Distribution of the endemic Balkan flora on serpentine I. – obligate serpentine endemics

Serpentine (ophiolithic) substrate covers large areas in the Balkans, more so than in any other part of Europe. These areas extend from north to south mainly in the mountainous central regions and represent specialized habitats for basiphilous-calcifugal plants. Biodiversity in the area is high, with a great number of interesting local and regional endemics. The high number of endemics indicates the importance of serpentine habitats as centres for floristic differentiation and speciation. The number of Balkan endemics growing on serpentine is c. 335 taxa (species and subspecies) of which 123 are obligate. Their distribution is presented in 50 × 50 km UTM squares as adopted in the Atlas Florae Europaeae project coordinated at Helsinki. The richest (in number of taxa) squares are situated in NW Greece (Epirus), the island of Evvia, N Albania together with SW Serbia, and N Greece (Vourinos). They indicate important centres of plant diversity in the Balkans, areas to be noted for conservation strategy. Features responsible for the distribution and abundance of these obligate serpentine endemics include: 1) edaphic isolation in relation to type of bedrock (lime, dolomite, marble, schist, etc.), 2) mountain island isolation (Smolikas, Vourinos, Ostrovica, etc.), 3) island isolation (Evvia) and 4) continuous long-term isolation without interruption or disturbance of speciation.     

Richness and diversity of Pontic flora on serpentine of Serbia

Serpentine substrate in Serbia covers wide areas mainly in Kosovo and in central, western and south-western part of the country. On the serpentines of Serbia, particularly on the skeleton soils of hills and on lower elevation mountain slopes, there are some xerophilous and steppe-like vegetations. These xerophilous grasslands include mostly Pontic, Pontic-Submediterranean and/or Mediterranean-Submediterranean-Pontic plants. The distribution of 161 taxa of Pontic, Pontic-Submediterranean and Mediterranean-Submediterranean-Pontic areal — types on serpentinites of Serbia was analyzed in order to distinguish centers of richness and diversity. The distribution of taxa was analyzed with respect to geographic, ecological and climatic factors. The qualitative composition of Pontic flora on the serpentine areas was also compared. The greatest floristic richness and the center of diversity of Pontic flora on serpentine of Serbia was recorded in central part of the area investigated.     

Climatic and spatial patterns of diversity in the serpentine plants of California

Abstract . The insular distribution of distinctive substrates, such as outcrops of serpentine rock, may either promote plant diversity by enhancing opportunities for speciation or reduce diversity by increasing rates of extinction. To examine the relationship between diversity and the spatial structure of habitats, we studied large‐scale patterns of diversity in the flora of serpentine in California. We used multiple linear regressions on geographical information system (GIS)‐derived data for 85 subregions of the state to analyse the climatic and spatial correlates of plant species richness. The diversity of plants endemic to serpentine declined from north to south and from the coast inland, in association with decreasing rainfall; the same trends were seen in the total flora, but the trends were stronger in serpentine endemics. Diversity of serpentine endemics increased with the area of serpentine and decreased with the mean isolation of serpentine patches in a subregion. The diversity of endemics was not correlated with the number of serpentine patches or their mean perimeter‐to‐area ratio. We conclude that patchiness in this terrestrial habitat does not appear to promote diversity, even at the large spatial scale associated with speciation and endemism.     

Floristic elements in European vascular plants: an analysis based on Atlas Florae Europaeae

Aim To identify floristic elements in the European flora by an analysis of the distributions of species and species groups mapped in Atlas Florae Europaeae. Location Europe, as defined by Flora Europaea. Methods We analysed the native distributions of 2762 species and 33 species’ aggregates from 79 families, which represent c. 20% of the European flora. The distributional data base, derived from Atlas Florae Europaeae, includes records from 4420 50 × 50‐km UTM grid squares. We classified species into floristic elements by a three‐stage clustering procedure, which consisted of: (1) constructing a dissimilarity hierarchy by complete linkage clustering, using a distance measure based on Jaccard’s coefficient; (2) cutting the hierarchical tree at the 0.95 level to create initial clusters, and forcing small clusters to link with larger ones until the sum of within‐group pairwise distances exceeded a threshold value; and (3) checking the allocation of all species to the redefined clusters and reassigning species if appropriate, using the cosine of the angle between the species and cluster centres to measure the similarity of species to clusters. Results The clustering procedure classified 2793 taxa into 18 floristic elements, which included between 66 and 289 taxa; two species had unique, non‐overlapping distributions and could not be classified. Main conclusions The analysis highlights the floristic diversity of the mountains of central and southern Europe, and of the Mediterranean region. The floristic elements of northern latitudes and the temperate lowlands tend to be composed of wide‐ranging species and include only a low proportion of European endemics. The montane elements, including those centred on montane areas in the Mediterranean region, are composed predominantly of perennial species and include high or very high proportions of European endemics. Classifications that recognize one ‘Alpine’ and one ‘Mediterranean’ biogeographical zone in Europe fail to reflect this floristic diversity.     

Bromeliaceae diversity and conservation in Minas Gerais state,Brazil

Field work and data from herbaria collections (2686 records) representing 283 taxa (265 species and 18 infraspecific taxa) of Bromeliaceae occurring at Minas Gerais state, southeastern Brazil, were analyzed in order to obtain distribution and diversity information, and to determine IUCN (The World Conservation Union) conservation status for each taxon. A map containing 1° × 1° grid cells was used to identify priority areas for new research collections, areas of high species diversity, and Bromeliaceae conservation status. A clear decrease in Bromeliaceae diversity is observed between the eastern and the western portions of Minas Gerais, and low floristic similarities were found between neighboring grid cells. The rocky mountains of Cadeia do Espinhaço are considered the most important area for Bromeliaceae endemics. From the 283 taxa of Bromeliaceae that occur at Minas Gerais, 118 (42%) are considered threatened, and 124 taxa (44% of the total) do not occur inside any protected area. The region of the Quadrilátero Ferrífero in the southern portion of the Cadeia do Espinhaço is the most threatened, and urgent strategies for conservation of this rich Bromeliaceae flora are needed. Northeastern Minas Gerais, particularly the rocky outcrops or inselbergs located in the Jequitinhonha and Mucuri rivers drainage basins need additional collection efforts and conservation actions focused on these saxicolous taxa.     

Genetics,taxonomy and the conservation of British <Emphasis Type="Italic">Euphrasia</Emphasis>

In Britain the genus Euphrasia comprises ca 20 diploid and tetraploid plant species, including several endemics. However, their conservation is impeded by taxonomic uncertainty. Analysis of cpDNA and AFLP variation was used to assess their taxonomic status and establish the extent of barriers to gene exchange among them. Differences in ploidy level constitute a very strong barrier to genetic exchange, although this is not absolute. The diploid endemics E. vigursii and E. rivularis form morphologically and genetically definable units which show some level of reproductive isolation. Within tetraploid Euphrasia, the species showed varying degrees of distinctness. Analysis of geographically paired samples from two widespread outcrossing taxa E. arctica and E. nemorosa provides evidence for extensive genetic exchange between them. However AFLP data indicate that this outbreeding species complex possesses a gene pool distinct from that of the widespread inbreeding tetraploids. The widespread and endemic inbreeding tetraploids contain examples of morphologically and genetically definable taxa, but also species whose distinctness is more equivocal. The conservation implications of this study are that species-based action plans are potentially suitable for conservation of the diploid endemics E. vigursii and E. rivularis. In contrast we contend that a species-based conservation framework, developed with reproductively isolated and genetically distinct groups in mind, requires modification for conservation of the complex and dynamic diversity found within the tetraploids. The adoption of ‘taxonomic’ action plans, designed to protect the evolutionary processes generating Euphrasia diversity, may provide a supplementary solution for conserving this type of variation.     

Floristic composition and endemism pattern of vascular plants in Ethiopia and Eritrea

Traditional attempts to delineate floristic regions are typically based on the qualitative analysis of species distribution, often ignoring the phylogenetic relationships among their taxa. Ethiopia and Eritrea are in the Horn of Africa, known as one of the world's biodiversity hotspots. We quantitatively classified the flora of Ethiopia and Eritrea into meaningful geographical units by analyzing the taxonomic and phylogenetic β‐diversity at genera, total species, and endemic species levels at a scale of 0.5° × 0.5° grid cells. Hierarchical clustering was used to quantitatively delimitate the flora and analysis of similarities was used to test the significant difference between the derived groups in taxonomic composition and phylogenetic relatedness. In total, two floristic subprovinces, five floristic districts, and 13 floristic subdistricts, as well as three centers of species endemism associated with three floristic subdistricts were identified. Our results also showed that the species diversity, endemism, and turnover of the highlands in Ethiopia and Eritrea were much higher than the lowlands, indicating that the floristic differences are closely related to the topography of the East African Rift. In this study, we provided a scientific framework for the composition and relationships of the floristic units in the Horn of Africa, and similarly provided a scientific basis for better conservation of the diversity in this region.     

Plant species diversity of Adriatic islands: An introductory survey

Abstract

The European Mediterranean region is one of the world's major centres of biodiversity. Research on plant species diversity in this region has neglected the area along the eastern part of the Adriatic basin in comparison to the other Mediterranean areas. The main aim of this study was to focus on this neglected area, by supplying data which is at present lacking in order to discuss the species-area relationship (SAR), floristic richness and endemism of the Adriatic islands and coast. Floristic data for 106 Croatian islands collected by different authors were integrated, systematised and presented in a form usable by other researchers worldwide. The Power (Arrhenius) function was used for modelling (by non-linear regression) the SAR. Residuals around the regression curve (as indicators of floristic diversity without the influence of island area) were calculated for each island. The proportion of endemics in the total island flora varies from 0% up to 28.6%, and 17.5% for narrow endemics. Floristic richness of the broader region was estimated (on the basis of SAR extrapolation) on 1807 species for all Croatian islands, and on 2797 species for the entire Mediterranean area in Croatia.     

ORIGINS AND CONSEQUENCES OF SERPENTINE ENDEMISM IN THE CALIFORNIA FLORA

Habitat specialization plays an important role in the creation and loss of biodiversity over ecological and evolutionary time scales. In California, serpentine soils have a distinctive flora, with 246 serpentine habitat specialists (i.e., endemics). Using molecular phylogenies for 23 genera containing 784 taxa and 51 endemics, we infer few transitions out of the endemic state, which is shown by an analysis of transition rates to simply reflect the low frequency of endemics (i.e., reversal rates were high). The finding of high reversal rates, but a low number of reversals, is consistent with the widely hypothesized trade‐off between serpentine tolerance and competitive ability, under which serpentine endemics are physiologically capable of growing in less‐stressful habitats but competitors lead to their extirpation. Endemism is also characterized by a decrease in speciation and extinction rates and a decrease in the overall diversification rate. We also find that tolerators (species with nonserpentine and serpentine populations) undergo speciation in serpentine habitats to give rise to new serpentine endemics but are several times more likely to lose serpentine populations to produce serpentine‐intolerant taxa. Finally, endemics were younger on average than nonendemics, but this alone does not explain their low diversification.     

The Linnean shortfall in oceanic island biogeography: a case study in the Azores

Aim Speciation processes on islands are still poorly understood. Previous studies based on the analysis of distribution data from checklists found that the flora of the Azores archipelago differs from other island floras in the exceptionally low number of radiations and the low number of single‐island endemics. The general mechanism(s) responsible for these apparently unique patterns remained unclear. One possible explanation for the distinctiveness of the Azorean endemic flora is the lack of a consistent and critical taxonomic framework for the floras of the Atlantic archipelagos. In this study, molecular variation within a range of Azorean endemic plant lineages was analysed to determine whether inadequacies in the current taxonomy of endemics might be an explanation for the unusual diversity patterns observed in the endemic flora of the Azores. Location Azores archipelago. Method Sixty‐nine populations of eight endemic species or subspecies belonging to five genetic lineages were sampled from all Azorean islands but one. Nuclear and plastid DNA regions were sequenced, and relationships among internal transcribed spacer (ITS) region ribotypes established using statistical parsimony. Results Molecular diversity patterns differ from current taxonomic groupings, with all lineages comprising previously overlooked genetic entities. Main conclusions Recognition as distinct taxa of the genetically distinct entities discovered in this study would drastically change the diversity patterns and make them more similar to those of other Atlantic archipelagos. The results serve to highlight that current knowledge of endemic diversity on oceanic islands may be far from complete, even in relatively well‐known groups such as angiosperms. This limitation is rarely considered in macroecological and evolutionary studies that make use of data from taxonomic checklists to draw inferences about oceanic island biogeographic processes.     

The role of outcrops in the diversity of Patagonian vegetation: Relicts of glacial palaeofloras?

Outcrops around the world enhance biodiversity as they provide heterogeneous environments and varied habitats for species with different requirements than those living in the surroundings, and in this way they increase alpha and beta diversity. We studied the floristic composition of the vegetation of rock outcrops in northwestern Patagonia, Argentina, and compared them to the surrounding matrix of shrubland and steppe. For this we sampled 50 outcrops and 50 matrix plots close to them, identified all the species present, and analyzed their floristic composition with Detrended Correspondence Analysis (DCA). We also analyzed the floras of the north and south faces of the outcrops. The resulting ordinations were related to geographic gradients of the region. The proportions of alien to native species, different life forms, and phylogenetic groups of the outcrop floras were compared to the matrix with G-tests. Our results showed similar dominant families, life form proportions and percentage of alien species in the outcrops and the surrounding matrix. However, species composition of the outcrops was markedly different. North Patagonian outcrops present several taxa not found in the matrix, especially in their southern, less insolated walls. The previously recorded distribution of most of these exclusive species is found in colder areas further south. Thus, we hypothesize that outcrops could be acting as relicts of cold-adapted glacial paleofloras that were probably more extended during glacial times and retreated south after the last glacial maximum.     

Genetic diversity and population structure of the serpentine endemic Calystegia collina (Convolvulaceae) in northern California

We used enzyme electrophoresis to evaluate genetic diversity in 32 populations of Calystegia collina, a clonal plant species endemic to serpentine outcrops in northern California (USA). Of 34 loci examined 56% were polymorphic, but on average only 17% were polymorphic within local populations. Neither the total number of alleles nor the number of multilocus genotypes differed significantly between populations in small vs. large serpentine outcrops. Genetic and geographic distances between populations were positively correlated, but this relationship was not significantly affected by the isolation of serpentine outcrops. Populations were highly differentiated (F(st) = 0.417) and little genetic variation was explained by geographic region or serpentine outcrop.Observed heterozygosity within populations almost always exceeded Hardy-Weinberg expectations. In many populations, all 30 sample ramets were uniformly heterozygous at one or more loci yet were genetically variable at other loci. These results imply that many C. collina populations originate from one or a few genetic founders, with little recruitment from seeds. Genetic variation within uniformly heterozygous populations must be the product of multiple, closely related founders or somatic mutations within the population. We conclude that vegetative reproduction, perhaps coupled with somatic mutation, helps maintain genetic diversity in these isolated but long-lived populations.     

Flora and vegetation of rocky outcrops/cliffs near the Hyrcanian forest timberline in the Mazandaran mountains,northern Iran

Due to their numerous endemic/sub‐endemic and rare plant species, rocky outcrops and cliffs, particularly those occurring at the timberline and forest/steppe ecotones of the Hyrcanian area, are considered as among the most important and fragile ecosystems in Iran. As a representative of such ecosystems, one of the last remnants of relatively undisturbed timberline and ecotone areas of the central Hyrcanian region was selected for phytogeographical, floristic and vegetation analyses. The flora and vegetation of rocky outcrops and crevices at altitudes of 2500–3000 m a.s.l. was surveyed by 40 relevés of 25 m² surface area. A total of 215 vascular plants belonging to 55 families and 150 genera were identified in the different vegetation types. Hemicrytophytes (55.8%) were the dominant life form and Euro–Siberian/Irano–Turanian biregional plants (28.2%) were the most common chorotype at the study sites. A phytogeographical analysis indicated that Euro–Siberian elements (including Hyrcanian endemics) precede other uniregional chorotypes in the timberline and upper‐mountain parts of the central Hyrcanian area. The Caucasus, an important biodiversity hotspot close to Iran, has a considerable number of taxa in common with the Irano–Turanian floristic regions. Five vegetation types were identified using a modified TWINSPAN procedure and subsequently analysed by indirect gradient analysis applying both species‐related (species richness, life form and phytogeographical elements) and topographic/bedrocks features of the studied relevés. The analysis revealed that the vegetation of the area is mainly affected by altitude, heat index, northness, slope inclination and bedrock features.     

雅鲁藏布江中游沙地植物区系特征

从雅鲁藏布江中游沙地植物区系的地理成分来看,其特有种非常丰富。在82个主要建群种和常见伴生种中,有31种为特有种,而且这些特有种大都是新近从邻近植物区系中分化出来的,但特有属很少或几乎没有。这说明,本区沙地植物区系是一个年轻的区系。本区沙地植物区系成分还表明,它既不完全是一个衍生的区系,也不完全是就地起源的,而是以东亚区系为主,在青藏高原的隆升过程中,发生了其邻近植物区系成分的迁移和渗透。     

Floristic Features of Sand Vegetation in the Middle Reaches of the Yarlung Zangbo,Xizang (Tibet)

The floristic features of the sand vegetation in the middle reaches of the Yarlung Zhangbo River are discussed．From the geographic elements of the floristic it can be seen that the endemic species are quite rich．Among 82 main edificatos and common companions,31 species are endemics,and most of them are neoendemics,which have differentiated from their ancestors in the adjacent floras,but there is almost no endemic genus．It indicates that the sand flora is a new and young one．The floristic elements also show that the flora is neither totally derived nor entirely native,and it has formed based on the East-Asian element． Meanwhile,the migration and percolation of the adjacent floristic elements have taken place during the lift of the Qinghai-Xizang Plateau．     

Determinants of alpha and beta vascular plant diversity in Mediterranean island systems: the Ionian islands,Greece

The Ionian archipelago is the second largest Greek archipelago after the Aegean, but the factors driving plant species diversity in the Ionian islands are still barely known. We used stepwise multiple regressions to investigate the factors affecting plant species diversity in 17 Ionian islands. Generalized dissimilarity modelling was applied to examine variation in the magnitude and rate of species turnover along environmental gradients, as well as to assess the relative importance of geographical and climatic factors in explaining species turnover. The values of the residuals from the ISAR log₁₀‐transfomed models of native and endemic taxa were used as a measure of island floristic diversity. Area was confirmed to be the most powerful single explanatory predictor of all diversity metrics. Mean annual precipitation and temperature, as well as shortest distance to the nearest island are also significant predictors of vascular plant diversity. The island of Kalamos constitutes an important plant diversity hotspot in the Ionian archipelago. The recent formation of the islands, the close proximity to the mainland source and the relatively low dispersal filtering of the Ionian archipelago has resulted in islands with a flora principally comprising common species and a low proportion of endemics. Small islands keep a key role in conservation of plant priority sites.     

Plant species richness and diversity of the serpentine areas on the Witwatersrand

Soil chemistry can play an important role in determining plant diversity. Serpentine soils are usually toxic to many plant taxa, which limits plant diversity compared to that on adjacent non-serpentine soils. The usually high concentrations of toxic metals in serpentine soils are considered to be the edaphic factors that cause low diversity and high endemism. This paper aimed primarily to determine whether there is a relationship between serpentine soil chemistry and species richness on the Witwatersrand and to compare species richness of the serpentine areas with that of adjacent non-serpentine areas as well as with the species richness of the serpentine areas in the Barberton Greenstone Belt. The alpha- and beta-diversity of the Witwatersrand serpentine and non-serpentine areas was also investigated. A secondary aim of this study was to determine which of the non-serpentine taxa were more common on the serpentine than off the serpentine, which taxa were more common off the serpentine than on the serpentine and which taxa were equally common on and off serpentine soils. There was no significant difference in alpha-diversity between the serpentine and the adjacent non-serpentine areas, but beta-diversity is higher between serpentine plots than between non-serpentine plots. Although soil factors do affect species richness and diversity of plants on the Witwatersrand to a limited extent, the concentrations of soil chemicals in serpentine soils are not sufficiently different from those in non-serpentine soils to significantly influence the species richness and diversity of the serpentine soils. The high, but similar, diversity on serpentine and non-serpentine soils on the Witwatersrand indicates that soil factors do not play a significant role in determining diversity on potentially toxic soils in the area.     

Patterns of endemism in the limestone flora of South African lowland fynbos

Taxonomie and biological aspects of endemism and Red Data Book status were studied amongst the limestone endemics of the lowland fynbos in the Cape Floristic Region, South Africa. Of the 110 limestone endemics, 1.8% are widely distributed in the Cape Floristic Region and 56.4% are regional endemics. Relative to flora of non-limestone lowland fynbos (n=538 species), the families which were overrepresented in terms of limestone endemics included the Ericaceae, Fabaceae, Polygalaceae, Rutaceae and Sterculiaceae. The Restionaceae was the only underrepresented family. The local limestone endemics were not significantly different from regional endemics in terms of their biological attributes. An analysis of the frequency of the biological traits associated with the limestone-endemic flora established a biological profile for a limestone endemic: a dwarf-to-low shrub with soil-stored seeds which are ant or wind dispersed. In terms of the species richness of limestone endemics, the De Hoop Nature Reserve was the hotspot within the region. Relative to the total species richness, the Hagelkraal and Stilbaai areas contained higher-than-predicted numbers of rare species. These areas require urgent attention if the unique floral diversity associated with limestone substrata within the Bredasdorp-Riversdale centre of endemism is to be conserved.     

Diversity and ecology of saxicolous vegetation mats on inselbergs in the Brazilian Atlantic rainforest

Inselbergs occur as mostly dome-shaped rock outcrops in all climatic and vegetational zones of the tropics. Consisting of Precambrian granites and gneisses, they form ancient and stable landscape elements. Due to harsh edaphic and microclimatic conditions, the vegetation of inselbergs differs markedly from those of the surroundings. Monocotyledonous mats form one of the most characteristic communities of this ecosystem. The floristic composition of this community was studied on six inselbergs located in the Brazilian Atlantic rainforest. Dominating are Bromeliaceae ( Alcantarea , Encholirium ), Velloziaceae ( Vellozia ), Cactaceae ( Coleocephalocereus ) and the Cyperaceae Trilepis . The alpha diversity of the mats was relatively uniform among the six outcrops. However, beta diversity varied considerably between the different sites. Beta diversity was highest at the most speciose locality indicating a high degree of stochasticity in colonization. In contrast to the low diversity mats on West African inselbergs, the Brazilian rock outcrops bear a floristically more diverse mat community rich in endemics. Thus the edaphically controlled inselberg vegetation reflects the outstanding diversity of the Mata Atlaântica. Possibly the high species richness of mats on East Brazilian inselbergs is a consequence of a large species-pool. The processes that regulate regional and local diversity in the Mata Atlaântica are not fully clear. It is assumed that historical (i.e. long-term stability) and biotic (i.e. evolutionary interchange of taxa between canopies and rock outcrops followed by differentiation of local populations) conditions have promoted high rates of speciation and their coexistence in isolated habitats. A danger to the unique vegetation of East Brazilian inselbergs is the establishment of invasive weeds.     

Defining hotspots of characteristic species for multiple taxonomic groups in the Netherlands

Biogeographical zonation based on single taxa poses major limitations on planning for nature conservation. This paper identifies biogeographical patterns of multiple taxa in the Netherlands, where no endemics are present at species level, on the basis of characteristic species. We used occurrence data on five species groups in order to identify spatially coherent, ecologically important regions. TWINSPAN was used to cluster grid squares according to similarity in species composition for each taxonomic group. Species that are characteristic of each of the clusters were identified using a preference index, and corresponding clusters among the taxonomic groups were identified with Kappa statistics. Regions containing characteristic species for several taxonomic groups were defined as ‘hotspots’. Stepwise discriminant analysis was then used to characterize these hotspots according to differences in environmental conditions. The analysis yielded five regions that are clearly distinct in terms of species composition for individual taxonomic groups. Each region is characterized by a set of unique species that occur in the zonation of at least two of the taxonomic groups. Stepwise discriminant analysis revealed significant environmental differences among these regions. The concept of hotspots as operationalized in this study can make nature conservation planning more efficient. In combination, the hotspots defined here comprise the majority of the species occurring in the Netherlands for the studied groups. Therefore, this regionalization should be taken into account when prioritizing nature conservation efforts.