Indigenous and spontaneous vegetation: their relationship to urban development in the city of Leeds, UK

The concepts of indigenous and spontaneous vegetation are considered as subsets of the broader category, semi-natural vegetation. Indigenous vegetation is conceptualised as that which has originated in a rural landscape and developed over a time period of several centuries or more, either naturally or as a result of traditional management methods, together with the environmental conditions supporting it. In contrast, spontaneous vegetation is that which has naturally colonised derelict urban sites, mainly within the last century. An investigation, using map and aerial photographic data, examined the relative proportions of potentially indigenous and spontaneous vegetation on proposed development sites in Leeds, a large industrial city in the UK. Results suggested that spontaneous vegetation occupied approximately 13% by area of the development sites while possible indigenous vegetation occupied as little as 5%. However, further analysis suggested that approximately 25% of the proposed development sites were within 0.5 km of a designated site containing indigenous vegetation. It is argued that both types of semi-natural vegetation can make positive contributions to the urban environment but that public perception of spontaneous vegetation and, in particular, the locations where it occurs, are often negative. Further research into public perceptions of semi-natural vegetation and ways of incorporating it into urban development are required.     

城市行道树抗倒伏关键技术与措施

以沈阳市区行道树为研究对象，研究探讨城市绿地行道树移植后各种导致树木倒伏的因素，并针对行道树倒伏等相关问题，提供切实可行的抗倒伏关键技术，为城市行道树发挥景观生态效果提供技术支持。     

Feasibility study on the estimation of the living vegetation volume of individual street trees using terrestrial laser scanning

As an important part of urban greening, the canopy of street trees has ecological benefits, such as oxygen production, noise reduction, and dust reduction. The living vegetation volume (LVV) can reflect the spatial structure of the canopy intuitively and enables the estimation of the ecological service value of street trees. Terrestrial laser scanning (TLS) has shown excellent performance for providing three-dimensional data of individual trees with high precision, enabling the accurate quantification of the LVV. In this study, we divided the LVV into the total living vegetation volume (tLVV) and the effective living vegetation volume (eLVV); the latter does not include branches. The eLVV of 40 ginkgo trees separated in two roads in Nanjing was calculated from TLS data. A novel method named LAIM for accurate eLVV calculation based on point cloud data was proposed. The point cloud data of individual tree was segmented along the Z-axis and image processing methods were used. With this, eLVV of each tree was obtained. The results were compared with data obtained from a clustered point cloud generated using convex hulls. The Bland-Altman analysis was used to investigate the consistency of the two methods. Furthermore, we used correlation analysis and all-subsets regression to choose the variables, and the eLVV was fitted using six models. Finally, we evaluated O₂ production, CO₂ and SO₂ absorption by the street trees based on eLVV, the ecological benefits of street trees were quantified. The results showed the following: (1) The number of layers and the dilation size of the point cloud were crucial parameters in the LAIM. (2) For ginkgo trees, the mean difference between the eLVV obtained from the LAIM and the convex hull method was − 0.53–0.19 m³, indicating that the results were highly consistent for the two methods. (3) The eLVV fitting performance was better for the exponential function model (R² =0.8523, RMSE=0.6838 m³) and linear model (R² =0.8361, RMSE=0.7224 m³). The tree height and crown width significantly affected the eLVV estimation. (4) The evaluation about ecological benefits of Zhaoyang Road was better than Cuizhu Road. The quantified ecological benefits were conducive to road ecological evaluation. This study quantified the eLVV of individual trees using TLS, highlighting the importance of live vegetation in urban greening. The results can provide technical support for estimating the ecological service value of urban street trees.     

Effects of vegetation structure and environmental characteristics on pollinator diversity in urban green spaces

With accelerating urbanization, insect pollinators in urban ecosystems face challenges such as reduced pollen sources, habitat fragmentation, and damage to the nesting environment. Urban green spaces (UGS) are essential for the stability of pollinator communities. However, little is known about the relationship between vertical layer heterogeneity and horizontal layer complexity of vegetation structure in UGS and pollinator communities. The present study aimed to assess how vegetation structure and environmental characteristics shape the insect pollinator community in UGS. To this end, this study was conducted with seven typical vegetation types which were selected according to the biotope mapping classification system (BMCS) in the ring parks around Hefei City, in Anhui province, China. A total of 11,401 pollinators belonging to 6 orders and 34 families were identified during the eight-month survey. Among the seven habitats under the BMCS, mainly successional short-cut shrub and partly open green space, trees two- or multi-layered broad-leaved mixed forest and partly closed green space, and mainly successional tall grass and partly open green space were identified as high-quality insect pollinator habitats. According to the results of the generalized linear regression, the explanatory power of the four best-fitting generalised linear models is relatively high (over 77%). In four optimal models, the effect of vegetation structure on pollinator community was greater than that of environmental characteristics. The redundancy discriminant analysis showed that the flowering abundance of nectar plants, herb richness, and shrub coverage rate were the three most important factors influencing insect pollinator communities, with a cumulative explanatory power of up to 78.8%. Pollinator abundance was positively influenced by spontaneous herbs and low-intensity management. However, high-intensity management, low diversity of plants, low nectar plant richness, ignoring seasonal nectar plant configuration, and dense tree distribution could limit pollinator reproduction and population growth. These results reflect the status of insect pollinator community in UGS in Hefei city and present a possible direction for improving urban green habitats and plant configurations.     

Importance of urban street tree policies: A Comparison of neighbouring Southern California cities

Research points to numerous benefits provided by urban street trees including qualitative and quantitative public health, economic, and environmental advantages for a city and its residents. As with other key aspects of city management that help develop municipal success, urban forestry requires foresight, commitment and planning that lead to effective policies and strategies. Good street tree management based on effective policies can maximise street tree benefits. Poorly conceived policies or the absence of effective policies can lead to the opposite result. A case study of the neighbouring cities of Loma Linda and Redlands, California illustrates this difference. The urban tree care and protection policies in these two cities have evolved differently. The differences may be attributable to contrasting municipal commitments to preservation and to best-practice management principles. Based on a comparative analysis of street tree policies of the two cities, it can be concluded that a local culture favouring tree protection and reflective guidelines and policies can result in proactive and successful management of an urban forest. Such policies also include provision for gathering data essential for strategic tree planting, care and removal.     

Psychological benefits of green exercise in wild or urban greenspaces: A meta-analysis of controlled trials

Green exercise, the combination of exercise and nature exposure, is known to benefit physical and mental health. However, there is a lack of quantitative evidence to support the psychological advantage of green exercise over non-green exercise. Also, it is unclear if there are psychological differences between green exercise in wild environments and urban greenspaces. Therefore, we conducted a systematic literature search for outcomes concerning measures including the Profile of Mood States (POMS), Spielberger State-Trait Anxiety Inventory (STAI), Semantic Differential Method (SDM), Positive and Negative Affect Schedule (PANAS), and Restorative Outcome Scale (ROS). Nineteen studies with 1662 participants were included in a meta-analysis to examine the advantages of green exercise and compare them in the two types of natural environments. The results indicate that green exercise may lower negative affect, including anxiety, tension, anger, depression, and fatigue. Meanwhile, green exercise may lead to higher positive moods and emotions, including vigor, comfort, natural feeling, and relaxation. Nevertheless, the effect on overall positive affect was not statistically significant. The comparative results suggest that wild environments may be more effective than urban greenspaces in improving vigor and comfort during green exercise. In conclusion, our findings support the advantages of green exercise over non-green exercise, meanwhile implying potential psychological differences between exercises in wild environments and urban greenspaces. Due to the limited number of studies and high heterogeneities, a future review is warranted to re-examine the psychological benefits.     

The impacts of roadside vegetation barriers on the dispersion of gaseous traffic pollution in urban street canyons

Vegetation barriers have been widely applied along urban streets to improve roadside air quality. For a deep investigation of their influences, field measurements and numerical simulations are performed in this study. Carbon monoxide (CO) is selected as a representative of gaseous traffic emissions for both field observations and numerical models. Computational Fluid Dynamics (CFD) models of the standard k-ε turbulent model and Eulerian approach for species transport are solved by FLUENT solver. Results obtained from numerical simulations show a good agreement with field observations on the distribution of roadside CO. In perpendicular wind conditions, both field observations and numerical simulations present a prominent CO reduction over the slow lanes (footpath and bikeway) when vegetation barriers exist. To effectively mitigate roadside air pollution, numerical simulations also provide the optimal heights for roadside vegetation barriers in the given street canyons. For street canyons with an aspect ratio (the ratio of building height to street width) ranging from 0.3 to 1.67, 1.1 m can be used as an optimal height, and 2.0 m could serve as an alternative if tall vegetation barriers are considered. For street canyons with an aspect ratio of lower than 0.3, 0.9 m to 2.5 m can be considered as the optimal heights for roadside vegetation barriers. According to sensitivity analysis, the optimal heights for vegetation barriers are largely insensitive to wind velocities in the given street canyons. In the more complicated urban street canyons and complex meteorological conditions, the optimal heights can be determined by specific numerical simulations. These findings are expected to provide important insights into alleviation of gaseous mobile emissions in terms of vegetation barrier design in urban streets.     

Remote sensing for the assessment of ecosystem services provided by urban vegetation: A review of the methods applied

The study and assessment of ecosystem services through remote sensing has increased substantially over the last two decades, as evidenced by the publication of studies that have applied it. The technological development of satellite images has improved in terms of spatial, spectral, radiometric, and temporal resolution, allowing the space-time observation, classification and monitoring of vegetation on the surface of the Earth. However, there are remaining methodological challenges for assessing ecosystem services due to the diversity of applications, the resources used, and its study in complex environments such as cities. This systematic review is based on identifying and analysing the variety of methods concerning the application of remote sensing for the assessment of ecosystem services provided by vegetation in cities, through a classification of these methods according to the data collection source (passive sensors, passive and active sensors and the fusion of other data sources with sensors). The classification of methods has been applied to a selection of existing articles in indexed scientific databases based on a non-statistical meta-analysis that make a direct reference to the topic of interest. The results show the approaches found in every method classified, their relationships with the geographical scale and the image resolutions used, and the advantages and limitations from the data processes that comprise remote sensing. We conclude from this analysis with three key factors to consider in the selection of remote sensing methods for the assessment of ecosystem services provided by urban vegetation: the definition of the approach(es), the urban scale to be assessed, and the image resolution available.     

新疆野苹果居群年龄结构及郁闭度研究

对新疆巩留与新源2地的新疆野苹果居群年龄结构及郁闭度进行测定和分析,旨在为新疆野苹果资源的保护保存提供依据。结果表明,在随机选取的200个单株中,巩留居群Ⅰ级幼树为0,而且Ⅱ级小树数量也极少,仅2株,只占1%,年龄级构成有下降性特征,存活曲线呈断点凸型,故年龄结构应属老衰类型,郁闭度为0.47;新源居群有Ⅰ级幼树,10株占5%,Ⅱ级小树达26株占13%,年龄级构成有稳定中略有上升的特征,存活曲线呈弧形凸型,故年龄结构应属稳定类型,郁闭度为0.80。上述结果显示,巩留新疆野苹果居群破坏严重,亟待加强保护,而新源新疆野苹果居群保存较完好。     

干旱及复水对野生苦瓜幼苗生长和生理特性的影响

为了研究干旱及复水处理对野生苦瓜幼苗生长和生理特性的影响,探讨野生苦瓜的抗旱机制,为其栽培育种提供理论依据。以野生苦瓜‘JH01’为试验材料,对干旱胁迫4、8、12、16 d和复水处理2、5 d野生苦瓜幼苗部分生理指标的变化进行研究。结果显示,随着干旱胁迫时间的延长,植株长势变弱,叶片萎蔫程度加重,叶片相对电导率、丙二醛含量、超氧阴离子含量、过氧化氢含量和脯氨酸含量逐渐上升,叶绿素含量呈先升高后降低的变化趋势;复水后,各指标得到了不同程度的恢复,复水5 d时叶绿素含量、相对电导率、过氧化氢含量均恢复到接近对照水平;此外,脯氨酸的可塑性指数达0.98,明显大于其他生理指标,叶绿素含量的可塑性指数最小为0.29。综上表明,野生苦瓜幼苗具有一定的耐旱能力,复水对干旱胁迫具有缓解作用。     

Diversity and ecology of vascular plants established on the extant world-longest ancient city wall of Nanjing,China

Spontaneous vegetation established on the city wall constitutes a characteristic greenspace within the urban matrix. Nanjing city wall of the Ming Dynasty (NJCW), as an extraordinary huge defensive masonry project, was built in 1393, the extant, basically intact ancient city wall is 25.09 km long, 9–26 m high, and is protected now as a key national cultural relic. Species composition and life forms of the vascular plants established on the vertical or inclined wall surfaces of NJCW were investigated, and its diaspore sources and dispersal modes were also analyzed. Totally, 159 species in 125 genera of 70 families were found inhabiting the joints between bricks or between block stones, trees, shrubs and woody lianas accounts for 51.57% of the species assemblage, while herbaceous plant species makes up 48.43% of them. Fifteen alien species were found colonizing NJCW, including 12 invasive species. Six 100-m-long quadrats were sampled in different segments of NJCW, each quadrat contained 39–77 species, and 755–3006 individuals. In total, 10785 individuals of vascular plants were recorded, consisting of 104 species in 89 genera of 56 families. 65.25% of the total individuals, and 53.85% of the total species are adapted to the primary dispersal of diaspores by wind, whereas 34.75% of the individual assemblage, and 46.15% of the species assemblage are adapted to the primary dispersal of seeds by birds. A bird-dispersed, native pioneer tree, Broussonetia papyrifera, was the most abundant species among the six quadrats, even developed coppices on the vertical wall surface. Location and aspect of the quadrats may have affected the species diversity of vascular plants established on its wall surfaces. A diversity of vascular plants established on NJCW, as a valuable urban ecological heritage, is worthy of sustainable wall management, while management priorities should be given to those large trees inhabiting the walls made of bricks, and to the invasive alien species to prevent them from further spreading over the adjacent urban habitats.     

京津冀地区矿山排渣场植被演替规律

植被自然恢复演替过程对矿山废弃地人工辅助植被恢复设计与实施效果评价均具有重要的借鉴价值。为了探索京津冀地区矿山排渣场植被演替规律,以京津冀地区典型矿山为例,运用典型样地和样方法,在详细调查获取数据的基础上,分析矿山排渣场自然恢复50年内的植物多样性变化特征。结果表明：当年内植物多样性指数变化呈波浪状,先增加后减少,然后再增加;先锋植物为一年生草本植物,植物种群从藜→蒿草;植物种群变化可划分为6个阶段：一年生草本阶段→多年生草本阶段→灌草阶段→灌木阶段→灌木与林木混合阶段→林木阶段。可见,矿山排渣场植被自然恢复具有较强的规律性,基于植物自然演替规律,首年内宜种植一年生草本类植物,有利于促进矿山废弃地植被恢复进程。     

Making trees visible: A GIS method and tool for modelling visibility in the valuation of urban trees

Tree visibility is a key determinant of cultural ecosystem services of urban trees. This paper develops a flexible, efficient and easy-to-use GIS method for modelling individual tree visibility to support tree valuation. The method is implemented as a GRASS GIS AddOn tool called v.viewshed.impact, making it available to a broad spectrum of users and purposes. Thanks to empirically validated underlying algorithms and parallel processing, the method is accurate and fast in analysing high-resolution datasets and large numbers of trees. We demonstrate the method in two use cases in Oslo, Norway, showing that it provides an alternative to field-based assessment of visibility indicators in tree valuation methods and facilitates the inclusion of complex visibility indicators not possible to assess in the field. We argue that the method could also be used for tree management and planning, urban ecosystem accounting and neighbour conflict resolution related to trees.     

白雷蘑菌丝生物学特性的初步研究

白雷蘑是山西省著名的野生食用菌．该菌营养丰富、味道鲜美。为了开发利用这一自然资源,我们对其菌丝体生物学特性进行了研究。实验表明．以腐殖土浸出液制成的葡萄糖酵母青琼脂(DYA)加富培养基是其母种的适宜培养基．原种适宜培养基配方是杂木屑40％．棉籽壳40％,麸皮15％,腐殖土5％。最适pH为6～7,最适温度是21～23℃．培养过程中,4～6℃的低温处理对促进菌丝生长有较好作用。     

果树自交不亲和花粉S基因研究进展

果树自交不亲和属于配子体自交不亲和,配子体自交不亲和至少由S位点的花柱S基因和花粉S基因2个基因决定,花柱S基因已被确定为S-RNase基因,而花粉S基因研究在近年才取得进展,一个在花粉中特异表达的基因SFB(Shaplotype-specificF-boxprotein)被发现,并且多方面的证据表明该基因是花粉S基因的最佳代表。就花粉S基因的筛选、该基因的结构特点、可能的作用机理等方面的研究进展予以综述。     

Simulated impact of sea level rise on phreatic level and vegetation of dune slacks in the Voorne dune area (The Netherlands)

Effects of sea level rise and different coastline management options on the phreatic level in a coastal dune area are calculated, using a scenario with 60 cm sea level rise in the course of the next century, resulting from global climatic changes. Changes in the phreatic level - both lowering and rising - are evaluated for their effects on the dune slack vegetation, using a newly developed interaction model hydrology-vegetation. Some indications of changes in nature conservation values are presented.     

大杯蕈原生质体菌株筛选的研究

对野生大杯蕈（Ｃｌｉｔｏｃｙｂｅ ｍａｘｉｍａ）原生质体的分离再生及再生菌株的构建进行研究,以纤维素酶、溶壁酶、崩溃酶、β－葡萄糖苷酸酶的去壁效果最好,而新生酶,几丁质酶,蜗牛酶的云壁效果较差。２种以上的酶液混合使用能提高去壁效果。酶解液在０．１％￣２．０％浓度范围内原生质体释放量随酶解液的浓度升高几乎呈直线上升。酶解３￣５ｈ释放的原生质体最多。酶解液ｐＨ值在５．０￣６．０范围内原生质体的产量较高     

Examining the socio-psychological predictors of tree-planting behaviour using the theory of planned behaviour: A study of a cohort of Nigerian urban workers

A model of socio-psychological precursors of tree-planting behaviour using the theory of planned behaviour was tested among a cohort of Nigerian civil servants in Ibadan, Nigeria. Data collection involved the self-administration of a pre-tested, closed-ended questionnaire among 400 randomly selected respondents. Results show that tree-planting behaviour reduced progressively from 17.5%–8.0% over ten years and in the last year respectively. Age and education had main effects on tree-planting behaviour but sex did not. Attitude, subjective norm and perceived behavioural control were significant predictors of, and explained 21.0 % of the variance in intention to plant trees. Intention to plant trees is a significant predictor/determinant of tree-planting behaviour. Being younger and having lower education are significantly predisposing to increased tree-planting while sex is immaterial in issues of tree-planting. The improvement of the appraisal of the virtuousness of tree-planting; the acceptability of tree-planting by significant others and the autonomous power to act concerning tree-planting, will engender stronger intention to plant trees and subsequently improve tree-planting behaviour. Socio-psychological realities deserve tremendous focus in matters of tree-planting agenda.     

山杏下胚轴再生不定芽影响因子研究(英文)

山杏成熟种子在改良MS培养基上培养获得下胚轴,将其切段后培养在改良MS培养基+TDZ2.0mg/L+NAA0.5mg/L的再生培养基上,经15d的暗期培养后,其再生频率可达到37%以上。试验表明分裂素TDZ促进不定芽再生的效果优于6-BA,生长素NAA效果优于2,4-D,2-3周龄的下胚轴再生效果较好,但下胚轴的取材部位对再生无显著影响。     

EST-SSR标记及其在果树研究中的应用

近年来大量ESTs数据的出现已成为开发SSR标记的重要来源。EST-SSR作为一种新型的分子标记,不仅具备传统基因组SSR标记的特点,而且以其开发经济和通用性高等优势已在很多植物中得到开发和应用。简要介绍了EST-SSR标记的原理和特点,重点综述了其在果树的遗传多样性分析、遗传连锁图谱的构建、比较作图和分子系统发育等研究领域的应用现状,期望为今后该项技术在果树研究上的应用提供参考。