The colonization history of Olea europaea L. in Macaronesia based on internal transcribed spacer 1 (ITS-1) sequences, randomly amplified polymorphic DNAs (RAPD), and intersimple sequence repeats (ISSR)

Phylogenetic relationships in the Olea europaea complex and the phylogeography of 24 populations of the Macaronesian olive (O. europaea ssp. cerasiformis) were assessed by using three molecular markers: nuclear ribosomal internal transcribed spacer 1 (ITS-1) sequences, randomly amplified polymorphic DNAs (RAPD), and intersimple sequence repeats (ISSR). Parsimony analysis of the ITS-1 sequences and Neighbour-joining (NJ) analyses of RAPD and ISSR banding variation revealed four major lineages in the O. europaea complex: (1) ssp. cuspidata; (2) ssp. cerasiformis from Madeira; (3) ssp. laperrinei; and (4) ssp. cerasiformis from the Canary Islands plus ssp. europaea. These results provide unequivocal support for two independent dispersal events of Olea to the Madeira and Canary Islands. Molecular and morphological evidence led to recognition of two separate olive taxa in Macaronesia, to date included in ssp. cerasiformis. NJ analyses of the combined RAPD and ISSR data suggest that the colonization of the Canaries by O. europaea may have followed an east to west stepping-stone model. An interisland dispersal sequence can be recognized, starting from the continent to Fuerteventura, Gran Canaria, Tenerife, La Gomera, and finally La Palma. High dispersal activity of the lipid-rich Olea fruits by birds in the Mediterranean region is congruent with multiple dispersal of olives to Macaronesia and successive colonization of the archipelagos. The observation of strong genetic isolation between populations of different islands of the Canary Islands suggests, however, that subsequent interisland dispersal and establishment has been very rare or may not have occurred at all.     

The shrubland vegetation in western Shewa,Ethiopia and its possible recovery

Shrubland vegetation and environmental data in western Shewa, Ethiopia have been analysed. Vegetation data include cover-abundance values of vascular plant species; environmental data comprise physical and chemical properties of the soil, altitude, slope, grazing and browsing pressure. The vegetation data were subj ected to hierarchical and non-hierarchical classification and ordination with correspondence analysis. The classification resulted in seven different vegetation types, ranging from grassland with scattered shrubs to degenerated forest. Ordination of the data and biplot analysis showed that the vegetation is influenced by anthropogenic factors and altitudinal variation. Sand content is related to a low level of anthropogenic influence whereas silt content is related to a high level. This is explained by historical events rather than by the present situation. Total nitrogen, organic carbon, altitude and slope are positively correlated and these variables are negatively related to anthropogenic influences. The shrubland vegetation may have expanded from lower altitudes and drier sites as forests gradually disappeared. The recovery of an economically more rewarding vegetation type may be achieved through pro viding alternative sources of fuel and construction and through prohibiting cultivation and grazing in the shrublands on the hillsides. Regeneration can be accelerated by actively introducing seedlings of tree species that do not need a heavy canopy cover for establishment and growth.     

Systematics, ecology and phylogeographic significance of Olea europaea L. ssp. maroccana (Greuter & Burdet) P. Vargas et al., a relictual olive tree in south-west Morocco

Within the genus Olea , the olive ( Olea europaea L.) possesses the largest geographic distribution, and several subspecies have been described. South-west Morocco harbours an endemic olive, O. europaea ssp. maroccana (Greuter & Burdet) P. Vargas et al. , located in the western part of the High Atlas (mainly on the southern slope of the Ida-ou-Tanane massif) and in the western Anti Atlas. The existence and the taxonomic position of this tree have long remained uncertain, but the combination of several morphological traits is unique. Nuclear and cytoplasmic DNA polymorphism also demonstrate that this tree is a well-differentiated and relictual taxon, probably originating from an ancestral unit within tropical Africa. Our findings refute the opinions of several authors who consider ssp. maroccana to be intermediate between the cultivated olive ( O. europaea ssp. europaea ) and the Saharan olive ( O. europaea ssp. laperrinei (Batt. & Trab.) Cif.). According to cpDNA and mtDNA analysis, the Moroccan olive and the Canarian olive ( O. europaea ssp. guanchica P. Vargas et al. ) are related and belong to the same sub-taxon. This biogeographical affinity is strongly supported by other recent phylogenetic studies. The long-term viability of ssp. maroccana is threatened by several factors: (1) limited distribution and reduced numbers of individuals within isolated populations, (2) fragmentation processes related to human and livestock pressures, and (3) putative gene flow between this taxon and the cultivated olive. In order to ensure the long-term survival of this endemic olive, a specific program of conservation should be implemented in the near future.     

Influence of cattle grazing practices on forest understorey structure in north‐eastern New South Wales

Abstract In eastern Australia the practice of grazing cattle in eucalypt forests and woodlands, as a supplementary activity to farmland grazing, is widespread. It is typically accompanied by burning at frequent intervals by graziers to promote more nutritious and digestible growth of the ground cover for their livestock. Collectively, these forest grazing practices affect understorey structure, which in turn affects other biotic and abiotic components of these ecosystems. In order to test how significant the effects of forest grazing practices are relative to the effects of other management practices and environmental variables and the degree to which grazing practices determine understorey vegetation structure, we surveyed 58 sites on the northern tablelands of New South Wales, Australia. All sites were located in eucalypt forest and were stratified by grazing status (presence or absence): time since logging, time since wildfire, geology, aspect, slope and topographic position. At each site an index of vegetation complexity and the most abundant plant species were recorded. The data were analysed by a backwards stepwise multiple regression. Grazing practices had the greatest influence on understorey vegetation complexity of any of the measured attributes. The grazed sites were characterized by a significantly lower vegetation complexity score, different dominant understorey species, reduced or absent shrub layers, and an open, simplified and more grassy understorey structure compared with ungrazed sites. Time since logging and time since wildfire also significantly affected understorey structure. Our results indicate that cattle grazing practices (i.e. grazing and the associated frequent fire regimes) can have major effects on forest structure and composition at a regional level.     

Physiological and Biochemical Aspects of Frost Resistance in Оlea europaea L.

Russian Journal of Plant Physiology - The results of studies on the frost resistance of Olea europaea L. varieties and its subspecies O. europaea subsp. cuspidata (Wall. and G. Don) Cif....     

四川岷山火溪河地区人为干扰后的植被组成及分布

以平武县地形图、植被图、野外植被调查结果为数据源制作研究区植被图和数字高程模型(Digital Elevation Model,DEM),在Arcview GIS平台下通过植被分类和图层叠加分析法,研究了人为干扰后植被的组成及植被类型在主要地形梯度上的分布特征。结果表明:(1)受人为干扰特别是森林采伐活动影响,研究区针阔混交林消失,针叶林面积缩小,阔叶林和灌丛面积增加。(2)植被类型在海拔梯度上分布规律性明显;除农田外,其它植被类型在坡度上的面积比例与研究区面积在各坡度段所占比例很相似;针叶林、阔叶林、农田、灌丛对坡向有明显选择性。(3)人为干扰活动改变了研究区植被类型及其面积比重,并使植被在海拔段上的分布带有明显人类干扰的痕迹。     

On the origin of the invasive olives (Olea europaea L., Oleaceae)

The olive tree (Olea europaea) has successfully invaded several regions in Australia and Pacific islands. Two olive subspecies (subspp. europaea and cuspidata) were first introduced in these areas during the nineteenth century. In the present study, we determine the origin of invasive olives and investigate the importance of historical effects on the genetic diversity of populations. Four invasive populations from Australia and Hawaii were characterized using eight nuclear DNA microsatellites, plastid DNA markers as well as ITS-1 sequences. Based on these data, their genetic similarity with native populations was investigated, and it was determined that East Australian and Hawaiian populations (subsp. cuspidata) have originated from southern Africa while South Australian populations (subsp. europaea) have mostly derived from western or central Mediterranean cultivars. Invasive populations of subsp. cuspidata showed significant loss of genetic diversity in comparison to a putative source population, and a recent bottleneck was evidenced in Hawaii. Conversely, invasive populations of subsp. europaea did not display significant loss of genetic diversity in comparison to a native Mediterranean population. Different histories of invasion were inferred for these two taxa with multiple cultivars introduced restoring gene diversity for europaea and a single successful founder event and sequential introductions to East Australia and then Hawaii for cuspidata. Furthermore, one hybrid (cuspidata x europaea) was identified in East Australia. The importance of hybridizations in the future evolution of the olive invasiveness remains to be investigated.     

High-Andean vegetation and environmental gradients in northwestern Patagonia,Argentina

Abstract. We analysed the heterogeneity of high-elevation vegetation on three mountains along a west-east transect at 41 °S lat. in the Andes of northwestern Patagonia, Argentina. In this area, high-Andean vegetation occurs as islands on mountain tops above Nothofagus pumilio forests ? with the timberline at ca. 1700 m a.s.l. We recorded floristic, topographic and substrate data in 166 sites stratified according to longitude, altitude, slope and aspect. Vegetation data were classified with TWINSPAN and ordinated with Detrended Correspondence Analysis. The relationship between environmental and floristic variation was analysed using Canonical Correspondence Analysis. In order of importance, geographical longitude, altitude and aspect were the major determinants of vegetation variation, whereas substrate texture and slope appeared less important. The combination of these factors resulted in two main vegetation gradients. The first gradient is related to a moisture availability gradient, primarily determined by longitude and secondarily to variation in wind exposure (east vs. west aspect). The second vegetation gradient is related to variation in temperature, primarily determined by altitude, and secondarily by variation in insolation related to the contrast between north and south aspects. The four communities obtained with TWINSPAN are therefore associated with four characteristic habitat types: moist-cold, moist-warm, dry-cold and dry-warm. The community of warm and dry environments is the richest and has elements in common with dry steppe communities situated at lower elevations to the east, while the vegetation of the cold-moist habitat type has unique elements that are typical of the southern Andes. Although current climatic factors appear to be the major determinants of high-Andean vegetation gradients, historical events of Pleistocene times probably also affected the vegetation patterns we see today.     

中条山混沟地区森林乔木种的数量分类与环境解释

通过对中条山混沟地区森林植被调查资料的多元分析——TWINSPAN分类、CCA排序与环境解释,划分了该地区的植被类型,给出了植被与环境因子的定量关系。结果如下:1)40个样地可划分为青檀林(Form.Pteroceltis tatarinowii)、栾树林(Form. Koelreuteria paniculata)、槲栎林(Form. Quercus aliena)、栓皮栎林(Form. Quercus variabilis)、鹅耳枥+葛萝槭林(Form. Carpinus turczaninowii+Acer grosseri)、元宝槭+千金榆林(Form. Acer truncatum+Carpinus cordata)和辽东栎林(Form. Quercus liaotungensis)7种群落类型,体现了中条山地带性植被类型为暖温带落叶阔叶林的特点。2)群落类型的划分主要反映了CCA排序第一、二轴的环境梯度,CCA排序第一轴突出反映了海拔与土壤养分梯度,第二轴与土壤pH值、湿度指数和坡度显著相关。总体来说,海拔和土壤因子是影响混沟地区乔木物种分布分异的最主要环境因子。3)环境因子和空间因子解释了物种格局变化的46.14%,其中环境因子占30.79%,空间因子占8.48%,空间因子和环境因子交互作用解释的部分占6.87%。良好的环境解释反映了调查取样和环境因子选取的合理性,同时也体现了混沟地区植被的原始性。     

Tracing and interpreting fine-scale human impact in northern Fennoscandia with the aid of modern pollen analogues

A set of moss samples (n=58) was collected and analysed to obtain modern pollen analogues for both natural and human induced vegetation types in northern Fennoscandia. Vegetation types with settlement, trampling and grazing were selected from the different latitudinal forest zones (birch, pine, and mixed forest). The moss species varied between samples but the size of the sample was kept constant. Numerical analyses such as Redundancy Analysis (RDA) indicate that in northern areas human presence is mainly visible as increased values of Gramineae, Rumex acetosa/acetosella, R. obtusifolius, Solidago-type and Achillea-type pollen. Partial RDA further reveals that settlement is strongly correlated with high values of Rumex acetosa/acetosella, whereas trampled sites are significantly characterised by Gramineae and, to a smaller extent, Cyperaceae pollen. It is therefore possible to distinguish the impact of different types of human activities on vegetation on the basis of the pollen spectra. Later, these data will be used to interpret the presence, nature, and duration of human impact from fossil records from the same area. Received June 6, 2001 / Accepted December 12, 2001     

河北坝上草原东沟植物群落生态梯度的数量分析

运用DCCA排序轴分类,将河北坝上草原东沟的植物群落划分为8类,效果较好．排序图表达了植物群落的环境梯度、结构梯度和人为干扰．第1轴反映了群落在海拔和坡度方面的空间梯度,第2轴反映了群落的坡向分异格局,两轴综合反映了群落沿水分梯度的空间分异．群落的层片构成和各层片物种组成也表现出相应的空间分布格局．白桦局限在阴坡高海拔陡峭处．阴坡灌木与草本层片优势种分别为金露梅与细叶苔草,阳坡则为蒿类和冰草．阳坡群落各层片优势种还存在海拔和坡度分布格局．另外,放牧、耕作和伐树等人为干扰对群落时空分布也有显著影响．一般来说,生境条件较好的群落,人为干扰较严重．     

Assessment of spatial and habitat use overlap between Himalayan tahr and livestock in Kedarnath Wildlife Sanctuary,India

Livestock grazing and associated habitat degradation are considered as major reasons for declining populations of wild ungulates. In the Himalaya, livestock grazing has been practiced for centuries. We studied the spatial and habitat use overlap between the Himalayan tahr (Hemitragus jemlahicus) and domestic migratory livestock (Capra aegagrus hircus and Ovis aries) in the subalpine and alpine areas of the Kedarnath Wildlife Sanctuary, Uttarakhand, India, from April 2003 to March 2004 to investigate if there was an impact of livestock grazing on the habitat use of tahr in this area. Habitat parameters such as altitude, aspect, slope, and vegetation cover used by the tahr and livestock were quantified and compared. Minimal spatial overlap was observed. Tahr demonstrated preference for higher altitude and steeper terrain and occupied rocky terrain with comparatively less grass, shrub, and tree cover, while livestock occupied lower slope categories with low rock cover and more shrub and tree cover. Livestock used altitude, slope, and aspect categories in proportion to their availability. However, the difference in use of altitude and slope was not significant, and an increase in the population of the tahr over the years in the study area was concomitant to the decrease in the livestock use of the area, which raises doubts as to whether this minimal habitat overlap is an outcome of spatial displacement or exclusion of the tahr from certain habitats.     

Association classification of a 30 hm2 dynamics plot in the monsoon broad-leaved evergreen forest in Pu’er,Yunnan, China

季风常绿阔叶林是我国南亚热带典型的地带性植被, 建立森林动态监测样地是研究生物多样性维持和群落构建机制的重要平台。该文以普洱30 hm ²森林动态监测样地为研究对象, 采用多元回归树、重要值、主成分分析与指示种相结合的方法对样地内750个样方进行群丛数量分类, 以获取季风常绿阔叶林森林植被群丛类型。结果表明: 森林动态监测样地共发现木本植物271种, 隶属于78科178属, 群落类型为短刺锥(Castanopsis echidnocarpa)群系, 可划分4个群丛类型, 分别是珍珠花+毛银柴-短刺锥+泥柯群丛(Lyonia ovalifolia + Aporosa villosa - Castanopsis echidnocarpa + Lithocarpus fenestratus Association)、云南瘿椒树+耳叶柯-短刺锥+西南木荷群丛(Tapiscia yunnanensis + Lithocarpus grandifolius - Castanopsis echidnocarpa + Schima wallichii Association)、大果杜英+黄药大头茶-短刺锥+西南木荷群丛(Elaeocarpus sikkimensis + Polyspora chrysandra - Castanopsis echidnocarpa + Schima wallichii Association)、西桦+尼泊尔桤木-短刺锥+枹丝锥群丛(Betula alnoides + Alnus nepalensis - Castanopsis echidnocarpa + Castanopsis calathiformis Association)。群丛间物种分布存在较多过渡重叠, 指示物种是区分群丛类型的主要依据, 海拔与坡向对群丛分类有较大的影响, 坡度对群丛分类影响较小。     

Vegetation structure along the altitudinal gradient at the treeline of Mount Paektu,North Korea

Vegetation structure of the treeline was studied on the southeastern slope of Mount Paektu (North Korea). Fifteen temporary plots (20m×20m) were situated along the altitudinal transect. Seven square samples (phytosociological relevés 5 m×5 m) were analyzed in each plot. Although the character of the vegetation was rather continuous altitudinally, five similar groups of vegetation samples were distinguished by the TWINSPAN procedure. The distribution of samples in the classification showed not only the effect of altitude but also the effect of competition between the tree and the shrub layers and other factors. In the canonical correspondence analysis (CCA) ordination several environmental variables were used (such as altitude of each plot, distance of each plot from the forest edge and the cover percentage of tree, shrub, herb and moss/lichen layers). The variable ‘cover of tree layer’ had the strongest relation to the species data. Continuous changes of species richness along the altitude were confirmed. Species richness decreased significantly with altitude.     

完达山林区森林采伐和非采伐区马鹿、狍子对冬季生境因子选择的比较

2003—2005年的冬季,在黑龙江省完达山地区的五泡林场,通过样线调查,利用逐步判别分析的方法,对冬季马鹿和狍子在森林采伐区和非采伐区生境选择的差异进行了比较研究,其结果表明,在该地区虽然两物种在生境选择上发生部分重叠,但在生境利用方式上均存在显著差异在采伐区马鹿主要利用中坡位或上坡位、半阴半阳或阳坡、人为干扰距离大于1000m、海拔相对较高、食物丰富度较高、乔木胸径较小、灌木密度较高的灌丛或杂木林生境;狍子主要利用中坡位或下坡位、阳坡、海拔相对较低、食物丰富度适中、乔木胸径较大、灌木密度较低、人为干扰距离要求不严格的杂木林或柞树林生境。在非采伐区,马鹿主要选择距人为干扰大于1000m、海拔较高、食物丰富度较高、乔木胸径较小的杂木林生境;狍子主要选择中坡位或下坡位、人为干扰距离要求不严格、海拔较低、食物丰富度较适中和乔木胸径较大的杂木林或杨-桦混交林生境。     

Altitudinal effects on habitat selection of dung beetles (Scarabaeoidea: Aphodiidae) in the northern Iberian peninsula

The effects or vegetation cover on the abundance and species richness of dung beetles (Aphodiidae) were examined in three altitudinal zones: lowland (520–600 m), mid-altitude (950–963 m) and highland (1230–1275 m). Pitfall traps baited with fresh cattle dung were placed in three vegetation types at each altitudinal zone: forest, heathland and pasture. Species richness was lower in forests than in the other vegetation types. The total abundance of beetles also varied with vegetation type, but the effect was dependent on altitude. Number of individuals was higher in pasture at highlands and in heathland and forest at mid-altitude and lowlands. An altitudinal dependence of distribution of individuals between vegetation types was also found for the more abundant species in the study area. These results could be explained if the local distribution of individuals between vegetation types was determined by microcli-matic factors, mainly temperature. Differences in altitude between sites are associated with temperature changes, determining the habitat selection of species at each altitude.     

India's biodiversity hotspot under anthropogenic pressure: A case study of Nilgiri Biosphere Reserve

This paper presents data on the impact of biotic pressure in terms of grazing by livestock and wood cutting by humans on the plant community in the Nilgiri Biosphere Reserve of India. Grass, and herbaceous plant biomass, number of cattle dung piles, number of woody stems available and damaged by human activities and weed biomass were assessed at different proximity along transects radiating from village-forest boundary to forest interior to measure the ecological impact of livestock grazing and fire wood collection. The grass biomass was positively correlated to overgrazing indicating the adverse effect on natural vegetation by cattle. Woodcutting was intense along the forest boundary and significantly declined as distance increased. Similarly, weed biomass and number of thorny species declined positively with proximity from village-forest boundary and the weed biomass was significantly higher in the pastoral sites compared to residential sites. The results suggest that human impact adversely affects natural vegetation and promotes weed proliferation in forest areas adjoining human settlements in the ecologically important Nilgiri Biosphere Reserve. Continued anthropogenic pressure could cause reduction in fodder availability to large herbivores like elephants, which in turn leads to an increase in human–elephant conflict.     

天童常绿阔叶林林窗的地形分布格局

为探究多维地形因素对林窗分布的影响,以天童20 hm²常绿阔叶林动态监测样地内的林窗为对象,结合地理信息系统软件,分析了林窗空隙率、林窗密度以及林窗面积在海拔、坡度、坡向、坡形、坡位5种地形因子下的分布格局.结果表明: 该样地林窗空隙率为13.1%,林窗密度为9.5个·hm^-2,林窗平均面积为137.82 m²;因高海拔台风干扰的强度较大,高海拔段(≥500 m)林窗的空隙率和密度显著大于中低海拔段(<500 m);台风带来的强降雨极易引起小范围滑坡,使得沟谷的林窗空隙率和密度显著大于侧坡,林窗平均面积显著大于侧坡和山脊.台风及其带来的强降雨是造成林窗在海拔及坡位梯度上具有显著性差异的主要原因.     

天童常绿阔叶林林窗的地形分布格局

为探究多维地形因素对林窗分布的影响,以天童20 hm²常绿阔叶林动态监测样地内的林窗为对象,结合地理信息系统软件,分析了林窗空隙率、林窗密度以及林窗面积在海拔、坡度、坡向、坡形、坡位5种地形因子下的分布格局.结果表明: 该样地林窗空隙率为13.1%,林窗密度为9.5个·hm^-2,林窗平均面积为137.82 m²;因高海拔台风干扰的强度较大,高海拔段(≥500 m)林窗的空隙率和密度显著大于中低海拔段(<500 m);台风带来的强降雨极易引起小范围滑坡,使得沟谷的林窗空隙率和密度显著大于侧坡,林窗平均面积显著大于侧坡和山脊.台风及其带来的强降雨是造成林窗在海拔及坡位梯度上具有显著性差异的主要原因.     

历山自然保护区猪尾沟森林群落植被格局及环境解释

应用TWINSPAN、DCA和DCCA,从植物种,植物群落与环境的生态关系方面,研究历山自然保护区猪尾沟森林群落的植被分布格局,并给予合理的环境解释。结果如下：（1）采用TWINSPAN数量分类方法,将植被划分为9个群落类型。（2）对于特定的研究区域猪尾沟,制约森林群落类型,植物种分布格局的主要因素是海拔梯度,即水、热两个环境因子。（3）DCCA排序图明显反映出排序轴的生态意义,第一轴基本上突出反映了各植物群落所在环境的海拔梯度,即热量因素,沿第一轴从左到右,海拔逐渐升高,植物群落或植物种对热量要求降低;第二轴主要表现了各植物群落或植物种所在环境的坡度,坡向,即水分和光照因素,沿第二轴从下到上,坡度渐缓,坡向渐向阳。