本文建立的雷达图分析法得到的食味评价排序与常规感官评价法的排序基本一致,表明本文建立的雷达图分析法适用于稻米食昧品质的初步评价.     

江西省生物多样性保护与自然保护区建设

建立自然保护区是保护生物多样性的重要途径之一,通过分析并比较了江西省自然保护区建设与发展过程,认为保护区面积和级别、保护类型、法律意识、资金投入、科技支撑和管理机构等方面存在的问题是制约自然保护区发展的主要因素。针对性提出了江西省自然保护区建设的对策:(1)加大宣传力度、提高保护意识;(2)完善管理机构、提高管理水平;(3)增加资金投入、加快建设步伐;(4)规范法律法规、加大执法力度;(5)强化科学研究、培养专业队伍;(6)发挥自身优势、开展生态旅游。     

人工湿地在城市建设中的作用

综述了人工湿地在小区生活污水处理、城市景观美化、减轻城市洪涝灾害、生物多样性保护及环境教育等方面的重要作用。     

限制灌水对3种草坪外观质量及生理指标的影响

[目的]探究限制灌水对草坪外观及生理指标的影响,为草坪草的选择、节水灌溉和科学养护管理提供科学依据.[方法]采用盆栽结合大田试验的方法,以3种主要应用的草坪为研究对象,安排3个试验因子T1(高羊茅:黑麦草:硬羊茅=5:3:2)、T2(高羊茅:草地早熟禾=4:1)、T3(高羊茅单播),在限制灌溉水条件下,对3种草坪在水分胁迫时期内的外观质量、生理指标进行了测定.[结果]随着限制灌水胁迫时间的延长,3种草坪的外观质量逐渐下降,土壤含水量与草坪外观质量间表现出显著的正相关;3种草坪的叶片相对含水量、叶绿素含量和根系活力均随水分胁迫时间的延长而逐渐下降.[结论] T3草坪下降幅度最大,T2次之,T1草坪表现出较好的抗旱性.     

典型草原开垦弃耕后不同年限群落植物多样性和空间结构特征

本文旨在研究不同退耕年限下典型草原群落空间结构和植物多样性的变化特征。以长武王东沟流域不同退耕年限的典型草原为研究对象,采用空间序列代替时间序列的方法,对植物群落空间结构和植物多样性的变化特征进行了调查和研究,旨在为草地恢复和管理提供一定的理论基础。结果表明,随着退耕年限的增加,群落高度、盖度、多样性指数、地上生物量、平均个体大小和禾草类功能群所占比例均显著增加（P<0.05）,而群落均匀度指数、密度均显著降低（P<0.05）。在演替的过程中,群落中主要植物种的优势地位发生了明显的替代变化,由演替初期的冰草（Agropyron cristatum）、散穗早熟禾（Poa subfastigiata）,经过中期的异燕麦（Helictotrichon schellianum）、散穗早熟禾,到演替后期的散穗早熟禾。植物群落的空间结构也发生了显著变化,由初期的高密度、小个体分布到后期的低密度、大个体分布。退耕时间对草地群落的物种组成、空间结构及系统功能等方面均存在显著影响。     

Effects of dietary Lactobacillus acidophilus and Bacillus subtilis on laying performance,egg quality,blood biochemistry and immune response of organic laying hens

The objective of this study was to evaluate the effects of two different probiotic micro‐organisms on the performance, egg quality and blood parameters of organically reared hens. A total of 900 16‐week‐old Hy‐Line layer hybrids were randomly assigned to three groups of 300 birds each. The control (CTR) group was fed a corn–soya bean cake‐based diet; the L group was fed the same diet supplemented with 0.1% Lactobacillus acidophilus, while the B group was fed the same diet supplemented with 0.05% Bacillus subtilis. Data were recorded at the beginning (weeks 5 and 6: T1) and at the end (weeks 19 and 20: T2) of the experiment, and no differences in hen performance were recorded between dietary groups or sampling times. All of the investigated clinical chemistry parameters, except GGT, were affected by diet (p < 0.05), with the best results recorded for the probiotic‐treated groups. The immune‐response values showed higher blood bactericidal activity in the B and L groups at T2 (p < 0.05) and a lower lysozime concentration in the B group at T1. Higher antibody production against Newcastle disease virus was observed in the L group compared to the CTR (p = 0.013). No differences in oxidative status were recorded, and no effects of diet on egg quality were observed. Among the physical egg characteristics, only the Roche scale colour was affected by diet (p < 0.05): the egg yolk was paler in the L group. The age of the hen was the most relevant factor affecting physical egg characteristics. The chemical parameters of the egg were almost unaffected by supplementation with probiotics except for the lipid content, which decreased with the L diet (p < 0.05). Both probiotic inclusions had beneficial effects on hen metabolism and welfare, and L. acidophilus induced the best immune response.