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Ascophyllum nodosum is a foundation macroalgae of the intertidal zone that distributes across latitude 41.3-69.7°N. We tested the hypothesis that growth of A. nodosum near the northern distribution edge increases with warming. We retrospectively quantified the growth of eight A. nodosum populations at West Greenland and North Norway (from 64°N to 69°N). For seven populations, we measured growth rates since 1997-2002 and for one of them we extended the time series back to 1956 using published estimates. Individuals at northern populations elongated between 2.0 and 9.1 cm year and this variability correlated with temperature and annual ice-free days. A spatial comparison of A. nodosum growth across the species distribution range showed that Northern (and coldest) populations grew at the slowest rates. Our results demonstrate that arctic climate change enhances the growth of A. nodosum populations and suggest that their productivity may increase in response to projected global warming. [ABSTRACT FROM AUTHOR]

Frequent intermediate disturbances can produce qualitatively different spatial heterogeneity and environmental variability than large infrequent disturbances, which facilitates the coexistence of disparate species types. We hypothesized that species coexistence will be maximized at sites exposed to recurring hurricanes with intermediate frequencies and effects. Consequently, we sought to determine if exposure vulnerability (EV) from three hurricanes with intermediate effects and frequencies (Ivan-2004, Dennis-2005 and Dean-2007), or the interaction between exposure and topography, could be used to explain forest structural dynamics and composition. We used data obtained in 2006 and 2012 from within 45, 25 × 25 m (2.8125 ha) permanent sample plots, established according to a randomized block design, and stratified according to elevation and aspect/sites (NE and SW facing ridges) in a tropical montane wet forest, John Crow Mountains, Jamaica. There was a significant reduction in basal area (BA) (14%), tree volume (10%), and density (26%) and there was a negative shift in the height profile of trees. Understory light (2008), stem density, and mortality increased with EV but decreased with aspect. The NE aspect/sites had higher EV after Dean and the other hurricanes. Consequently, BA, volume and density increased significantly for light-demanding species at the NE sites, but declined significantly overall with minimal changes at SW sites. Moreover, diversity was significantly higher at sites with higher EV for the three hurricanes. The frequent hurricanes with intermediate effects may have therefore maintained/increased spatial heterogeneity, which promoted the coexistence of species with disparate life histories at more exposed sites. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess aquatic plant distribution patterns in a Mediterranean temporary pond network (Doñana National Park, SW Spain). We analyzed differences in species composition employing multivariate ordination techniques; we specifically examined the importance of hydroperiod and physical and chemical variables in the five geomorphological areas across which the pond network is spread. The ponds significantly segregated along a north-south gradient, matching the segregation pattern of the aquatic plant assemblages. Ponds in the three northernmost areas showed higher levels of species richness than ponds in the two southernmost areas. In the north, ponds were present at higher densities, spanned a broader hydroperiod range, and had lower conductivity levels; these features were associated with the presence of wet-meadow species and larger numbers of submerged and emergent species. In the south, alkaline waters were mainly associated with different charophyte species, and the predominance of long-hydroperiod ponds helped in increasing the number of floating species. Managed ponds, which had been artificially deepened, contributed to increase pond heterogeneity and hydroperiod breadth across the entire network. At present, such ponds are key to the preservation of Doñana's rich and unique aquatic plant community. [ABSTRACT FROM AUTHOR]

Background: Jatropha curcas L. (Jatropha) is believed to have originated from Mexico and Central America. So far, characterization efforts have focused on Asia, Africa and Mexico. Non-toxic, low phorbol ester (PE) varieties have been found only in Mexico. Differences in PE content in seeds and its structural components, crude oil and cake from Jatropha provenances cultivated in Central and South America were evaluated. Seeds were dehulled, and kernels were separated into tegmen, cotyledons and embryo for PE quantitation by RP-HPLC. Crude oil and cake PE content was also measured. Results: No phenotypic departures in seed size and structure were observed among Jatropha cultivated in Central and South America compared to provenances from Mexico, Asia and Africa. Cotyledons comprised 96.2-97.5 %, tegmen 1.6-2.4 % and embryo represented 0.9-1.4 % of dehulled kernel. Total PE content of all nine provenances categorized them as toxic. Significant differences in kernel PE content were observed among provenances from Mexico, Central and South America (P < 0.01), being Mexican the highest (7.6 mg/g) and Cabo Verde the lowest (2.57 mg/g). All accessions had >95 % of PEs concentrated in cotyledons, 0.5-3 % in the tegmen and 0.5-1 % in the embryo. Over 60 % of total PE in dehulled kernels accumulated in the crude oil, while 35-40 % remained in the cake after extraction. Conclusions: Low phenotypic variability in seed physical, structural traits and PE content was observed among provenances from Latin America. Very high-PE provenances with potential as biopesticide were found in Central America. No PE-free, edible Jatropha was found among provenances currently cultivated in Central America and Brazil that could be used for human consumption and feedstock. Furthermore, dehulled kernel structural parts as well as its crude oil and cake contained toxic PE levels. [ABSTRACT FROM AUTHOR]

Understanding factors controlling ecosystem structure and function is key to predicting the effects of climate change on vegetation distribution and carbon sequestration. Cyclones play a large role in structuring ecosystems and cyclone intensity is expected to increase on a warming planet. The effects of cyclones on broad-scale ecosystem patterns could be substantial but are poorly understood. This study assessed forest structure and biodiversity patterns across an elevation gradient (300-3000 m) in mountainous, humid forests of Taiwan, an island experiencing an average of 3-6 typhoons (regional name of cyclones) annually, and contrasted those patterns with a gradient within the Wuyi Mountains of China (500-2100 m), where the climate is similar to Taiwan but typhoon occurrence is rare and effects are generally minimal. In both Taiwan and the Wuyi Mountains, tree species richness and diversity decreased with increasing elevation. Tree size and stature decrease from low to high elevations in the typhoon-protected Wuyi Mountains. In contrast, the biomass and stature of forests in Taiwan increased from low to high elevations. The relationship between forest stature and climate was also contrasting in relation to typhoon disturbance in that we found decreasing tree height and basal area with increasing temperature in Taiwan, but not in the Wuyi Mountains. The more than twofold increase in tree height and biomass with increasing elevations reported here for subtropical humid forests of Taiwan is a unique pattern that highlights the potential role of cyclones in driving elevational patterns of forest structure. Climate change-induced alterations in tropical cyclone regimes may affect elevational patterns of forest structure and carbon sequestration in regions experiencing frequent cyclones. [ABSTRACT FROM AUTHOR]

The degree to which tree species will shift in response to climate change is uncertain yet critical to understand for assessing ecosystem vulnerability. We analyze results from recent studies that model potential tree species habitat across the eastern United States during the coming century. Our goals were to quantify and spatially analyze habitat projections and their congruence under multiple climate scenarios and to assess the implications of habitat change for forest vulnerability and adaptation to climate change in and around protected areas. We assessed habitat projections of species habitat extent and forest composition for 35 tree species under climate change from 2000 to 2100 within National Park Service management units in the Appalachian Landscape Conservation Cooperative (ALCC), spanning an approximately 1,500 km latitudinal gradient. Our results show that forest composition and species ranges could change substantially under all greenhouse gas emissions scenarios and that model correspondence was stronger for projections of habitat declines than increases. Model correspondence generally increased at finer spatial scales, but varied by tree species and focal area. In the ALCC, forest composition was projected to change the most in protected area centered ecosystems (PACEs). Northeastern PACEs were projected to be suitable for tree species currently in southeastern PACEs, suggesting that intermediate suitable habitat regions could promote tree species persistence and mitigate the impacts of climate change on eastern forests. These results suggest that climate-specific management of eastern U.S. forest ecosystems will be critical but challenging, requiring integrated assessment and management of PACEs and protected areas as well as higher-resolution monitoring and modeling to inform spatially explicit management decisions within eastern U.S. parks. [ABSTRACT FROM AUTHOR]

In the Mississippi River Delta, the common wetland grass, Phragmites australis, displays high genetic diversity, as several genetically distinct populations are co-occurring. Differences in salinity tolerance may be an important factor determining these populations' distribution in the delta. Our study investigated the salt tolerance of four genotypes exposed to 0, 10, 20, 30, and 40 ppt salinity. The growth rate, biomass, and the light-saturated photosynthetic rate were stimulated at 10 ppt salinity and inhibited at salinities higher than 20 ppt, compared to controls. Increased concentrations of Cl and Na were found in the roots and older leaves of plants exposed to high salinities. Salt tolerance levels differed between genotypes. High salinity tolerance was mainly achieved by reduced water uptake and vacuole compartmentalization of toxic ions. The most tolerant genotype sustained biomass and photosynthesis even at 40 ppt, whereas the most sensitive genotype did not survive salinities higher than 20 ppt. Our findings show that the observed occurrence of different genotypes in the Mississippi River Delta is correlated to genetically determined differences in salinity tolerance. Further investigations are needed to better understand the role that salinity tolerance plays in the invasion of certain introduced P. australis genotypes. [ABSTRACT FROM AUTHOR]

Levins's asymmetrical α index quantifies between species overlap over resources more realistically than similar-purpose single-value indices. The associated community-wide $$\bar \alpha$$ index expresses the degree of 'species packing'. Both indices were formulated upon competing animal (i.e., mobile) organisms and are independent of population densities. However, overlap over resources for nonmobile organisms such as plants may have an impact even below carrying capacity. The proposed $$\hat \alpha$$ index, based on Levins's α index, quantifies spatial overlap for plants integrating information on species spatial distribution and crowding conditions. The $$\hat \alpha$$ index is specifically designed for plant distribution data collected in discrete plots with density expressed as percent coverage (%cover) of substratum. We also propose a community-wide $${\hat \alpha_{\text{c}}}$$ index, conceptually analogous to $$\bar \alpha$$ , but furnished with a measure of dispersion ( se $${\hat \alpha_{\text{c}}}$$ ). Species importance within the community is inferred from comparisons of pairwise $$\hat \alpha$$ 's with $${\hat \alpha_{\text{c}}}$$ . The $$\hat \alpha$$ and $${\hat \alpha_{\text{c}}}$$ indices correlate closely and exponentially with plant density, and correct apparent over- and underestimations of interaction intensity at low and very high crowding by Levins's α and $$\bar \alpha$$ , respectively. Index application to aquatic plant communities gave results consistent with within-community and general ecological patterns, suggesting a high potential of the proposed $$\hat \alpha$$ and $${\hat \alpha_{\text{c}}}$$ indices in basic and applied macrophyte ecological studies and management. [ABSTRACT FROM AUTHOR]

We describe a probabilistic sampling design of circular permanent plots for the long-term monitoring of protected dry grasslands in Switzerland. The population under study is defined by the perimeter of a national inventory. The monitoring focus is on the species composition of the protected grassland vegetation and derived conservation values. Efficient trend estimations are required for the whole country and for some predefined target groups (six biogeographical regions and eleven vegetation types). The target groups are equally important regardless of their size. Consequently, intensified sampling of the less frequent groups is essential for sample efficiency. The prior information needed to draw a targeted sample is obtained from the sampling frame and external databases. The logistics and generalized delineation of the target population may pose further problems. Thus, investments in fieldwork and travel time should be well balanced by selecting a cluster sample. Second, any access problems in the field and non-target units in the sample should be compensated for by selecting reserve plots as they otherwise may considerably reduce the effective sample size. Finally, the design has to be flexible as the sampling frame may change over time and sampling intensity might have to be adjusted to redefined budgets or requirements. Likewise, the variables and biological items of interest may change. To fulfil all these constraints and to optimally use the available prior information, we propose a multi-stage self-weighted unequal probability sampling design. The design uses modern techniques such as: balanced sampling, spreading, stratified balancing, calibration, unequal probability sampling and power allocation. This sampling design meets the numerous requirements of this study and provides a very efficient estimator. [ABSTRACT FROM AUTHOR]

Hypocotyl saponin composition of 1,198 accessions of wild soybean ( Glycine soja) collected from China, Korea, Japan and Russia Far East was analyzed by thin-layer chromatography to determine polymorphic variation and geographical distribution. Eight common distinguishable saponin phenotypes were identified: Aa, Ab, AaBc, AbBc, Aa+α, Ab+α, AaBc+α and AbBc+α. The latter four +α type were new. All eight types were identified in China. Type Ab+α was absent in Korea. Types Ab+α and AbBc+α, and Aa+α and Ab+α were not identified in Japan and Russia far east, respectively. Six new triterpene saponins were detected in +α type via LC-PDA/MS/MS analyses. They were, tentatively, designated as H-αg, H-αa, I-αg, I-αa, J-αg and J-αa. These saponins were inherited together by a single dominant allele. A gene symbol Sg- 6 was assigned. Hence, the new saponins were collectively named as Sg-6 saponins. The frequency of Sg- 6 allele was 17.6 % in Chinese, 10.0 % in Korean and 1.0 % in Japanese wild soybean. The wild soybeans having Sg-6 saponins can be utilized in soybean breeding programs as well as in saponin biosynthesis studies in soybean. [ABSTRACT FROM AUTHOR]

Anadenanthera colubrina var. cebil is a discontinuously distributed native tree species in South American subtropical forests. Thirteen quantitative traits and eight nuclear microsatellite loci were examined in individuals from two biogeographic provinces of Argentina to determine the number and composition of genetically distinguishable groups of individuals and explore possible spatial patterns of the phenotypic and genetic variability. Means of reproductive traits were higher in the Yungas than in the Paranaense biogeographic province, whereas five out of eight nonreproductive quantitative traits showed higher mean values in the latter. Variance coefficients were moderate, and there were significant differences between and within provinces. Three clusters were defined based on spatial model for cluster membership for quantitative traits. One cluster grouped the individuals from the Paranaense biogeographic province whereas the individuals from the Yungas biogeographic province grouped regarding its population of origin. Parameters of molecular genetic variability showed higher values in the Yungas than in the Paranaense biogeographic province. Observed heterozygosity was lower than expected heterozygosity in both biogeographic provinces, indicating an excess of homozygosity. The homozygosity test by Watterson and the exact test by Slatkin suggested diversifying selection for locus Ac41.1. Bayesian clustering spatial model for microsatellites loci data were performed for both all loci and for all loci excluding locus Ac41.1. In both analyses two clusters were inferred. Analysis of molecular variance revealed similar results for all genotypes and for all genotypes defined excluding locus Ac41.1. Most of the total variance is attributable to genetic variation within clusters. The presence of homogeneous clusters was detected for both the phenotypic and molecular genetic variability. Two Bayesian clustering analyses were performed according to molecular genetic data, and two clusters were inferred. Individuals were assigned to their provinces of origin. Genetic molecular variation was higher in the populations of the Yungas biogeographic province which translates into highly qualified populations for conservation. Populations from the Paranaense biogeographic province showed the highest mean value of number of seeds per fruit making them valuable as well with regard to the exploitation of management strategies as a means to recover the impacted areas where these populations are located. [ABSTRACT FROM AUTHOR]

Species distribution models (SDMs) were built with US Forest Inventory and Analysis (FIA) publicly available plot coordinates, which are altered for plot security purposes, and compared with SDMs built with true plot coordinates. Six species endemic to the western US, including four junipers ( Juniperus deppeana var. deppeana, J. monosperma, J. occidentalis, J. osteosperma) and two piñons ( Pinus edulis, P. monophylla), were analyzed. The presence-absence models based on current climatic variables were generated over a series of species-specific modeling extents using Random Forests and applied to forecast climatic conditions. The distributions of predictor variables sampled with public coordinates were compared to those sampled with true coordinates using t tests with a Bonferroni adjustment for multiple comparisons. Public- and true-based models were compared using metrics of classification accuracy. The modeled current and forecast distributions were compared in terms of their overall areal agreement and their geographic mean centroids. Comparison of the underlying distributions of predictor variables sampled with true versus public coordinates did not indicate a significant difference for any species at any extent. Both the public- and true-based models had comparable classification accuracies across extent for each species, with the exception of one species, J. occidentalis. True-based models produced geographic distributions with smaller areas under current and future scenarios. The greatest areal difference occurred in the species with the lowest modeled accuracies ( J. occidentalis), and had a forecast distribution which diverged severely. The other species had forecast distributions with similar magnitudes of modeled distribution shifts. [ABSTRACT FROM AUTHOR]

Background: Propolis (bee glue) is a resinous honeybee product having a long history of application in many countries as a traditional remedy for treating wounds, burns, soar throat, stomach disorders, etc. It has been proved to possess beneficial biological effects, including antimicrobial, antioxidant, anti-inflammatory, cytotoxic, antiulcer, and many others. Bees gather propolis from diverse resinous plant parts and in different phytogeographic regions its chemical composition might vary significantly. In this article we report the results of the first study on the chemical profiles of propolis from Oman, its plant origin and antibacterial activity. Results: The chemical profiles of Omani propolis extracts were obtained by GC-MS analysis after silylation. Over 50 individual compounds were identified in the samples, belonging to different compound types: sugars, polyols, hydroxy acids, fatty acids, cardanols and cardols, anacardic acids, flavan derivatives, triterpenes, prenylated flavanones and chalcones. The profiles were dissimilar from other known propolis types. They demonstrate that although Oman is not a large country, the plant sources of propolis vary significantly, even in the same apiary and the same season. Based on chemical profiles, and isolation and identification of major marker compounds (new propolis constituents), new plant sources of propolis were found: Azadiracta indica (neem tree) and Acacia spp. (most probably A. nilotica). The ethanol extracts of the studied propolis samples demonstrated activity against S. aureus (MIC < 100 μg. mL-1) and E. coli (MIC < 380 μg. mL-1). Conclusion: Omani propolis is different form the known propolis types and demonstrates significant chemical diversity. Its most important plant source is the resin of Azadirachta indica, and as a result its typical components are C5-prenyl flavanones. Other plant sources have been identified, too, playing some role in resin collection by bees in Oman: Acacia spp. (most probably A. nilotica) and Mangifera indica. The results demonstrate also the potential of Omani propolis as antimicrobial. [ABSTRACT FROM AUTHOR]

Background and aims: The Bragança Peninsula, in northern Brazil is characterized by macrotides (4 m) and specific edaphic conditions, which determine the local mangrove forest's development. This study, conducted during the dry season evaluated the spatial patterns of Rhizophora mangle and Avicennia germinans species across an inundation gradient. Methods: Along a transect of 700 m, measurements of structure forest, soil moisture, porewater salinity, extractable phosphorus (extr.-P) in sediments, and phosphorus in the leaves (leaf-P) were conducted. Result: The A. germinans (100 %) occurred in high intertidal (HI) zone. A. germinans (59 %) and R. mangle (41 %) co-occurred in mid intertidal (MI) zone, while R. mangle (58 %) predominated in low intertidal (LI) zone, followed by A. germinans (37 %) and Laguncularia racemosa (5 %). Covariance analysis (ANCOVA) indicated that salinity and soil moisture means are significantly different between the mangrove forests, but do not correlate with inundation frequency (IF). The means of extr.-P were significantly different in mangrove forests and correlated with IF and leaf-P. Conclusion: The inundation frequency, the availability of P in the sediments, phosphorus in the leaves and interstitial salinity are all important factors contributing to the distribution of the mangrove tree species A. germinans and R. mangle on the Bragança Peninsula. [ABSTRACT FROM AUTHOR]

To investigate the dynamics of phytoplankton size structure in the Pearl River estuary, concentrations of size-fractionated chlorophyll a (Chl a) were determined during four cruises carried out in 2008 and 2010. The distribution of Chl a in this geographical location showed a high degree of temporal variation. Chl a concentrations were highest in autumn, approximately three times higher than those in summer and winter. Microphytoplankton was the dominant contributor, accounting for 66.9% of the Chl a concentration in autumn 2008. In summer and spring 2008, nano-sized cells dominated the phytoplankton population throughout the study region. During the winter cruise, two different areas of water were found, characterized by (1) low salinity and high nutrient content and (2) high salinity and low nutrient content; nano- and picophytoplankton co-dominated the first area, while microphytoplankton dominated the second. It is arguable that grazing could have played a role in determining phytoplankton community size structure in winter. Nutrient concentrations were assumed not to limit phytoplankton growth during the investigation period. Size-differential capacity in competing for the resources available under different hydrodynamic conditions seemed to be the major factor in determining seasonal variation in the structure of the phytoplankton communities. High N:P ratios in the Pearl River estuary had major implications for nutrient pollution control. Our results indicated that studies of phytoplankton size structure provide greater insight into phytoplankton dynamics and are necessary to better manage water quality in the Pearl River estuary. [ABSTRACT FROM AUTHOR]

Aims: Arbuscular mycorrhizal (AM) fungi, a group of obligate symbionts of terrestrial plants, have a global distribution range. Yet, we lack concrete synthetic and empirical evidence that could reveal whether distinct ecological niches are distributed across Glomeromycota through determining linkages between environmental factors and the distribution of these taxa. Methods: We have modelled the probability of occurrence of Gigasporaceae and Acaulosporaceae as a function of candidate environmental factors. These families are among the most common but non-ubiquitous taxa in AM-driven ecosystems. We have constructed our database using studies with a global scope and carried out our analysis through a logistic regression approach. Results: The probability of occurrence of Acaulosporacae increased in acidic environments and soils with high bulk density. By contrast, a key factor that affected probability of occurrence of Gigasporaceae was precipitation. Conclusions: Through the analysis of an unprecedentedly large amount of data we could infer that niche processes mediate occurrence of a group of fungi at scales broader than the local scale of the individual studies gathered in the analysed dataset. Knowledge of well-supported niche features could enhance discovery of new taxa of AM fungi, and would facilitate development of study designs with greater ecological realism. [ABSTRACT FROM AUTHOR]

Background and Aim: Biotic and abiotic factors contribute in shaping the distribution through the soil profile of elements released by mineral weathering; among them, leaching and biocycling dominate in temperate environments. We evaluated if the intensity of leaching and biocycling of nutrients can be modulated by element deficiencies linked to the abundance of serpentine in the soil parent material, i.e. if the most deficient elements are more efficiently retained. Methods: We selected twelve poorly developed soils from Northern Italian beech stands, with variable amounts of serpentinites in the parent material, and determined total and exchangeable Ca, Mg and K, as well as an index of abundance of serpentine minerals. Results: The total element content depended on the abundance of serpentines, while only exchangeable Mg was related to the parent material. The vertical trend of Ca and K indicated the role of biocycling in all soils, but the relative availability of Ca (ratio between exchangeable and total content) was much higher in the top horizons of serpentine-rich soils. Conclusions: The different element availability among soils suggested that the vertical distribution of available elements was linked to the parent material and that losses were limited in serpentine-rich soils, probably because plants take up the deficient elements as soon as they are released from litter and thus limit their leaching in deeper soil horizons. [ABSTRACT FROM AUTHOR]

Wild common bean (Phaseolus vulgaris L.) is distributed throughout the Americas from Mexico to northern Argentina. Within this range, the species is divided into two gene pools (Andean and Middle American) along a latitudinal gradient. The diversity of 24 wild common bean genotypes from throughout the geographic range of the species was described by using sequence data from 13 loci. An isolation-migration model was evaluated using a coalescent analysis to estimate multiple demographic parameters. Using a Bayesian approach, Andean and Middle American subpopulations with high percentage of parentages were observed. Over all loci, the Middle American gene pool was more diverse than the Andean gene pool (πsil=0.0089 vs 0.0068). The two subpopulations were strongly genetically differentiated over all loci (Fst=0.29). It is estimated that the two current wild gene pools diverged from a common ancestor ∼111 000 years ago. Subsequently, each gene pool underwent a bottleneck immediately after divergence and lasted ∼40 000 years. The Middle American bottleneck population size was ∼46% of the ancestral population size, whereas the Andean was 26%. Continuous asymmetric gene flow was detected between the two gene pools with a larger number of migrants entering Middle American gene pool from the Andean gene pool. These results suggest that because of the complex population structure associated with the ancestral divergence, subsequent bottlenecks in each gene pool, gene pool-specific domestication and intense selection within each gene pool by breeders; association mapping would best be practised within each common bean gene pool. [ABSTRACT FROM AUTHOR]

Sedum plumbizincicola X.H. Guo et S.B. Zhou ex L.H. Wu (Crassulaceae), a new species restricted to lead-zinc mining areas in Zhejiang Province, China, is described and illustrated. This taxon belongs to sect. Sedum (H. Ohba) S.H. Fu based on the adaxially gibbous carpels and follicles. It superficially resembles S. alfredii Hance and three other Sedum species found in the same area, but differs from these other taxa in bearing 4-merous flowers. Differences in geographical distribution, growth habit, phenology, macromorphology, leaf and stem anatomy, as well as seed micromorphology among S. plumbizincicola, S. alfredii and other related taxa in the genus Sedum are also reported. nrDNA internal transcribed spacers (ITS) sequences from seven populations of S. plumbizincicola support the recognition of this as a taxonomic entity distinct from S. alfredii. [ABSTRACT FROM AUTHOR]

Macrofossils of Carpinus have been widely reported from the Cenozoic of the Northern Hemisphere. However, the leaf cuticules of the genus have rarely been described. A new species, named Carpinus tengchongensis Dai et B.N. Sun, sp. nov., is identified based on 13 leaf fossils, collected from the late Pliocene Mangbang Formation, Tengchong County of Yunnan Province, China. The important characters of the fossil are its oblong-ovate leaf shape, obliquely cordate base, doubly serrulate margin, straight and moderately thick primary vein, pinnate secondary veins, percurrent tertiary veins, orthogonally reticulate areoles, absence of veinlets, anomocytic stomata with double-layered stomatal rim, well-formed T-pieces and trichome bases, which indicates an affinity within the genus Carpinus section Carpinus subsection Monbeigianae, especially with C. tsaiana. Carpinus fossils were present from the Eocene to Pliocene with disjunctive distribution in the North Temperate Zone, which broadly reflected the present distribution pattern and probably demonstrates the tolerance of Carpinus to environmental change. [ABSTRACT FROM AUTHOR]

This study examined the detailed pollen morphological structures of sixteen Hypericum taxa (four endemic, twelve non endemic) including eight sections showing the natural distribution in Turkey: H. sect. Ascyreia ( H. calycinum L.), H. sect. Heterophyllum ( H. heterophyllum Vent.), H. Sect. Taeniocarpium ( Hypericum confertum Choisy subsp. confertum, H. venustum Fenzl , H. linaroides Bosse), H. sect. Drosocarpium ( H. montbretii Spach, H. bithynicum Boiss.), H. sect. Crossophyllum ( H. adenotrichum Spach, H. orientale L.), H. sect. Olympia ( H. olympicum L. subsp. olympicum), H. sect. Origanifolia ( H. origanifolium Willd., H. avicularifolium Jaub and Spach subsp. depilatum (Freyn and Bornm.) Robson var. depilatum, H. avicularifolium Jaub. and Spach subsp. byzantinum) and H. sect. Hypericum ( H. tetrapterum Fries, H. perforatum L., H. triquetrifolium Tura). These taxa were studied under light microscope and scanning electron microscope for the first time. Of the taxa studied, H. tetrapterum has the smallest pollen grains (on average 15.85-17.20 × 15.45-16.05 μm); and H. olympicum subsp. olympicum the largest grains (on average 22.90-23.10 × 21.40-22.10 μm). The pollen grains of 15 taxa are subprolate and one taxon is prolate-spheroidal. The regular pollen grains of all 16 taxa are 3-zonocolporate. Ornamentation is microreticulate; lumina regularly spaced in eight taxa, tectum perforatum; tectal perforations regularly spaced in seven taxa and tectum perforatum; and tectal perforations grouped together in one taxon. Endoaperture is cruciform porus, with short lateral and meridional extensions in ten taxa, cruciform porus, transversally elongated, with very small lateral extensions in one taxon and lalongate colpus in five taxa. Basic pollen types are ten taxa in type X, five taxa in type IV and one taxon in type II. [ABSTRACT FROM AUTHOR]

The main aim of the present study was testing the value of the morphological and anatomical characteristics of the needles in distinguishing Cedrus atlantica, C. libani and C. brevifolia. Nine populations were sampled in their natural habit and 25 characters were used to describe the variation of the brachyblast needles and to analyze the differences between species. The results indicated that morphological and anatomical needle characters provide valuable tools in discrimination of the taxa. The scored differences were statistically significant, as revealed in the Tukey's t test, discrimination analysis and hierarchical analysis of variation. The results support treating C. libani, C. atlantica and C. brevifolia as independent species. [ABSTRACT FROM AUTHOR]

The occurrence of diploid and tetraploid cytotypes in Thymus section Mastichina (Lamiaceae) was investigated by chromosome counting and flow cytometric measurements of DNA content. To cover the entire native distribution of the section across the Iberian Peninsula, plant material was sampled from 29 populations, representing all three taxa ( Thymus albicans, T. mastichina subsp. mastichina and T. mastichina subsp. donyanae). We provide first estimates of genome size for taxa of this section. Analyses revealed the existence of new cytotypes in T. mastichina subsp. mastichina (2 n = 2 x = 28, 30) and confirmed the existence of previous ones (2 n = 4 x = 56, 58, 60). We also confirmed the presence of exclusively diploid cytotypes (2 n = 2 x = 30) in the southwestern Iberian endemics T. albicans and T. mastichina subsp. donyanae. We conclude that the southwestern Iberian Peninsula acted as a Pleistocene glacial refugium that may have permitted speciation processes within this section. Several hypotheses concerning these processes and the origin and distribution of the studied taxa are discussed. [ABSTRACT FROM AUTHOR]

Despite their genetic homogeneity, many taxonomic species are described as European dogroses ( Rosa L. section Caninae (DC.) Ser.) with consistent morphological variability. Here we report a morphometric study of 27 hip and leaf characters of proximate dogrose populations that include Rosa agrestis, a member of the subsection Rubigineae, in Flanders. In principal components analysis one R. agrestis population in Kanne had intermediate morphology between R. canina and R. corymbifera, on the one hand, and three other R. agrestis populations, on the other, suggesting hybridogenic origin. Half-sib R. agrestis seedlings were grown under controlled conditions and their leaf characters were studied. A tendency toward deviating morphology in seedlings from the Kanne population, analogous to the mother plants in the field, and a correlation for specific leaf characters between mother plants and their corresponding seedlings reinforce a genetic basis for the observed divergence in the Kanne population. The assumed hybridogenic mother plants did not produce fewer seeds per hip than the others of the pure populations. In addition, for all sampled dogroses, which included six species, the diameter of the discus was correlated with the number of seeds per hip, whereas the diameter of the orifice was not correlated with this character. This implies that only the diameter of the orifice and not the diameter of the discus might be decisive for species identification among European dogroses. [ABSTRACT FROM AUTHOR]

Clematis s.l. (including Archiclematis and Naravelia) is a genus of approximately 300 species with cosmopolitan distribution. The diversity of its pollen was surveyed in 162 taxa belonging to all infrageneric groups of Clematis s.l. Pollen morphology was investigated by use of scanning electron microscopy to identify useful characters, test taxonomic and systematic hypotheses, and elucidate pollen character evolution on the basis of the molecular phylogeny. Clematis pollen is small to medium (14.8-32.1 μm × 14.2-28.7 μm), oblate to prolate ( P/ E = 0.9-1.4) in shape. The apertures may be tricolpate and pantoporate sometimes with 4-zonocolpate and pantocolpate pollen grains as transitional forms. The tricolpate pollen grains are predominant and occur in all the sections of the genus, whereas pantoporate pollen grains can be found in sect. Tubulosae, sect. Viorna, sect. Viticella, and Naravelia only. Phylogenetic mapping of aperture types reveals that the pantoporate pollen type may be the apomorphy in the genus and evolved several times. The surface ornamentation in all taxa studied is similar and characterized by microechinae evenly distributed on the microperforate tectum. The size and density of spinules on the tectum vary greatly but successive in the whole genus. According to the character syndromes of the ornamentation, separating sect. Brachiata from sect. Meclatis is supported. Though pollen morphology may contribute to investigation of problematic taxa, the taxonomic value of pollen morphology is limited at the species level. [ABSTRACT FROM AUTHOR]

Molecular characterization of Tulipa L. species can elucidate the relationships among the species and provide more information about the taxonomy of this valuable genus. In this study, the genetic relationship among 39 Tulipa accessions from Khorassan and Yazd Provinces, located in east and northeast Iran, were analyzed using inter-simple sequence repeat (ISSR) primers. Ten selected ISSR primers from 20 screened primers generated a total of 97 polymorphic DNA bands. Unweighted pair-group method of cluster analysis based on Dice similarity values separated the accessions into nine groups. Seven species were recognized within these groups, and T. micheliana Hoog was the most frequently encountered species. The subgroups formed within both T. micheliana and T. lehmanniana Merckl. revealed a low level of diversity within these species. T. biebersteiniana Schultes & Schultes fil. and T. biflora Pallas accessions made a separate clusters. The grouping of accessions was generally consistent with principal coordinate analysis (PCA) and clearly showed the position of species in the subgenera and sections of Tulipa. These results clearly showed the usefulness of DNA fingerprinting for identification of Tulipa accessions, and it is imperative to collect and characterize more genetic variability from the other distribution areas of this genus. [ABSTRACT FROM AUTHOR]

Detailed knowledge of the spatial distribution of sources is a crucial prerequisite for the application of pollen dispersion models such as, for example, COSMO-ART (COnsortium for Small-scale MOdeling - Aerosols and Reactive Trace gases). However, this input is not available for the allergy-relevant species such as hazel, alder, birch, grass or ragweed. Hence, plant distribution datasets need to be derived from suitable sources. We present an approach to produce such a dataset from existing sources using birch as an example. The basic idea is to construct a birch dataset using a region with good data coverage for calibration and then to extrapolate this relationship to a larger area by using land use classes. We use the Swiss forest inventory (1 km resolution) in combination with a 74-category land use dataset that covers the non-forested areas of Switzerland as well (resolution 100 m). Then we assign birch density categories of 0%, 0.1%, 0.5% and 2.5% to each of the 74 land use categories. The combination of this derived dataset with the birch distribution from the forest inventory yields a fairly accurate birch distribution encompassing entire Switzerland. The land use categories of the Global Land Cover 2000 (GLC2000; Global Land Cover 2000 database, 2003, European Commission, Joint Research Centre; resolution 1 km) are then calibrated with the Swiss dataset in order to derive a Europe-wide birch distribution dataset and aggregated onto the 7 km COSMO-ART grid. This procedure thus assumes that a certain GLC2000 land use category has the same birch density wherever it may occur in Europe. In order to reduce the strict application of this crucial assumption, the birch density distribution as obtained from the previous steps is weighted using the mean Seasonal Pollen Index (SPI; yearly sums of daily pollen concentrations). For future improvement, region-specific birch densities for the GLC2000 categories could be integrated into the mapping procedure. [ABSTRACT FROM AUTHOR]

Using functional traits together with abundance effects strengthens the prediction of interactions between pairs of species in ecological networks. Insights into the way species interact as well as prediction accuracy can be gained when thresholds for trait value combinations that make interactions possible are optimized through model selection. I present novel data of two subalpine plant-pollinator communities and build several stochastic models integrating flower abundance and morphological threshold rules that allow or restrict interactions between species. The number of correctly predicted interactions was highest when thresholds were set so that the insect's proboscis was not shorter than the nectar-holder depth minus 1-1.6 mm, and not wider than the nectar-holder width minus 0.5 mm. In comparison with models based solely on plant abundance effects, the model incorporating optimized size thresholds better predicted the distribution of the trait differences between plants and insects. This indicates that a mechanistic approach of interaction webs based on optimized size thresholds provides valuable information on community structure. The possible implications for community functioning are discussed. [ABSTRACT FROM AUTHOR]

Background and aims: Legumes of the genus Lessertia have recently been introduced to Australia in an attempt to increase the range of forage species available in Australian farming systems capable of dealing with a changing climate. This study assessed the diversity and the nodulation ability of a collection of Lessertia root nodule bacteria isolated from different agro-climatic areas of the Eastern and Western Capes of South Africa. Methods: The diversity and phylogeny of 43 strains was determined via the partial sequencing of the dnaK, 16srRNA and nodA genes. A glasshouse experiment was undertaken to evaluate symbiotic relationships between six Lessertia species and 17 rhizobia strains. Results: The dnaK and 16S rRNA genes of the majority of the strains clustered with the genus Mesorhizobium. The position of the strains at the intra-genus level was incongruent between phylogenies with few exceptions. The nodA genes from Lessertia spp. formed a cluster on their own, separate from the previously known Mesorhizobium nodA sequences. Strains showed differences in their nodulation and nitrogen fixation patterns that could be correlated with nodA gene phylogeny. L. diffusa, L. herbacea and L. excisa nodulated with nearly all the strains examined while L. capitata, L. incana and L. pauciflora were more stringent. Conclusion: Root nodule bacteria from Lessertia spp. were identified mainly as Mesorhizobium spp. Their nodA genes were unique and correlated with the nodulation and nitrogen fixation patterns of the strains. There were marked differences in promiscuity within Lessertia spp. and within strains of root nodule bacteria. [ABSTRACT FROM AUTHOR]

Background: Poplars accumulate inordinate amounts of B in their leaves and are candidate plants for the remediation of B contaminated soil. We aimed to determine the effect of heterogeneous B distribution in soil by comparing the growth and B accumulation of young Populus tremula trees growing in soil with heterogeneous and homogeneous B distributions. Methods: The first of two experiments focused on the tolerance and B accumulation of P. tremula under heterogeneous soil B distributions, while the second was designed to study fine root growth under such conditions in detail. Results: Growth and B accumulation of P. tremula were unaffected by the spatial distribution of B. Root and shoot growth were both reduced simultaneously when leaf B concentrations increased above 800 mg kg. In the heterogeneous soil B treatments, root growth was more reduced in spiked soil portions with B concentrations >20 mg kg. Fine root length growth was stronger inhibited by B stress than secondary growth. Conclusions: The root growth responses of P. tremula to B are primarily a systemic effect induced by shoot B toxicity and local toxicity effects on roots become dominant only at rather high soil B concentrations. Local heterogeneity in soil B should have little influence on the phytoremediation of contaminated sites. [ABSTRACT FROM AUTHOR]

Nuclear genome size was determined to investigate the relationships between all 19 species of Araucaria de Jussieu. Species from the two other genera of Araucariaceae, Wollemia and Agathis, were also studied. The genome size of 17 out of the 19 species of Araucaria are reported here for the first time. All Araucariaceae have the same chromosome number 2 n = 26. However, the nuclear DNA contents (2C value) for Araucaria range from 31.3 to 45.4 pg. There is a good correlation between genome size and division in sections, and geographical distribution. The two species from South America have 44.7 and 45.4 pg, the two species from Australia have 35.7 and 44.4 pg and the two species from New Guinea 34.7 and 40.4 pg. All 13 species of New Caledonia and the one from Norfolk Island have a similar, if not identical, amount of nuclear DNA of, on average, 31.9 pg. This corroborates the identical DNA rbcL sequences found for the New Caledonian araucarias. It suggests that the species from New Caledonia diversified more recently and it questions their status as separate species . Compared with this 31.9 pg a strong increase seems to have occurred in the genome size of the 'mainland' araucarias. Genome sizes are evaluated and compared with available taxonomic treatments and extant geographic spreading. The nuclear DNA contents found within the sections are close, making it possible to assign an unknown plant to a section. A difference of 1 pg, which amounts to a difference of 978 Mbp, far exceeds a single character. Nuclear DNA content, as measured by flow cytometry, may conveniently be used to produce systematic data . It is applicable even with young plants or seeds for monitoring the trade in endangered species. [ABSTRACT FROM AUTHOR]

Rapid range expansions are becoming more prevalent, especially as climate continues to change. The escape of ornamental plants within their native range represents a significant, but often overlooked component of this process. Few studies have focused on the role of ornamental plants in range expansions using molecular markers to identify the possibility of mixed native and cultivar populations. The purpose of the present study was to determine the genetic variation of a native woody plant with ornamental conspecifics at the edge of its distribution. We selected Ilex aquifolium L. (English holly) which grows naturally in Denmark but is spreading eastward in Scandinavia, possibly due to a combination of climate change and introduction of more frost-tolerant cultivars. We sampled 187 individuals from older and recently established populations, and cultivated I. aquifolium throughout Denmark, and compared them using nuclear SSR and AFLP. The overall results showed no structure or clustering of plants from the historical or the expanding range, or of wild or cultivated plants. The only clusters found were for a group of cultivated hybrid I. aquifolium. The samples represented four genetic groupings, indicating either hybridization between cultivated and wild I. aquifolium or replacement of the latter by cultivars. Thus, ornamental genotypes of I. aquifolium contribute to the northeastern range expansion of the species and eventual invasiveness within its native range. [ABSTRACT FROM AUTHOR]

In California prairies, native perennial grasses have been almost entirely replaced by Eurasian winter-annual grasses. Landscape-scale descriptions of perennial versus annual grass distribution are lacking. To quantify perennial persistence in California grasslands, 50 randomly selected grassland meadows were sampled within three latitudinal belts of central California, from the Pacific coast inland to the Central Valley. Native perennial grasses were present at all but four of the sampling sites, although usually at low density. Proximity to the Pacific coast was positively correlated to perennial grass cover at all latitudes. Annual degree days above 18 °C and increasing slope were significantly negatively correlated to perennial grass dominance, and average warm season precipitation was significantly positively correlated to perennial dominance. Cover of non-native annual grasses was significantly lower in prairies <2 km from the coast than in all other sites. Non-native perennial grasses were occasionally important grassland community components at sites near the coast, but relatively uncommon inland. These results suggest that environmental conditions near the California coast tend to increase the success of perennial grasses, including exotic perennials. Intensity and duration of seasonal water stress likely play a central role in determining perennial grass distribution in California. [ABSTRACT FROM AUTHOR]

The question of the stability of distribution ranges of species is fundamental in ecology. However, the way in which stable distribution ranges are shaped by natural selection is still poorly studied. For a long time, botanists have studied empirically how self-fertilization and dispersal traits change from the centre to the periphery of species' distribution ranges, but theoretical arguments are lacking. In this commentary, we use a recent evolutionary model by Cheptou and Massol () that analyses the joint evolution of dispersal and the mating system in a metapopulation. Considering that distribution ranges may result in gradients in pollen limitation for plants, habitat availability, or inbreeding depression for plants, we analyse how the association of dispersal and self-fertilization varies across distribution ranges. Interestingly, we show that such gradients result in a change in both traits and may favor evolutionary stable range limits for plant distribution. Based on empirical and theoretical results, we discuss the plausibility of such gradients as a way to explain range limits in plants. [ABSTRACT FROM AUTHOR]

Tillaea aquatica (Crassulaceae) is considered as annual wetland species threatened by changes in land use and progressing eutrophication in large part of its European distribution range. We summarised the historical and recent data on this species, and analysed its distribution and associated habitat changes in the Czech Republic. We used permanent plots as well as seed bank and seed dispersal studies to obtain better insight into the plant's survival strategy. During the second half of the twentieth century T. aquatica disappeared from most historical localities situated mainly in large fishponds. After 1999, altogether 18 new populations were found in small fry ponds and other fish-farming ponds. The largest populations of Tillaea were found in ponds with long-term bottom exposure where the vegetation of perennial herbs was eliminated by herbicides or grazing. Propagules easily dispersible by water, on gumboots or tyres of vehicles, and long-term soil seed bank also might contribute to persistence of the species in the habitats, diminishing the chance of extinction. As the fishpond management has changed, and so have done the original habitats of Tillaea, the species could survive in habitats different from those in the past. In this article, we suggest management measures aimed at promoting survival of Tillaea under new circumstances. [ABSTRACT FROM AUTHOR]

In this work, we analyse the role of climatic constraints in shaping the distribution of alien plant species along the elevation gradient in the European Alps. Alien species occurrence was recorded in 278 plots located beside rivers, from 100 to 2,100 m a.s.l. Climate variables were calculated from the data recorded by 145 meteorological stations and interpolated by a multiple regression approach. Both richness and occurrence of aliens were modelled. In particular, relationships between the occurrence of alien plants and (1) elevation or (2) the climatic variables, were tested by applying generalised linear models and generalised linear mixed models; the model parameters obtained were used to estimate upper elevation limits of alien occurrence and their related climate values. Sixty-eight alien species were encountered, the majority (71%) invasive in Italy and worldwide. A steep decrease in alien species richness with elevation was found, with the probability of alien species occurrence decreasing by half for each 100 m increase in elevation. Minimal adequate models based on (1) non-transformed climatic variables and (2) derived PCA values, confirmed that occurrence of alien plant species along the elevation gradient was positively related to the minimum temperature, the mean temperature and the heat sum for the spring season, rather than to the incidence of absolute minimum temperature and frost days, as usually assumed. Although further experimental analyses are needed, these results support the hypothesis that, referring to climate factors, elevation limits along rivers are mainly established by low spring temperatures which operate at the level of population viability rather than plant survival. [ABSTRACT FROM AUTHOR]

Climate change projections forecast a warming and an associated change in the distribution and intensity of rainfalls. In the case of the Mediterranean area, this will be reflected in more frequent and severe drought periods in the future. Within a long-term (9 years) manipulation experiment, we aimed to study the effect of the soil drought (15-20% decreased soil moisture) and warming conditions (+1°C warming) projected for the next decades onto photosynthetic rates and water relations, and onto the antioxidant and anti-stress defense capacity of Erica multiflora, a common species of the dry Mediterranean coastal scrublands, in two different seasons, spring and summer. Results indicated that none of the applied treatments was severe enough to induce a pronounced negative response of photosynthesis in this species well adapted to harsh Mediterranean conditions, but also highlighted important seasonal differences. Photosynthesis was limited by photoinhibition in spring and by stomatal closure in summer. Isoprenoid emission and the level of enzymatic and non-enzymatic antioxidants were lower in summer than in spring, whereas pigment and total phenolic contents were generally higher in summer. Volatile isoprenoid emissions were largely inhibited by drought and were not stimulated by warming. Drought and warming increased the oxidation state of ascorbate and reduced total glutathione levels in spring, but not in summer. It is concluded that E. multiflora plants can adapt to prolonged drought and warming, at least at the level simulated by our manipulative experiment, through changes in the seasonal physiological and antioxidant response of leaves. [ABSTRACT FROM AUTHOR]

The origin and evolution of angiosperms can be unravelled by using fossil records to determine first occurrences and phytogeographic histories of plant families and genera. Many angiosperm families, for example the Onagraceae, have a poor macrofossil record, but are more common in palynological records. Modern Onagraceae produce pollen clearly distinct from that of other angiosperms. Combined morphological features obtained by use of light and scanning electron microscopy have enabled assignment of fossil Onagraceae pollen to extant genera, and therefore tracing of the origin and past distributions of extant Onagraceae lineages. We studied a Miocene palynoflora from the Daotaiqiao Formation of north-east China. Using the single-grain technique, we examined individual Onagraceae pollen/tetrads using both light and scanning electron microscopy. Fossil Onagraceae pollen is more frequent than macrofossil remains, but is still rare, and usually represented by a single taxon in palynological samples. Remarkably, samples from the Miocene of north-east China contain five different species: two of Circaea, one of Epilobium, and two of Ludwigia. Such a large number of Onagraceae taxa from a single palynoflora is unknown elsewhere. Whereas Ludwigia pollen is known from Cenozoic sediments of the northern hemisphere, the Circaea pollen is the first fossil pollen assignable to this extant genus. This is also the first fossil record of Epilobium from China. Although the young geological age of this sample does not enable consideration of time of origin for the genera encountered, the co-occurrence of Circaea, Epilobium, and Ludwigia in the mid to late-Miocene of East Asia sheds some light on their phytogeographic histories. [ABSTRACT FROM AUTHOR]

Calypogeia sphagnicola is one of nine species of the genus Calypogeia known in Europe. Occurrence of the species is closely connected with peat bogs. Nowadays, two forms of this species are distinguished- C. sphagnicola f. sphagnicola and C. sphagnicola f. paludosa. The results of the present study, based on two classes of markers-isozymes and sequences of chloroplast genom ( trnH- psbA, rpoC1)-unanimously support the genetic differentiation within the taxon and show that the present-day forms represent genetically distinct species. Phylogenetic analysis resolved two lineages that correspond with the present-day forms with high bootstrap support, which differ in ploidy level: C. sphagnicola f. sphagnicola is haploid, whereas C. sphagnicola f. paludosa is a diploid form. Allopolyploid origin of the diploid form was revealed by the isozyme pattern. Nei's genetic distance between the two present-day forms of C. sphagnicola was 0.472. The forms in Poland have an allopatric pattern of geographic distribution: C. sphagnicola f. sphagnicola occurs exclusively in the lowlands of the northern part of the country on raised peat bogs, whereas C. sphagnicola f. paludosa is found only in the mountains of southern Poland, mainly in the subalpine zone, where it grows on Sphagnum- Polytrichum hummocks on the upper part of north-facing slopes. Plants regarded in this study as C. sphagnicola f. sphagnicola morphologically correspond to the syntype specimen of C. sphagnicola. [ABSTRACT FROM AUTHOR]

A new species, Orthosiphon americanus Harley & A. J. Paton (Lamiaceae), is described. This represents the first known occurrence of the genus in the New World. The species' relationships and phytogeography are discussed. [ABSTRACT FROM AUTHOR]

Cuscuta (dodder, Convolvulaceae) is a genus of about 200 species of obligate stem parasites with subcosmopolitan distribution. The diversity of pollen and ovule production was surveyed in 128 species and ten varieties. Taxa were assigned to Cruden's mating system categories based on their pollen-ovule ratios. Variation and correlations among floral characters were analyzed using regression and ANOVA, while the mating system categories were subjected to a linear discriminant and canonical variates analysis to assess their cohesiveness. Our data strongly suggest that most Cuscuta species possess a wide range of mixed-mating systems. Whereas four ovules develop in each flower, pollen production varies over three orders of magnitude. Several Cuscuta taxa are highly outcrossing, but no species could be identified that are exclusively selfing. The transition from the one-style flowers of subg. Monogynella to the two-style flowers of subgenera Cuscuta and Grammica, and from simultaneous to sequential maturation of the two stigmas in the latter subgenus, has decreased the role of herkogamy as a facilitator of outcrossing. These evolutionary changes are associated with an increase of species richness in subgenus Cuscuta, and especially in subgenus Grammica. Morphological features were not individually found to have a strong correlation to the mating system, but in general, larger corollas and stigmas were associated with greater pollen-ovule ratios. Cuscuta presents some puzzling results when considered in light of the sex allocation theory, as only some infrageneric lineages demonstrate the predicted pollen size-number tradeoff, while Cuscuta gracillima complex (in subgenus Grammica) displays an unexpected negative relationship between pollen size and style length. The relationship between host range and mating system is discussed, prompting further research into the co-evolution of pollination systems and life history traits between parasites and their host species. [ABSTRACT FROM AUTHOR]

The tribe Stipeae with an estimated number of ca. 600 species is part of the grass subfamily Pooideae and has near worldwide distribution. Its species are often dominant constituents of steppe vegetation and other grasslands, especially in Eurasia, the Americas and Australia. The taxonomy of Old World Stipeae has been studied to date primarily on the basis of morphology and anatomy, while existing molecular phylogenetic investigations have mainly dealt with New World or Australian taxa. We studied 109 new ingroup taxa with a focus on Old World Stipeae (in addition with an extensive outgroup sampling) using chloroplast and nuclear ribosomal DNA sequences (3′ trnK region, ITS1-5.8S gene-ITS2), and discuss taxonomic key characters. Five highly supported monophyletic lineages were identified, some of which were rather unexpected: (a) the narrowly defined Stipa core clade, which is primarily Eurasian but extends into Africa north of the Sahara Desert, (b) the majority of Old World Piptatherum, (c) a 'Transcontinental Stipeae Clade' encompassing Eurasian, African, American and Australian lineages, (d) a Himalayan to E Asian clade and (e) the single species Achnatherum splendens. The large 'Transcontinental Stipeae Clade' contained several lineages of Eurasian Stipeae different from the Stipa core (a), i.e., genera Aristella, Celtica, Oloptum gen. nov., Stipella stat. et. gen. nov., species of Achnatherum, and the species-rich lineages of Nassella/ Jarava in America and of Austrostipa in Australia. In our circumscription Ptilagrostis was nested in (d), a clade (which included some species of Achnatherum and poorly studied Himalayan species ascribed to either Stipa or Orthoraphium) and whose internal structure remained unclear. Oloptum, gen. nov., is described, and the following combinations are made: Achnatherum pelliotii, comb. nov., Aristella keniensis, comb. nov., Oloptum miliaceum, comb. nov., Stipella, stat. et. gen. nov., S. capensis, comb. nov., S. nitens, comb. nov., S. parviflora, comb. nov., S. staintonii, comb. nov., and S. tigrensis, comb. nov. [ABSTRACT FROM AUTHOR]

The failure of seeds to arrive at all suitable sites (seed limitation) greatly affects plant distribution and abundance. In contrast to tropical forests, the degree of seed limitation in Neotropical savannas is unclear because empirical studies at the community level are scarce. We estimated seed limitation of 23 woody species from annual seed rain measurements along a tree density gradient in the savannas of Central Brazil. These savannas differ in tree density and canopy cover, from closed to open savannas, and are located along shallow topographic gradients. We also studied post-dispersal seed predation and removal of 17 representative woody species, and seed viability loss over time of 12 common woody species under dry-storage conditions. Annual seed rain was lower in open (410 seeds/m) than in closed savannas (773 seeds/m). Average seed limitation across woody species was higher than 80% along the tree density gradient. More than 60% of seeds of the studied woody species were predated or removed within 30-45 days in all savannah types. Seeds of most common woody species (66%) lost their viability in less than 12 months of dry storage. This study shows that Neotropical savannah woody plants are strongly seed-limited because of low and poor distribution of seeds among sites, post-dispersal seed removal, and short seed longevity. The high seed limitation of tree species in Neotropical savannas, particularly in open savannas, also may contribute to maintain their relatively low tree densities and help to explain the spatial variation of tree abundance along topographic gradients. [ABSTRACT FROM AUTHOR]

Abstract: Pollinia pollini (Costa) (Hemiptera: Asterolecanidae) is considered as one of the most important pest infesting olive trees in Egypt. The aim of this work is to study the survey of host plants, geographical distribution and natural enemies as well as the dynamic of P. pollini on olive trees in Egypt. The obtained results indicated that P. pollini infested only olive trees in two Governorates. These are Alexandria and Fayoum Governorates. No parasitoid species were collected and recorded in the present work. Three species of predators were recorded that attacked P. pollini in Egypt. These are the coccinellids, Coccinella undecimpunctata L., Scymnus seriacus Mars. and the Neuroptera species, Chrysoperlla carnae Steph. Also the present study included the dynamics of P. pollini and its predators on olive trees in Alexandria Governorate during 2010 and 2011. Statistical analysis of the effect of weather factors on the population of P. pollini during the 2years under consideration was discussed. It was concluded that maximum, minimum temperatures and % relative humidity are significant on the population of P. pollini. The trend over both years indicated the occurrence of two generations per year for P. pollini on olive trees in Alexandria. [Copyright &y& Elsevier]

Surface temperatures have risen globally during the last 30 years, especially in alpine areas. It is recognized that these increases are influencing phenology, physiology and distribution of plants. However, few studies have addressed the effects of climate warming at the species range boundary, where plants are expected to be more stressed. We analysed 11-year data sets of inflorescence production of four alpine plants ( Carex foetida, Leucanthemopsis alpina, Senecio incanus, Silene suecica) at the southern boundary of their distribution range in the N-Apennines (N-Italy), in relation to air temperature and snow cover persistence. Inflorescence production of all species fluctuated greatly and was significantly affected by the variation of the mean temperature of June/July. We found significant relationships also between species data series and the snow cover persistence. Moreover, species responded differently to such parameters. One species showed a significant decrease of the reproductive effort, whereas the other three showed a stable trend of inflorescence production. We have shown that some alpine species are favoured by increased temperature and reduced snow cover even at the boundary of their range, where they are thought to be particularly sensitive to warming. However, the aptitude to cope with climate change might be limited by competition against thermophilous species migrating from lower altitude and in some cases by the low altitude of mountain peaks that prevent species upward migration. The individualistic response of species to climate change found here, support the statement that the composition of plant communities might rapidly change in the future. [ABSTRACT FROM AUTHOR]

The factors responsible for the patterns of niche differentiation and narrow endemism have rarely been investigated in annual Mediterranean plants. This topic was addressed here by performing comparative studies on realized niches, regional occupancy, global biogeographical distribution and seed traits of a set of Arenaria (Caryophyllaceae) species inhabiting southern Provence (SE France), focusing in particular on Arenaria provincialis, a narrow endemic restricted to the hills and modest calcareous mountains around the city of Marseille. Field studies were carried out from 2008 to 2009 at 624 sites in the limestone mountains where Arenaria species are likely to occur. The Arenaria species occurring in southern Provence vary greatly in their patterns of regional occupancy and their biogeographical distribution. Multivariate analysis of the realized niche showed that they have some similar limiting environmental factors in common, but they do not all occupy the same habitats. Studies on the fruits and seeds showed that the endemic A. provincialis has a larger seed than its congeners and a capsule that remains closed and falls from the plant at maturity. This well-differentiated diaspore specific to A. provincialis may be responsible for the limited dispersal capacity of this species. Phylogenetic analyses showed that A. provincialis is not closely related to the other taxa inhabiting southern Provence, but rather to Arenaria occurring in highland areas in the south of France. The restricted pattern of distribution of A. provincialis is probably due to the past isolation event from which it originated and to its limited dispersal capacity, rather than resulting from its ecological niche range. [ABSTRACT FROM AUTHOR]

The botanical survey of Wadi Wateer, located in the southeastern Sinai, revealed the presence of a plant that provides an important new record to the Flora of Egypt: Cocculus hirsutus (L.) Theob. This plant has not been recorded previously as existing in its wild form in the Flora of Egypt. The plant cover in Wadi Wateer is dominated by plant taxa belonging to the Saharo-Sindian phytogeographical element. However, many plants in the wadi have been attributed to the Sudanian chorotype, such as Acacia tortilis (Forssk.) Hayne subsp. raddiana (Savi) Brenan, Chrozophora brocchiana Vis., Lycium shawii Roem & Schult., Moricandia sinaica (Boiss.) Boiss., Cocculus hirsutus (L.) Theob. and Cocculus pendulus (J.R. & G. Forst.) Diels. The presence of Sudanian chorotype plant taxa [including the newly recorded Cocculus hirsutus (L.) Theob.] provides evidence that Wadi Wateer and Aqaba Gulf functioned as migratory tracks for these African plants, assisting their penetration into the Saharo-Sindian, Mediterranean and Irano-Turanian phytogeographical regions in the Sinai and Asia. This study suggests that Wadi Wateer should be declared a protected area for its habitat and climatic diversity as well as for its phytogeographical significance. [ABSTRACT FROM AUTHOR]

Climate change is driving latitudinal and altitudinal shifts in species distribution worldwide, leading to novel species assemblages. Lags between these biotic responses and contemporary climate changes have been reported for plants and animals. Theoretically, the magnitude of these lags should be greatest in lowland areas, where the velocity of climate change is expected to be much greater than that in highland areas. We compared temperature trends to temperatures reconstructed from plant assemblages (observed in 76,634 surveys) over a 44-year period in France (1965-2008). Here we report that forest plant communities had responded to 0.54?°C of the effective increase of 1.07?°C in highland areas (500-2,600?m above sea level), while they had responded to only 0.02?°C of the 1.11?°C warming trend in lowland areas. There was a larger temperature lag (by 3.1 times) between the climate and plant community composition in lowland forests than in highland forests. The explanation of such disparity lies in the following properties of lowland, as compared to highland, forests: the higher proportion of species with greater ability for local persistence as the climate warms, the reduced opportunity for short-distance escapes, and the greater habitat fragmentation. Although mountains are currently considered to be among the ecosystems most threatened by climate change (owing to mountaintop extinction), the current inertia of plant communities in lowland forests should also be noted, as it could lead to lowland biotic attrition. [ABSTRACT FROM AUTHOR]

The aims of the present study were to: (1) investigate whether CORINE land cover classes reflect significant differences in floristic composition, using a very detailed CORINE land cover map (scale 1:5000); (2) decompose the relationships between floristic assemblages and three groups of explanatory variables (CORINE land cover classes, environmental characteristics and spatial structure) into unique and interactive components. Stratified sampling was used to select a set of 100-m plots in each land cover class identified in the semi-natural wetland surrounding a lake in central Italy. The following six classes were considered: stable meadows, deciduous oak dominated woods, hygrophilous broadleaf dominated woods, heaths and shrublands, inland swamps, canals or watercourses. The relationship between land cover classes and floristic composition was tested using several statistical techniques in order to determine whether the results remained consistent with different procedures. The variation partitioning approach was applied to identify the relative importance of three groups of explanatory variables in relation to floristic variation. The most important predictor was land cover, which explained 20.7% of the variation in plant distribution, although the hypothesis that each land cover class could be associated with a particular floristic pattern was not verified. Multi Response Permutation Analysis did not indicate a strong floristic separability between land cover classes and only 9.5% of species showed a significant indicator value for a specific land cover class. We suggest that land cover classes linked with hygrophilous and herbaceous communities in a wetland may have floristic patterns that vary with fine scale and are not compatible with a land cover map. [ABSTRACT FROM AUTHOR]

At scales from microsites to entire ranges, species' distributions reflect limited adaptation and/or limited dispersal. To what extent are specific distribution patterns and processes similar across scales? We investigated environmental effects-presumed because of adaptation-and independent spatial effects-presumed because of dispersal-on distribution at two scales (landscape patches of approximately 1,300 m, sampled along transects, and 4-m cells, sampled in contiguous grids within populations) and on individual performance (water status, reproduction) in the California annual, Clarkia xantiana ssp. xantiana. Because water limitation helps set this species' regional borders, we expected occupancy and performance at smaller scales to correlate with topographic and soil features affecting water relations. At the patch scale, environmental features associated with reduced water stress (i.e., steep slopes that face north; coarse, soft soils; igneous rather than metasedimentary parent rock) predicted occupancy. Spatial aggregation was not detected, but incomplete occupancy of apparently suitable patches indicated that dispersal limits occupancy. At the scale of small cells, relationships between environmental variables, occupancy, density, and performance varied among populations. Associations sometimes resembled those at the patch scale but sometimes opposed them. Spatial aggregation in cell occupancy and/or density occurred in all populations, implying limited dispersal, whereas spatial aggregation of water potential values in some populations might have arisen from spatially structured unmeasured environmental variables. Limited adaptation to drought and limited patch colonization appear to affect patch occupancy in C. xantiana ssp. xantiana, whereas smaller-scale patterns indicate consistent effects of limited dispersal and somewhat variable environmental effects. [ABSTRACT FROM AUTHOR]