Ecological disturbances are recognized as a crucial factor influencing the attributes of ecological communities. Depending on the specific adaptation or life cycle, plant species show different ...responses to disturbances of different magnitudes. Herben et al. (Journal of Vegetation Science, 27, 628–636) proposed six disturbance indicator values (DIVs) that describe the niches of Central‐European plant species along gradients of disturbance frequency and severity. Here, we ask if the DIVs can be used in community ecology for bioindication of disturbance regime?
We used a dataset of riparian forests sampled within mountain catchments (the Sudetes, SW Poland). As the regime of disturbance is driven by changes in floods from the spring toward the mouth, we calculated the position of every plot along longitudinal (upstream–downstream) gradient and used it as a proxy for the disturbance severity and frequency. We then calculated the community‐weighted means (CWMs) for each of the six indices for each plot and analyzed whether these indices reflected the position of the plots along the rivers. We expected an increase in the severity indices and a decrease in the frequency indices downstream along the rivers. Moreover, we analyzed relationships between disturbance indices and species optima along longitudinal gradient.
Surprisingly, means for all analyzed indices increased along the rivers. Severity indices showed the strongest association with the longitudinal gradient. The disturbance severity index for herbs was the only index that differed significantly among species with different responses along longitudinal gradient. On these results, we identified a strong correlation between the severity and frequency indices as the main problem.
We conclude that the DIVs have considerable applicative potential; however, the determination of ecological niches separately for disturbance severity and frequency is difficult because different components interact to shape the realized niche of each species. All analyzed indices encompass different attributes of the disturbance regime including both severity and frequency.
We tested disturbance indicator values (DIVs) for its potential use in community ecology for bioindication of disturbance regime. The DIVs have considerable applicative potential; however, the determination of ecological niches separately for disturbance severity and frequency is difficult because different components interact to shape the realized niche of each species. All analyzed indices encompass different attributes of the disturbance regime including both severity and frequency.
•Riparian forests are the most species-rich forests both at local and regional scales.•The contribution of rare species is similar in riparian and other forest types.•Eight groups of rare species ...reflect riparian complexity and dynamics.•Alpha diversity decreased along rivers, total species richness showed a unimodal response.•The effect of topography on riparian richness depends on the position in a river network.
This study aimed to analyze plant species richness in riparian forests at both local and regional scales across several watersheds in the Sudetes (Poland, Central Europe). Specifically, species richness in riparian forest was compared to other forest types in the same region. It was also hypothesized that due to high complexity and dynamics, riparian forests share a higher number of rare species. In addition, the longitudinal pattern of species richness was analyzed at both local and regional scales. Finally, the effect of topography on species richness in riparian forests in spring areas and along rivers of various sizes was analyzed.
Riparian forests have significantly higher alpha diversity than beech and ravine forests, but oak forests showed a similar level of diversity. However, a comparison of accumulation curves showed, that riparian forests are the most species-rich at a regional scale. All forest types had a similar share of rare species. Eight uniform groups of rare species were distinguished in riparian forests and reflected the riparian complexity and dynamics.
The number of plant species per plot was highest in spring areas and decreased from headwaters to lower reaches. The estimated total number of species showed a similar pattern; however, the highest number was estimated for riverine forests along 3rd order streams and therefore suggest a unimodal pattern of gamma diversity along a longitudinal (upstream–downstream) gradient. The effect of topographic variables on species richness differed depending on the position in the river network.
Species turnover is ubiquitous. However, it remains unknown whether certain types of species are consistently gained or lost across different habitats. Here, we analysed the trajectories of 1827 ...plant species over time intervals of up to 78 years at 141 sites across mountain summits, forests, and lowland grasslands in Europe. We found, albeit with relatively small effect sizes, displacements of smaller‐ by larger‐ranged species across habitats. Communities shifted in parallel towards more nutrient‐demanding species, with species from nutrient‐rich habitats having larger ranges. Because these species are typically strong competitors, declines of smaller‐ranged species could reflect not only abiotic drivers of global change, but also biotic pressure from increased competition. The ubiquitous component of turnover based on species range size we found here may partially reconcile findings of no net loss in local diversity with global species loss, and link community‐scale turnover to macroecological processes such as biotic homogenisation.
Our cross‐habitat synthesis reveals a ubiquitous component of biodiversity change in plant communities. We find directional temporal turnover towards plant species with larger geographic ranges across contrasting habitats. This turnover, likely driven in part by aspects of species niche, may help reconcile findings of no net loss in local diversity with global species loss, and link temporal turnover at the community scale to macroecological processes such as biotic homogenisation.
Aim
Species–area relationships (SARs) are fundamental scaling laws in ecology although their shape is still disputed. At larger areas, power laws best represent SARs. Yet, it remains unclear whether ...SARs follow other shapes at finer spatial grains in continuous vegetation. We asked which function describes SARs best at small grains and explored how sampling methodology or the environment influence SAR shape.
Location
Palaearctic grasslands and other non‐forested habitats.
Taxa
Vascular plants, bryophytes and lichens.
Methods
We used the GrassPlot database, containing standardized vegetation‐plot data from vascular plants, bryophytes and lichens spanning a wide range of grassland types throughout the Palaearctic and including 2,057 nested‐plot series with at least seven grain sizes ranging from 1 cm2 to 1,024 m2. Using nonlinear regression, we assessed the appropriateness of different SAR functions (power, power quadratic, power breakpoint, logarithmic, Michaelis–Menten). Based on AICc, we tested whether the ranking of functions differed among taxonomic groups, methodological settings, biomes or vegetation types.
Results
The power function was the most suitable function across the studied taxonomic groups. The superiority of this function increased from lichens to bryophytes to vascular plants to all three taxonomic groups together. The sampling method was highly influential as rooted presence sampling decreased the performance of the power function. By contrast, biome and vegetation type had practically no influence on the superiority of the power law.
Main conclusions
We conclude that SARs of sessile organisms at smaller spatial grains are best approximated by a power function. This coincides with several other comprehensive studies of SARs at different grain sizes and for different taxa, thus supporting the general appropriateness of the power function for modelling species diversity over a wide range of grain sizes. The poor performance of the Michaelis–Menten function demonstrates that richness within plant communities generally does not approach any saturation, thus calling into question the concept of minimal area.
In spite of the great popularity of Ellenberg's Indicator Values (EIVs) in plant ecology, animal ecologists seldom use EIVs to address ecological questions. In this study we used EIVs to test their ...potential usefulness for the prediction of suitable habitat for pre-diapause larvae of the endangered butterfly species Euphydryas aurinia. Nine transects crossing grasslands in SW Poland with abundant populations of E. aurinia were designed. We sampled 76 vegetation plots along the transects. In addition, the presence of the larval webs of E. aurinia in sampled plots was also recorded. We then calculated the mean community EIVs of light, nitrogen, soil reaction, moisture and temperature for each sample plots. Generalized linear mixed-effects models (GLMMs) were used to assess which factors determine the local occurrence of larval webs of E. aurinia. We found the larval webs only in 12 plots, while the host plant was present in 39 of the examined plots. The presence of the host plant was the most important predictor in both models including all plots or including only plots with host plants. The other significant predictor was the mean EIV of light, and its importance increased in models considering all plots. We attributed the importance of the EIV of light to the site openness and density of the vegetation layer. A positive relationship between this predictor and the presence of larval webs indicates that sites with looser vegetation, a lower contribution of shrubs and tall herbs and better penetration of photosynthetically active radiation to lower vegetation layers are preferred by E. aurinia for oviposition. Moreover, the significance of EIV of light may be linked with management practices. Many light-demanding species decline after cessation of mowing as a result of litter accumulation and the dominance of tall herbs. An absence of light-demanding species decreases the community's mean EIV of light and thus indicates the influence of meadow abandonment.
It is generally hypothesized that forest dieback is a characteristic of alder swamp forests (alder carrs, Alnion glutinosae alliance). Different internal and external factors may trigger this ...process, including human disturbance, changes in river discharge, unusually severe and prolonged flooding, terminal age of an even-aged alder forest (ca. 100-150 years) and others. Although forest dieback in this type of forest may cause major changes in environmental conditions, the influence of this change on the floristic composition has not been well recognized. The study aimed to detect any possible changes in floristic variation in alder swamp forest following forest dieback. Vegetation plots in alder swamp forests affected by forest dieback were resurveyed 20 years after a previous study. PERMANOVA was used to test the significance of the compositional change and nonmetric multidimensional scaling (NMDS) with passively fitted means of the Ellenberg's Indicator Values were used to interpret its ecological meaning. In addition, different structural and diversity indices were compared, including species richness, percentage cover of vegetation layers, Shannon and Simpson diversity and evenness. Finally, we analyzed changes in the frequency of vascular plant species using Chi square tests. We recorded clear and significant compositional changes following alder swamp forest dieback. This change was most related to the gradient of moisture, followed by the gradients of light and temperature. The analysis of the individual species showed that the species of hummocks declined, while the species of hollows increased. Moreover, the current communities are dominated by some hydrophytes that were not recorded 20 years ago. Forest dieback resulted in profound changes in the hydrological regime. The observed changes are consistent with a model of cyclic succession as proposed for alder swamps. In addition, we conclude that the natural forest dynamics have to be taken into consideration while interpreting the results of re-survey studies.
Biodiversity time series reveal global losses and accelerated redistributions of species, but no net loss in local species richness. To better understand how these patterns are linked, we quantify ...how individual species trajectories scale up to diversity changes using data from 68 vegetation resurvey studies of seminatural forests in Europe. Herb-layer species with small geographic ranges are being replaced by more widely distributed species, and our results suggest that this is due less to species abundances than to species nitrogen niches. Nitrogen deposition accelerates the extinctions of small-ranged, nitrogen-efficient plants and colonization by broadly distributed, nitrogen-demanding plants (including non-natives). Despite no net change in species richness at the spatial scale of a study site, the losses of small-ranged species reduce biome-scale (gamma) diversity. These results provide one mechanism to explain the directional replacement of small-ranged species within sites and thus explain patterns of biodiversity change across spatial scales.
AIM: Formalized classifications synthesizing vegetation data at the continental scale are being attempted only now, although they are of key importance for nature conservation planning. Therefore, we ...aim to provide a vegetation classification and to describe the main biogeographical patterns of floodplain forests and alder carrs in Europe. LOCATION: Europe. METHODS: A database of more than 40 000 vegetation plots of floodplain forests and alder carrs across Europe was compiled. After geographic stratification, 16 392 plots were available for classification, which was performed using the supervised method Cocktail. We also searched for new associations using semi‐supervised K‐means classification. The main biogeographic patterns and climate‐related gradients in species composition were determined using detrended correspondence analysis and cluster analysis. RESULTS: Thirty associations of floodplain forests and alder carrs were distinguished, which belong to five alliances. The Alnion incanae includes riparian, seepage and hardwood floodplain forests in the nemoral and hemiboreal zones (dominated by Alnus glutinosa and Fraxinus excelsior) and in the boreal zone (dominated by A. incana). The Osmundo‐Alnion represents oceanic vegetation dominated by Alnus glutinosa, Fraxinus angustifolia and F. excelsior distributed mostly on the Iberian Peninsula and composed of species with Atlantic distribution and Iberian endemics. The Populion albae comprises floodplain forests frequently dominated by Fraxinus angustifolia, Populus alba and P. nigra that are widespread in floodplains of large rivers under summer‐dry climates in the Mediterranean region. The Platanion orientalis represents eastern Mediterranean floodplain forests dominated by Platanus orientalis. The Alnion glutinosae includes forest swamps dominated by Alnus glutinosa distributed mostly in the nemoral and hemiboreal zones. The main biogeographic patterns within European floodplain forests and alder carrs reflect the climatic contrasts between the Mediterranean, nemoral, boreal and mountain regions. Oceanic floodplain forests differ from those in the rest of Europe. The hydrological regime appears to be the most important factor influencing species composition within regions. CONCLUSIONS: This study is the first applying a formalized classification at the association level for a broad vegetation type at the continental scale. The proposed classification provides the scientific basis for the necessary improvement of the habitat classification systems used in European nature conservation.
•River density promotes the functional richness, xerophytes and alien species.•Settlements decrease the functional dispersion and the percentage of forest species.•Functional richness promotes alien ...species and decreases the percentage of forest species.•Functional dispersion decreases the share of non-invasive ruderals and xerophytes.
Urban parks constitute one of the most important elements of the urban green infrastructure. However, knowledge on how the surrounding landscape influences the functional diversity of plant species is still insufficient. The aim of this study was to assess the impacts of different landscape features in proximity of urban parks on their functional diversity and to recognise the community-level coexistence patterns of the plant species. We demonstrated that an increasing river net density had a positive impact on the functional richness and promoted the occurrence of native xerophytes, non-invasive archaeophytes and invasive kenophytes in urban parks. On the contrary, a higher contribution of settlements drove a decrease in the functional dispersion and had a negative impact on the frequency of deciduous forest species. The conservation of urban parks should be a focus for the maintenance of a high variety of pioneer habitat conditions, which are suitable for rare archaeophytes and xerothermic species. The management of invasive species should be the focus of their removal from open habitats and to prevent them from entering the forest interiors. This may be achieved, for instance, by the maintenance of well-developed edge zones composed of a high number of competitive shrubs and nitrophilous tall herbs of native origin.
•We compared ravine forest plots from protected and managed areas.•Only subtle differences were found in overall plant species composition.•There were no differences in plant species richness and ...diversity indices.•No differences were found in ecological groups of plant species.•Low intensity forest management may resemble natural disturbances.
The influence of management practices on forest ecosystems is usually analyzed by a comparison of species composition and richness. Different types of management practices increase plant species richness, mainly due to an increase in the number of ruderal and open habitat species. So far, most of the studies have been performed in the forest types that were most common in the studied regions. In this study we focused on broadleaved ravine forests that are spatially limited to specific habitat conditions, including steep rocky slopes with skeletal soil and unstable ground. These forests are local biodiversity hotspots, and, due to limited accessibility, have been subject to only limited management practices, mainly removal of single trees.
We collected a dataset of 215 plots sampled between 1991 and 2015 in both managed forests and protected areas. We used multivariate techniques to compare the differences in the overall species composition. In addition, we compared differences in diversity, structural and habitat indices to find any possible differences. There were no differences in both the plot level and accumulative species richness and diversity indices between protected and managed forests. In addition, a comparison of habitat conditions and different ecological groups, including ruderal and open habitat species, alien species and ancient forest indicator species also revealed no differences. The only significant differences between the protected and managed forests related to the evenness and shrub cover.
We concluded that low intensity forest management in ravine forests resembles natural disturbances, which are characteristic of natural ravine forests. The species composing these communities are adapted to frequent natural disturbances and thus forest management did not influence significant habitat conditions. However, to fully understand the effect of these practices on biodiversity, a comparison of structural characteristics is needed.
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