首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 34 毫秒
1.
A working group within the European Union funded COST Action E12, “Urban Forests and Trees”, carried out a survey between 1999 and 2001 to study current tree establishment practice in European towns and cities. An extensive questionnaire requesting information on the urban area, selection of tree species, establishment and aftercare practices and the main damaging factors was sent to tree professionals in urban areas in each of 17 countries.Indicators such as the relationship between the urban population and the number of street trees were used to compare urban areas. While most central European cities have a ratio of 50–80 street trees per 1000 inhabitants, the tree density was as low as 20 street trees per 1000 inhabitants for Nice. Often only a few species are planted and this may give cause for concern, since species diversity is considered an important factor in increasing the resilience of the urban tree population to abiotic and biotic stresses.The planting of larger street trees of 20–30 cm circumference, usually with hessian-wrapped rootballs, is becoming increasingly common practice. However, some countries report the use of mostly bare-rooted stock of much smaller trees (less than 12 cm circumference). Establishment costs for street trees range from less than 200 Euro to over 1500 Euro each. Poor site conditions, and impacts such as utility trenching are considered to be major restrictions to healthy tree life. Vandalism affects up to 30%of newly planted street trees in some towns and cities.Overall, the survey reveals large differences in tree establishment and management practices among European cities. There is a need to provide urban tree managers with guidance on good practice for tree selection and establishment based on empirical information. The survey was a first step towards collecting the necessary urban forest information from across Europe.  相似文献   

2.
Summary

Modern drying technology provides the opportunity to obtain dried fruits with high concentrations of bioactive compounds. Such products may also be fortified with functional ingredients. The adoption of dried fruit as a carrier of functional ingredients for consumers is indispensable to launch this kind of product successfully on the market. Thus, the aim of this study was to collect data on consumer perceptions and interests in dried fruits (plain or fortified) through a questionnaire distributed on the Internet to 1,092 Dutch, French, and Polish respondents. In this quantitative study, the respondents were first asked to rank statements about a product with different positive influences on human health. Products which lowered the risk of cancer or heart diseases were mainly of interest to Polish and Dutch respondents, whereas French consumers emphasised the prevention of intestinal problems. Furthermore, we checked the level of consumer interest in dried fruits enriched with a particular functional ingredient (e.g., anti-oxidants, natural fruit sugars, or prebiotics). Products with anti-oxidants seemed to be the most promising in all three countries investigated. Among five different forms of product (i.e., candy, fruit teas, cereals, bars, or cookies) in which dried fruit could be incorporated, cereals were selected by approx. 33% of all respondents as the best product to which a functional dried fruit could be added. In summary, dried fruits can be adopted as carriers of functional ingredients, especially when promoted as a source of anti-oxidants.  相似文献   

3.
A plasmid containing target DNA and a standard curve for real-time quantitative PCR of the coldinduced Cor3 gene of Volvariella volvacea were constructed. These will provide the basis for further research on Cor3 gene expression at low temperature, and ultimately for assigning a role for the gene in the low temperature autolysis of V. volvacea.  相似文献   

4.
A flavor-related enzyme from Toona sinensis (TS), ?-glutamyl-transpeptidase (GGT), was purified 40.67-fold with 13.40% recovery using ammonium sulfate precipitation, dialysis and gel filtration chromatography. Gel filtration chromatography and sodium dodecyl sulfate acryl amide gel electrophoresis (SDS-PAGE) revealed that GGT was a heterodimer with a molecular weight of 90 kDa, and the molecular size of its two subunits was 26 kDa and 64 kDa, respectively. The apparent Km and Vmax of GGT were 3.623 μmol/mL and 2.831 μmol/mL/min of protein, respectively. The optimum reaction temperature was 60°C, while the optimum pH was 7.0. GGT can tolerate temperatures of 70°C for a short time and can keep stable activity at 60°C for more than 2 hours. The effect of metal ions on GGT activity showed that Cu2+ and Zn2+ had strong inhibition, while Fe3+ had strong activation, and other metal ions had only a slight effect. LC-MS analysis indicated that GGT catalyzed (S, S)-γ-glutamyl-(cis-S-1-propenyl)-thioglycine, a flavor precursor found in TS, to release glutamic acid moiety.  相似文献   

5.
A 531 bp fragment of a putative mitochondrial intermediate peptidase (mip) gene from Lentinula edodes was amplified by PCR using a pair of degenerate primers designed according to conserved sequences of mip genes reported in other Basidiomycetes. Alignment analysis revealed that this putative partial mip gene from L. edodes exhibited high homology with corresponding segments of mip genes from the other Basidiomycetes. Since the gene encoding MIP appears to be very closely linked with the A type mating gene of Basidiomycetes, identification of mip may prove a useful tool for locating and cloning the A type mating gene in L. edodes and other edible fungi.  相似文献   

6.
Nowadays, gathering information about tree health conditions in cities is necessary. Trees are essential in regulating urban microclimate and mitigating the urban heat island effect. Therefore, their health status should be crucial in urban vegetation monitoring. The growing number of new cameras, sensors and research methods allows for a broader application of thermal data in remote sensing vegetation studies. This research aimed to evaluate whether it is possible to use thermal infrared data to assess the health condition of selected species of deciduous trees in an urban environment. More specifically, the data must have a 3.6–4.9 µm spectral range, obtained during the day and the night. For this purpose, research was carried out in the city center of Warsaw (Poland) in 2020. During the airborne data acquisition, thermal data, laser scanning and RGB images were collected. Synchronously with airborne data, 617 ground references were obtained in different health condition classes (healthy, slightly poor condition, poor condition and dying) for five tree species: Acer platanoides, Acer pseudoplatanus, Aesculus hippocastanum, Tilia cordata and Tilia × euchlora. The results were as follows: (i) healthy trees were cooler than trees in poor condition and dying both during the daytime and nighttime; (ii) the difference in the canopy temperatures between healthy and dying trees was 1.06 °C of mean value on the nighttime data and 3.28 °C of mean value on the daytime data; (iii) all condition classes significantly differ from each other on daytime thermal data. The aerial thermal data can be considered a new alternative to hyperspectral data. Thermal sensing represents another method of assessing the health condition of trees in an urban environment – especially data obtained during the day, which can differentiate condition classes better than data obtained at night. The method based on thermal infrared and laser scanning data fusion could be a quick and efficient solution for identifying trees in poor health.  相似文献   

7.
  相似文献   

8.
We report the successful micropropagation of a critically endangered medicinal plant Aconitum heterophyllum Wall., using low concentrations of plant growth regulators (PGRs) and molecular validation of the clonal stocks. The maximum rate of in vitro shoot multiplication was obtained on 1.0 × Murashige and Skoog (MS) medium containing 0.25 mg L?1 Kinetin (Kn) plus 0.25 mg L?1 Indole acetic acid (IAA). Up to 100% rooting was obtained 15 for shoots cultured on 1.0 × MS medium supplemented with 1.0 mg L?1 IAA. Adding 0.25 mg L?1 2,4-dichlorophenoxyacetic acid (2, 4-D) to 1.0 × MS medium resulted in 100% callus formation, while adding 0.25 mg L?1 IAA plus 0.25 mg L?1 Kn to 1.0 × MS medium containing 0.25 mg L?1 2,4-D resulted in 100% generation of embryogenic callus. Inter-simple sequence repeat (ISSR) marker analysis was carried out to check for possible somaclonal variation in the plantlets obtained after three consecutive sub-cultures. Of the 15 ISSR primers used, 10 were found to be monomorphic, with 95–98% similarity, and were used for cluster analysis by the unweighted pair group using arithmetic averages (UPGMA) method. The results revealed that in vitro-regenerated plantlets did not exhibit any genetic polymorphism.  相似文献   

9.

Context

During the past three decades, China’s agroecosystem has undergone dramatic alterations because of changes in climatic and management factors, which threatened agricultural sustainability.

Objectives

We investigated how climatic and management factors affected agricultural ecosystem services (AES).

Methods

We adopted the GIS-based Environmental Policy Integrated Climate (EPIC) model to simulate the five critical AES: food production, soil organic carbon (SOC), nitrate leaching, water erosion, and wind erosion from 1980 to 2010 and used a partial least square regression model to quantify the contributions of the drivers of the variation in the AES on the main grain-producing area (MGPA), climatic zone, and national scales.

Results

On the MGPA scale, SOC exhibited no obvious change and food production increased, whereas the negative environmental effects largely increased. The MGPA is important to ensure the safety of China’s food supply. At the climatic zone scale, food production and SOC increased, water erosion in the tropical-subtropical monsoonal zone and water and wind erosion in the temperate monsoonal zone decreased, whereas N leaching, water erosion, and wind erosion increased in other climate zones. At the national scale, food production, SOC, N leaching, and wind erosion increased, whereas water erosion decreased. The crop cultivated area played a major role in the effect on food production and SOC. The dominant factors for N leaching, water erosion, and wind erosion varied with crop type and study scales.

Conclusions

Adjustment of agricultural management measures is vital and possible to minimize the tradeoffs, increase the synergies among agro ecosystem services, and promote adaptation to the changing climate.
  相似文献   

10.
  相似文献   

11.
The world is changing rapidly, challenging the sustainability of landscapes and the resources and ecosystem services they provide to people and to plants and animals. Changes in land use and climate will alter the structure and composition of landscapes, and landscape functions may also be disrupted if the changes drive systems past thresholds into novel, no-analog configurations. Although landscapes will persist in some form, it is unlikely that they will provide the same values to people or habitat for wildlife that are the focus of current sustainability efforts. Tradeoffs among services to people or resources for wildlife will be inevitable. For the concept of sustainability to be relevant under these conditions, we must ask, “Sustainability of what, for whom?” Landscapes cannot be all things to all people (or organisms). Decisions about how to balance competing needs and goals and set priorities requires an understanding of landscape structure, function, and change—the foundation elements of landscape ecology.  相似文献   

12.
Treatment of S-180 tumor-bearing mice with polysaccharide extracted from Pholiota adiposa mycelium resulted in lower tumor weights, increased carbon particle clearance and phagocytic indices, and significantly higher serum levels of TNF-α and IL-2, compared with untreated controls. Our data suggest that the anti-tumor activity of P. adiposa polysaccharide is related to immuno-enhancing activity.  相似文献   

13.
Prosopis cineraria (L.) Druce, commonly called khejri, is an important multipurpose, leguminous tree of the Thar Desert. ‘Thar Shoba’ is a variety of khejri without thorns which was developed as a vegetable. In order to develop markers for varietal identification, 80 RAPD primers were tested, of which nine were polymorphic between ‘Thar Shoba’ and trees in a natural population of khejri. Phenetic analysis revealed that ‘Thar Shoba’ formed a separate cluster from the natural population with similarity coefficients of 0.57–0.78. The 10-mer primers OPBE05, OPBA13, OPA12, and OPA14 were each found to differentiate ‘Thar Shoba’ from the natural population by one amplicon. These differential amplicons were sequenced and SCAR markers were developed based on the sequences that differentiated ‘Thar Shoba’ from the natural population. Natural populations of khejri from different regions of the Thar Desert, and clonally multiplied ‘Thar Shoba’ plants in the ICAR-CIAH bud-wood genebank, were used to validate these primers. These markers will be useful in further developing the bud-wood genebank, and for certification, identification, and protection of the khejri variety ‘Thar Shoba’.  相似文献   

14.
Various methods for storing, retrieving, and analyzing historic land use records by means of electronic data processing are evaluated. The procedures are illustrated with data from a pilot study on the Swiss Plateau which is part of a broader landscape historical monitoring program at the Swiss Federal Institute of Forest, Snow and Landscape Research. The land use matrix was derived from topographic maps, aerial photographs and other land use records and spans approximately 100 yrs with an updating cycle of 7 to 20 yrs. A special technique was developed to generate series of digital maps and to superimpose the data layers of various time steps. Each landscape element is described with time-stamped attributes to ensure access to the entire life history from any point in space or time. The proposed data model proved to be a powerful tool for routine updating of digital maps. It can be used by practitioners as well as scientists working with Geographical Information Systems (ARC/INFO or similar package). With this procedure, disturbance maps over any number of available updates can be quickly generated, allowing the user to identify zones of similar degrading or upgrading tendency. The procedures for analyzing changing landscape structures include calculation of information theoretic indices (diversity, dominance), calculation of fractals, edge analysis, as well as landscape assessment along random traverses. The latter proved to be especially powerful, where barrier/habitat frequencies were evaluated. On the basis of all parameters calculated, landscape structures on the study plot seem to be ecologically most favorable in the 1930's followed by a strong degradation in the World War II - and the post-World War II period. In contrast to many hypotheses, the landscape structures in the second half of the 19th century were structurally less favorable than between 1900 and 1930.  相似文献   

15.
Landscape Ecology - Variability in temperature and snow cover are characteristics of high-latitude environments that impose significant pressures on overwintering species. To cope with increased...  相似文献   

16.
Extracellular polysaccharide from Tremella aurantialba (TEP) significantly inhibited H2O2-induced haemolysis of RBCs, significantly decreased the amount of malondialdehyde (MDA) produced in mice liver homogenates as a result of autoxidation, and inhibited VitC-Fe2 -induced swelling of liver mitochondria.  相似文献   

17.
小型西瓜肉质细嫩、皮薄、脆甜、风味佳,具有较高的经济价值,近年栽培面积呈逐年上升趋势。因小型西瓜的生育特性与普通西瓜有明显差异,在栽培上也有其特殊性,故要求栽培技术和条件较高。目前小型西瓜种植密度较低,一般每667m~2450～1500株,产量相对较低,为1500～2500kg。  相似文献   

18.
Rootstocks of M.9 were produced either directly by micropropagation, by improved conventional propagation from apparently rejuvenated micropropagated plants or by conventional propagation throughout. These rootstocks were grown in the field for one year and then grafted with scions of ‘Cox’s Orange Pippin’. Performances of the composite trees were evaluated one year following grafting. Trees with rootstocks which came directly from micropropagation had many suckers and burrknots and usually had poorly developed scions. Trees with rootstocks from improved conventional propagation from micropropagated plants were similar to trees with rootstocks from conventional propagation throughout in being almost devoid of suckers and burrknots and having well developed scions.  相似文献   

19.
Criminal behavior has been traditionally linked to green space. However, studies on the relationship between green space and crime vary in their conclusions and even contradict each other. This variability is primarily attributed to the mixing-up of specific crimes and the less-explored influencing mechanisms. This study considers Toronto and focuses on a specific kind of crime, assault, for exploring whether green space influences the neighborhood assault rate. If so, then how does it affect the assault rate? By considering the neighborhood as the spatial analysis unit, the indicators of green space and its component structure (namely the composition of trees, shrubs, and grass) are included in the regression analysis model used in this study. The dual effect (both positive and negative) of walkability on crime is treated as the moderator in the regression model. Our analysis revealed that high percentages of green space, tree area, and grass area potentially inhibit assault occurrence, while the shrub area percentage has no statistically significant association with the assault rate. When walkability reaches a certain degree (84th or/and 50th percentiles in this study), it can enhance the inhibitory impact of the green space and its component structure (including trees, shrubs, and grass) on the assault rate. Comparatively, this reduction effect is more significant for green space composed of grass. Therefore, we can infer that increasing the percentage of trees and grass, while simultaneously improving walkability, can reduce residents’ risk of being assaulted at the neighborhood level.  相似文献   

20.
任怡然  赵强  由春香  郝玉金 《园艺学报》2017,44(6):1021-1028
为进一步揭示苹果(Malus×domestica)中GA信号转导机制以及MdDELLAs的生理功能,以‘嘎拉’苹果为试材,克隆基因MdRGL3a(GenBank:DQ007887),并通过在拟南芥中过量表达,分析该基因的功能。qRT-PCR结果表明,MdRGL3a在苹果不同组织中都有表达,其中在花和果实中表达量较高。在拟南芥中异位表达MdRGL3a,表现为根长和下胚轴变短,种子萌发较慢,叶片变小,植株矮化。过表达MdRGL3a拟南芥植株对赤霉素介导的生长反应敏感性降低,证明MdRGL3a是GA信号途径中的一个负调控因子。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号