南京地区繁缕和小繁缕群体的研究

繁缕(Stellaria media)和小繁缕(S.apetala)是两个形态相似的近缘种,有人把后者作为前者的亚种或变种来处理。本文通过对南京地区不同生境的三个自然群体和三个人工控制栽培群体的取样,以群体为单位,分别测算了叶、萼片、雄蕊、花瓣、果实和种子的8个数量性状的变异,绘制了多角形图;对花粉粒和种子进行了扫描;还通过花蕾套袋试验对种子活力作了检查。结果发现繁缕和小繁缕都是近亲繁殖植物,在形态上区别明显,对生态环境的要求基本相同,但小繁缕似更能耐受人为的践踏和刈割。     

大棚黄瓜霜霉病生态防治方法研究——温度控制试验研究初报

黄瓜霜霉病是对黄瓜生长发育危害最大的世界性病害。通过两年共10个处理的田间对比试验发现,大棚黄瓜霜霉病的发生发展与环境温度条件存在着十分密切的关系,在一定温度范围内(15℃—48℃),棚内日最高气温越高,发病期越晚,病越轻,产量越高。控制方法是:在大棚内日最低气温稳定大于10℃后,每隔一天对大棚进行一次40—47℃、并维持2小时左右的高温处理(其中大于42℃持续1.5小时左右,大于45℃持续1小时左右),然后大面积通风换气。方法简便易行、效果很好。     

Floristic and structural variation in the Tamaulipan thornscrub,northeastern Mexico

Abstract. A generalized research strategy is presented for identifying the ecological effects of the physical environment and management in a poorly known region of subtropical, semiarid thornscrub in northeastern Mexico. Vegetation samples were stratified across a small number of climatic subregions, substrate types and topographic situations. Classification analysis and PCo A of the species x site matrix of incidence data after application of the Information Statistic were used. The analyses suggested that the regional variation in climate, substrates and topography was responsible for the major floristic differences in the vegetation. The distributions of most plant species were related to the variation in the physical environment. PCo A of the species x site cover data after application of the Bray-Curtis dissimilarity metric revealed evidence of vegetation change due to overgrazing in each major floristic group, but not to selective cutting for timber and firewood.     

Impacts of introduced common wasps (Vespula vulgaris) on experimentally placed mealworms in a New Zealand beech forest

An introduced social wasp Vespula vulgaris may compete with native birds for honeydew and invertebrates in New Zealand forests. Experimentally hidden mealworms (Tenebrio molitor) persisted longer at two sites following wasp poisoning that at two sites where wasps were not poisoned. Mealworms persisted longer in the morning than in the afternoon within all study sites. An unusually low mealworm removal rate during a morning trial before wasp poisoning heavily influences the results of this experiment but we have no ecological reason to ignore it. Wasps may therefore be having a heavy impact on invertebrate abundance on very short time scales (within a day following dawn emergence). They may also remove cached food items that would otherwise be retrieved by the South Island robin (Petroica australis australis) during cold or dark feeding conditions.     

Evaluation of three herbaceous index plant species for bioavailability of soil cadmium, chromium, nickel and vanadium

Uncultivated plants growing on disturbed sites may be useful for assessing the bioavailability of some metals in soils, and thus the potential for metal mobilization up the terrestrial food chain, an important element in ecological risk assessment. A planted chicory cultivar (Cichorium intybus L. var. foliosum Hegi.) and the uncultivated plants horseweed (Canada fleabane) (Erigeron canadensis L.) and dogfennel (Eupatorium capillifolium (Lam.) Small) were evaluated for their ability to act as index plant species for soil Cd, Cr, Ni, and V at two field sites where these metals had been applied five yr previously to two highly weathered sandy Ultisols. Soil Cd was available to all analyzed plant tissues of all three plant species at both sites, particularly on the sandier Blanton soil. Chicory was an effective index plant for Cd on the finer textured Orangeburg soil but functioned as an indicator plant (toxicity symptoms were observed) on the sandier Blanton soil. Horseweed and dogfennel were effective index plants for Cd in both contaminated soils. Soil Cr, Ni, and V were less bioavailable than soil Cd and plant metal uptake was more sensitive to residual soil Cr, Ni, and V than was soil extraction with double acid. Horseweed and chicory may have potential as index plants for soil Cr. Chicory may have potential as a Ni index plant. Chicory and dogfennel may have potential as V index plants.     

Sediment quality assessment in the delta of rivers Rhine and Meuse based on field observations,bioassays and food chain implications

The quality of sediment was assessed in 46 sites in the delta of the rivers Rhine and Meuse (The Netherlands) by means of physical-chemical analysis, field observations on the macrobenthic community structure, accumulation studies and bioassays using Chironomus riparius, Daphnia magna and Photobacterium phosphoreum. The results of chemical analyses were classified using national criteria for sediment quality. Results of field studies and bioassays were classified using criteria derived from research in reference areas or based on data from literature. Risk assessment was carried out according to the sediment quality triad and by means of multi criteria analysis (MCA). The Triad approach was used to demonstrate causal relations between effects on the macrozoobenthos community structure, effects demonstrated in bioassays and sediment pollution. This was done by making a comparison of sediment contamination levels with toxicity data from literature for the test organisms of the bioassays. Using the MCA method, for each site a numerical value was derived for total environmental risk in the present situation, based on observed effects. In this way, a relative risk ranking of all sites was realized. The MCA values for the present situation were also compared with MCA scores based on estimated risks after remediation in 1995, in order to set priorities for sites where remediation is expected to cause a significant reduction in environmental risk. In most of the 46 sites studied so far, the macrofauna community was poorly developed, judged by a low number of benthic species, low abundances and a high dominance of species regarded as relatively tolerant to chemical pollution. In bioassays high sediment toxicity was demonstrated for 24 sites. Using the sediment quality triad approach, 25 sites were identified as areas where pollution can be held responsible for the effects observed in the field. From a comparison of contaminant concentrations in different types of food with maximum tolerable risk levels, and the application of a bioaccumulation model it was concluded that the sediment pollution also implies high risks for plant-, benthos- or fish-eating birds (secondary poisoning of top predators). In the Nieuwe Merwede highest MCA risk scores were found for shallow parts where highly polluted sediments are found. It is concluded that the sediment quality triad and the MCA provide additional information which can be used to establish priorities for remedial action. Based on an ecotoxicological evaluation of the improved quality of new sediments that will be deposited after removal of the polluted sediments in the Nieuwe Merwede, it is concluded that in this upstream part of the Rhine delta remedial action will be effective.     

Ecological optima and tolerances of Thelypteris limbosperma,Athyrium distentifolium,and Matteuccia struthiopteris along environmental gradients in Western Norway

The distribution and abundance of Thelypteris limbosperma, Athyrium distentifolium, and Matteuccia struthiopteris are modelled statistically in relation to 14 environmental variables along the major climatic, topographic, and edaphic gradients in western Norway. The data are from 624 stands from which measurements or estimates of mean January and mean July temperatures, humidity, altitude, aspect, and slope are available. From 182 of these stands eight soil variables have also been measured. The species responses are quantified by two numerical methods: Gaussian logit regression and weighted averaging (WA) regression. The estimated WA optima suggest that A. distentifolium has an ecological preference for low July and January temperatures, high altitudes, and soils of low-medium pH and base content. The species shows statistically significant Gaussian responses with summer temperature, humidity (= Martonnes humidity index), altitude, slope, aspect, pH, cation exchange capacity, and base saturation with optima of 8.7 °C, 188.9, 1220 m, 28°, 29°, 4.8, 13.77 mEq 100 g dry soil^-1, and 13.4%, respectively. These suggest that the occurrence and relative abundance of A. distentifolium are well predicted by summer temperature, topography, and soil pH and base status. T. limbosperma has WA optima that suggest that it favours moderately high winter and summer temperatures, high humidity, medium altitude, and soils of low pH and base content. It has significant Gaussian responses to summer temperature (optimum =12.6 °C), winter temperature (-1.8 °C), humidity (179.2), altitude (459.5 m), slope (22.5°), and Na (0.7 mg 100 g dry soil^-1). These suggest that climatic factors, altitude, and slope are significant predictors for its occurrence and abundance. M. struthiopteris has high WA optima for summer temperature, pH, Ca, Mg, K, Na, cation exchange capacity (CEC), and base saturation, and a low optima for humidity and winter temperature. Of these, summer temperature (16.0 °C), Ca (63.1 mg 100 g dry soil^-1), Mg (41.0 mg 100 g dry soil^-1), K (23.6 mg 100 g dry soil^-1), Na (5.0 mg 100 g dry soil^-1), CEC (60.7 mEq 100 g dry soil^-1), and base saturation (56.3%) have significant Gaussian logit responses, as do aspect (150.2°) and loss-on-ignition (9.4%). These results suggest that the occurrence and relative abundance of M. struthiopteris are well predicted by high soil base cations, a generally southern aspect, low organic content in the soil, and high July temperatures.     

Using XAD resins to study the effects of reduced organic micropollutant concentrations in River Rhine and Meuse water on phytoplankton growth

Laboratory incubation experiments were used to study the effect of reduced concentrations of organic micropollutants in water from the rivers Rhine and Meuse on the specific growth rate of the river phytoplankton community. Before incubation, part of the water sampled was treated with XAD-4 and XAD-8 resins to absorb dissolved organic compounds. Four dilutions were made by mixing untreated water with XAD-treated water in the ratios 100:0 (control), 70:30, 40:60 and 0:100. The phytoplankton specific growth rate increased significantly with the increased fraction treated with XAD in all but one incubation experiment. In these experiments, the specific growth rate was on average 9% higher in the fraction in which 100% was treated with XAD than in the controls. In the Rhine and Meuse river water, phytoplankton growth seemed to be inhibited by organic compounds. This inhibition was ascribed to the presence of dissolved organic micropollutants. Removing organic micropollutants using XAD resins to study the toxic effects of these compounds on field phytoplankton communities can be concluded to be a promising tool for risk assessment of micropollutants but needs to be supported by additional methodological research.     

Self-Reported Substantial 1-Year Weight Change Among Men and Women in the United States

Population-based data have not been readily available on relatively short-term changes in weight. Therefore, we sought to determine the nature of self-reported substantial (> 10%) weight change over one year in a representative sample of the US population which participated in the 1989 National Health Interview Survey (NHIS). Across all ages, a larger proportion of women than men reported both weight loss as well as weight gain of any amount (18.9% vs. 16.1% for weight loss and 20.0% vs. 16.1% for weight gain). In sex-specific logistic regression analyses, significant risk factors common to both sexes for substantial weight loss included divorced/separated marital status, smoking, increased number of blood pressure checks, increased BMI (body mass index) and increased number of bed days. Black race reduced the risk of weight loss for both men and women. Sex-specific risk factors for weight loss in men only were widowhood or never married marital status, while increasing age was a protective factor in women only. Concerning weight gain > 10% over the past year, increased number of blood pressure checks and having one or more diabetic parents were significant risk factors among both men and women; while never being married, increased age, BMI, and education exerted a protective effect in both sexes. For women only, risk factors for weight gain included black race, increased number of contacts with a health professional, and being unemployed. Intention to lose weight was associated with both weight gain and weight loss in both sexes, although it did not serve as a confounder in any of these relationships. A greater likelihood of substantial weight loss among women relative to men was diminished for persons with higher BMI, higher number of blood pressure checks, being widowed, divorced or separated, and intention to lose weight. A greater likelihood of substantial weight gain among women relative to men was diminished for persons with low BMI. The results of this cross-sectional study of weight change, involving a one-year follow-up period, generally correspond with the results obtained by longitudinal studies involving a longer follow-up.     

东北地区生态环境中的Se及其生态效应

对东北地区不同环境要素Ｓｅ的分布与转化规律的研究表明,基岩、土壤、粮食和动物毛Ｓｅ含量分别为０．１２、０．１５０－０．５４０、０．００９６－０．０７６５和０．０４０５－０．１４１４μｇ．ｇ＾－１;城市和农村儿童发Ｓｅ含量为０．４６０和０．１８２μｇ．ｇ＾－１。根据不同要素Ｓｅ含量和生态效应,可将该区分为Ｓｅ适宜区、缺乏区和过渡区３个１级区,每个１级区又分为高Ｓｅ源区的低Ｓｅ源区。