Mean Ellenberg Indicator Values Research Articles

Classification of forest vegetation in Yaraligöz Education and Observation Forest, Kastamonu, Türkiye

Abstract. Karaköse M, Terzioglu S. 2023. Classification of forest vegetation in Yaraligöz Education and Observation Forest, Kastamonu, Türkiye. Nusantara Bioscience 15: 161-171. Forest ecosystems, which contain approximately half of the 12,975 plant taxa known to be distributed in Türkiye, are very important in terms of biological diversity. The fact that forests are seen as wood-producing ecosystems and have been planned for these purposes for many years has resulted in forests being kept away from being evaluated in terms of ecosystem and socio-economic aspects. Today, forest management plans have begun to be prepared in which all components of the forest are considered, and biological diversity is reflected. Based on this understanding, this investigation was performed during 2011-2012 to analyze the forest vegetation of Yaraligöz Education and Observation Forest. The study area is located in the north-western part of Türkiye within the Euro-Siberian phytogeographic region. Phytosociological studies were carried out using the classical Braun-Blanquet approach, and 51 relevés were collected from the research area. The database contains 184 vascular plant taxa, dominated by the Euro-Siberian elements and Hemicryptophytes. The relevés were classified using the Modified TWINSPAN, and the forest vegetation types' distribution was analyzed using non-metric multi-dimensional scaling. A comprehensive comparison among all described syntaxa within the study area and other closely related forests was provided. Topographic factors and mean Ellenberg indicator values were evaluated to interpret the ecological relationships among forest plant associations. Four associations, two (Daphno pontica-Pinetum hamatae and Galio rotundifolii-Abietum equi-trojani) of which are new syntaxa to science, were defined as belonging to the Euxine Province within Erico-Pinetea, Carpino-Fagetea sylvaticae, Quercetea pubescentis, and Vaccinio-Piceetea. The distribution of these four forest associations was mostly affected by light intensity, nutrients, moisture content, and altitude. The results of this vegetation study provided precious knowledge for monitoring vegetation change and nature conservation projects in the Yaraligöz.

Altitude is a better predictor of the habitat requirements of epixylic bryophytes and lichens than the presence of coarse woody debris in mountain forests: a study in Poland

Key messageIn order to preserve the continuity of epiphytic and epixylic cryptogamic flora, two things are essential: maintaining the near-natural character of a forest community in relation to the montane zonation and more sustainable forest management in relation to deadwood.ContextLichens and bryophytes are common species that inhabit dead wood. The relationship between their habitat requirements, which can be expressed by their Ellenberg indicator values and the characteristics of dead logs, are not yet known.AimsWe formulated the hypothesis that altitude is positively correlated with the demands of species for higher light and lower temperature, while the decomposition stage of deadwood is positively correlated with species’ requirements for nutrients and moisture. Moreover, we assumed that there would be differences in the habitat requirements among specific groups of species, i.e., lichens, liverworts, and mosses.MethodsA total of 629 logs that were colonized by bryophytes and lichens were analyzed in terms of their mean Ellenberg indicator values in order to determine whether there is a link between the location, decomposition of logs and the species’ environmental requirements.ResultsAltitude correlated with the moisture and nutrients in the habitats of liverworts and mosses and light and soil acidification only in mosses.ConclusionsThe obtained results demonstrate that the altitudinal distribution of epixylic species in a montane region is of greater importance than the deadwood properties like decomposition stage and moisture content.

Niche differentiation between Malus sylvestris and its hybrid with Malus domestica indicated by plant community, soil and light

AbstractQuestionMalus sylvestris is considered an endangered tree species in Central Europe. Hybridization with Malus domestica poses a serious threat to the genetic integrity of the wild species. Here we investigate whether M. sylvestris and the hybrid M. domestica × sylvestris occur in the same habitat or have different ecological niches and whether M. sylvestris is threatened by displacement by the hybrid.LocationNorthern Bavaria.MethodsTaxon delimitation was accomplished using six genetic microsatellite markers and 613 Germany‐wide references of M. sylvestris and 75 cultivars. To determine differences in the ecological niches between M. sylvestris and hybrids, light availability for the trees was estimated via gap fractions in hemispherical photographs. Soil particle size fractions and pH values were determined for each horizon. Vegetation relevé data were collected, and mean Ellenberg indicator values calculated. For habitat differences, means in combination with frequency patterns of the parameters were compared, and logistic models and detrended correspondence analysis (DCA) of community data were calculated.ResultsGenetic markers identified 22 M. sylvestris and 11 hybrid specimens, meaning that in the study area the wild taxon is much more frequent than the hybrid. Ecological site differences between M. sylvestris and its hybrid with M. domestica were best explained by light availability, pH and mean Ellenberg moisture value. In contrast to the ecological demands of the hybrid, Malus sylvestris tolerated wet soil and flooding and even somewhat shadier conditions in the later successional stages. DCA revealed that differences in the composition of the plant communities in which the taxa were found were primarily driven by soil moisture.ConclusionsOur data suggested different ecological niches, which are appropriate to reduce the risk of replacement of M. sylvestris by the hybrid M. domestica × sylvestris. Hence, these findings provide important implications for a more targeted planning of in‐situ conservation strategies of M. sylvestris genomes with low levels of admixture and help to protect plant communities suitable for the threatened wild apple.

Temporal changes in the ground vegetation in spruce forests in the Erzgebirge (Ore Mountains) — bryophytes are better indicators of the impact of liming and of sulphur and nitrogen deposition than the herb layer

AbstractQuestionsHow have species composition and diversity in the herb and bryophyte layer of spruce forest communities developed on unlimed plots and on plots with varying liming intensity under the conditions of decreasing sulphur (S) deposition and unabated high nitrogen (N) deposition?LocationSpruce stands in the Erzgebirge, East Germany.MethodsWe repeated herb and bryophyte layer surveys on 36 quasi‐permanent plots after approx. 23 years (1989/1991 vs 2012/2014). Over this period, the study area experienced a sharp decline in S deposition and repeated liming of the spruce stands. Our plots represent a gradient of liming from zero to four applications. We analyse the change in species composition and species diversity depending on the liming intensity using Ellenberg indicator values (EIV), correspondence analysis, indicator species analysis and diversity parameters (alpha diversity, Lennon similarity).ResultsOn the unlimed plots, the species composition of the herb layer remained unchanged over the study period, despite the decrease in the coverage of Calamagrostis villosa and Deschampsia flexuosa and in the total coverage of the herb layer. In contrast, the bryophyte layer showed a significant increase in coverage and species richness with the decrease in S deposition. Liming led to a sharp increase in species richness in the herb layer, due to the appearance of disturbance indicators. The mean EIVs for acidity and nitrogen (EIV‐R and EIV‐N) also increased significantly. All observed effects increased with increasing liming intensity. We also noticed an increase in species richness over time in the bryophyte layer on the limed plots. However, this was less pronounced than on the unlimed plots, and decreased with increasing liming intensity. This was because the appearance of disturbance indicators or of typical species for the Calamagrostio villosae‐Piceetum was partially compensated for by the disappearance of acid indicators as a result of liming. The species turnover was thus much higher in the bryophyte layer than in the herb layer.ConclusionsIn contrast to the herb layer, the bryophyte layer proves to be a sensitive indicator of changes in air pollution. The effects of greatly reduced S deposition on the bryophyte layer outweigh those of continuous N deposition in the study area. Liming acts as a disturbance in both the herb layer and the bryophyte layer. This influence increases with increasing liming intensity. Our results do not support a general application of liming in large, contiguous forest areas. Rather, this measure should be applied in a differentiated manner.

Forest floor bryophyte and lichen diversity in Scots pine and Norway spruce production forests

Bryophytes and lichens are two main components of the forest floor vegetation. They provide essential ecosystem services, including nutrient recycling and water regulation. Here, we contrast the species richness, cover and community composition of forest floor bryophytes and lichens in Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) dominated production forests. The study sites were located in the hemiboreal zone of southern Sweden, and represented early-, mid- and late rotation stands. Our aim was to examine the potential consequences for forest floor biodiversity from the decreasing use of Scots pine production forests in this region.Whereas Scots pine and Norway spruce stands did not differ in bryophyte cover, we found a higher cover of lichens in Scots pine stands, and highest in the intermediate aged stands. Also the species richness of lichens was higher in the Scots pine stands, while bryophyte species richness was higher in the Norway spruce stands. Differences in canopy cover and associated light transmittance to the forest floor appears to be important drivers for distinctive different forest floor communities in the Scots pine and Norway spruce stands, as revealed by Non-Metric Multidimensional Scaling (NMDS). Mean Ellenberg indicator values for bryophytes and lichens showed that species associated with Scots pine stands were characterized by their tolerance of brighter conditions, higher insolation, and better adaptation to a continental climate. Norway spruce stands instead had a comparably larger proportion of species tolerating lower light, but also indicators of higher available nutrient levels, humidity, and pH. The outcome of the Ellenberg indicator species analysis, as well as the larger cover of lichens,and adaptations to drought found among some mosses, revealed that forest floor communities are shaped by different environmental factors in Scots pine and Norway spruce production stands. These environmental differences, and the quantified shifts in forest floor communities identified in this study, indicate the large shifts in understory bryophyte and lichen species composition and abundance that is likely to occur if Scots pine stands are converted to Norway spruce.

Long‐term vegetation changes in Nardus grasslands indicate eutrophication, recovery from acidification, and management change as the main drivers

AbstractQuestionsWhich trends and patterns of community change occurred in Nardus grasslands over recent decades in parts of the Continental biogeographic region of Germany? Are patterns and trends consistent across two study regions? Do impacts of environmental changes on Nardus grasslands in Central Europe correspond to those identified in the European Atlantic biogeographic region?LocationEast Hesse Highlands, Germany.MethodsIn 2012–2015, we re‐surveyed quasi‐permanent plots that had been initially surveyed between 1971 and 1987, and re‐measured soil parameters. We tested for differences in species frequency and cover, mean Ellenberg indicator values, species richness, and soil variables. Nitrogen and sulphur deposition data were analysed to evaluate possible effects of atmospheric pollutants. We used regression and redundancy analyses to identify environmental drivers responsible for changes in species composition.ResultsAcross regions, we found significant increases in soil pH, Ellenberg R and N indicator values, plant nutrient indicators, forbs, species of agricultural grasslands and of fallows. By contrast, the C:N ratio, Nardus grassland specialists, low‐nutrient indicators, and graminoids declined. Changes in species composition were related to changes in pH and management. There was a strong decrease in sulphur and a moderate increase in nitrogen deposition, whose local‐scale pattern did not correlate with changes in soil parameters. However, there was an effect of local NHy changes on species composition.ConclusionsThe findings indicate significant overall eutrophication, a trend towards less acidic conditions and insufficient management, which are widely consistent across our study regions and correspond to recent reports of vegetation changes and recovery from acidification in the Atlantic biogeographic region. We assume the reduced sulphur deposition during recent decades to be a major driver of these changes, combined with increased nitrogen deposition and reduced management intensity. This suggests a large‐scale validity of processes that influenced changes in Nardus grasslands of Western and Central Europe.

The segetal flora of winter cereals and allied crops in Italy: species inventory with chorological, structural and ecological features

We present the first inventory of the segetal flora of Italian winter cereal crops and allied crop types. The database consists of over 30,000 records, derived from different sources. We provide information and analyses on life forms, chorotypes, Ellenberg indicator values and preferential habitats of the flora. The inventory includes 987 vascular taxa and nothotaxa (868 species, 118 subspecies and 1 nothosubspecies), belonging to 354 genera and 55 families. Characteristic segetal species are 128, while 740 are generalist or accidental species from other habitats. Species exclusive of segetal habitats are 47. One species is extinct, and one is not confirmed in Italy. We recorded 42 neophytes, 15 archaeophytes and 10 cryptogenic species. Segetal species that are threatened in Europe are 45. Species in the Italian Red List are four, and five are threatened endemic species. The most frequent species are Papaver rhoeas (1,045 records), Convolvulus arvensis (623) and Ranunculus arvensis (571). Most species are therophytes (64%) and have a Mediterranean (36%), wide (14%) or eastern (13%) distribution range. Mean Ellenberg indicator values revealed relevant ecological affinities between the inventoried flora and cultivated winter cereals. Our work represents the basis for future applied studies in botany, ecology and agronomy.

Numerical classification and ordination of Esenli (Giresun) forest vegetation

The forest vegetation of Esenli Forest Planning Unit was investigated between 2015 and 2018 from the phytosociological point of view. The study area is situated in the Euxine province of Euro-Siberian Region. Phytosociological studies were carried out in accordance with the classical Braun-Blanquet methodology, and 131 releves were collected during the field survey. The releves were classified using the Modified TWINSPAN classification, and general distribution patterns of vegetation were analysed using indirect ordination analysis (Principal Component Analysis) with the R-Project available in the JUICE program. In addition to topographic factors, ecological factors were assessed using the mean Ellenberg Indicator Values to observe the ecological relationships among communities. Four new plant associations (Cirsio trachylepidis-Pinetum sylvestris, Angelico sylvestri-Alnetum barbatae, Circaeo lutetianae-Fagetum orientalis, and Veronico chamaedryo-Piceetum orientalis) were described as belonging to humid montane coniferous and thermophilous deciduous forests within four classes. Distribution pattern of plant communities was strictly influenced by altitude, inclination, moisture, nutrient content, and light.

Vertical variation in epiphytic cryptogam species richness and composition in a primeval Fagus sylvatica forest

AbstractQuestionBiodiversity surveys of epiphytic bryophytes and lichens on standing trees are mostly restricted to the lowermost 2 m, since sampling above this level is time‐consuming and therefore expensive. However, sampling only the stem base is likely to result in underestimation of forest epiphyte diversity, because microclimate and physico‐chemical site conditions, both of which vary with height above the ground, play important roles for poikilohydric organisms. We investigate variation in epiphyte diversity and composition along the vertical gradient in forests and discuss factors that may potentially account for height‐dependent distribution patterns.LocationMontane primeval beech forest Havešová in the Carpathians, eastern Slovakia.MethodsTen circular plots, each 500 m2, were selected randomly in an area severely affected by windfall. Epiphytes were sampled along the stems of recently uprooted trees, from base to the canopy. Mean Ellenberg indicator values (EIV) for light, moisture, acidity and nitrogen availability were used as surrogate variables for environmental interpretation of compositional patterns for sampling segments of 2 m along the stem.ResultsBy sampling only the lowest 2 m, 10% of the total bryophyte and 48% of the lichen species would have been missed. We detected systematic patterns of compositional variation for both groups along the vertical gradient. While pleurocarpous mosses and liverworts were mostly restricted to the stem base, acrocarpous mosses and crustose lichens occurred along the stem almost to the top. Foliose and fruticose lichens were concentrated at intermediate heights and in the upper canopy. Patterns of variation in EIVs suggested that increasing light availability, decreasing moisture and increasing inputs of acidic and nitrous substances are responsible for the compositional shifts along the vertical gradient.ConclusionsSampling only the stem base implies severe underestimation of the epiphyte diversity in temperate broad‐leaved forests. The middle and the upper parts of tree stems have distinctive compositions of epiphytic cryptogams, because microclimate and physico‐chemical site factors vary with height above the ground.

Shifts of arable plant communities after agricultural intensification: a floristic and ecological diachronic analysis in maize fields of Latium (central Italy)

ABSTRACTChanges in agricultural practices represent one of the main causes of shift in species composition of arable plant communities. In particular, the intensification of agriculture going on worldwide since several decades led to heavy transformations of arable plant diversity. Basing on a study conducted in 1964 in Latium (central Italy), we re-surveyed the arable plant communities of 21 maize fields in order to assess the shifts that occurred over 50 years. The results showed a relevant decrease in the number of species (both in the total number and in the mean number per relevé), accompanied by a major species turnover. An increase in neophyte, wide-distribution, geophyte, C4 photosynthetic pathway, and monocot species was observed, while the incidence of insect-pollinated taxa decreased. The calculation of the mean Ellenberg indicator values per relevé showed an increase, in particular, of nutrients and moisture levels.

Contrasting vegetation change (1974–2015) in hedgerows and forests in an intensively used agricultural landscape

AbstractQuestionsHow did hedgerows and forests change in area between 1974 and 2015 and did hedgerows still show the same vegetation composition in 2015? To what degree did the vegetation change in hedgerows and how do these changes compare to changes in forests? What is the nature of the species that changed and, from these, can we make general inferences about possible drivers of change?LocationThe countryside in the municipality of Turnhout, province of Antwerp, northern Belgium.MethodsThrough a resurvey of 54 and 20 quasi‐permanent plots in hedgerows and forests, respectively, we investigated shifts in the herb layer over the period 1974–2015. The plot‐level mean Ellenberg Indicator Values (EIVs) were calculated and soil samples were taken in 2015. We compared diversity statistics and used used Generalized Linear Mixed‐Effects Models (GLMMs) to detect trends in species richness (SR) and EIVs. Via a non‐metric multidimensional scaling (NMDS) ordination based on the Sørensen dissimilarity, we compared shifts at the community level.ResultsOur study shows severe, but opposite changes in SR in forests and hedgerows. In forests, SR declined and a homogenization occurred. The shifts in EIVs indicate that forest vegetation evolved to more shade‐tolerant and nutrient‐demanding species, likely due to eutrophication combined with natural forest succession. In hedgerows, SR significantly increased. The species pool became more diverse and more heterogeneous. Changes in EIVs suggest a change towards more light‐demanding species, possibly caused by fragmentation of the network, and towards species indicative for nutrient‐rich habitats, benefiting from eutrophication.ConclusionsIn general, SR in hedgerows is higher than in forests in our studied region, being a suitable habitat for a wide range of plant species in the countryside. However, the loss of almost 30% of the hedgerow habitat in 41 years confronts us with the challenge of protecting the hedgerow remnants, in the interest of agro‐biodiversity.

Patterns of long‐term vegetation change vary between different types of semi‐natural grasslands in Western and Central Europe

AbstractQuestionsHas plant species richness in semi‐natural grasslands changed over recent decades? Do the temporal trends of habitat specialists differ from those of habitat generalists? Has there been a homogenization of the grassland vegetation?LocationDifferent regions in Germany and the UK.MethodsWe conducted a formal meta‐analysis of re‐survey vegetation studies of semi‐natural grasslands. In total, 23 data sets were compiled, spanning up to 75 years between the surveys, including 13 data sets from wet grasslands, six from dry grasslands and four from other grassland types. Edaphic conditions were assessed using mean Ellenberg indicator values for soil moisture, nitrogen and pH. Changes in species richness and environmental variables were evaluated using response ratios.ResultsIn most wet grasslands, total species richness declined over time, while habitat specialists almost completely vanished. The number of species losses increased with increasing time between the surveys and were associated with a strong decrease in soil moisture and higher soil nutrient contents. Wet grasslands in nature reserves showed no such changes or even opposite trends. In dry grasslands and other grassland types, total species richness did not consistently change, but the number or proportions of habitat specialists declined. There were also considerable changes in species composition, especially in wet grasslands that often have been converted into intensively managed, highly productive meadows or pastures. We did not find a general homogenization of the vegetation in any of the grassland types.ConclusionsThe results document the widespread deterioration of semi‐natural grasslands, especially of those types that can easily be transformed to high production grasslands. The main causes for the loss of grassland specialists are changed management in combination with increased fertilization and nitrogen deposition. Dry grasslands are most resistant to change, but also show a long‐term trend towards an increase in more mesotrophic species.

Improving estimates of environmental change using multilevel regression models of Ellenberg indicator values.

Ellenberg indicator values (EIVs) are a widely used metric in plant ecology comprising a semi‐quantitative description of species’ ecological requirements. Typically, point estimates of mean EIV scores are compared over space or time to infer differences in the environmental conditions structuring plant communities—particularly in resurvey studies where no historical environmental data are available. However, the use of point estimates as a basis for inference does not take into account variance among species EIVs within sampled plots and gives equal weighting to means calculated from plots with differing numbers of species. Traditional methods are also vulnerable to inaccurate estimates where only incomplete species lists are available.We present a set of multilevel (hierarchical) models—fitted with and without group‐level predictors (e.g., habitat type)—to improve precision and accuracy of plot mean EIV scores and to provide more reliable inference on changing environmental conditions over spatial and temporal gradients in resurvey studies. We compare multilevel model performance to GLMMs fitted to point estimates of mean EIVs. We also test the reliability of this method to improve inferences with incomplete species lists in some or all sample plots. Hierarchical modeling led to more accurate and precise estimates of plot‐level differences in mean EIV scores between time‐periods, particularly for datasets with incomplete records of species occurrence. Furthermore, hierarchical models revealed directional environmental change within ecological habitat types, which less precise estimates from GLMMs of raw mean EIVs were inadequate to detect. The ability to compute separate residual variance and adjusted R 2 parameters for plot mean EIVs and temporal differences in plot mean EIVs in multilevel models also allowed us to uncover a prominent role of hydrological differences as a driver of community compositional change in our case study, which traditional use of EIVs would fail to reveal. Assessing environmental change underlying ecological communities is a vital issue in the face of accelerating anthropogenic change. We have demonstrated that multilevel modeling of EIVs allows for a nuanced estimation of such from plant assemblage data changes at local scales and beyond, leading to a better understanding of temporal dynamics of ecosystems. Further, the ability of these methods to perform well with missing data should increase the total set of historical data which can be used to this end.

Legacy of historical litter raking in temperate forest plant communities

AbstractQuestionEuropean temperate forests have been managed for millennia, and this management has left a long‐lasting legacy in soil chemistry and plant species composition and diversity. One of the most common practices was the raking of leaf litter, which was used as bedding for farm animals. We asked, what is the legacy of historical litter raking for contemporary forest plant communities?LocationCzech Republic.MethodsWe explored the effect of historical litter raking on species richness and diversity of the forest herbaceous layer. We also tested whether long‐term soil acidification and nutrient depletion caused by litter raking were reflected in Ellenberg indicator values for nutrients and soil reaction and in the higher abundance of specialists of acidophilous forest types. We used written historical evidence to identify areas where litter raking was practised in the 19th century. We analysed the differences between vegetation plots located in areas affected and unaffected by the past litter raking. Our analysis included almost 2,500 vegetation plots recorded between 1980 and 2015.ResultsLitter raking was historically practised in a striking 85% of forested townships. Although litter raking had no significant effect on overall species richness, we found significant differences of diversity patterns among forest types. Historically raked plots were taxonomically more similar. We found no difference in the mean Ellenberg indicator values for soil reaction and nutrients between the affected and unaffected plots, and only a weak positive response of selected herb species of acidophilous forests.ConclusionsWe provide the first empirical evidence of the historical litter‐raking legacy in forest communities on a large scale. Despite its historical frequency, we found only a weak legacy of historical litter raking in present‐day plant communities. Future studies could potentially use other, finer‐scale methods in smaller territories to complement our results.

Ellenberg's indicator values support prediction of suitable habitat for pre-diapause larvae of endangered butterfly Euphydryas aurinia.

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.

Contrasting patterns of fine-scale herb layer species composition in temperate forests

Although being well described at the landscape level, patterns in species composition of forest herb layer are rarely studied at smaller scales. Here, we examined fine-scale environmental determinants and spatial structures of herb layer communities in thermophilous oak- and hornbeam dominated forests of the south-eastern part of the Czech Republic.Species composition of herb layer vegetation and environmental variables were recorded within a fixed grid of 2 × 2 m subplots regularly distributed within 1-ha quadrate plots in three forest stands. For each site, environmental models best explaining species composition were constructed using constrained ordination analysis. Spatial eigenvector mapping was used to model and account for spatial structures in community variation. Mean Ellenberg indicator values calculated for each subplot were used for ecological interpretation of spatially structured residual variation.The amount of variation explained by environmental and spatial models as well as the selection of variables with the best explanatory power differed among sites. As an important environmental factor, relative elevation was common to all three sites, while pH and canopy openness were shared by two sites. Both environmental and community variation was mostly coarse-scaled, as was the spatially structured portion of residual variation. When corrected for bias due to spatial autocorrelation, those environmental factors with already weak explanatory power lost their significance. Only a weak evidence of possibly omitted environmental predictor was found for autocorrelated residuals of site models using mean Ellenberg indicator values.Community structure was determined by different factors at different sites. The relative importance of environmental filtering vs. spatial processes was also site specific, implying that results of fine-scale studies tend to be shaped by local conditions. Contrary to expectations based on other studies, overall dominance of spatial processes at fine scale has not been detected. Ecologists should keep this in mind when making generalizations about community dynamics.

Multiple environmental changes drive forest floor vegetation in a temperate mountain forest.

Human‐induced changes of the environment and their possible impacts on temperate forest understory plant communities have been examined in many studies. However, the relative contribution of individual environmental factors to these changes in the herb layer is still unclear. In this study, we used vegetation survey data covering a time period of 21 years and collected from 143 permanent plots in the Northern Limestone Alps, Austria. Data on soil chemistry (49 plots), light condition (51 plots), soil temperature and moisture (four and six plots), disturbance (all plots), climate (one station in a clearing area), and airborne sulfur (S) and nitrogen (N) deposition (two forest stands) were available for analyses. We used these data together with plot mean Ellenberg indicator values in a path analysis to attribute their relative contributions to observed vegetation changes. Our analysis reveals a strong directional shift of the forest understory plant community. We found strong evidence for a recovery of the ground‐layer vegetation from acidification as response to decreased S deposition. We did not observe a community response to atmospheric N deposition, but we found a response to altered climatic conditions (thermophilization and drying). The path analysis revealed that changes in the light regime, which were related to small‐scale disturbances, had most influence on herb layer community shifts. Thermophilization and drying were identified as drivers of understory community changes independent of disturbance events.

Resurveying hedgerows in Northern Germany: Plant community shifts over the past 50 years

Resurveying is a powerful approach to investigate responses of plant species communities to a changing environment. We present a resurvey of hedgerows from the “Knick” landscape of eastern Schleswig-Holstein, Germany. The original survey was done by H. E. Weber in 1967 and new data from totally 51 semi-permanent plots was sampled in 2015. Hedgerows are a key near-natural habitat that can harbour a great biodiversity in otherwise agriculturally intensified landscapes.Our study reveals a distinct shift in the herbaceous species composition of the hedgerows over the past five decades. To understand the reasons for these changes, we compared the mean Ellenberg indicator values (EIVs) and measured pH values, as well as hedge shape parameters of the hedgerows between the recent and the original study. The main driver behind the change in species composition appeared to be the increase in nutrient supply. The hedge shape changed as well, indicating an altered hedgerow management. Interestingly, we found a contradictory relationship between measured pH values and mean EIVs for reaction: while the former showed a decrease over time, the latter suggested an increase.Species richness decreased in some groups (shrubs and herbaceous forest species) but increased in others (grass species and arable weed species), with an overall decline in species richness. An analysis of the species' changes in frequency in relation to their EIVs showed that species with higher nitrogen and temperature scores were more likely to have increased.

The effect of harvest, mulching and low-dose fertilization of liquid digestate on above ground biomass yield and diversity of lower mountain semi-natural grasslands

The effect of the biomass conversion system called integrated production of solid fuel and biogas from biomass (IFBB) on above ground biomass yield and diversity in semi-natural grasslands of lower mountain ranges was investigated over a time span of 5 years. The system uses late cut grassland biomasses and produces energy carriers and a liquid fertilizer, the effect of which was tested against the alternative of harvest without fertilization and mulching without fertilization. The biomass yield significantly improved both in fertilized and mulched treatments, whereas it remained low in the unfertilized treatment. The effects on diversity were less explicit. Species numbers remained stable in the fertilized and unfertilized cutting treatment and decreased in the mulching treatment. The applied treatment showed no significant effect on diversity indices (H′, E and T). Mean Ellenberg indicator values for nutrients revealed that species accustomed to nutrient poor habitats increased in the unfertilized cut treatment and decreased in the fertilized and mulched treatment.

Why mean indicator values are not biased

AbstractQuestionsZelený & Schaffers (Journal of Vegetation Science 2012, 23: 419–431)) blame mean Ellenberg indicator values for producing ‘highly biased results’ that are ‘too good to be true’, statements causing considerable confusion among plant ecologists. I ask if (1) the detrimental phenomena they observed can be reproduced in yet another real‐world data set using the recently revised indicator values of Landolt et al. (Flora indicativa. Ecological indicator values and biological attributes of the flora of Switzerland and the Alps, 2010, Haupt, Bern, CH), (2) the issue of supposed bias also applies to species‐based functional traits, and (3) the assumed ‘bias’ also concerns principal components analysis.MethodsIn a first step, I probe the effect of randomizing indicator values by verification of classifications through ANOVA and CCA using published data. Then, I repeat the same procedure replacing the matrix of indicator values with a species by traits matrix. In a third step I apply testing with ANOVA to an ordination of principal components. Finally, patterns of alternative vegetation descriptors (species, mean indicator values, traits frequency, site factors) are compared using Mantel correlation.ResultsThe results at first glance confirm the failings of tests as found by Zelený & Schaffers. However, when using traits data instead of mean indicator values, precisely the same happens, raising the possibility that mean species‐based traits are also ‘biased’. The effect prevails when applied to PCA scores. I conclude that Zelený & Schaffers overlooked that unrealistic significances in ANOVA emerge from statistical dependence; they are artefacts of a non‐valid null model.ConclusionsRestrictions in the use of mean indicator values and species‐based traits concern statistical tests only that assume statistical independence from species scores when there is none. I conclude that mean indicator values deserve rehabilitation as there is no bias involved in their use.