Landscape Fragmentation and Ice Storm Damage in Eastern Ontario Forests

With return times between 20 and 100 years, ice storms are a primary disturbance type for temperate forests of eastern North America. Many studies have been conducted at the forest patch and plot scales to examine relations between damage and variables describing site, composition and structure. This paper presents results from a landscape scale study of fragmentation relations with damage in eastern Ontario forests. Data previously collected for two independent and spatially non-overlapping patch level damage studies were used. A Generalized Linear Model (GLM) was used to analyse relations between damage and fragmentation metrics representing patch isolation, edge density, and the relative size and distribution of patches in the landscape. The metrics were applied using spatial extents of 1 × 1 km and 4 × 4 km, following analyses of the variability of numbers of patches and of the lacunarity of forest patterns over a range of extents. The results showed that patch isolation, as measured by the mean Euclidean distance between patches (ENN) was significantly related to damage.     

Forests improve qualities and values of local areas in Denmark

Afforestation can create multiple societal benefits. One fifth of the Danish municipalities plans to afforest in the next 5 years, amongst other reasons to attract new inhabitants. The attractiveness and values of afforested areas have been investigated in two independent Danish studies. In the first study qualitative and quantitative surveys in two municipalities indicated that forests improved quality of life of the respondents. A short distance from the residence to nearest forest usually resulted in a higher frequency of forest visits and a more positive view on the nature qualities of the local area in general, compared to respondents living further from forests. Proximity to nature, including forests, was furthermore mentioned as the most important reason for choice of their present home by 17% of the respondents. These results are supported by the second study in which house prices are used to elicit the residents' valuation of forested housing areas. By using the hedonic price method house owners' willingness to pay for proximity to forests was found to be significant and positive, and in most circumstances the aggregated value is expected to exceed the cost of afforestation.     

旱塬区林地及耕地土壤水分动态变化研究

采用烘干法对采集于渭南旱塬地中耕地与林地的土壤样本进行了土壤水分含量的测定分析。结果表明:从整体来看,渭南市旱塬上耕地与林地土壤水分在10月份表现为2m以上土壤水分变化幅度较大,2～5m变化幅度较小,其主要原因是受到降水影响;11月份、2月份受冬季气候的影响,土壤水分含量整体偏高,变化幅度不大,不同的是11月份耕地在4～5m的范围内变化幅度相对较大,林地在0～1.5m范围内变化幅度大,2月份只有林地在4.5～5m的范围内变化幅度较大;3月份和4月份受春旱的影响,土壤含水量整体偏低,变化幅度较小,不同的是3月份耕地在0～0.6m和1.6～2.2m的范围内变化幅度大,林地在1.4～2.0、2.0～3.2和4.2～4.6m这3个区间内土壤含水量变化幅度较大,4月份只有耕地在2.6～3.2m的范围内变化幅度较大。     

推进果菜产业化兴业富民奔小康

龙旺庄街道办事处共有36个行政村,3.2万人口,耕地面积5.2万亩。近几年来,我们紧紧围绕农业和农村经济结构调整这一主线,大力发展果蔬生产加工、出口一条龙产业化经营,努力扩大招商引资,加快建设食品专业经济园区,走出了一条农业经济国际化的路子,有效地促进了农民、财政双增收。去年全处完成地方财政收入2488万元,完成工业总产值31.5亿元,实现出口创汇1.018亿美元,农民人均纯收入达到4166元。 培植“龙头”,努力提高果蔬加工出口能力 二十世纪八十年代,我们依托当地丰富的果蔬资源优势,兴建了第一个果蔬保鲜公司,对果蔬产品进行加工升…     

4种纯林空气负离子浓度研究

利用负离子仪对上海市松江区中央公园的4种纯林内的空气负离子浓度进行测定,并通过比较分析,得出如下结果：桂花、紫叶李、蚊母树纯林在5月和7月份的空气负离子浓度日变化曲线呈双峰型,石楠呈单峰型;在6月和8月份紫叶李、蚊母树和石楠纯林日变化曲线相似,几乎平行;不同纯林日平均负离子浓度有差异,相关性分析表明,纯林内的空气负离子浓度与温度和相对湿度的几乎无显著相关性,为合理利用负离子资源提供一定依据。     

Population Dynamics of Songbirds in the Boreal Mixedwood Forests of Alberta,Canada: Estimating Minimum and Maximum Extents of Spatial Population Synchrony

Ecological phenomena vary over space and time and interpretation of these processes also varies depending on the measurement scale. As the spatial scale of observation increases and decreases, changes in population abundance will likely exhibit alternating patterns of asynchrony and synchrony. While the study of how and why population dynamics change with spatial scale of measurement is intrinsically interesting, most population ecologists seek to study mechanisms of population change on a discrete study area. Our study develops methods that population ecologists can use to determine spatially appropriate sampling designs, and demonstrates how such spatial scales can be determined for 25 species of songbirds using long-term data from the boreal mixedwood forest of Alberta, Canada. To determine minimum scales of synchrony in population dynamics, we calculated the average correlation of changes in population abundance over time across different numbers of fixed-radius point-count samples. We then used a randomization test to remove the effect of number of replicates from the determination of appropriate spatial scale. The maximum extent of synchrony was estimated as the distance where population dynamics were no longer correlated. Estimates of the minimum scale of synchrony differed between species, ranging from 3.1 to 18.6 ha. The maximum scale of synchrony was estimated to be greater than or equal to 8 km for 14 of the 25 species examined, and to be greater than or equal to 70 km for Tennessee Warbler (Vermivora peregrina). Maximum spatial extents were significantly correlated with body mass and territory size.     

芹菜与人类健康

芹菜为伞形科草本植物旱芹的茎叶．属一年或二年生草本植物。原产地中海沿岸。我国栽培芹菜．已有两千多年的历史。芹菜有旱芹和水芹两种．常吃的是旱芹，水芹只在南方才能吃到。     

毛乌素沙地不同林型下土壤肥力综合评价

土壤理化性质是评估林下土壤肥力重要指标;土壤肥力差异影响植被分布、演替轨迹等;探究土壤肥力质量,以期为鄂尔多斯地区毛乌素沙地人工造林树种选择、科学经营森林等提供参考。以鄂尔多斯地区毛乌素沙地杨柴(Hedysarum mongolicum)、藏锦鸡儿(Caragana tibetica)、沙地柏(Sabina vulgaris)、柠条锦鸡儿(Caragana korshinskii)、沙柳(Salix linearistipularis)5种典型林型下土壤为研究对象,选取土壤pH、有机质、全氮、全磷、全钾、铵态氮、速效磷、速效钾含量等指标作为评价土壤肥力因子,基于隶属度函数法对数据标准化,确定各项指标隶属度值,采用主成分分析法确定各指标权重,结合隶属度值及权重值,应用综合评价法对不同林型下土壤进行综合肥力评价,利用内梅罗指数法和综合评价法得出结论辅助验证。结果表明:1)研究区土壤pH变化范围为7.31~10.46,均值为8.35。2)7项因子对不同研究区综合土壤肥力贡献率依次为全钾(0.177)>速效磷(0.148)>铵态氮(0.138)>速效钾(0.134)>有机质(0.127)>全磷(0.099)>全氮(0.057)。3)不同林型下土壤应用综合评价法和内梅罗指数法确定土壤综合肥力质量变化趋势一致,依次为杨柴林>藏锦鸡儿林>沙地柏林>柠条锦鸡儿林>沙柳林。研究区土壤整体属于碱性土壤;土壤中全钾含量较高,对林地土壤肥力贡献率最高;土壤全氮、全磷含量较低,是林地土壤肥力主要限制因子;杨柴林林下土壤肥力较高,相较其它林分立地条件较好。     

Perception and preferred reuse of vegetated vacant lots along main streets in a shrinking city

Vacant land in cities is linked to generating insecurity and urban decline. However, vegetated vacant lots offer easy opportunities for reuse and have ecological, economic, and social potential. Four medium-sized vacant lots (0,7–1,5 ha) with spontaneous vegetation located along main streets in Ostrava (Czechia) have been purposefully selected for this study. Structured interviews (n = 383) were collected to assess the perception of passers-by and their reuse preferences for these lots. Structural equation models were then performed to test the effect of sociodemographic variables. This paper aims to evaluate whether vegetated vacant lots in a historic urban fabric are perceived as an asset or liability by visitors and to assess the prospects for a publicly-accepted reuse of such spaces in a shrinking Central European city. Results indicate that the selected lots are perceived ambivalently. Older visitors show a more positive perception of the vacant lots, while no significant gender differences were identified. Educated respondents visited the vegetated vacant lots less often and perceived them more negatively compared to their less educated counterparts. Policy implications are provided in the end.     

被人们遗忘的蔬菜第一大作用功能 ——调节人体的酸碱平衡

蔬菜,尤其是绿叶蔬菜都属于碱性食物.蔬菜,可以中和人体内大量的酸性食物,如肉类、淀粉类食物. 蔬菜是我国人民膳食结构中极为重要的组成部分,中国人尤其喜食新鲜蔬菜.从营养学的角度看,蔬菜的营养功能主要是供给人体所必需的多种维生素、矿物质、微量元素、酶以及一部分热能和蛋白质;还能帮助消化、改善血液循环等;但它最重要的功能是...     

农业部部长韩长赋到海南视察冬季瓜菜情况

2010年1月21日，海南省委副书记、省长罗保铭在三亚天域酒店会见了农业部部长韩长赋一行。会见时，罗保铭代表海南省委、省政府，对农业部长期给予海南的支持与帮助表示感谢，并介绍了近几年海南农业增长和农民增收势头良好的情况。他说，国务院赋予海南国际旅游岛的六大战略定位，其中之一就是“国家热带现代农业基地”，海南农业发展迎来了前所未有的重大机遇。     

Perception and preference of trees: A psychological contribution to tree species selection in urban areas

Trees can enhance human mental and physical well-being in urban environments. However, the tree benefits in urban planning are insufficiently recognised, and there is little knowledge on the tree characteristics that are relevant to humans and how they are evaluated. This paper presents perceptual tree parameters and their relation to human preferences. In study 1, participants sorted 24 tree images by perceived similarity. Hierarchical cluster analysis and multidimensional scaling (MDS) revealed the distinction between conifers and deciduous trees, crown shape, the two-dimensional crown size to trunk height ratio and the crown density as important to humans. In study 2, participants rated the trees based on their preferences. Multiple linear regression analyses showed that a high two-dimensional crown size to trunk height ratio and a high crown density predicted deciduous tree preferences. These findings are discussed in light of the savannah hypothesis and the Gestalt grouping principle of closure. In the task of tree selection and placement for urban areas, the identified perceptual tree parameters may allow for achieving a coherent overall picture with a simultaneous increase of tree species richness. Thus, urban landscape planning can apply the presented findings for increasing ecosystem health and residential satisfaction.     

四种调味香辛料与人体健康

香辛料指生长在热带的芳香植物的根、树皮、种子或果实,具有调味增香的作用,其中很多种类有不同程度地抑菌、防腐、治病等功效.从中选取蒜、姜、葱、辣椒4种调味香辛料,探讨它们与人体健康的关系.     

农村人力资本、劳动力转移与经济增长的门槛模型分析

劳动力转移与经济增长之间并非简单的相关关系或线性关系,而是随着人力资本水平的不同表现出阶段性变化。我国省际面板门槛模型的结果表明:劳动力转移对经济增长的作用存在显著的基于农村人力资本的"三门槛效应";我国劳动力整体人力资本水平不高,仍有一半省份人力资本水平在第二门槛以下;我国农村劳动力人力资本水平存在显著的东中西区域差异,在我国经济转型的过程中,劳动力应该按照人力资本水平的不同进行梯度转移。