Somodi I.,Center for Ecological Research |
Lepesi N.,Eötvös Loránd University |
Lepesi N.,Geological and Geophysical Institute of Hungary |
Botta-Dukat Z.,Center for Ecological Research
Ecology and Evolution | Year: 2017
It has long been a concern that performance measures of species distribution models react to attributes of the modeled entity arising from the input data structure rather than to model performance. Thus, the study of Allouche et al. (Journal of Applied Ecology, 43, 1223, 2006) identifying the true skill statistics (TSS) as being independent of prevalence had a great impact. However, empirical experience questioned the validity of the statement. We searched for technical reasons behind these observations. We explored possible sources of prevalence dependence in TSS including sampling constraints and species characteristics, which influence the calculation of TSS. We also examined whether the widespread solution of using the maximum of TSS for comparison among species introduces a prevalence effect. We found that the design of Allouche et al. (Journal of Applied Ecology, 43, 1223, 2006) was flawed, but TSS is indeed independent of prevalence if model predictions are binary and under the strict set of assumptions methodological studies usually apply. However, if we take realistic sources of prevalence dependence, effects appear even in binary calculations. Furthermore, in the widespread approach of using maximum TSS for continuous predictions, the use of the maximum alone induces prevalence dependence for small, but realistic samples. Thus, prevalence differences need to be taken into account when model comparisons are carried out based on discrimination capacity. The sources we identified can serve as a checklist to safely control comparisons, so that true discrimination capacity is compared as opposed to artefacts arising from data structure, species characteristics, or the calculation of the comparison measure (here TSS). © 2017 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.
Borics G.,Center for Ecological Research |
Nagy L.,Romanian Water Authority |
Miron S.,Romanian Water Authority |
Grigorszky I.,Debrecen University |
And 4 more authors.
Hydrobiologia | Year: 2013
The restoration and management of shallow, pond-like systems are hindered by limitations in the applicability of the well-known models describing the relationship between nutrients and lake phytoplankton biomass in higher ranges of nutrient concentration. Trophic models for naturally eutrophic small, shallow, endorheic lakes have not yet been developed, even though these are the most frequent standing waters in continental lowlands. The aim of this study was to identify variables that can be considered as main drivers of phytoplankton biomass and to build a predictive model. The influence of potential drivers of phytoplankton biomass (nutrients, other chemical variables, land use, lake use and lake depth) from 24 shallow eutrophic lakes was tested using data in the Pannonian ecoregion (Hungary and Romania). By incorporating lake depth, TP, TN and lake use as independent and Chl-a as dependent variables into different models (multiple regression model, GLM and multilayer perception model) predictive models were built. These models explained >50% of the variance. Although phytoplankton biomass in small, shallow, enriched lakes is strongly influenced by stochastic effects, our results suggest that phytoplankton biomass can be predicted by applying a multiple stressor approach, and that the model results can be used for management purposes. © 2013 Springer Science+Business Media Dordrecht.
PubMed | Apathy Istvan Association, University of South Australia, Polish Academy of Sciences, University of Szeged and 5 more.
Type: | Journal: Annals of botany | Year: 2016
Dolines are small- to large-sized bowl-shaped depressions of karst surfaces. They may constitute important microrefugia, as thermal inversion often maintains cooler conditions within them. This study aimed to identify the effects of large- (macroclimate) and small-scale (slope aspect and vegetation type) environmental factors on cool-adapted plants in karst dolines of East-Central Europe. We also evaluated the potential of these dolines to be microrefugia that mitigate the effects of climate change on cool-adapted plants in both forest and grassland ecosystems.We compared surveys of plant species composition that were made between 2007 and 2015 in 21 dolines distributed across four mountain ranges (sites) in Hungary and Romania. We examined the effects of environmental factors on the distribution and number of cool-adapted plants on three scales: (1) regional (all sites); (2) within sites and; (3) within dolines. Generalized linear models and non-parametric tests were used for the analyses.Macroclimate, vegetation type and aspect were all significant predictors of the diversity of cool-adapted plants. More cool-adapted plants were recorded in the coolest site, with only few found in the warmest site. At the warmest site, the distribution of cool-adapted plants was restricted to the deepest parts of dolines. Within sites of intermediate temperature and humidity, the effect of vegetation type and aspect on the diversity of cool-adapted plants was often significant, with more taxa being found in grasslands (versus forests) and on north-facing slopes (versus south-facing slopes).There is large variation in the number and spatial distribution of cool-adapted plants in karst dolines, which is related to large- and small-scale environmental factors. Both macro- and microrefugia are therefore likely to play important roles in facilitating the persistence of cool-adapted plants under global warming.
Popiela A.,University Of Szczecin |
Lysko A.,Pomeranian University |
Molnar A.V.,Debrecen University |
Kacki Z.,Wrocław University |
Lukacs B.A.,Center for Ecological Research
Acta Botanica Gallica | Year: 2015
Elatine triandra Schkuhr is the most variable and widespread species within the genus Elatine L.; it has been recorded in all continents, except Antarctica, but it is mainly located in Europe. The study is based on an extensive data set of European literature, herbaria and web data that covers the period 1828-2012. The range of the species in Europe is disjunctive, covering the southern and western parts of the Central European Plain and the southern part of the Fennoscandian Shield. At a smaller scale, the species can also be found along some river valleys. In Central Europe many localities, particularly isolated ones in the northern part of the range, are now only historical. From the data set we determined that E. Triandra may be best observed between May and October. We found that species records show a near-significant shift since 1828. Depending on the environmental conditions, individuals of the taxon develop as one of two morphs: terrestrial or aquatic. The aquatic morph is characterized by stems, internodes, lamina and petiole that are twice as long as those of the terrestrial form. Elatine triandra seeds show consistent characteristics, both in terms of morphs and populations. Our studies show that the best diagnostic features, in addition to the construction of flowers, are the size, shape and surface structure of seeds. In Central Europe, E. Triandra occurs exclusively in communities classified as Isoëto-Nano-Juncetea. © 2015 Société botanique de France.
Fekete I.,College of Nyíregyháza |
Kotroczo Z.,Corvinus University of Budapest |
Varga C.,College of Nyíregyháza |
Nagy P.T.,Károly Róbert College |
And 4 more authors.
Soil Biology and Biochemistry | Year: 2014
In a Quercetum petraeae-cerris forest in northeastern Hungary, we examined effects of litter input alterations on the quantity and quality soil carbon stocks and soil CO2 emissions. Treatments at the Síkfo kút DIRT (Detritus Input and Removal Treatments) experimental site include adding (by doubling) of either leaf litter (DL) or wood (DW) (including branches, twigs, bark), and removing all aboveground litter (NL), all root inputs by trenching (NR), or removing all litter inputs (NI). Within 4 years we saw a significant decrease in soil carbon (C) concentrations in the upper 15cm for root exclusion plots. Decreases in C for the litter exclusion treatments appeared later, and were smaller than declines in root exclusion plots, highlighting the role of root detritus in the formation of soil organic matter in this forest. By year 8 of the experiment, surface soil C concentrations were lower than Control plots by 32% in NI, 23% in NR and 19% in NL. Increases in soil C in litter addition treatments were less than C losses from litter exclusion treatments, with surface C increasing by 12% in DL and 6% in DW. Detritus additions and removals had significant effects on soil microclimate, with decreases in seasonal variations in soil temperature (between summer and winter) in Double Litter plots but enhanced seasonal variation in detritus exclusion plots. Carbon dioxide (CO2) emissions were most influenced by detritus input quantity and soil organic matter concentration when soils were warm and moist. Clearly changes in detritus inputs from altered forest productivity, as well as altered litter impacts on soil microclimate, must be included in models of soil carbon fluxes and pools with expected future changes in climate. © 2014 Elsevier Ltd.
Biro E.,Pannon University Georgikon Faculty |
Babai D.,Center for the Humanities |
Bodis J.,Pannon University Georgikon Faculty |
Molnar Z.,Center for Ecological Research
Journal for Nature Conservation | Year: 2014
Use of traditional ecological knowledge (TEK) is often recommended to relieve knowledge deficit in conservation. However, studies on traditional knowledge of threatened species are scarce, especially in Europe. Twenty-three interviews about 20 threatened plant species (name, habitat, flowering time, human use, population trends, causes of decline or growth) were conducted in each of the two contrasting landscapes, traditional in Romania (Gyimes), abandoned in Hungary (Zala). Amount of knowledge relevant to conservation was less than expected. Habitat and flowering time was known the best, and causes of population decline and growth the least. Better known plants had richer TEK on their dynamics (65% of species in Gyimes, and 35% in Zala). We documented many cases of positive and negative effects of manuring, fertilization, eradication, grazing, mowing, picking, drought, succession, and abandonment. Most knowledge originated from personal experience, and shared knowledge seemed to be limited. Knowledge deficiency may be explained by the stability of the landscape, and the ignorance of many threatened species by locals in Gyimes (lack of knowledge), and by the abandonment of traditional land use and ignorance in Zala (loss of knowledge). We argue that substantial TEK on threatened species may be expected for those species that have been utilized as a resource or have hindered the utilization of a resource. We argue that TEK can provide relevant information to conservation less at the population, and more at the habitat and landscape level. © 2014.
Valko O.,Mta Of Biodiversity And Ecosystem Services Research Group |
Tothmeresz B.,Debrecen University |
Kelemen A.,Debrecen University |
Simon E.,Debrecen University |
And 3 more authors.
Agriculture, Ecosystems and Environment | Year: 2014
For an effective conservation and management in grasslands it is essential to understand mechanisms sustaining biodiversity. To gain knowledge is especially crucial in stressed grasslands harbouring a unique flora and fauna, like alkali grasslands. Aboveground vegetation, seed bank and environmental factors were studied in three stands of the following alkali grassland types: (i) Artemisia dry alkali grasslands at highest elevations; (ii) Puccinellia high and (iii) Puccinellia low grasslands at medium to low elevations, and (iv) Juncus wet alkali grasslands at the lowest elevations. We tested the following hypotheses: (i) Seed bank species diversity and density are the highest in the most stressed grassland types, where regeneration by seeds could have a major importance in sustaining vegetation diversity. (ii) Seed bank density of hygrophytes increases with decreasing elevation, because the cover of hygrophytes in the vegetation increases with decreasing elevation. The mean seed bank density ranged from 30,104 up to 51,410seeds/m2, which is higher than in most dry grasslands. Both the lowest seed bank density and diversity were detected in the most stressed Puccinellia high grasslands; Spergularia salina was the only abundant seed bank species (possessing at least 1000seeds/m2). These results not supported our first hypothesis. We detected the highest seed densities of almost all hygrophyte species in the lowest-elevated Juncus grasslands. But, we did not find a significant monotonous correlation between elevation and the overall hygrophyte seed bank density; because most of the hygrophyte species were missing from the seed bank at the medium-elevated, but most saline Puccinellia grasslands. Thus, our results only partly supported the second hypothesis. In total we detected more species in the seed bank than in the aboveground vegetation which emphasises that seed bank plays an important role in sustaining the diversity of alkali grasslands. However, characteristic graminoids possessed no considerable seed bank, except for Juncus compressus (up to 38,619seeds/m2). We can conclude that persistence and establishment of most alkali grassland species are not supported by the local persistent seed bank. © 2013 Elsevier B.V.
Engloner A.I.,Center for Ecological Research
Community Ecology | Year: 2015
In aquatic macrophyte ecology, species abundance is usually estimated by cover values expressed on the ordinal scale. Recently, there has been increasing demand for three-dimensional estimates of plant abundance. To extend ordinal cover data into three dimensions, a new formula is proposed which considers the vertical developmental types of plants. In this, a constant k is used with three different values reflecting three groups of macrophytes, namely the "free floating leaved"; "rooted, floating leaved" and "submersed leaved" species. By using the new formula, inappropriate conversion and evaluation of ordinal abundance data occurring frequently in the literature may also be avoided.
Molnar Z.,Center for Ecological Research
Phytocoenologia | Year: 2013
Traditional vegetation knowledge of herders was studied in the Hortobágy steppe. In this paper (1) the habitat types/ vegetation types herders distinguish, (2) the names they use for these folk habitats, (3) the botanical equivalents of folk habitats, and (4) the herders' description of the main vegetation types distinguished by phytosociologists are presented. Ecological anthropological methods such as participant observation, interviews, free listings were used for eliciting herders' knowledge. There were 2239 records of habitat names and features, and 1432 records of the knowledge of habitat requirements of plant species collected from 78 herders. Herders distinguished 47-66 habitat types using 185 names. Many categories were more or less equivalent to the level of plant association, and some described mosaics of habitats. Herders divided the steppe into three large habitat groups: wet habitats (lapos in Hungarian, 16-21 habitat categories), saline habitats (called szík, szíkes, 11-16 categories), and habitats found on chernozem soils (called partos, telek, 8-13 categories). Another 10-14 categories were used by them to name habitats in arable areas and settlements. Herders distinguished and described habitats based on their productivity, salinity, wetness, dominant species, relative elevation on the steppe habitat gradient, surface geomorphology, land-use, density of vegetation, and passabilty. We will argue that traditional herders' knowledge can provide new information for scientists, e.g. on local vegetation dynamics and history. Understanding herders' vegetation knowledge, motivations and constraints in herding could also contribute to the improvement of nature conservation management e.g. by making communication between herders and scientists/conservationists more concrete, and perhaps by providing better targets for conservationists and environmental managers. Traditional vegetation knowledge is a neglected part of European culture, and it is fading quickly. An effective collection and understanding of this deep vegetation knowledge can best and most effectively be accomplished by scientists with experience in botany. © 2013 Gebrüder Borntraeger.
Tinya F.,Center for Ecological Research |
Odor P.,Center for Ecological Research
Forest Ecology and Management | Year: 2016
Light is one of the most important drivers of understory vegetation in forests, influencing the patterns of total cover as well as the abundance of individual species. Based on a multi-scale approach, the relationships between the amount and pattern of relative diffuse light and forest understory were studied in an old-growth, temperate mixed forest (Hungary). The recorded vegetation variables were the cover of the vascular understory (herbs, woody seedlings), the bryophyte layer, and some selected vascular understory species. The pattern of light showed aggregations at two scales: 10 × 10 and 25 × 25 m. Both vascular understory and bryophyte cover had significant positive correlations with light availability, and their spatial pattern was related to it. The pattern of seedlings displayed the strongest relationships with that of light at a coarser scale (25 × 25 m) than herbs and bryophytes (10 × 10 m). At the species level, Festuca heterophylla, Fragaria vesca and Poa nemoralis were characterized as light-demanding herbaceous species (their spatial pattern was congruent with light), Brachypodium sylvaticum and Carex pallescens were transitional, while some species proved to be shade-tolerant (e.g. Ajuga reptans, Dryopteris carthusiana, Viola reichenbachiana). Regarding seedlings, the patterns of Betula pendula, Carpinus betulus, Pinus sylvestris and Quercus petraea were related to the pattern of light. According to our observations, diversity and composition of vascular forest understory and bryophytes were related to heterogeneous light conditions. Forest management should maintain continuous shelter on the stand level; however, smaller gaps are necessary for the survival of light-demanding forest herbs and bryophytes, and larger gaps for tree seedlings. © 2016 Elsevier B.V.