Rare plant species: floristic, phytocoenotic and population approach

The system of concepts used when estimating the rarity of plants is analyzed and the basic categories of rarity are defined, namely: true, diffuse, peripheral and temporal. The insufficiency of scientific information on ecological and coenotic relationships of rare plants is demonstrated and the necessity of a complex assessment of population system of a rare plant species is substantiated. The importance and limitations of the information on rare plants contained in the Red Books and the Red Lists for phytosozological practice is discussed.     

Alpine vascular plant species richness: the importance of daily maximum temperature and pH

Species richness in the alpine zone varies dramatically when communities are compared. We explored (i) which stress and disturbance factors were highly correlated with species richness, (ii) whether the intermediate stress hypothesis (ISH) and the intermediate disturbance hypothesis (IDH) can be applied to alpine ecosystems, and (iii) whether standing crop can be used as an easily measurable surrogate for causal factors determining species richness in the alpine zone. Species numbers and standing crop were determined in 14 alpine plant communities in the Swiss Alps. To quantify the stress and disturbance factors in each community, air temperature, relative air humidity, wind speed, global radiation, UV-B radiation, length of the growing season, soil suction, pH, main soil nutrients, waterlogging, soil movement, number of avalanches, level of denudation, winter dieback, herbivory, wind damage, and days with frost were measured or observed. The present study revealed that 82% of the variance in␣vascular species richness among sites could be explained by just two abiotic factors, daily maximum temperature and soil pH. Daily maximum temperature and pH affect species richness both directly and via their effects on other environmental variables. Some stress and disturbance factors were related to species richness in a monotonic way, others in an unimodal way. Monotonic relationships suggest that the harsher the environment is, the fewer species can survive in such habitats. In cases of unimodal relationships (ISH and IDH) species richness decreases at both ends of the gradients due to the harsh environment and/or the interaction of other environmental factors. Competition and disturbance seemed only to play a secondary role in the form of fine-tuning species richness in specific communities. Thus, we concluded that neither the ISH nor the IDH can be considered useful conceptual models for the alpine zone. Furthermore, we found that standing crop can be used as an easily measurable surrogate for causal factors determining species richness in the alpine zone, even though there is no direct causality.     

Mapping potential habitats of threatened plant species in a moist tall grassland using hyperspectral imagery

We examined the capability of hyperspectral imagery to map habitat types of under-storey plants in a moist tall grassland dominated by Phragmites australis and Miscanthus sacchariflorus, using hyperspectral remotely-sensed shoot densities of the two grasses. Our procedure (1) grouped the species using multivariate analysis and discriminated habitat types (species groups) based on P. australis and M. sacchariflorus shoot densities, (2) used estimated shoot densities from hyperspectral data to draw a habitat type map, and (3) analyzed the association of threatened species with habitat types. Our identification of four habitat types, using cluster analysis of the vegetation survey coverage data, was based on P. australis and M. sacchariflorus shoot density ratios and had an overall accuracy of 77.1% (kappa coefficient = 0.71). Linear regression models based on hyperspectral imagery band data had good accuracy in estimating P. australis and M. sacchariflorus shoot densities (adjusted R ² = 0.686 and 0.708, respectively). These results enabled us to map under-storey plant habitat types to an approximate prediction accuracy of 0.537. Among the eight threatened species we examined, four exhibited a significantly biased distribution among habitat types, indicating species-specific habitat use. These results suggest that this procedure can provide useful information on the status of potential habitats of threatened species.     

Phytogeography of Italian deciduous oak woods based on numerical classification of plant distribution ranges

Abstract. 358 vascular plant species occurring in the deciduous oak woods of Italy were subdivided into 18 phytogeographical groups (chorotypes) through a numerical classification of their total ranges. The distribution patterns of the chorotypes are illustrated by chorograms, i.e. isopleth maps showing the joint distribution of species in Europe and surroundings regions. Except for Mediterranean species, which occur only occasionally in deciduous forests, the oak-wood flora of Italy consists of four main phytogeographical elements, which have a similar incidence (ca. 25 % each): (a) narrow-ranging, southern European species, (b) southeastern European species of submediterranean woodlands, (c) central-European species, (d) widely distributed European species. The oak woods of Italy differ from their central-European counterparts as to the relatively high floristic diversity, and in the presence of several narrow-ranging taxa, centred in different refugial areas for forest vegetation during the glacial period. There is a relation between the distribution patterns of the chorotypes and their relative frequencies in different communities; the latitudinal and longitudinal extensions of the ranges reflect the thermic and hygric conditions of the communities. The oak woods of northern and southern Italy are phytogeographically well-characterized; the former have a maximum of wide-ranging, central European species, the latter host several narrow-ranging taxa. The woodlands of central Italy have intermediate phytogeographical features, which is one of the main reasons for the difficulties in their syntaxonomical arrangement.     

Conservation of a rare plant requires different methods in different habitats: demographic lessons from Actaea elata

Understanding species decline and conserving endangered species requires demographic information, and variation in the environment may affect demography. Actaea elata is a globally rare, perennial herb found in a range of Pacific Northwest forest stand types that differ in canopy openness. Canopy openness increases reproductive output in this species and so was expected to have demographic impact. We performed a demographic analysis of A. elata in contrasting forest stands (broadleaved vs. coniferous) over two annual intervals, and predicted that population growth rate would be higher in the open-canopy broadleaved stand. Population growth was determined using stage-based matrix models, and the most influential transitions were identified using elasticity analyses. The finite rate of population increase (λ) was lower for the two transition periods at the broadleaved stand than at the coniferous stand (λ = 0.86 and 0.87 vs. 0.94 and 0.98), even though the former population was more fecund. The decline in the broadleaved stand reflects greater mortality and retrogression to previous stages, partly as a consequence of herbivory. In contrast, lower recruitment occurred in the coniferous stand, but there was also less mortality and retrogression. Our results suggest that management decisions for conservation of A. elata should be tailored to differing habitats, with a focus on preventing mortality in some populations and increasing recruitment in others.     

Modelling floristic species richness on a regional scale: a case study in Switzerland

In this paper a multivariate linear regression model is proposed for predicting and mapping regional species richness in areas below the timberline according to environmental variables. The data used in setting up the model were derived from a floristic inventory. Using a stepwise regression technique, five environmental variables were found to explain 48.9% of the variability in the total number of plant species: namely temperature range, proximity to a big river or lake, threshold of minimum annual precipitation, amount of calcareous rock outcrops and number of soil types. A considerable part of the unexplained variability is thought to have been influenced by variations in the quality of the botanical inventory. These results show the importance of systematic floristic sampling in addition to conventional inventories when using floristic data as a basis in nature conservation. Nevertheless it is still possible to interpret the resulting diversity patterns ecologically. Regional species richness in Switzerland appears to be a function of: (i) environmental heterogeneity; (ii) threshold values of minimum precipitation; and (iii) presence of calcareous rock outcrops. According to similar studies, environmental heterogeneity was the strongest determinant of total species richness. In contrast to some studies, high productivity decreased the number of species. Furthermore, the implications of this work for climate change scenarios are discussed.     

Spatial distribution of rare species: statistical approach

Many species are locally rare (have low occurrences in a given region). The method is proposed for the analysis of spatial distribution of such species. The procedure is based on the comparison of actual mean distances between records with Monte-Carlo-simulated mean distances expected for random occurrence pattern. The method was applied to two datasets: benthic macrofauna from the Barents and Kara Seas (Kucheruk, Kotov, 2002) and the Black Sea interstitial ciliates (original data). For both datasets, the number of rare species positively correlates with number of common species per site and with the total number of species. Furthermore (and irrespectively of total diversity pattern), rare species usually were locally clumped in their distribution: each of the species was mostly found at sites that were close together. This tendency, however, was significant for the macrofauna species but not for ciliates.     

Hybrid necrosis: autoimmunity as a potential gene-flow barrier in plant species

Ecological factors, hybrid sterility and differences in ploidy levels are well known for contributing to gene-flow barriers in plants. Another common postzygotic incompatibility, hybrid necrosis, has received comparatively little attention in the evolutionary genetics literature. Hybrid necrosis is associated with a suite of phenotypic characteristics that are similar to those elicited in response to various environmental stresses, including pathogen attack. The genetic architecture is generally simple, and complies with the Bateson-Dobzhansky-Muller model for hybrid incompatibility between species. We survey the extensive literature on this topic and present the hypothesis that hybrid necrosis can result from autoimmunity, perhaps as a pleiotropic effect of evolution of genes that are involved in pathogen response.     

Achieving Target 2 of the Global Strategy for Plant Conservation: building a preliminary assessment of vascular plant species using data from herbarium specimens

The Global Strategy for Plant Conservation calls for a preliminary assessment of the conservation status of all known plant species by the year 2010. To date insufficient progress has been made on meeting this target. New efforts to develop a preliminary list beyond using the full IUCN criteria in plant assessments are needed. Here we present an algorithm that provides a preliminary assessment of the conservation status of plant species using data from herbarium specimens. We use Hawaiian specimen data from the United States National Herbarium to calibrate the parameters of the algorithm and then use specimen data from the Arecaceae, Commelinaceae, Gesneriaceae and Heliconiaceae as examples of the application of the algorithm. The algorithm was calibrated to insure 95% accuracy in placing the Hawaiian plant species into previously and independently determined threatened categories. Our results indicate that 28% of the Hawaiian taxa, 27% of the species of Arecaceae, 45% of the species of Commelinaceae, 32% of the species of Gesneriaceae, and 35% of the species of Heliconiaceae are Not Threatened and will not need any further evaluation for the preliminary assessment. Species identified here as Potentially Extinct and Potentially Threatened can be further assessed by additional herbarium material and/or conservation specialists for final evaluation using other assessment strategies (e.g., regional and national lists, taxonomic expert assessment, etc.).     

Spatial (a)synchrony in population fluctuations of five plant species in fragmented habitats

The spatial scale at which populations show synchronous temporal fluctuations in abundance, relative to the spatial scale over which they can disperse, may influence the persistence of local and regional populations. There have been frequent demonstrations of spatial synchrony in population dynamics of animal populations. But few studies have investigated the degree of spatial synchrony in less mobile taxa, e.g. plants, where life history, dispersal and interaction with the environment would be different due to a sessile phase. This study has during three years investigated the synchrony in local population size changes in four short-lived species, and during a nine-year period for one long-lived species, in a semi-natural grassland landscape in southern Sweden. The spatial scale of this study was less than 15 km, which is quite small in comparison with other studies, but the temporal scale was of similar magnitude as the few studies on plant abundances and synchrony. When using detrended estimates of population size change, a significant pattern of decreasing synchrony with increasing distance was found for the two short-lived species that were most confined to manage semi-natural grasslands. Spatial synchrony was detected up to a few km. However, the species displayed synchrony in different years. The degree of synchrony can thus vary considerably across years and among species. Spatially autocorrelated weather conditions could partly explain the spatial scale of synchrony found during certain time intervals. However, the prevailing asynchrony suggests that local factors dominate the dynamics of the populations at the investigated scale.     

Conservation biology of a rare plant species,Eriocaulon kornickianum (Eriocaulaceae)

Historical and current ecological and genetic factors were examined in western popultions of Eriocaulon kornickianum to determine the cause and consequence of rarity in this disjunct species and to assess its extinction vulnerability. Reproductive biology was examined, which included an examination of breeding systems, seed set, and pollen viability. Recruitment into and maintenance of the populations was evaluated using seed bank estimates. A disturbance study was conducted that examined the effects of competing vegetation and associated species, and included clipping, burning, and artificial seeding. Enzyme electrophoresis was used to measure genetic variation in an effort to examine gene flow within and among populations. Many factors are contributing to the decline of the western populations of this species and include an annual or weak perennial life history, no vegetative reproduction, low seed set, little seed bank contribution to population growth and maintenance, genetic homogeneity, a restricted habitat, and poor competitive abilities. Continuing studies of genetic variation are being used to examine historical factors that may have resulted in a genetic bottleneck observed in the western populations.     

Prediction of species composition of plant communities in a rural landscape based on species traits

The species composition of a community is a subset of the regional species pool, and predicting the species composition of a community from ecological traits of organisms is an important objective in ecology. If such a prediction can be made feasible, we could assess the risk of invasion of locally new species (alien species and genetically modified species) into natural communities. We developed and tested statistical models to predict a community’s species composition from ecological traits of the species pool. Various types of communities (forest, meadow, and weed communities) exist in a small area of traditional rural landscape in Japan, and have been maintained by human activities. These communities and the tracheophytes species pool in the 1-km² research area were considered. We used logistic regression and decision-tree analysis to construct predictive models of community species composition based on plant traits, using the presence or absence of species in a community as the dependent variable and ecological traits as independent variables. Plant traits were grouped by cluster analysis, and the average in each trait group was used for model building to avoid multiple collinearity. Statistical prediction models were significant in all communities. About 60–75% of species composition could be predicted from the measured plant traits in forest communities, but 33–56% in the meadow and weed communities. Our results showed the possibility of predicting the species composition of plant communities from the ecological traits of the plant species together with the information on local species pool.     

Characterization of different habitats on the basis of the species traits and eco-field approach

A living organism is part of a perceived “spatial configuration” (i.e., an eco-field) when it changes the properties of the medium in which it lives. This happens because species evolve strategies to tackle ecological constraints; these strategies appear as species traits (physiology, morphology, behavior), and species traits affect environmental features. On the basis of species traits, data on carabid beetles from different habitats in two widely separated regions of Italy were analyzed in order to test the eco-field idea. The results revealed that the underlying environmental factors influencing the distribution of species traits over different habitats are anthropogenic disturbance, and stable vs. unstable stages of ecological succession. This approach, based on eco-field and species traits, has potential power in studies in which it is more important to emphasize ecological similarity than taxonomical heterogeneity.     

Few-sweep estimation of evoked potential based on a generalized subspace approach

A generalized subspace approach is proposed for single channel brain evoked potential (EP) extraction from background electroencephalogram (EEG) signal. The method realizes the optimum estimate of EP signal from the observable noisy signal. The underlying principle is to project the signal and noise into signal and noise coefficient subspace respectively by applying projection matrix at first. Secondly, coefficient weighting matrix is achieved based on the autocorrelation matrices of the noise and the noisy signal. With the coefficient weighting matrix, we can remove the noise projection coefficients and estimate the signal ones. EP signal is then obtained by averaging the signals estimated with the reconstruction matrix. Given different signal-to-noise ratio (SNR) conditions, the algorithm can estimate the EP signal with only two sweeps observable noisy signals. Our approach is shown to have excellent capability of estimating EP signal even in poor SNR conditions. The interference of spontaneous EEG has been eliminated with significantly improved SNR. The simulation results have demonstrated the effectiveness and superior performance of the proposed method.     

Predicting potential impacts of climate change on the geographical distribution of enchytraeids: a meta-analysis approach

The expectation that atmospheric warming will be most pronounced at higher latitudes means that Arctic and montane systems, with predominantly organic soils, will be particularly influenced by climate change. One group of soil fauna, the enchytraeids, is commonly the major soil faunal component in specific biomes, frequently exceeding above‐ground fauna in biomass terms. These organisms have a crucial role in carbon turnover in organic rich soils and seem particularly sensitive to temperature changes. In order to predict the impacts of climate change on this important group of soil organisms we reviewed data from 44 published papers using a combination of conventional statistical techniques and meta‐analysis. We focused on the effects of abiotic factors on total numbers of enchytraeids (a total of 611 observations) and, more specifically, concentrated on total numbers, vertical distribution and age groupings of the well‐studied species Cognettia sphagnetorum (228 observations). The results highlight the importance of climatic factors, together with vegetation and soil type in determining global enchytraeid distribution; in particular, cold and wet environments with mild summers are consistently linked to greater densities of enchytraeids. Based on the upper temperature distribution limits reported in the literature, and identified from our meta‐analyses, we also examined the probable future geographical limits of enchytraeid distribution in response to predicted global temperature changes using the HadCM3 model climate output for the period between 2010 and 2100. Based on the existing data we identify that a maximum mean annual temperature threshold of 16 °C could be a critical limit for present distribution of field populations, above which their presence would decline markedly, with certain key species, such as C. sphagnetorum, being totally lost from specific regions. We discuss the potential implications for carbon turnover in these organic soils where these organisms currently dominate and, consequently, their future role as C sink/source in response to climate change.     

National and European perspectives on climate change sensitivity of the habitats directive characteristic plant species

The main goal of the Habitats Directive, a key document for European conservation, is to maintain a ‘favourable’ conservation status of selected species and habitats. In the face of near-future climatic change this goal may become difficult to achieve. Here, we evaluate the sensitivity to climate change of 84 plant species that characterise the Danish habitat types included in the Habitats Directive. A fuzzy bioclimatic envelope model, linking European and Northwest African species’ distribution data with climate, was used to predict climatically suitable areas for these species in year 2100 under two-climate change scenarios. Climate sensitivity was evaluated at both Danish and European scales to provide an explicit European perspective on the impacts predicted for Denmark. In all 69–99% of the species were predicted to become negatively affected by climate change at either scale. Application of international Red List criteria showed that 43–55% and 17–69% would become vulnerable in Denmark and Europe, respectively. Northwest African atlas data were used to improve the ecological accuracy of the future predictions. For comparison, using only European data added 0–7% to these numbers. No species were predicted to become extinct in Europe, but 4–7% could be lost from Denmark. Some species were predicted to become positively affected in Denmark, but negatively affected in Europe. In addition to nationally endangered species, this group would be an important focus for a Danish conservation strategy. A geographically differentiated Danish conservation strategy is suggested as the eastern part of Denmark was predicted to be more negatively affected than the western part. No differences in the sensitivity of the Habitats Directive habitats were found. We conclude that the conservation strategy of the Habitats Directive needs to integrate the expected shifts in species’ distributions due to climate change.     

The distribution and composition of vascular plant communities on Heard Island

Summary Six major higher plant communities are defined for sub-Antarctic Heard Island: tussock grassland, meadow, herbfield, pool complex, cushion-carpet, fellfield. The communities were mapped at a scale of 1:50000, using colour aerial photographs and field observations. The floristic composition of twelve vegetation transects and of thirty sample quadrats along these is used to describe the communities and identify dominant or indicator species. The vegetation is compared with that of other sub-Antarctic islands.