Florian Jansen

Do limiting factors at Alaskan treelines shift with climatic regimes

Trees at Alaskan treelines are assumed to be limited by temperature and to expand upslope and/or to higher latitudes with global warming. However, recent studies describe negative temperature responses and drought stress of Alaskan treeline trees in recent decades. In this study, we have analyzed the responses of treeline white spruce to temperature and precipitation according to different climatic regimes in Alaska, described as negative (cool) and positive (warm) phases of the Pacific Decadal Oscillation (PDO). We found that in three consecutive phases (positive from 1925?46, negative from 1947?76, and positive again from 1977?98), the growth responses to temperature and precipitation differed markedly. Before 1947, in a phase of warm winters and with summer temperatures being close to the century mean, the trees at most sites responded positively to summer temperature, as one would expect from treeline trees at northern high latitudes. Between 1947 and 1976, a phase of cold winters and average summers, the trees showed similar responses, but a new pattern of negative responses to the summer temperature of the year prior to growth coupled with positive responses to the precipitation in the same year emerged at some sites. As the precipitation was relatively low at those sites, we assume that drought stress might have played a role. However, the climate responses were not uniform but were modified by regional gradients (trees at northern sites responded more often to temperature than trees at southern sites) and local site conditions (forest trees responded more often to precipitation than treeline trees), possibly reflecting differences in energy and water balance across regions and sites, respectively. However, since the shift in the PDO in 1976 from a negative to a positive phase, the trees? climate?growth responses are much less pronounced and climate seems to have lost its importance as a limiting factor for the growth of treeline white spruce. If predictions of continued warming and precipitation increase at northern high latitudes hold true, the growth of Alaskan treeline trees will likely depend on the ratio of temperature and precipitation increase more than on their absolute values, as well as on the interaction of periodic regime shifts with the global warming trend. Once a climatic limitation is lifted, other factors, such as insect outbreaks or interspecific competition, might become limiting to tree growth.

Ecological preferences of alien plant species in North-Eastern Germany

The large, comprehensive vegetation database of Mecklenburg-Vorpommern/NE Germany with 51,328 relevés allowed us to study an entire regional flora of 133 non-native plants (NNP, immigration after 1492 AD) with regard to their preferences to all kinds of habitats and along different ecological gradients. For each relevé, we computed average Ellenberg indicator values (EIV) for temperature, light, moisture, reaction, nutrients and salt as well as plant strategy type weights. We partitioned the dataset into relevés with and without occurrences of NNP and compared them with respect to the relative frequencies of EIVs and strategy type weights. We identified deviations from random differences by testing against permuted indicator values. To account for bias in EIV between community types, NNP preferences were differentiated for 34 phytosociological classes. We tested significance of preferences for the group of NNP as a whole, as well as for single NNP species within the entire dataset, as well as differentiated by phytosociological classes and formations. NNP as a group prefer communities with high EIVs for temperature and nutrients and low EIVs for moisture. They avoid communities with low EIV for reaction and high EIV for salt. NNP prefer communities with high proportions of ruderal and low proportion of stress strategists. The differentiation by phytosociological classes reinforces the general trends for temperature, nutrients, moisture, R and S strategy types. Nevertheless, preferences of single species reveal that NNP are not a congruent group but show individualistic ecological preferences.

Formalized classification of European fen vegetation at the alliance level

Phytosociological classification of fen vegetation (Scheuchzerio palustris-Caricetea fuscae class) differs among European countries. Here we propose a unified vegetation classification of European fens at the alliance level, provide unequivocal assignment rules for individual vegetation plots, identify diagnostic species of fen alliances, and map their distribution. 29 049 vegetation-plot records of fenswere selected fromdatabases using a list of specialist fen species. Formal definitions of alliances were created using the presence, absence and abundance of Cocktail-based species groups and indicator species. DCA visualized the similarities among the alliances in an ordination space. The ISOPAM classification algorithm was applied to regional subsets with homogeneous plot size to check whether the classification based on formal definitions matches the results of unsupervised classifications. The following alliances were defined: Caricion viridulo-trinervis (sub-halophytic Atlantic dune-slack fens), Caricion davallianae (temperate calcareous fens), Caricion atrofusco-saxatilis (arcto-alpine calcareous fens), Stygio-Caricion limosae (boreal topogenic brown-moss fens), Sphagno warnstorfii-Tomentypnion nitentis (Sphagnumbrown-moss rich fens), Saxifrago-Tomentypnion (continental to boreo-continental nitrogen-limited brown-moss rich fens), Narthecion scardici (alpine fens with Balkan endemics), Caricion stantis (arctic brown-moss rich fens), Anagallido tenellae-Juncion bulbosi (Ibero-Atlantic moderately rich fens), Drepanocladion exannulati (arcto-borealalpine non-calcareous fens), Caricion fuscae (temperate moderately rich fens), Sphagno-Caricion canescentis (poor fens) and Scheuchzerion palustris (dystrophic hollows). The main variation in the species composition of European fens reflected site chemistry (pH, mineral richness) and sorted the plots from calcareous and extremely rich fens, through rich andmoderately rich fens, to poor fens and dystrophic hollows.

Changes in landscape naturalness derived from a historical land register : a case study from NE Germany

The naturalness of landscapes and its assessment is a major issue in landscape management and nature conservation (Ridder 2007a; Verhoog et al. 2007). Additionally, natural sites serve as a reference for ecosystem restoration and landscape planning (Siipi 2004; SER 2004; van Andel and Aronson 2006; Zerbe et al. 2009). However, it is often not clearly specified what naturalness is or could be (Ridder 2007b) with regard to time scale and human impact. Definitions and methods of assessment have been introduced and discussed by various authors (see for example Peterken 1996; Machado 2004; Kowarik 2006; Timmermann et al. 2006a; Ridder 2007b; Walentowski and Winter 2007; Reif and Walentowski 2008). The definition of a starting point (‘‘natural state‘‘) with which ecosystems or landscapes in a given condition are to be compared turns out to be a crucial point. In most of these studies vegetation is identified as a measure for naturalness, as vegetation reflects anthropogenically changed abiotic and biotic site conditions and can be used as an indicator for landscape properties (Ellenberg 1996). It also offers important criteria for nature conservation assessments (Mueller-Dombois and Ellenberg 1974; Maarel 2005). In the past decades, numerous methods have been applied to describe and reconstruct historical landscapes (see e.g. surveys by Egan and Howell 2001). One of the most important sources for historical landscape ecology are historical maps with which ancient landscapes can be reconstructed. In Central Europe, detailed mapping reaches back for about several hundred years (Küchler and Zonneveld 1988). Although there exist a great number of investigations and elaborate methodology with regard to the analysis of land-use and land-cover change in Central Europe (e.g. Bastian and Bernhardt 1993; Hobbs 1994; Ihse 1996; Skĺnes 1996; Pärtel et al. 1999; Zerbe and Brande 2003; Coppin et al. 2004; Zerbe 2004; Bender et al. 2005; Wanja et al. 2007), a detailed reconstruction of abiotic site conditions in historical landscapes such as, e.g., soil water and nutrient conditions has hardly been achieved. A particular situation for historical landscape reconstruction is given in NE Germany with the Swedish Register Maps which have been drawn around 1700 AD on a scale of about 1:8,300. These historical maps, including comprehensive annotations in textbooks, offer detailed information about settlements, land use, inhabitants, and the property state of land as well as vegetation, abiotic site conditions, and yield. Thus, our study aims to provide a reconstruction of the landscape 300 years ago and its abiotic site conditions, in order to assess the naturalness of F. Jansen (&) S. Zerbe M. Succow Institute of Botany and Landscape Ecology, Ernst-Moritz-Arndt-University, Grimmer Str. 88, 17487 Greifswald, Germany e-mail: jansen@uni-greifswald.de

Ecological Indicator Values of Europe (EIVE) 1.0: a powerful open-access tool for vegetation scientists

Background: Ecological indicator values (EIVs) have a long tradition in vegetation ecological research in Europe. EIVs characterise the ecological optimum of species along major environmental gradients using ordinal scales. Calculating mean indicator values per plot is an effective way of bioindication. Following first systems in Russia and Central Europe, about two dozen EIV systems have been published for various parts of Europe. Aims: As there was no EIV system available at European scale that could be used for broad- scale analyses, e.g. in the context of the European Vegetation Archive (EVA), we develop such a system for the first time for the vascular plants of Europe. Location: Europe. Methods: We compiled all national and major regional EIV systems and harmonized their plant nomenclature with a newly developed contemporary European taxonomic backbone (EuroSL 1.0). Using regression, we rescaled the individual EIV systems for the main parameters to continent-wide quasi-metric scales, ranging from 1 to 99. The data from each individual system were then translated into a probability curve approximated with a normal distribution, weighed with the logarithm of the area represented and summed up across the systems. From the European density curve we extracted then a mean and a variance, which characterise the distribution of this species along this particular ecological gradient. Results and conclusions: Our consensus approach of integrating the expert knowledge of all existing EIV systems allowed deriving the first consistent description of the ecological behaviour for a significant part of the European vascular flora. The resulting Ecological Indicator Values of Europe (EIVE) 1.0 will be published open access to allow bioindication beyond country borders. Future releases of EIVE might contain more parameters, non- vascular plants and regionalisation or could be re-adjusted and extended to hitherto non- covered species through co-occurrence data from EVA.

Naturräumlich-ökologische Analyse der Flechtenflora von Deutschland

Zusammenfassung: Schiefelbein, U., Jansen, F., Litterski, B. & Wirth, V. 2015. Naturräumlich-ökologische Analyse der Flechtenflora von Deutschland. — Herzogia 28: 624–653. Die Flechtenflora von Deutschland wird auf der Grundlage der Angaben von Wirth et al. (2013; Die Flechten Deutschlands) analysiert, wobei Naturräume die geografische Basis für die Analysen bilden. Bewertet werden Artendiversität, Exklusivität des Arteninventars, substratspezifische Eigenschaften (Substratbindung, pH-Werte und Nährstoffgehalt/Eutrophierung der besiedelten Substrate) und klimatische Faktoren (Licht, Luftfeuchte). Die artenreichsten Naturräume sind nach den Bayerischen Alpen, dem Schwarzwald und Odenwald-Spessart die ebenfalls sehr niederschlagsreichen Naturräume Eifel, Weserbergland, Harz, Fränkische Alb, Sauerland und Bayerisch-Böhmischer Wald. Die artenärmsten Landschaften liegen überwiegend im südlichen Teil des Nordostdeutschen Tieflandes. Die Exklusivität des Arteninventars eines Naturraumes wird als Anzahl der Arten, die in Deutschland nach 1950 nur in einem bis zwei Naturräumen nachgewiesen wurden, definiert. In der gesamten Bundesrepublik sind es 638 Arten, davon kommen die meisten in den Bayerischen Alpen, im Schwarzwald, Bayerischen Wald, Odenwald-Spessart und in der Schwäbischen Alb vor. Im gesamten Deutschland überwiegen die Gesteinsbewohner (47,6% des Gesamtarteninventars), gefolgt von Rinden- (31,5%) und Erdbodenbewohnern (15,1%). Die Landschaften mit dem größten Anteil an Silikatbewohnern sind Fichtelgebirge, Schwarzwald, Rhön, Erzgebirge und Bayerischer Wald. Die höchsten Anteile an Kalkflechten kommen im Thüringer Becken, im Fränkischen Jura, in der Schwäbischen Alb, im Neckarland und im Main-Tauber-Gebiet vor. Erdboden bewohnende Flechten saurer Standorte sind am stärksten in den pleistozänen Landschaften und Erdboden bewohnende Flechten basischer Standorte in den kalkreichen, aber waldarmen Landschaften (nördliches Harzvorland, Mitteldeutsches Schwarzerdegebiet, Thüringisches Becken, Oberpfälzer Hügelland) vertreten. Die artenreichsten Landschaften beherbergen auch die meisten hygrophytischen Flechten. Die kalk- bzw. basenreichen Landschaften mit einem sehr geringen Waldanteil an der Gesamtfläche (nördliches Harzvorland, Mitteldeutsches Schwarzerdegebiet und Thüringisches Becken) fallen dagegen durch den großen Anteil an xerophytischen Flechten auf. Die Naturräume lassen sich anhand der Flechtenfloren zu mehreren Gruppen zusammenfassen (z. B. Naturräume, in denen saures und basisches Gestein gleichermaßen anstehen; Naturräume, in denen die sauren Substrate überwiegen; Kalklandschaften; Pleistozäne Landschaften nördlich der Alpen; Pleistozäne Landschaften in Norddeutschland).

Phytocoenologia : the leading journal with a focus on vegetation classification

This annual Editorial of 2017 summarizes the developments of the journal Phytocoenologia in the two years following its re-launch in 2015. Both the Editorial Team and the topics and regions of publications are very diverse. Starting with 2015, Impact Factors and CiteScores profoundly improved compared to the previous years, which, together with some other measures, has rendered Phytocoenologia an increasingly attractive publication venue. Narrowing the scope of Phytocoenologia explicitly down to “vegetation survey and classification” was arguably one of the cornerstones of recent success. The bibliometric analyses have also allowed us to demonstrate that both in absolute numbers and with regard to the proportion of such papers, Phytocoenologia can now be considered the leading journal in the field of vegetation classification worldwide. The citation network of Phytocoenologia includes a wide array of journals, although many remain to be covered in the Web of Science, to the bibliometric disadvantage of Phytocoenologia. We shortly present the four Editors’ Choice articles of 2016 and a selection of some other outstanding contributions of that volume. The Editors’ Award 2016 goes to Rui B. Elias and colleagues for their combination of vegetation classification and distribution modelling to derive a map of the natural vegetation of the Azores. In conclusion, the Editors aim to provide a service to vegetation ecologists worldwide by maintaining and further improving the qualities of Phytocoenologia.