The abundance of hollow-bearing trees in urban dry sclerophyll forest and the effect of wind on hollow development

Anthropogenic change, particularly in urban landscapes, has resulted in the fragmentation of indigenous vegetation into often small isolated ‘remnants’. The persistence of arboreal fauna in small urban remnants in part depends on the distribution and abundance of habitat resources within the remnant. We surveyed 44 small (<2.5 ha) eucalypt remnants located within the south-eastern suburbs of metropolitan Melbourne to ascertain the abundance of hollow-bearing trees, an important ecological resource. The probability of a live or dead tree containing a hollow was investigated in relation to site variables that influenced exposure to wind, a factor thought to increase the propensity of hollow formation in eucalypt trees. A total of 2678 live and 224 dead eucalypt trees were surveyed, of which 350 live (12%) and 70 dead (31%) trees were hollow-bearing. The probability of a tree being hollow-bearing was strongly positively associated with the diameter of the tree, however, past management practices have lead to a paucity of large (>80 cm DBH) trees in small urban remnants. We found that variables that measured exposure to wind were correlated with the chance that a live tree will be hollow-bearing while reducing the chance that a dead tree will be hollow-bearing. Although highly variable, the number of hollow-bearing trees contained within small urban remnants (mean of 5.8 ha⁻¹) fell well below that contained in areas of un-logged non-urban forest. Our results indicated that large numbers of hollow-bearing tree are unlikely to be recruited into urban remnants for a significant time-span and as such there is an increased importance placed on maintaining the current inventory of hollow-bearing trees for the maintenance of biodiversity in urban areas.     

Do different methods used to estimate soil phosphorus availability across Europe give comparable results?

Each European country is using its own method for the determination of phosphorus availability to plants, together with an appropriate interpretation scheme of the P status and fertilizer recommendations. In order to compare systems, a soil exchange program was organized: 16 P methods were compared on 135 soils from 12 countries. The amount of extracted P decreased in the order P_total > P_oxal. > P_AL > P_Me3 > P_Bray > P_AAEDTA, P_DL, P_CAL > P_Olsen > P_{paper strip}, P_AAAc, P_Morgan > P_H2O, P_CO2, P_CaCl2. Isotopically exchangeable P was also measured. A large variability was observed in the results obtained by laboratories using the same method, thus demonstrating the great importance of an identical lab procedure as a prerequisite to any comparison. The traditional correlation/regression approach revealed its limitations when applied to non‐homogeneously distributed data and was replaced by more robust techniques that showed laboratory differential bias and confidence intervals of the log‐transformed values. Even though all the methods reacted in the same way to increasing amounts of added P in several trials, there were wide differences between results obtained with different methods. The interpretation schemes for P status were also compared and revealed that about 50 % of the tested soils were P‐deficient. This observation appears not to be in line with a generally high P fertilization during the last decades in Europe and should lead to a better evaluation of the plant‐available soil phosphorus.     

第三产业绿色技术创新效率时空差异及动态演变

本研究旨在提出促进长江经济带第三产业绿色技术创新水平提升的建议,为推进经济带协同一体的高质量发展提供理论依据。基于Min-DS模型,测度2001—2018年第三产业绿色技术创新效率,并结合Dagum基尼系数和Kernel密度估计,揭示区域及其子地区绿色技术创新效率变化的时空差异特征、贡献率及动态演变规律。以长江经济带为例研究得知：在观察期内经济带第三产业绿色技术创新效率总体呈上升趋势,下游地区效率具有显著优势;但各省市效率变化趋势存在较大差异,效率强度区域的空间分布随时间改变;上中下游地区内及之间绿色技术创新效率的时空差异是经济带时空差异的主要来源。本研究系统分析了长江经济第三产业绿色技术创新效率的分布及演变特征,得到了其提升绿色技术创新水平的有效路径。     

云南荔枝主要病虫害发生规律

为掌握云南荔枝病虫害发生种类及主要病虫害发生规律,精准防控荔枝病虫害,于2019—2021年在云南省5个荔枝主栽区采用实地调查、专题调研的方法,全面调查荔枝病虫害种类及为害情况,并用圆形分布统计方法对主要病虫害发生规律进行分析。结果表明,云南省荔枝常见病害7种,以荔枝霜疫霉病、荔枝炭疽病和荔枝叶斑病为害为主;虫害31种,以荔枝蒂蛀虫、荔枝蝽、吸果夜蛾类为害为主。5—8月是荔枝蒂蛀虫、荔枝霜疫霉病、吸果夜蛾类害虫和荔枝蝽集中发生时期,4—9月是荔枝炭疽病集中发生时期,3—9月是荔枝叶斑病集中发生时期。目前,3—9月是云南荔枝主要病虫害集中发生时期,该时期是云南荔枝病虫害防治关键时期。     

长江经济带城市土地利用效率与生态系统健康耦合时空格局分析

为深入探究区域城镇化与生态环境协调发展水平,以长江经济带为例,基于城市土地利用效率与生态系统健康视角构建相关理论框架,综合运用SBM-Undesirable模型、VOR模型及耦合协调度模型测算长江经济带城市土地利用效率与生态系统健康,分析两者的耦合协调特征并识别了其协调发展问题区域。结果表明:(1)2005—2018年长江经济带城市土地利用效率年均值达0.746,整体上呈波动式缓慢上升的趋势,空间集聚特征较为显著。生态系统健康得分均值为0.473,整体呈现小幅波动的趋势,地理空间上则呈现显著的南北分异特征;(2)城市土地利用效率与生态系统健康耦合协调度均值在0.611～0.624区间内小幅增长,截至2018年,区域内实现协调发展的市域达92.62%,耦合结果在空间上表现为由“相对随机”向“南高北低”的分布转变;(3)城市土地利用效率与生态系统健康耦合协调问题区域主要存在于长江经济带中下游部分市域,主要原因在于城市土地利用效率或生态系统健康单方面滞后抑制了城市协调发展水平的提升。总体而言,长江经济带城市土地利用与生态系统之间相互影响、相互促进的程度正逐步深化,交互过程中形成的耦合系统基本实现了平稳发展。     

芝麻饼肥与鸡粪有机肥不同混用量对烤烟生长、质量和经济效益的影响

本文在常规施肥的基础上配施芝麻饼肥和鸡粪有机肥,研究不同混用量对烤烟生长、质量和经济效益的影响。结果表明：纯施芝麻饼肥不利于烟株早生快发,烟株成熟期推迟,生育期延长,且大田农艺性状、经济效益与化学成分协调性均较差。本试验中,1125 kg/hm²的鸡粪有机肥,配施375 kg/hm²的芝麻饼肥,效果最好,可改善烤烟的产量和质量,对烟株中后期生长有明显的促进作用,可提高烟叶产量、产值、均价和上等烟比例。施用芝麻饼肥对花叶病与青枯病有抑制作用,对抗赤星病不利。     

基于形态和颜色特征的花生品质检测方法

花生为我国主要的经济作物之一。本文采用基于彩色特征空间和数学形态学的方法,对花生的品质进行了检测:用数码相机微距拍摄获得花生图像,中值滤波与提取边缘后,优选6个颜色特征和7个形态特征对花生进行品质检测,结果表明,和形态特征相比,颜色特征能够更好的分辨不同品质和种类的花生,分辨率达到了实用的要求。     

海峡西岸经济区景观格局特征研究

运用景观生态学的空间格局指数法,结合遥感和GIS技术,研究了海峡西岸经济区(海西区)2008年生态系统组成、景观格局特征以及与环境因子的关系。研究结果表明:(1)海西区主要由森林、草地、农田、水域、城镇和荒地构成,各景观类型高程分布差异显著。(2)森林是海西区的优势景观类型,呈规模化集中分布,草地和农田是海西区重要景观类型,斑块数量最多,分布零散;城镇和荒地的结构特征最差,表明其稳定性差,受人为干扰强烈。(3)水域的景观特征处于中间水平,斑块类型差异显著,但景观整体稳定性较强。(4)降水量、气温等自然因素是影响海西区景观格局的主要因素,人口密度和GDP等人为因素影响相对较弱。     

Web Sources for Researching Agricultural Economics

ABSTRACT

As the recent and ongoing information revolution gradually turns traditional library materials into electronic formats, many agricultural resources have become available online. This selective Webliography covers the major online resources for studying and conducting research in agricultural economics and related fields and includes associations and organizations, databases and articles, dictionaries, directories and search engines, government agencies, industry outlooks, market information, statistics, working papers, news, prices, and miscellaneous resources. Web sites were selected based on the quality of the information and their importance to researchers in the various areas of agricultural economics. Most of the sources are free, with many of them being produced by U.S. government agencies.     

Assessing the statistical training in animal science graduate programs in the United States: survey on statistical training

Statistical analysis of data and understanding of experimental design are critical skills needed by animal science graduate students (ASGS). These skills are even more valuable with the increased development of high-throughput technologies. The objective of this study was to evaluate the perceived statistical training of U.S. ASGS. A survey with 38 questions was shared across U.S. universities, and 416 eligible ASGS from 43 universities participated in this study. The survey included questions on the demographics and overall training, graduate education on statistics, and self-assessment on statistics and career path of ASGS. Several analyses were performed: relationship between perceived received education (PRE; i.e., how ASGS evaluated their graduate education in statistics) and perceived knowledge (PK; i.e., how ASGS evaluated their knowledge in statistics from their education); ranking of statistical topics based on PRE, PK, and confidence in performing statistical analyses (CPSA); cluster analysis of statistical topics for PRE, PK, and CPSA; and factors (demographic, overall training, interest in statistics, and field of study) associated with the overall scores (OS) for PRE, PK, and CPSA. Students had greater (P < 0.05) PRE than PK for most of the statistical topics included in this study. The moderate to high repeatability of answers within statistical topics indicates substantial correlations in ASGS answers between PRE and PK. The cluster analysis resulted in distinct groups of “Traditional” and “Nontraditional” statistical topics. ASGS showed lower (P < 0.05) scores of PRE, PK, and CPSA in “Nontraditional” compared with “Traditional” statistical methods. Several factors were associated (P < 0.05) with the OS of PRE, PK, and CSPA. In general, factors related to greater training and interest in statistics of ASGS were associated with greater OS, such as taking more credits in statistics courses, having additional training in statistics outside the classroom, knowing more than one statistics software, and more. This study provided comprehensive information on the perceived level of education, knowledge, and confidence in statistics in ASGS in the United States. Although objective measurements of their training in statistics are needed, the current study suggests that ASGS have limited statistical training on topics of major importance for the current and future trends of data-driven research in animal sciences.