Observer and relocation errors matter in resurveys of historical vegetation plots

Aim: Revisits of non-permanent, relocatable plots first surveyed several decades ago offer a direct way to observe vegetation change and form a unique and increasingly used source of information for global change research. Despite the important insights that can be obtained from resurveying these quasi-permanent vegetation plots, their use is prone to both observer and relocation errors. Studying the combined effects of both error types is important since they will play out together in practice and it is yet unknown to what extent observed vegetation changes are influenced by these errors. Methods: We designed a study that mimicked all steps in a resurvey study and that allowed determination of the magnitude of observer errors only vs the joint observer and relocation errors. Communities of vascular plants growing in the understorey of temperate forests were selected as study system. Ten regions in Europe were covered to explore generality across contexts and 50 observers were involved, which deliberately differed in their experience in making vegetation records. Results: The mean geographic distance between plots in the observer+relocation error data set was 24m. The mean relative difference in species richness in the observer error and the observer+relocation data set was 15% and 21%, respectively. The mean pseudo-turnover between the five records at a quasi-permanent plot location was on average 0.21 and 0.35 for the observer error and observer+relocation error data sets, respectively. More detailed analyses of the compositional variation showed that the nestedness and turnover components were of equal importance in the observer data set, whereas turnover was much more important than nestedness in the observer+relocation data set. Interestingly, the differences between the observer and the observer+relocation data sets largely disappeared when looking at temporal change: both the changes in species richness and species composition over time were very similar in these data sets. Conclusions: Our results demonstrate that observer and relocation errors are non-negligible when resurveying quasi-permanent plots. A careful interpretation of the results of resurvey studies is warranted, especially when changes are assessed based on a low number of plots. We conclude by listing measures that should be taken to maximally increase the precision and the strength of the inferences drawn from vegetation resurveys

Evaluating structural and compositional canopy characteristics to predict the light‐demand signature of the forest understorey in mixed, semi‐natural temperate forests

Questions: Light availability at the forest floor affects many forest ecosystem processes, and is often quantified indirectly through easy‐to‐measure stand characteristics. We investigated how three such characteristics, basal area, canopy cover and canopy closure, were related to each other in structurally complex mixed forests. We also asked how well they can predict the light‐demand signature of the forest understorey (estimated as the mean Ellenberg indicator value for light [“EIVLIGHT”] and the proportion of “forest specialists” [“%FS”] within the plots). Furthermore, we asked whether accounting for the shade‐casting ability of individual canopy species could improve predictions of EIVLIGHT and %FS. Location: A total of 192 study plots from nineteen temperate forest regions across Europe. Methods: In each plot, we measured stand basal area (all stems >7.5 cm diameter), canopy closure (with a densiometer) and visually estimated the percentage cover of all plant species in the herb (7 m). We used linear mixed‐effect models to assess the relationships between basal area, canopy cover and canopy closure. We performed model comparisons, based on R2 and the Akaike Information Criterion (AIC), to assess which stand characteristics can predict EIVLIGHT and %FS best, and to assess whether canopy shade‐casting ability can significantly improve model fit. Results: Canopy closure and cover were weakly related to each other, but showed no relation with basal area. For both EIVLIGHT and %FS, canopy cover was the best predictor. Including the share of high‐shade‐casting species in both the basal‐area and cover models improved the model fit for EIVLIGHT, but not for %FS. Conclusions: The typically expected relationships between basal area, canopy cover and canopy closure were weak or even absent in structurally complex mixed forests. In these forests, easy‐to‐measure structural canopy characteristics were poor predictors of the understorey light‐demand signature, but accounting for compositional characteristics could improve predictions

Global maps of soil temperature

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km2 resolution for 0–5 and 5–15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km2 pixels (summarized from 8519 unique temperature sensors) across all the world\u27s major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (−0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications

<scp>ReSurveyEurope</scp>: A database of resurveyed vegetation plots in Europe

AbstractAimsWe introduce ReSurveyEurope — a new data source of resurveyed vegetation plots in Europe, compiled by a collaborative network of vegetation scientists. We describe the scope of this initiative, provide an overview of currently available data, governance, data contribution rules, and accessibility. In addition, we outline further steps, including potential research questions.ResultsReSurveyEurope includes resurveyed vegetation plots from all habitats. Version 1.0 of ReSurveyEurope contains 283,135 observations (i.e., individual surveys of each plot) from 79,190 plots sampled in 449 independent resurvey projects. Of these, 62,139 (78%) are permanent plots, that is, marked in situ, or located with GPS, which allow for high spatial accuracy in resurvey. The remaining 17,051 (22%) plots are from studies in which plots from the initial survey could not be exactly relocated. Four data sets, which together account for 28,470 (36%) plots, provide only presence/absence information on plant species, while the remaining 50,720 (64%) plots contain abundance information (e.g., percentage cover or cover–abundance classes such as variants of the Braun‐Blanquet scale). The oldest plots were sampled in 1911 in the Swiss Alps, while most plots were sampled between 1950 and 2020.ConclusionsReSurveyEurope is a new resource to address a wide range of research questions on fine‐scale changes in European vegetation. The initiative is devoted to an inclusive and transparent governance and data usage approach, based on slightly adapted rules of the well‐established European Vegetation Archive (EVA). ReSurveyEurope data are ready for use, and proposals for analyses of the data set can be submitted at any time to the coordinators. Still, further data contributions are highly welcome.</jats:sec

Soziologie und Ökologie von Avenula adsurgens subsp. adsurgens in Grasländern der Karpaten

This paper focuses on ecological requirements and phytosociological affinity of Avenula adsurgens subsp. adsurgens. Although this grass is widely distributed in central and south-eastern Europe reaching dominance in certain grassland types, the knowledge on its ecology and coenology is very poor. Moreover, some of the published data on its distribution are wrongly related to Avenula praeusta. We studied the taxon within an area of about 300 km2 (Central Slovakia) where it occurs in diverse habitats. Data from a systematic phytosociological survey were used to assess interspecific associations and ecological indicator values of the taxon. Detailed measurements from a transect along a spruce colonisation gradient were used to evaluate its relationship to a set of topographical, microclimatical, pedological and soil-microbiological characteristics. Tillers of A. adsurgens subsp. adsurgens were cultivated for two growing seasons to estimate characteristics of its clonal morphology and growth and its ability of spatial spreading. In the studied area, the taxon occurred mainly over the volcanic bedrock along a wide range of altitudes. It was concentrated in slightly managed or abandoned montane grasslands (800–1100 m) of the Violion caninae and Nardo strictae-Agrostion tenuis alliances. Phytosociologically the taxon seems not to be an important diagnostic species of these communities, rather an indicator of their successional development. Its highest cover was recorded in early to mid-successional stages without significant proportions of woody species. In stands with traditional management by mowing, grazing or their combination, the taxon was common (albeit with lower percentage cover), but more intensive ma-nagement including amelioration or fencing led to its retreat. Ellenberg ecological indicator values of A. adsurgens subsp. adsurgens were set as follows: light 7, temperature 5, continentality 4, moisture 4, soil reaction 5 and nutrients 3. Along a successional gradient, the taxon cover was positively correlated with percentage cover of herb litter, catalase activity, canopy openness and potassium content and negatively correlated with percentage cover of needles and canopy index reflecting the cumulative effects of spruce colonisation. The horizontal spreading of the taxon was enabled by the formation of spacers with a maximum length of 25.5 cm. We suppose that the ability to spread horizontally by spacers, together with the observed clonal plasticity, tall stature and fast growth by intensive tillering, belong to important attributes of A. adsurgens subsp. adsurgens promoting its success and dominant role in the abandoned grasslands.Diese Arbeit behandelt die ökologischen Ansprüche und die pflanzensoziologische Anbindung von Avenula adsurgens (Schur ex Simonkai) Sauer & Chmelitschek subsp. adsurgens, um ihre Rolle in Graslandgesellschaften sowie ihre erfolgreiche Ausbreitung nach Nutzungsaufgabe zu klären. Obwohl diese Grassippe in Mittel- und Südost-Europa weit verbreitet ist und hier bestimmte Graslandtypen sogar dominiert, ist wenig über ihre Ökologie und Vergesellschaftung bekannt. Zudem beziehen sich einige Publikationen über ihre Verbreitung fälschlicherweise auf Avenula praeusta. Avenula adsurgens subsp. adsurgens ist hoch polyploid (2n = 18x = ±126 Chromosomen). Der ausdau ernde und polykarpe Hemikryptophyt bildet mithilfe von bis zu 30 cm langen extravaginalen Ausläufern lockere Horste. Die Sippe ist subkontinental verbreitet und kommt in Österreich, der Slowakei, Ungarn, Bosnien, Mazedonien, Rumänien, Bulgarien, der Türkei und der Ukraine vor. In der Slowakei gilt die Sippe als potenziell gefährdet (IUCN-Kategorie LR:nt, ut. A. praeusta). Sie wächst in Grasländern der kollinen bis submontanen Stufe und kann dort nach Aufgabe der traditionellen Landnutzung zur Dominanz gelangen. Allgemein wird die Dominanz hochwüchsiger mehrjähriger Gräser in Grasländern der temperaten Zone dem klonalen Wuchs dieser Arten oder besonderen Strategien zur Nähr-stoffnutzung zugeschrieben. So ist zu erwarten, dass die Bildung langer Ausläufer und auch die Plastizität der Ausläuferlänge unabhängig von den Umweltbedingungen Vorteile bedeuten. In dieser Arbeit beschäftigen wir uns mit den folgenden Fragen: 1) Wie ist A. adsurgens subsp. adsurgens vergesell-schaftet? 2) Welche ökologischen Ansprüche hat die Sippe und welches Management fördert ihre Entwicklung? 3) Gibt es einen Zusammenhang zwischen klonalem Wuchs und erfolgreicher Ausbreitung der Sippe im Zuge des Brachfalles von Grasländern

Bukovi gozdovi hribovja Cerová vrchovina (južna Slovaška)

Field phytosociological research of the Fagus sylvatica dominated forests in the volcanic Cerová vrchovina Mts. was carried out in 2001. Standard methods of the Zürich-Montpellier approach were applied. Tabular synthesis with numerical divisive classification (TWINSPAN) and indirect gradient analysis (PCA) were used to differentiate particular communities. Within the Fagion alliance, four associations were recognized: Carici pilosae-Fagetum, Dentario bulbiferae-Fagetum, Melico-Fagetum and Asperulo-Fagetum. Four different plant communities of the Tilio-Acerion alliance were detected: Roso pendulinae-Tilietum cordatae, Mercurialis perennis-Fagus sylvatica community, Athyrium filix-femina-Fagus sylvatica community and Dryopteris filix-mas-Fagus sylvatica community. Semioligotrophic communities were classified as Luzulo-Fagetum within the Luzulo-Fagion alliance. Influences of several ecological factors on species composition are discussed. The type of relief, stoniness and humus content of topsoil seem to play the most important role.Leta 2001 smo izvedli terenske fitosociološke raziskave sestojev, na gori vulkanskega izvora Cerová vrchovina v katerih dominira vrsta Fagus sylvatica. Uporabili smo standardno srednjeevropsko fitocenološko metodo. Za ločevanje posameznih združb smo naredili tabelarično sintezo s pomočjo numerične ločitvene klasifikacije (TWINSPAN) in indirektne gradientne analize (PCA). Znotraj zveze Fagion smo ločili štiri asociacije: Carici pilosae-Fagetum, Dentario bulbiferae-Fagetum, Melico-Fagetum in Asperulo-Fagetum. V zvezo Tilio-Acerion smo uvrstili štiri rastlinske sintaksone: Roso pendulinae-Tilietum cordatae, združba Mercurialis perennis-Fagus sylvatica, združba Athyrium filix-femina-Fagus sylvatica in združba Dryopteris filix-mas-Fagus sylvatica. Delno oligotrofne združbe smo uvrstili v asociacijo Luzulo-Fagetum in zvezo Luzulo-Fagion. Obravnavali smo vpliv številnih ekoloških faktorjev na vrstno sestavo. Relief, kamnitost in vsebnost humusa so med najpomembnejšim

Inaccessibility determines primary forests distribution in the Western Carpathians, but their future is not guaranteed

Currently, most forest landscapes are intensively managed and primary forests around the world are disappearing rapidly with strong negative impacts on biodiversity. However, national inventories of primary forests and consistent methodology to conduct these assessments are absent, which results in further loss of these unique ecosystems. We developed a comprehensive methodological approach to identify primary forests, and we conducted a complete national inventory within the territory of Slovak Republic (49,036 km2). We analyzed the primary forest distribution pattern and studied whether the last primary forests represented all types of potential forest vegetation. We also evaluated the area of primary forests destroyed and endangered by logging in the last decade. We identified 10.282 ha of primary forest remnants, which represent 0.47% of the total forested area and only 0.2% of the entire landscape. The distribution of primary forests was clustered. Primary forests were preserved in relatively higher elevations, steeper slopes, and undulating terrains (contrast relative relief). They were located in greater distances from roads and settlements compared to other forest habitats. Primary forests did not represent all types of the potential natural vegetation. Several habitat types are completely missing (e.g., flood plain forests). Despite the small total area of these valuable primary ecosystems, more than 30% of them are directly endangered by logging. Between 2009 and 2017, logging occurred on 27 localities, and 144.53 ha of primary forests was destroyed, mainly by the salvage logging. Primary forests are exposed to an increased pressure of rapidly developing forest management technology and forest product demands. Road construction increases accessibility in mountain areas that have been largely protected due to their inaccessibility for centuries. Protected areas, such as national parks or NATURA 2000 sites, do not ensure conservation of primary forests, and alarmingly 90% of logging in primary forests was conducted in national parks. Our extensive study highlights the ineffectiveness of protected areas in Europe and the importance of national primary forest inventories; we recommend the inclusion of European primary forest conservation strategies to stop the rapid loss of the last primary forests and their unique biodiversity.peerReviewe