Extent,distribution and origin of non-native forest tree species in Europe

ABSTRACT

The management of non-native tree species in European forests has a long history, but the information on the current number and geographic distribution of these species in European forests is incomplete and scattered across various datasets. This study aims to perform an inventory of the most frequent non-native tree species growing in European forests and analyse their current extent, geographic distribution and geographic origin. Our results show that at least 150 non-native tree species are currently growing in European forests and provenance trials. The genera represented by largest number of species are Eucalyptus, Pinus, Acacia and Abies. Species growing at the largest areas are Robinia pseudoacacia (2.44 million ha), Eucalyptus globulus (1.46 million ha), Picea sitchensis (1.16 million ha) and Pseudotsuga menziesii (0.83 million ha). In total, non-native tree species in Europe are found in an area of approximately 8.54 million ha, or 4.0% of the European forest area, and the five most abundant species account for up to 77% of this area. The largest number of these 150 species were introduced from North America (71), followed by Asia (45) and Australia (20). North American species occupy by far the largest area.     

Generalized allometric volume and biomass equations for some tree species in Europe

Since biomass is one of the key variables in ecosystem studies, widespread effort has aimed to facilitating its estimation. Numerous stand-specific volume and biomass equations are available, but these cannot be used for scaling up biomass to the regional level where several age-classes and structural types of stands coexist. Therefore simplified generalized volume and biomass equations are needed. In the present study, generalized biomass and volume regression equations were developed for the main tree species in Europe. These equations were based on data compiled from several published studies and are syntheses of the published equations. The results show that these generalized equations explain 64–99% of the variation in values predicted by the original published equations, with higher values for stem than for crown components.

Spatial occurrence of major tree species groups in Europe derived from multiple data sources

Pan-European distribution maps have been compiled for six main species groups in Europe. The aim was to combine detailed tree species information from plot data of the International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) with other existing spatial and statistical information on forests. The applied method involves the interpolation of the plot data using the geo-statistical interpolation method kriging and a scaling and calibration procedure which makes the maps correspond both to the Forest map of Europe on pixel level and to national forest inventory statistics at regional or national level. Output is a set of European-wide maps with a resolution of 1 km, showing the proportion of the main tree species groups as a percent of the total land area. The maps are considered to be potentially valuable input for various applications in the forestry and biodiversity field at a pan-European scale.     

浅谈乡土树种的优势

近年来，随着我国六大林业重点工程的全面实施，一些地方在大量使用优良的乡土树种的基础上，试验引进了部分外来优势树种，生态建设取得了预想的效果。但也有个别地方没有认识到乡土树种的优越性，认为外地的苗木比本地出色，引进栽植后却发现苗木成活率不高，生长不良，难以成林、成材，且易发生病虫害，不但影响了工程建设的进程和效果，同时也耗费了大量的人力、物力。     

防火林带树种筛选研究

防火林带树种筛选的研究是生物防火工作的重点内容之一。该文对浙江省绍兴地区木荷等18个常绿阔叶树种树叶的7个抗火性能相关指标(包括含水率、发热量、粗脂肪含量、苯-乙醇抽提物含量、燃点、粗灰分含量、叶燃烧速度)进行了测定和模糊聚类分析,认为木荷、杜英、红楠、金叶含笑和女贞等5个树种的抗火能力较强,可在浙江省绍兴地区适宜作为生物防火林带的首选树种加以推广。     

The Armillaria species in Europe

A literature survey is given of the five European honey mushrooms Armillaria mellea, A. borealis, A. bulbosa, A. cepistipes, and A. obscura (syn. A. ostoyae) (corresponding respectively to Korhonen's intersterile groups D, A, E, B, and C); two forms of A. cepistipes are discussed: the tiny A. cepistipes f. cepistipes from Czechoslovakia and West Germany and the more common A. cepistipes f. pseudo-bulbosa Romagnesi et Marxmüller. Nomenclature, geographical distribution, hosts, some characteristics, and practical importance (including pathogenicity) are treated.     

Agroforestry for high value tree systems in Europe

Most farm-based agroforestry projects focus on the integration of trees on arable or livestock enterprises. This paper focuses on the integration of understorey crops and/or livestock within high value tree systems (e.g., apple orchards, olive groves, chestnut woodlands, and walnut plantations), and describes the components, structure, ecosystem services and economic value of ten case studies of this type of agroforestry across Europe. Although their ecological and socio-economic contexts vary, the systems share some common characteristics. The primary objective of the farmer is likely to remain the value of tree products like apples, olives, oranges, or nuts, or particularly high value timber. However there can still be production, environmental or economic benefits of integrating agricultural crops such as chickpeas and barley, or grazing an understorey grass crop with livestock. Three of the systems focused on the grazing of apple orchards with sheep in the UK and France. The introduction of sheep to apple orchards can minimise the need for mowing and provide an additional source of revenue. Throughout the Mediterranean, there is a need to improve the financial viability of olive groves. The case studies illustrate the possibility of intercropping traditional olive stands with chickpea in Greece, or the intercropping of wild asparagus in high density olive groves in Italy. Another system studied in Greece involves orange trees intercropped with chickpeas. Stands of chestnut trees in North-west Spain can provide feed for pigs when the fruit falls in November, and provide an excellent habitat for the commercial production of edible mushrooms. In Spain, in the production of high quality walnut trees using rotations of up to 50–60 years, there are options to establish a legume-based mixed pasture understorey and to introduce sheep to provide financial and environmental benefits.     

Planning tree species diversification in Kenya based on differences in tree species composition between farms. I. Analysis of tree uses

Concerns exist about the limited diversity of tree species in agricultural landscapes. Complete tree inventories were carried out on 201 farms from four villages in western Kenya to establish whether significant differences in tree species composition existed between farms, and if so their magnitude and implications for new introductions and plantings. Tree species composition was interpreted to encompass elements of both tree identity and abundance. Tree identity was viewed from both taxonomic and function (e.g. fruit, timber, medicine) perspectives. Novel types of ordination using the Hellinger ecological distance and polynomial Redundancy Analysis indicated wide heterogeneity between farms with respect to tree species composition. For the 12 most prevalent functions of trees, the analyses showed significant differences (p<0.05). Partitioning of variance identified that village location explained much of the differences between farms suggesting that farmers share tree species within villages more than between villages. Differences between farms were assessed on two-dimensional ordination graphs. For five important tree functions, including beverage, charcoal, construction, fodder and medicine, two species dominated the compositional differences. For these functions, diversification can be achieved by village-to-village sharing even in the absence of any new species introductions. A general process to determine the degree of tree diversity at farm and landscape levels and steps to increase it are discussed.     

Filling the vertical gap between canopy tree species and understory shrub species:biomass allometric equations for subcanopy tree species

Subcanopy tree species are an important component of temperate secondary forests.However,their biomass equations are rarely reported,which forms a vertical gap between canopy tree species and understory shrub species.In this study,we destructively sampled six common subcanopy species(Syringa reticulate var.amurensis(Rupr.) Pringle,Padus racemosa(Lam.) Gilib.,Acer ginnala Maxim.,Malus baccata(Linn.) Borkh.,Rhamnus davurica Pall.,and Maackia amurensis Rupr.et Maxim.) to establish biomass equatio...     

Genetic variation within European tree species

This paper reviews results of studies on genetic variation in various European coniferous and angiosperm tree species, with emphasis on Picea abies and Pinus sylvestris, Abies alba, Fagus sylvatica, and Castanea sativa. Most of the studies employ enzyme gene markers, but terpenes and other markers are also used. The comparison of data is complicated due to the variety of measures of genetic variation that are reported. Nevertheless, substantial differences in intra- and interpopulational genetic variation can be observed among and also within species. Causes for such heterogeneity are briefly discussed. The necessity for monitoring genetic variation and for standardizing measurement of genetic variation is emphasized.     

城市林业与林木引种

结合城市林业建设、城市森林生态体系建设及其对绿化树种资源的需要，论述了城市林业的内涵、城市林业的功能、城市森林的主要绿化模式、城市林业建设与林木引种的关系。同时，结合引种研究，论述了林木引种的基本原理及理论、林木引种程序与方法、林木引种的主要技术。认为在“气候相似论”、“生态历史分析法”、“生态因子论”和“综合因素论”的指导下，采用保护性引种技术、保证性引种技术、拟生引种栽培技术和顺应性引种技术等综合技术，对引进树种进行生态复合混交配置，创造有利的生境，才能使引进树种正常生长发育，取得较好的引种效果。同时，提出了城市森林建设及林木引种需要注意的事项。     

Evaluation of leaf display of evergreen broadleaved tree species and deciduous tree species in warm temperate conifer plantations

We investigated the sapling leaf display in the shade among trees of various leaf lifespans co-occurring under the canopy of a warm-temperate conifer plantation. We measured leaf-area ratio (aLAR) and morphological traits of saplings of evergreen broadleaved tree species and a deciduous tree species. Although we found large interspecific and intraspecific differences in aLAR even among saplings of similar size in the homogeneous light environment, we did not find a consistent trend in aLAR with leaf lifespan among the species. While deciduous trees annually produced a large leaf area, some evergreen broadleaved trees retained their leaves across years and had aLAR values as high as those of deciduous trees. Among leaf-level, shoot-level, and individual-level morphological traits, aLAR was positively correlated with current-year shoots mass per aboveground biomass in deciduous trees, and with the area of old leaves per aboveground mass in evergreen broadleaved trees. Thus, tree-to-tree variation in the degrees of annual shoot production and the accumulation of old leaves were responsible for the interspecific and intraspecific variations in aLAR.     

Niche analysis and tree species introduction

A method to determine the climatic requirements of tree species is outlined and related to the concept of multidimensional niche. The Bioclimate Prediction System devised by Nix, Busby and Hutchinson is used to analyse the bioclimatic component of the ‘realized niche’ of the species. The bioclimatic component of the ‘fundamental niche’ is then estimated using data from field trials outside the natural range. The method is demonstrated using the following eucalypt species: Eucalyptus citrodora, E. cladocalyx, E. fastigata, E. globulus spp. globulus, E. gomphocephala, E. grandis, E. maculata, E. paniculata, E. regnans, E. resinifera, E. robusta, E. sideroxylon and E. tereticornis. The bioclimates of their natural distributions in Australia are compared with conditions at trial sites in Africa. The method offers an explicit procedure for describing bioclimatic requirements and should assist the selection of appropriate species for trials.     

Planning tree species diversification in Kenya based on differences in tree species composition between farms. II. Analysis of tree niches.

Concerns exist about the limited diversity of tree species in agricultural landscapes. Complete tree inventories were carried out on 201 farms from four villages in western Kenya to establish whether significant differences in tree species composition existed between farms, and if so their magnitude and implications for new introductions and plantings. Novel types of ordination using the Hellinger ecological distance and polynomial Redundancy Analysis indicated wide heterogeneity between farms with respect to tree species composition of five niches, including homestead, cropland, fallow, woodlot, and external boundary (p ≤ 0.05). Multiple regression analysis confirmed the ordination results using the abundance of dominant species as the response variable. The relationship between location and species composition differed with those of two previous surveys. Methodological differences in sampling intensity, locations and time of sampling between these surveys could have caused the difference. The maps of spatial distribution of compositional types provided in the previous surveys were not confirmed, whereas villages were found to contain several farms with a species composition that was not typical of their village. Meaningful results about the species composition of a landscape should include several farms per village and use a sampling grid finer than 5×5 km².     

十大香花树种简介

花卉是大自然赋予人类一种有生命、富于情趣的精美艺术品 ,给人以美的享受 ,园艺专家把花之美概括为“色、香、姿、韵”四个字 ,其中花卉的香味美包括“香”与“味”两个方面 ,它们往往难以言传 ,却给人如梦似醉的美感。下面介绍 1 0种香花树种 ,它们或浓香、或清香、或幽香、或甜香……1　瑞香 ( Daphae odora Thunb.)瑞香科瑞香属常绿灌木 ,又名睡香、风流树。株高 1 .5～ 2 m,茎光滑 ;叶互生 ,稀疏 ,多集聚枝项 ;头状花序顶生 ,花有白、粉红、紫等色彩 ,尤以芳香著称 ,花期春夏之交 ,主要变种有毛瑞香、蔷薇瑞香、金边瑞香等 ,而以金边…     

秋季色叶树种的应用

不同的立地条件,同一树种的秋色表现不同.在成都市的立地条件下,秋色树种从高大乔木型、亚乔型到灌木型和地被型均有.银杏、榉树、无患子、天师栗、枫香、二球悬铃木、青桐、乌桕等树木以及杉科、械树科、漆树科、木兰科内的一些树木种类均可以形成漂亮的秋景,应在园林中多加应用.地被型多为终年彩色植物,已有广泛应用,也可作为秋景的下层铺垫.     

Flood tolerance of four tropical tree species

Many seasonally flooded habitats in the tropics are dominated by one or a few tree species. We tested the hypothesis that the inability to tolerate flooding restricts most species from becoming established in flood-prone habitats. We compared morphological and physiological responses to flooding in seedlings of Prioria copaifera Griseb., a species that forms monodominant stands in seasonally flooded habitats, and in three species confined to flood-free sites; namely, Calophyllum longifolium Willd., Virola surinamensis Aubl. and Gustavia superba (H.B.K.) Berg. Flooding reduced photosynthesis at Day 45 in all species by 10-30%. By Day 90, photosynthesis returned to the control rate in Prioria, but not in the other species. Flooding reduced stomatal conductance by 25-35% in all species except Calophyllum, and it reduced leaf area growth by 44% in Virola, but not in the other species. All species survived 90 days of flooding without mortality, leaf chlorosis, leaf necrosis, or leaf abscission. Flooding reduced root:shoot ratio significantly in Gustavia and Calophyllum, but not in the other species, and it reduced maximum root depth by 29% in Prioria, but by 61% or more in the species from flood-free habitats.     

Specific leaf area for five tropical tree species growing in different tree species mixtures in Central Panama

New Forests - Leaf traits have been shown to explain a great fraction of differences in growth rates in trees. With this study, we evaluate if differences in growth performance of different species...     

Automated tree detection and crown delineation using airborne laser scanner data in heterogeneous East-Central Europe forest with different species mix

Identifying tree locations is a basic step in the derivation of other tree parameters using remote sensing techniques, particularly when using airborne laser scanning. There are several techniques for identifying tree positions. In this paper, we present a raster-based method for determining tree position and delineating crown coverage. We collected data from nine research plots that supported different mixes of species. We applied a raster-based method to raster layers with six different spatial resolutions and used terrestrial measurement data as reference data. Tree identification at a spatial resolution of 1.5 m was demonstrated to be the most accurate, with an average identification ratio (IR) of 95% and average detection ratio of 68% being observed. At a higher spatial resolution of 0.5 m, IR was overestimated by more than 600%. At a lower spatial resolution of 3 m, IR was underestimated at less than 44% of terrestrial measurements. The inventory process was timed to enable evaluation of the time efficiency of automatic methods.