Hybridization of European oaks (Quercus ilex × Q. robur) results in a mixed isoprenoid emitter type

European oaks have been reported to emit isoprene or monoterpenes derived from recently fixed photosynthetic carbon. The emission type is plant species specific and can be used as chemo‐taxonomic marker. In the present article the isoprenoid biochemical properties of mature Quercus × turneri‘Pseudoturneri’ hybrids resulting from a crossing of a Mediterranean evergreen monoterpene‐emitting species (subgenus Sclerophyllodrys; Quercus ilex L.) and an isoprene‐emitting deciduous oak species (subgenus Lepidobalanus; Quercus robur L.) are described. Both species are compared with respect to the capacity for isoprenoid synthesis and the actual isoprenoid emission pattern of different tree‐types. The analysis showed that the oak hybrid combines properties of both parental species. Furthermore, it could be shown that the enzyme activities of isoprene synthase and monoterpene synthases are reflected in the isoprenoid emission pattern of the hybrids as well as in the observed emission rates.     

Two new species and one new variety of Oudemansiella (Agaricales) from Japan

Two new species and one new variety of Oudemansiella (Agaricales) from Japan are described and illustrated: (1) Oudemansiella latilamellata sp. nov. (subgenus Xerula, section Radicatae) has relatively broad lamellae and broadly ellipsoid spores with a subacute apex; (2) Oudemansiella rhodophylla sp. nov. (subgenus Xerula, section Radicatae), growing in deciduous forests of Fagus crenata, Quercus crispula, etc., is characteristic in having lamellae tinted reddish; and (3) Oudemansiella amygdaliformis var. bispora var. nov. (subgenus Xerula, section Albotomentosae) is distinguished from the type variety by having two-spored basidia and grows in evergreen oak forests (Castanopsis sieboldii, Quercus glauca, etc.) or bamboo groves.     

Conservation of Nuclear SSR Loci Reveals High Affinity of <Emphasis Type="Italic">Quercus infectoria</Emphasis> ssp. <Emphasis Type="Italic">veneris</Emphasis> A. Kern (Fagaceae) to Section <Emphasis Type="Italic">Robur</Emphasis>

Conservation of 16 nuclear microsatellite loci, originally developed for Quercus macrocarpa (section Albae), Q. petraea, Q. robur (section Robur), and Q. myrsinifolia, (subgenus Cyclobalanopsis) was tested in a Q. infectoria ssp. veneris population from Cyprus. All loci could be amplified successfully and displayed allele size and diversity patterns that match those of oak species belonging to the section Robur. At least in one case, limited amplification and high levels of homozygosity support the occurrence of “null alleles” caused by a possible mutation in the highly conserved primer areas, thus hindering PCR. The sampled population exhibited high levels of diversity despite the very limited distribution of this species in Cyprus and extended population fragmentation. Allele sizes of Q. infectoria at locus QpZAG9 partially match those of Q. alnifolia and Q. coccifera from neighboring populations. However, sequencing showed homoplasy, excluding a case of interspecific introgression with the latter, phylogenetically remote species. Q. infectoria ssp. veneris sequences at this locus were concordant to those of other species of section Robur, while sequences of Quercus alnifolia and Quercus coccifera were almost identical to Q. cerris.     

Leaf epidermal features of Quercus subgenus Cyclobalanopsis (Fagaceae) and their systematic significance

Leaf epidermal features are important taxonomic features in Quercus. We studied leaf epidermal features of 91 species and one forma of Quercus subgenus Cyclobalanopsis using light and scanning electron microscopy. Trichome terminology in oaks was assessed and clarified, aiming to score the epidermal features accurately for genus‐wide comparison. Nine trichome types, anomocytic and cyclocytic stomatal apparatus, smooth layer and platelet epicuticular wax flakes, and two trichome base types were found in subgenus Cyclobalanopsis. The epidermal features revealed three main groups in subgenus Cyclobalanopsis. The epidermal features of Quercus s.l. were uniform, supporting recognition of Cyclobalanopsis as a subgenus of Quercus rather than as a separate genus. Most leaf epidermal features show a mosaic pattern, although their numerous variations offered valuable resources for species identification. The leaf epidermal features that can be used for identification of Quercus leaves are also discussed and summarized. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 176 , 224–260.     

Molecular phylogeny of the subgenus Holothuria (Selenkothuria) Deichmann, 1958 (Holothuroidea: Aspidochirotida)

The subgenus Selenkothuria comprises 12 species of tropical shallow water sea cucumbers that share morphological features, such as rods in the body wall and tube feet, modified tentacles for suspension feeding, and cryptic colours. The taxonomic status of this taxon has been controversial, but currently it is accepted as a subgenus of the genus Holothuria. Phylogenetic analyses of mitochondrial genes [cytochrome c oxidase subunit 1 (COI), 16S RNA] of ten species of Selenkothuria and related subgenera showed the polyphyly of this subgenus; monophyly was rejected by a likelihood ratio test. A geographical split divides the species of this subgenus into three different groups: one Indo‐West‐Pacific (IWP) group and two American groups. The IWP group is more closely related to Holothuria (Semperothuria) cinerascens and to other subgenera such as Roweothuria, Holothuria, and Vaneyothuria, whereas the two American groups are more closely related to each other and to some species of the subgenus Halodeima. These results suggest multiple parallel originations and diversification of ossicle morphology within the subgenus Selenkothuria. The current scheme of subgenera for the genus Holothuria is not supported, suggesting the need for a new classification. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 165 , 109–120.     

Echiuropus bekmanae n.sp. (Crustacea, Amphipoda, Carinogammaridae) from Lake Baikal, retrieved by a new deep-water sampling device

Lake Baikal is well known for its exceptional diversity of gammarid amphipods, with 95% of endemics from its 270 described species representing about 20% of the world freshwater fauna. Echiuropus (Asprogammarus) bekmanae n.sp. was collected by an `autonomous trap system', a sampling device thoroughly described here. Although not necrophagous itself, this new species was found in two baited trap samples (at 750 and more than 1600 m) from 1995 and 1996. This rather small (13 mm) deep water species is the eighth species of the subgenus Asprogammarus, of the Baikal endemic genus Echiuropus. Diagnoses of the subgenus and the closer species are given.     

Molecular phylogeny of Phalaenopsis Blume (Orchidaceae) based on the internal transcribed spacer of the nuclear ribosomal DNA

The internal transcribed spacer (ITS1, 5.8S rDNA, and ITS2) region of nuclear ribosomal DNA (nrDNA) was sequenced from 53 species, which represent most of the living species diversity in the genus Phalaenopsis (Orchidaceae). A phylogeny was developed for the genus based on the neighbor-joining and maximum parsimony analyses of molecular data. Results of these analyses provided support for the monophyly of the genus Phalaenopsis and concurred in that the genera Doritis and Kingidium should be treated as being parts of the genus Phalaenopsis as suggested by Christenson (2001). Within the genus Phalaenopsis, neither subgenera Aphyllae nor Parishianae were monophyletic, and they were highly clustered with subgenus Proboscidioides plus sections Esmeralda and Deliciosae of subgenus Phalaenopsis based on ITS data. Those species also have the same characters of morphology of four pollinia and similar biogeographies. Furthermore, neither subgenus Phalaenopsis nor Polychilos was monophyletic. Within the subgenus Phalaenopsis, only section Phalaenopsis was highly supported as being monophyletic. As for the subgenus Polychilos, only section Polychilos was moderately supported as being monophyletic. In conclusion, the present molecular data obtained from the ITS sequence of nrDNA of the genus Phalaenopsis provide valuable information for elucidating the phylogeny of this genus.     

Tree species identity and forest composition affect the number of oak processionary moth captured in pheromone traps and the intensity of larval defoliation

1. Pure forests are often seen as being more prone to damage by specialist pest insects than mixed forests, and particularly mixed forests associating host and nonhost species. We addressed the effect of tree diversity on oak colonization and defoliation by a major specialist pest, the oak processionary moth (OPM)
2. We quantified the number of male OPM moths captured and larval defoliation in pure stands of two oak host species (Quercus robur and Quercus petraea) and in mixed stands associating the two oak species or each oak species with another nonhost broadleaved species. We conducted two complementary studies to test the effect of host species and stand composition: (i) we used pheromone trapping to compare the number of males OPM captured throughout the distribution of oak hosts in France and (ii) we noted the presence of OPM nests and estimated defoliation in mature forests of north‐eastern France.
3. Oak species and stand composition significantly influenced the number of male OPM captured and defoliation by OPM larvae. Quercus petraea was consistently more attractive to and more defoliated by OPM than Q. robur. Both oak trees were attacked more in pure stands than in mixed stands, in particular mixed stands associating oaks with another (nonhost) broadleaved species.
4. The results of the present study support the view that mixed forests are more resistant to specialist pest insects than pure stands, and also indicate that this trend depends on forest composition. Our study provides new insights into OPM ecology and has potential implications for forest management, including the management of urban forests where OPM causes serious human health issues.

     

Climate and geochemistry as drivers of eucalypt diversification in Australia

Eucalypts cover most of Australia. Here, we investigate the relative contribution of climate and geochemistry to the distribution and diversity of eucalypts. Using geostatistics, we estimate major element concentrations, pH, and electrical conductivity at sites where eucalypts have been recorded. We compare the median predicted geochemistry and reported substrate for individual species that appear associated with extreme conditions; this provides a partial evaluation of the predictions. We generate a site‐by‐species matrix by aggregating observations to the centroids of 100‐km‐wide grid cells, calculate diversity indices, and use numerical ecology methods (ordination, variation partitioning) to investigate the ecology of eucalypts and their response to climatic and geochemical gradients. We find that β‐diversity coincides with variations in climatic and geochemical patterns. Climate and geochemistry together account for less than half of the variation in eucalypt species assemblages across Australia but for greater than 80% in areas of high species richness. Climate is more important than geochemistry in explaining eucalypts species distribution and change in assemblages across Australia as a whole but there are correlations between the two sets of environmental variables. Many individual eucalypt species and entire taxonomic sections (Aromatica, Longistylus of subgenus Eucalyptus, Dumaria, and Liberivalvae of subgenus Symphyomyrtus) have distributions affected strongly by geochemistry. We conclude that eucalypt diversity is driven by steep geochemical gradients that have arisen as climate patterns have fluctuated over Australia over the Cenozoic, generally aridifying since the Miocene. The diversification of eucalypts across Australia is thus an excellent example of co‐evolution of landscapes and biota in space and time and challenges accepted notions of macroecology.     

壳斗科栎属青冈亚属的花粉形态及其系统学意义

对栎属青冈亚属17个种及炭栎花粉形态进行扫描电镜观察。结果表明:青冈亚属和炭栎花粉均为三拟孔沟,球形至长球形,(15～28.0)μm×(15.0～25.6)μm。花粉外壁纹饰可划分为3种:(1)蠕虫状(包括皱波状)、(2)聚合颗粒状、(3)棒状或小刺状。各纹饰在组间镶嵌分布。棒状及小刺状纹饰为栎属花粉较为原始式样,并为青冈亚属与高山栎组及部分巴东组(sect.Cerris)共有,推测其间具有较其它栎类更为接近的亲缘关系,可能为广义栎属中较为基础的类群,而与栎亚属sect.Quercuss.s.,Lobatae和Protobalanus关系较远。花粉形态对广义栎属系统分类价值仅适用于较高分类阶元。     

Ectomycorrhizal fungal communities of native and non-native Pinus and Quercus species in a common garden of 35-year-old trees

Non-native tree species have been widely planted or have become naturalized in most forested landscapes. It is not clear if native trees species collectively differ in ectomycorrhizal fungal (EMF) diversity and communities from that of non-native tree species. Alternatively, EMF species community similarity may be more determined by host plant phylogeny than by whether the plant is native or non-native. We examined these unknowns by comparing two genera, native and non-native Quercus robur and Quercus rubra and native and non-native Pinus sylvestris and Pinus nigra in a 35-year-old common garden in Poland. Using molecular and morphological approaches, we identified EMF species from ectomycorrhizal root tips and sporocarps collected in the monoculture tree plots. A total of 69 EMF species were found, with 38 species collected only as sporocarps, 18 only as ectomycorrhizas, and 13 both as ectomycorrhizas and sporocarps. The EMF species observed were all native and commonly associated with a Holarctic range in distribution. We found that native Q. robur had ca. 120% higher total EMF species richness than the non-native Q. rubra, while native P. sylvestris had ca. 25% lower total EMF species richness than non-native P. nigra. Thus, across genera, there was no evidence that native species have higher EMF species diversity than exotic species. In addition, we found a higher similarity in EMF communities between the two Pinus species than between the two Quercus species. These results support the naturalization of non-native trees by means of mutualistic associations with cosmopolitan and novel fungi.     

桂西地区南亚热带落叶栎林群落组成及物种多样性研究北大核心CSCD

落叶栎林是桂西地区南亚热带的典型次生林,也是该区域落叶阔叶林的重要群系组。该研究采用典型样方法对桂西地区落叶栎林群落进行调查,分析了该区域落叶栎林群落的物种组成、区系成分、物种多样性特征及其与地形因子的关系,为桂西地区南亚热带植物多样性保护与恢复提供依据。结果显示:(1)研究区落叶栎林群落维管束植物共计269种,隶属80科178属。(2)种子植物区系以热带成分为主,同时表现出一定程度的温带过渡性质。(3)聚类分析表明,调查的落叶栎林群落可分为云南波罗栎林、栓皮栎林、白栎林、麻栎林4种林分类型,其中以白栎林群落的物种多样性最高,且灌木层的物种多样性显著高于乔木层和草本层。(4)RDA分析显示,落叶栎林群落不同层次物种多样性的差异受地形因子的影响,多样性指标与经度、纬度、海拔之间具有明显的相关性(P<0.05),其中乔木层物种多样性主要与经度、纬度呈显著的相关性,灌木层物种多样性与纬度、海拔相关,草本层物种多样性与经度、纬度、海拔之间均有相关性。     

中国弧隔鼠尾草亚属(唇形科)的分布格局

弧隔鼠尾草亚属(Subg.Salvia Benth.)是中国原产鼠尾草属最大的属下类群,有44种13变种,大多含有与丹参(S.miltiorrhiza)类似的活性化合物成分和药用功效,是具有较高利用前景的野生药用植物资源。从形态学分析,该亚属具备原始类群的主要特征,物种分化明显,是研究鼠尾草属起源和演化的关键材料;从地理分布格局看,该亚属集中分布于青藏高原以及横断山脉的高海拔地区,较少扩散至低海拔的华中与华东,易受环境和全球气候变化的影响,生境人为干扰强烈,资源保护压力较大。据此,对弧隔鼠尾草亚属物种分布区进行了全面调查,结合标本记录,获得该类群具经纬度的物种分布记录2689条,海拔高度记录1007条,分布点涵盖286个县级地区。进一步对亚属内各组、系的水平与垂直分布格局深入分析。结果表明,亚属以横断山为核心区,主要分布于西藏东南至川西一带,零星扩散迁移至河北北部、湖北东部,其狭域分布的特有种比例非常高,占总物种数的45%。在物种海拔分布格局上,亚属内6个系具有替代分布现象,从高海拔的窄域分布物种逐渐过渡到低海拔的宽域分布物种。基于最大熵模型预测的亚属出现概率与物种实际分布范围基本吻合,从单一环境因子与出现概率的关系看,12月降水量、9月降水量、年温度变化范围、海拔、3月最高气温和温度季节性变化系数是影响物种分布的主导环境因子。鼠尾草雄蕊的分化是物种形成和多样性产生的关键因素,亚属内不同类群的分布格局与雄蕊花丝药隔比例的相关性表明,环境因子和传粉者选择可能共同作用形成现有弧隔鼠尾草亚属的分布格局。     

Conservation of genetic diversity in old‐growth forest communities of the southeastern United States

Question: How do studies of the distribution of genetic diversity of species with different life forms contribute to the development of conservation strategies? Location: Old‐growth forests of the southeastern United States. Methods: Reviews of the plant allozyme literature are used to identify differences in genetic diversity and structure among species with different life forms, distributions and breeding systems. The general results are illustrated by case studies of four plant species characteristic of two widespread old‐growth forest communities of the southeastern United States: the Pinus palustris – Aristida stricta (Longleaf pine – wiregrass) savanna of the Coastal Plain and the Quercus – Carya – Pinus (Oak‐hickory‐pine) forest of the Piedmont. Genetic variation patterns of single‐gene and quantitative traits are also reviewed. Results: Dominant forest trees, represented by Pinus palustris(longleaf pine) and Quercus rubra (Northern red oak), maintain most of their genetic diversity within their populations whereas a higher proportion of the genetic diversity of herbaceous understorey species such as Sarracenia leucophylla and Trillium reliquum is distributed among their populations. The herbaceous species also tend to have more population‐to‐population variation in genetic diversity. Higher genetic differentiation among populations is seen for quantitative traits than for allozyme traits, indicating that interpopulation variation in quantitative traits is influenced by natural selection. Conclusion: Developing effective conservation strategies for one or a few species may not prove adequate for species with other combinations of traits. Given suitable empirical studies, it should be possible to design efficient conservation programs that maintain natural levels of genetic diversity within species of conservation interest.     

Isolation and Characterization of 13 Microsatellite Loci from Korean <Emphasis Type="Italic">Quercus acuta</Emphasis> (Fagaceae)

Quercus acuta is an evergreen broadleaf tree that grows in the warm-temperate regions of Korea and Japan. Its habitats and populations are being destroyed, and a new northernmost limit of distribution has now been reported. To further our scientific understanding of its conservation and phylogeography, we isolated and characterized 13 microsatellite loci. An analysis of diversity was conducted among 35 individuals on Hong-do Island of Jeollanam-do, South Korea. Variability of the markers was also tested for 11 individuals from Jeju-do. At the population level, alleles numbered 2 to 12 and the observed and expected heterozygosities ranged from 0.0909 to 0.9143 and from 0.0909 to 0.9364, respectively. Those 13 loci were also tested for cross-species amplification in three other evergreen Quercus species within the same subgenus Cyclobalanopsis. In all, 6 of 13 loci could be amplified for all three species. The microsatellite markers described here provide a powerful genetics tool for population, conservation, systematics, and phylogeographic studies, not only for Q. acuta but also for other evergreen Quercus species.     

八仙山不同类型松栎林群落主要特征分析

为探究八仙山保护区不同类型森林群落的更新潜力、多样性程度以及稳定性水平,阐明三者间的关系,该文以保护区内油松林、蒙古栎林和油松-栓皮栎混交林(松栎混交林) 3种不同类型天然次生林为对象,调查建群种径级结构和更新潜力,计算不同层次群落多样性,测定M. Godron稳定性,并采用主成分法建立评价模型。结果表明:(1)油松种群径级结构近似正态分布,处于成熟期,但幼苗较少;栓皮栎、蒙古栎以及阔叶杂木的幼苗、幼树较多,更新潜力较大。(2)松栎混交林的乔木层多样性较高,而灌木层多样性最低,油松林的草本层多样性最低;松栎混交林群落总体物种丰富度最低而均匀度最高。(3) M. Godron稳定性表明,蒙古栎林距离稳定点较近,而油松林偏离较远。(4) PCA双序图表明,M. Godron稳定性与种群更新潜力、Alatalo均匀度呈较强正相关,综合排序依次为松栎混交林、蒙古栎林和油松林。综上结果表明,建群种更新潜力和物种均匀度对群落稳定性影响较大,林地管理应注重对幼苗幼树的保护。     

Multiple nuclear genes stabilize the phylogenetic backbone of the genus Quercus

Phylogenetic relationships among 108 oak species (genus Quercus L.) were inferred using DNA sequences of six nuclear genes selected from the existing genomic resources of the genus. Previous phylogenetic reconstructions based on traditional molecular markers are inconclusive at the deeper nodes. Overall, weak phylogenetic signals were obtained for each individual gene analysis, but stronger signals were obtained when gene sequences were concatenated. Our data support the recognition of six major intrageneric groups Cyclobalanopsis, Cerris, Ilex, Quercus, Lobatae and Protobalanus. Our analyses provide resolution at deeper nodes but with moderate support and a more robust infrageneric classification within the two major clades, the ‘Old World Oaks’ (Cyclobalanopsis, Cerris, Ilex) and ‘New World Oaks’ (Quercus, Lobatae, Protobalanus). However, depending on outgroup choice, our analysis yielded two alternative placements of the Cyclobalanopsis clade within the genus Quercus. When Castanea Mill. was chosen as outgroup, our data suggested that the genus Quercus comprised two clades corresponding to two subgenera as traditionally recognized by Camus: subgenus Euquercus Hickel and Camus and subgenus Cyclobalanopsis Øersted (Schneider). However, when Notholithocarpus Manos, Cannon and S. Oh was chosen as an outgroup subgenus Cyclobalanopsis clustered with Cerris and Ilex groups to form the Old World clade. To assess the placement of the root, we complemented our dataset with published data of ITS and CRC sequences. Based on the concatenated eight gene sequences, the most likely root position is at the split between the ‘Old World Oaks’ and the ‘New World Oaks’, which is one of the alternative positions suggested by our six gene analysis. Using a dating approach, we inferred an Eocene age for the primary divergences in Quercus and a root age of about 50–55 Ma, which agrees with palaeobotanical evidence. Finally, irrespective of the outgroup choice, our data boost the topology within the New World clade, where (Protobalanus + Quercus) is a sister clade of Lobatae. Inferred divergence ages within this clade and the Cerris–Ilex clade are generally younger than could be expected from the fossil record, indicating that morphological differentiation pre-dates genetic isolation in this clade.     

A NEW SPECIES OF BLACK OAK (QUERCUS,SUBG. ERYTHROBALANUS,FAGACEAE) FROM THE SIERRA MADRE OCCIDENTAL,MEXICO

Quercus mcvaughii is described as a new species of black oak (subgenus Erythrobalanus) from the Sierra Madre Occidental, in northern Durango and western Chihuahua, Mexico. It is most closely related to the more southern Q. crassifolia. Sessile or subsessile hairs, usually of different sizes, on the abaxial leaf surface distinguish Q. mcvaughii from Q. crassifolia, where hairs are similar in size and conspicuously stipitate. A key is provided for distinguishing similar species in the region. Intergradation of Q. mcvaughii with Q. crassifolia, Q. hypoleucoides, and Q. sideroxyla is reported.     

Molecular phylogeny of genus Vigna subgenus Ceratotropis based on rDNA ITS and atpB-rbcL intergenic spacer of cpDNA sequences

The genetic diversity and phylogenetic relationships among species in the genus Vigna subgenus Ceratotropis were investigated using sequence data from the ribosomal DNA ITS and atpB-rbcL intergenic spacer of chloroplast DNA regions. While both sets of sequences were of similar lengths about 700bp the rDNA-ITS was more informative than atpB-rbcL having 170% more polymorphic sites and five times as many parsimony-informative sites. The atpB-rbcL spacer may be appropriate for analysis of taxa above the species level in the genus Vigna. Results of analyzing rDNA-ITS revealed, with low level of statistical bias, separation of the subgenus into three groups that correspond to the three sections Aconitifoliae, Angulares, and Ceratotropis. The ancestral section is Aconitifoliae based on comparison with the outgroup species cowpea, Vigna unguiculata. The V. minima complex, V. minima, V. riukiuensis, and V. nakashimae, has a distinct evolutionary path within section Angulares. Other species in section Angulares are very closely related except V. trinervia. Vigna trinervia has an intermediate position between sections. Sequence data suggests one genome donor to V. reflexo-pilosa came from a lineage within section Angulares close to V. exilis, V. hirtella, and V. umbellata. Data presented supports the view that section Angulares is the most recently diversified section in the subgenus, as inferred by short terminal branch lengths among the species of this section.     

Biodiversity in different successional stages of Mediterranean enclaves distributed along Sinop Peninsula (Turkey)

The aim of this research was to evaluate plant diversity and the relationships between the distribution of Raunkiaer life forms and community structure, and species richness, at different successional stages in communities of Quercus ilex L., Erica arborea L. and Sarcopoterium spinosum (L.) Spach., distributed as enclaves in Sinop Province. Permanent sample plots were selected to determine plant diversity. The cover percentage of each plant species was recorded monthly during two vegetation periods. Raunkiaer life forms, and the Shannon–Wiener, Evenness, Simpson and Margalef indexes were determined. Twenty-three species in Quercus ilex, 96 species in Erica arborea, and 148 species in Sarcopoterium spinosum were identified. Hemicryptophyte dominancy was observed followed by phanerophytes in the Q. ilex community, and therophyte and hemicryptophyte dominancy in the E. arborea and S. spinosum communities, respectively. It was determined that the S. spinosum community was the most heterogeneous community while the Q. ilex community was more uniform than other communities. The variation in diversity indexes, homogeneity, and composition of life forms among communities adopting a similar climatic environment could result from a differentiation of environmental factors, which impact on community structuring, from biotic to abiotic at different successional stages of Mediterranean communities.