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Reactive oxygen species are produced transiently in response to cell stimuli, and function as second messengers that oxidize target proteins. Protein-tyrosine phosphatases are important reactive oxygen species targets, whose oxidation results in rapid, reversible, catalytic inactivation. Despite increasing evidence for the importance of protein-tyrosine phosphatase oxidation in signal transduction, the cell biological details of reactive oxygen species-catalyzed protein-tyrosine phosphatase inactivation have remained largely unclear, due to our inability to visualize protein-tyrosine phosphatase oxidation in cells. By combining proximity ligation assay with chemical labeling of cysteine residues in the sulfenic acid state, we visualize oxidized Src homology 2 domain-containing protein-tyrosine phosphatase 2 (SHP2). We find that platelet-derived growth factor evokes transient oxidation on or close to RAB5+/ early endosome antigen 1− endosomes. SHP2 oxidation requires NADPH oxidases (NOXs), and oxidized SHP2 co-localizes with platelet-derived growth factor receptor and NOX1/4. Our data demonstrate spatially and temporally limited protein oxidation within cells, and suggest that platelet-derived growth factor-dependent “redoxosomes,” contribute to proper signal transduction.
Bone losses are common as a consequence of unloading and also in patients with chronic obstructive pulmonary disease (COPD). Although hypoxia has been implicated as an important factor to drive bone loss, its interaction with unloading remains unresolved. The objective therefore was to assess whether human bone loss caused by unloading could be aggravated by chronic hypoxia.
In a cross-over designed study, 14 healthy young men underwent 21-day interventions of bed rest in normoxia (NBR), bed rest in hypoxia (HBR), and hypoxic ambulatory confinement (HAmb). Hypoxic conditions were equivalent to 4000 m altitude. Bone metabolism (NTX, P1NP, sclerostin, DKK1) and phospho-calcic homeostasis (calcium and phosphate serum levels and urinary excretion, PTH) were assessed from regular blood samples and 24-hour urine collections, and tibia and femur bone mineral content was assessed by peripheral quantitative computed tomography (pQCT).
Urinary NTX excretion increased (P < 0.001) to a similar extent in NBR and HBR (P = 0.69) and P1NP serum levels decreased (P = 0.0035) with likewise no difference between NBR and HBR (P = 0.88). Serum total calcium was increased during bed rest by 0.059 (day D05, SE 0.05 mM) to 0.091 mM (day D21, P < 0.001), with no additional effect by hypoxia during bed rest (P = 0.199). HAmb led, at least temporally, to increased total serum calcium, to reduced serum phosphate, and to reduced phosphate and calcium excretion.
In conclusion, hypoxia did not aggravate bed rest-induced bone resorption, but led to changes in phospho-calcic homeostasis likely caused by hyperventilation. Whether hyperventilation could have mitigated the effects of hypoxia in this study remains to be established.
This study introduces a simple generic model, the Generic Pest Forecast System (GPFS), for simulating the relative populations of non-indigenous arthropod pests in space and time. The model was designed to calculate the population index or relative population using hourly weather data as influenced by evelopmental rate, high and low temperature mortalities and wet soil moisture mortality. Each module contains biological parameters derived from controlled experiments. The hourly weather data used for the model inputs were obtained from the National Center of Environmental Prediction Climate Forecast System Reanalysis (NCEP-CFSR) at a 38 km spatial resolution. A combination of spatial and site-specific temporal data was used to validate the GPFS models. The oriental fruit fly, Bactrocera dorsalis (Hendel), was selected as a case study for this research because it is climatically driven and a major pest of fruit production. Results from the GPFS model were compared with field B. dorsalis survey data in three locations: 1) Bangalore, India; 2) Hawaii, USA; and 3) Wuhan, China. The GPFS captured the initial outbreaks and major population peaks of B. dorsalis reasonably well, although agreement varied between sites. An index of agreement test indicated that GPFS model simulations matched with field B. dorsalis observation data with a range between 0.50 and 0.94 (1.0 as a perfect match). Of the three locations, Wuhan showed the highest match between the observed and simulated B. dorsalis populations, with indices of agreement of 0.85. The site-specific temporal comparisons implied that the GPFS model is informative for prediction of relative abundance. Spatial results from the GPFS model were also compared with 161 published observations of B. dorsalis distribution, mostly from East Asia. Since parameters for pupal overwintering and survival were unknown from the literature, these were inferred from the distribution data. The study showed that GPFS has promise for estimating suitable areas for B. dorsalis establishment and potentially other non-indigenous pests. It is concluded that calibrating prediction models with both spatial and sitespecific temporal data may provide more robust and reliable results than validations with either data set alone.
Decision tools have been advocated to assist the prioritization of management areas for preventing and mitigating exotic invasions into native ecosystems. Currently, most tools have been created for specific invaders/regions and are thus often not sufficient to address the complex range of invasion scenarios that managers encounter. As exotic invasions continue to be a major issue, science-based, information-driven tools are pressingly needed. In this study, we explore the potential of utilizing the Analytic Hierarchy Process (AHP), one of the information-driven tools, to flexibly prioritize various invasion scenarios by incorporating a broad spectrum of management data. We tested the flexibility of the AHP management tool with two distinct invasion-stage-specific prioritizations for Amur honeysuckle (Lonicera maackii). The AHP tool successfully created two management prioritizations from contrasting invasion scenarios of established Amur honeysuckle invasion versus a hypothetical scenario of newly invading populations. The flexibility of AHP allowed users to alter input based on the stage of invasion in each scenario. In the established scenario, management priority was assigned to removing Amur honeysuckle from the most ecologically significant areas. For the new invasion scenario, priority was shifted to removing the invader from areas of most recent invasions. The two contrasting prioritizations demonstrate the flexibility of AHP as a management tool. We conclude that the flexible AHP tool could be useful for prioritizing management of exotic plant invasions.
Impacts of alien species on human health have recently become a major issue in medical research and invasion ecology, but comprehensive assessments of this subject are largely lacking. Here, we provide a literature review of alien species with public health impacts in Europe based on a systematic search in the Thomson Reuters Web of Science. We detected 77 relevant articles, of which 21 were reviews and 56 were original research articles. The taxonomic focus was on vascular plants (n=31 articles) and dipterans (n=25 articles). The original research articles mainly covered the spread of the study species, while early invasion stages (introduction, establishment) as well as impact and management were less investigated. Alien species of health concern in Europe are mostly introduced as contaminants, and mostly originate from climatically similar regions of the Northern Hemisphere. In those cases (36% of all articles) when information on the trend in range and abundance was provided, this trend was mostly increasing. We detected little information on the severity of the impacts (two articles) and the interaction with climate change (three articles). In 15 original articles (28%) specific management measures were suggested, in only one article the socioeconomic costs were assessed. We conclude that European research on human health impacts of alien species is biased towards few species, and that several important aspects such as early invasion stages, severity of impact and its temporal trends, and the scale of the socioeconomic costs caused are poorly understood. Interdisciplinary projects bridging gaps between ecologists medical researchers, socioeconomists and public health authorities are required to link alien species to severity and trends of impacts, which is a crucial requisite for risk assessment and decision making.
Hemidactylus frenatus is an Asian gecko species that has invaded many tropical regions to become one of the most widespread lizards worldwide. This species has dispersed across the Pacific Ocean to reach Hawaii and subsequently Mexico and other Central American countries. More recently, it has been reported from northwestern South America. Using 12S and cytb mitochondrial DNA sequences I found that South American and Galápagos haplotypes are identical to those from Hawaii and Papua New Guinea, suggesting a common Melanesian origin for both Hawaii and South America. Literature records suggest that H. frenatus arrived in Colombia around the mid-‘90s, dispersed south into Ecuador in less than five years, and arrived in the Galápagos about one decade later.
Ambrosia artemisiifolia is an invasive annual herb infamous for the high allergenicity of its pollen, which is related to increasing medical costs. Additionally, it can cause serious yield losses as agricultural weed. Common ragweed seeds accumulate in the soil and can remain therein viable for decades, which poses a problem for the sustainable management of these populations. A long term management should thus target a reduction of the soil seed bank. We observed the influence of four different mowing regimes on the ragweed soil seed bank at six roadside populations in eastern Austria. The mowing regimes were based on methods from common roadside management practice and specifically adapted to reduce seed production. After three years of application, the soil seed bank was indeed reduced by 45 to 80 percent through three of the four mowing regimes tested. Therefore, we suggest that the best mowing regime for the most effective reduction of the size of the soil seed bank is the one consisting of one cut just after the beginning of female flowering (around the 3rd week of August in Eastern Central Europe), followed by a second cut 2–3 weeks later.
As legislation, research and management of invasive alien species (IAS) are not fully coordinated across countries or different stakeholder groups, one approach leading to more or less standardized activities is based on producing lists of prominent IAS that attain high level of concern and are a subject of priority monitoring and management. These so-called Black, Grey and Watch (alert) Lists represent a convenient starting point for setting priorities in prevention, early warning and management systems. It is important that these lists be based on transparent and robust criteria so as to accommodate interests and perception of impacts by groups of concerned authorities and stakeholders representing sectors as diverse as, e.g. forestry, horticulture, aquaculture, hunting, and nature conservation, and to justify possible trade restrictions. The principles for blacklisting need to be general enough to accommodate differences among taxonomic groups (plants, invertebrates, vertebrates) and invaded environments (e.g. aquatic, terrestrial, urban, suburban, seminatural), and must take into account invasion dynamics, the impact the IAS pose, and management strategies suitable for each particular invader. With these assumptions in mind, we synthesize available information to present Black, Grey and Watch Lists of alien species for the Czech Republic, with recommended categorized management measures for land managers, policy makers and other stakeholders. We took into account differences in the listed species’ distribution, invasion status, known or estimated environmental impact, as well as possible management options, and apply these criteria to both plants and animals. Species with lower impact, but for which some level of management and regulation is desirable, are included on the Grey List. Some potentially dangerous species occurring in European countries with comparable climatic conditions, as well as those introduced in the past but without presently known wild populations in the Czech Republic, are listed on the Watch list. In total, there are 78 plant and 39 animal species on the Black List, 47 and 16 on the Grey List, and 25 and 27, respectively, on the Watch List. The multilayered approach to the classification of alien species, combining their impacts, population status and relevant management, can serve as a model for other countries that are in process of developing their Black Lists.
Distribution and abundance of exotic earthworms within a boreal forest system in southcentral Alaska
(2016)
Little is known about exotic earthworms (Oligochaeta: Lumbricidae) in Alaska outside its southeastern panhandle. This study documents the distribution of exotic earthworms in the relatively undisturbed Kenai National Wildlife Refuge (KNWR), a large, primarily wilderness refuge in southcentral Alaska. We sampled 69 sites near boat launches, along road corridors, and in low human impact areas > 5 km from the road, finding three species of earthworms (Dendrobaena octaedra, Dendrodrilus rubidus, and Lumbricus terrestris). Most road sites (90%) and boat launches (80%) contained earthworms; half (50%) of low human impact sites contained earthworms. Distance to roads was the only significant factor in predicting earthworm occurrence; soil pH, soil moisture, leaf litter depth, and vegetation cover were not. The disparate distributions of these three species suggest that within the KNWR road construction and vehicle traffic played a role in dispersal of the widespread, abundant Dendrobaena octaedra and uncommon Dendrodrilus rubidus; bait abandonment appeared to be the primary method of introduction of Lumbricus terrestris. While the distribution of harmful anecic earthworms in KNWR is currently limited, the prohibition of Lumbricus spp. as bait within conservation units in Alaska may be warranted.
Trichopsis vittata (Cuvier, 1831) is a small, freshwater gourami (Fam: Osphronemidae) native to southeast Asia. It was first detected in Florida in the 1970s and seems to have persisted for decades in a small area. In this study, we documented T. vittata’s ecophysiological tolerances (salinity and low-temperature) and qualitatively compared them to published values for other sympatric non-native species that have successfully invaded much of the Florida peninsula. Trichopsis vittata survived acute salinity shifts to 16 psu and was able to survive up to 20 psu when salinity was raised more slowly (5 psu per week). In a cold-tolerance experiment, temperature was lowered from 24 °C at 1 °C hr-1 until fish died. Mean temperature at death (i.e., lower lethal limit) was 7.2 °C. Trichopsis vittata seems as tolerant or more tolerant than many other sympatric non-native fishes for the variables we examined. However, T. vittata is the only species that has not dispersed since its introduction. Species other than T. vittata have broadly invaded ranges, many of which include the entire lower third of the Florida peninsula. It is possible that tolerance to environmental parameters serves as a filter for establishment, wherein candidate species must possess the ability to survive abiotic extremes as a first step. However, a species’ ability to expand its geographic range may ultimately rely on a secondary set of criteria including biotic interactions and life-history variables.
Established populations of non-natives may collapse without a clear causal mechanism. Hypothetically, fluctuations in habitat structural complexity may influence dynamics of invaders and the biotic resistance offered by predators. Herein I report observations of the collapse of a reproducing population of the nonnative African jewelfish (Hemichromis letourneuxi) in a Florida lake concurrent with an unusual low-water period. I test the hypothesis that predation may have played a key role in the collapse using a combination of field surveys of habitat and fish abundance and predator-prey experiments. Habitat complexity was high before and after the low water period but virtually nonexistent during low water. The abundance of African jewelfish and native juvenile bluegill (Lepomis macrochirus) and eastern mosquitofish (Gambusia holbrooki) declined concurrently with decreasing complexity but the native species rebounded when lake levels increased. Large-bodied natives such as largemouth bass (Micropterus salmoides) and adult bluegill showed no pattern of fluctuation related to habitat complexity. African jewelfish survival was 1.6 times greater at high versus low complexity and over 7 times higher versus no complexity in the presence of largemouth bass. Conversely, eastern mosquitofish, a species that exerts strong effects on small-bodied fishes in structurally complex habitats had no effect on African jewelfish survival. Predation effects on susceptible non-natives should be considered as a potential control action. Population collapse is understudied but may provide insights into long-term dynamics of invaders and information useful for management of problematic species.
We argue that human-mediated invasions are part of the spectrum of species movements, not a unique phenomenon, because species self-dispersing into novel environments are subject to the same barriers of survival, reproduction, dispersal and further range expansion as those assisted by people. Species changing their distributions by human-mediated and non-human mediated modes should be of identical scientific interest to invasion ecology and ecology. Distinctions between human-mediated invasions and natural colonisations are very valid for management and policy, but we argue that these are value-laden distinctions and not necessarily an appropriate division for science, which instead should focus on distinctions based on processes and mechanisms. We propose an all-encompassing framework of species range expansion. This does not detract from the importance of invasion biology as a discipline, but instead will help bring together research being conducted on multiple taxa, and by multiple disciplines, including epidemiology, that are often focused on an identical phenomenon: colonisation.
This study investigated laypersons’ perception of invasive alien plant species (IAPS) and attitudes towards their management with the help of a written questionnaire in the cities of Zurich, Geneva, and Lugano, Switzerland. Survey participants (n = 720) judged attractiveness from certain species on visual contact (eight IAPS were shown as photographs). Trachycarpus fortunei and Ludwigia grandiflora were liked most, while Ambrosia artemisiifolia was clearly disliked most. With the exception of Trachycarpus fortunei, all plant species were perceived as rather ordinary, familiar and native to Switzerland, and feelings of ordinariness, familiarity and nativeness were positively correlated. Few participants could correctly identify the species depicted. Knowledge of an IAPS (ability to identify it) and desire to have it around were negatively correlated. Participants agreed most with the eradication of IAPS that cause serious costs and problems. However, people were rather unwilling to remove Buddleja davidii, Solidago canadensis, and Trachycarpus fortunei which are already widely established ornamentals in settlement areas or gardens. Overall, willingness to remove an IAPS and to report it to the authorities decreased with increasing desirability (and thus beauty) of a species.
Acacia mearnsii De Wilde is on the top 100 of the world’s most invasive alien species and has successfully invaded many areas around the world. However, its distribution and expansion is seldom reported in China. This study for the first time conducted a survey on the new distribution of A. mearnsii at the Kunming Changshui Airport (Yunnan Province, China), through monitoring on population characteristics (number, density, height and ground diameter) and spatial distribution (spread distance). Our survey results show that A. mearnsii has spread rapidly across the airport. This study discusses three factors of environmental factors, human disturbance and weed characteristics behind this successful invasion. The species invasion has a strong potential to change the local vegetation structure, enhances the probability of bird strikes at the airport, and is vulnerable to invade new biogeographic regions if it is not controlled. Currently, eradication combined with mechanical control is considered to be the best option for control. Our study helps improve awareness about the potential risk of A. mearnsii invasion in other airports around China and the world.
Steilhänge der Mittelgebirge weisen eine kleinräumige standörtliche Vielfalt auf und wurden aufgrund ihrer exponierten Lage bereits frühzeitig durch den Menschen u. a. als Befestigungsanlage genutzt. Daraus resultierte häufig eine hohe floristische und vegetationskundliche Diversität mit hohem Naturschutzwert. Durch Umwelt- und Nutzungsveränderungen hat sich aber auch an diesen Standorten in den letzten Jahrzehnten ein starker Wandel vollzogen. Durch Auswertung alter Florenlisten und Vegetationsaufnahmen und durch aktuelle Erhebungen wollen wir die Vegetationszusammensetzung der Lengder Burg, eines Steilhangs auf Unterem Muschelkalk im südlichen Göttinger Wald (Süd-Niedersachsen, Deutschland), und ihre Veränderung aufzeigen und Rückschlüsse für die zukünftige Behandlung ziehen. Dazu wurden Angaben zur Gefäßpflanzenflora aus dem Zeitraum 1950 bis 1995 mit einer aktuellen floristischen Kartierung des Gesamtgebiets von 2016 verglichen. Die Vegetationszusammensetzung wurde anhand von 37 Vegetationsaufnahmen aus dem früheren Zeitraum harakterisiert. 29 dieser Flächen wurden 2009 bis 2016 erneut aufgenommen. Räumliche und zeitliche Unterschiede in der Diversität und Artenzusammensetzung wurden hinsichtlich verschiedener standörtlicher Parameter und ökologischer Artengruppen analysiert.
Die Vegetation lässt sich zwei Gruppen zuordnen: 1. Das Carici-Fagetum und seine Kontaktgesellschaften an südlich und westlich exponierten Steilhängen. 2. Das Hordelymo-Fagetum mit verschiedenen Ausbildungen auf dem Plateau und an flacheren Süd- und Nordhangbereichen. Im Carici-Fagetum ist ein deutlicher Diversitätsverlust und eine Zunahme in der Dominanzstruktur der Krautschicht zu erkennen, der im Vergleich der Aufnahmezeiträume auf eine zunehmende Homogenisierung der Vegetation hinweist. Zurückgegangen sind dabei besonders die typischen Kenn- und Trennarten dieser Waldgesellschaft bei gleichzeitiger Zunahme der Buche in der Verjüngung. Im Hordelymo-Fagetum bewirkt neben Gehölzen in der Strauch- und Krautschicht vor allem die Zunahme von Allium ursinum eine homogenere Artenzusammensetzung, jedoch ohne Diversitätsverlust. Neben Stickstoffeinträgen, dem Klimawandel sowie einem reduzierten Rehwild-Verbiss bedingt besonders der Nutzungswandel diese Veränderungen. Vor allem im Carici-Fagetum wirkte sich der Übergang zwischen früherer Nieder- und Mittelwald-Nutzung mit Waldweide über eine fast 100jährige Hochwald-Nutzung bis zum jetzigen Schutzwald stark aus. Gleichwohl weisen die steilen Hänge weiterhin einen hohen Anteil an Rote-Liste-Arten auf und tragen wesentlich zur hohen Biodiversität des Gebiets bei. Veränderungen in der Vegetation der Lengder Burg spiegeln die Veränderungen im Göttinger Wald insgesamt wider. Kleinflächige Offenhaltungsmaßnahmen zur Erhaltung wertvoller floristischer Elemente sind teilweise erfolgreich. Kleinwüchsige, lichtbedürftige Magerkeitszeiger verschwinden jedoch zunehmend aus den sich entwickelnden, hochwüchsigen Stauden-Säumen. In den benachbarten, unbewirtschafteten Hangbuchenwäldern sorgt die fehlende Nutzung nach Jahrhunderten der Auflichtung und Aushagerung für eine Sukzession in Richtung mesophilen Kalkbuchenwalds.
In Borstgrasrasen (Nardetalia) des Werra-Meißner-Gebietes (Nordhessen, Südniedersachsen) wurden 2012 nach 25 Jahren auf möglichst gleichen Untersuchungsflächen (quasi-Dauerflächen) Wiederholungsaufnahmen angefertigt, um den gegenwärtigen Zustand bzw. Veränderungen in diesem prioritären FFH-Lebensraumtyp zu erfassen. Es wurden insgesamt 61 Flächen untersucht. Neben der Artenzusammensetzung wurden auch Bodenparameter (pH, C/N-Verhältnis, Mächtigkeit der organischen Auflage) und die Nutzung erfasst.
Bei der Wiederholungsaufnahme 2012 waren, abgesehen von einer Aufforstungsfläche, noch auf allen Flächen Arten der Borstgrasrasen vorhanden. Die Flächen wurden 2012 überwiegend genutzt oder gepflegt, während 1986/87 Brachflächen noch bei weitem dominierten. Eine Düngung der Flächen erfolgte nicht. Trotz dieser generell günstigen Nutzungssituation lässt sich ein genereller Trend zur Eutrophierung feststellen, der sich hinsichtlich Artenzahl und Deckung in einer Zunahme von Arten des Wirtschaftsgrünlandes (Molinio-Arrhenatheretea) bei gleichzeitiger Abnahme der Borstgrasrasen-Kennarten äußert. Auch die Artenzahlen der übrigen Magerkeitszeiger nahmen im Mittel ab, während Verbrachungszeiger im Allgemeinen zunahmen. Eine Veränderung der Gesamtartenzahl war nicht festzustellen. Die mittleren Zeigerwerte spiegeln die Verschiebungen im Arteninventar durch erhöhte mittlere Reaktions- und Stickstoffzahlen wider. Strukturell hat in den vergangenen 25 Jahren vor allem eine generelle Zunahme der Moosschichtdeckung und eine Ausbreitung der Sträucher auf Brachflächen stattgefunden. Bei den Bodenparametern waren 2012 eine signifikante Erhöhung der pH-Werte, eine Einengung der C/N-Verhältnisse und eine Abnahme der Mächtigkeit der organischen Auflage (Of) feststellbar. Regressionsmodelle zeigen, dass dabei die Zunahme von Arten des Wirtschaftsgrünlandes direkt mit den ansteigenden pH-Werten zusammen hing, während die Veränderungen bei den Kennarten eher vom Ausgangs-C/N-Verhältnis, teilweise auch von der Entwicklung der organischen Auflage und der Nutzung abhängig waren. Die vorgefundenen Veränderungen werden vor dem Hintergrund möglicher Gefährdungsszenarien (Brache, Eutrophierung, Bodenversauerung, Klimawandel) diskutiert. Angesichts des unerwarteten Befundes einer Eutrophierung bei gleichzeitig nachlassender Bodenversauerung, wird die Hypothese aufgestellt, dass der seit den 1990er-Jahren erfolgte Rückgang der Schwefeldepositionen mit nachfolgender Erholung der Boden-pH-Werte und nachlassender Stressbelastung, z. B. durch Ammonium-Toxizität, die Veränderungen ausgelöst haben könnte. Außerdem deuten die Ergebnisse auf eine zumindest teilweise zu geringe Nutzungs- bzw. Pflegeintensität bzw. zu späte Nutzungstermine. Möglicherweise führt der erhöhte Eutrophierungsdruck hier auch zu verstärkten Anforderungen an das Management der Flächen. Eindeutige Indizien für klimabedingte Veränderungen im Arteninventar ließen sich nicht finden. Indirekte Effekte über eine erwärmungsbedingte Förderung der Mineralisationsraten oder ein ursächlicher Zusammenhang zwischen höheren Wintertemperaturen und der Zunahme der Moosdeckung lassen sich jedoch nicht ausschließen.
Transitional between the Pannonian Basin and the Eastern Carpathians the Transcarpathian Ukraine (Transcarpathia) has a diverse geology including Quaternary sediments, volcanites, limestones and flysch, and its climate at low altitudes is relatively warm and humid. We conducted a field survey in June 2016 focusing on mesophilous forest vegetation along a transect covering almost the whole lowaltitudinal part of Transcarpathia. We recorded 54 relevés in the field and further digitized 22 relevés from literature. Using classification analysis, we distinguished three clusters of oak-hornbeam forests (alliance Carpinion betuli; 1–3) and three clusters of scree and ravine forests (alliance Tilio platyphylli-Acerion; 4–6): (1) Slightly wet Pannonian oak-hornbeam forests occurring in the lowland part of the region (Circaeo-Carpinetum); (2) Mesophilous oak-hornbeam forests (Carici pilosae-Carpinetum); (3) Xero-mesophilous oak-hornbeam forests (a drier subtype of the Carici pilosae-Carpinetum and the association Primulo veris-Carpinetum); (4) Mesophilous scree forests (Phyllitido-Aceretum); (5) Forests of steep slopes (Aceri-Tilietum) and transitions to mesophilous oak-hornbeam forests (Carici pilosae-Carpinetum); (6) Cool and wet scree and ravine forests (Arunco dioici-Aceretum pseudoplatani). Using indirect ordination analysis, three environmental variables (altitude, heat load index and slope) were identified as factors of significant influence on the species composition. These factors well distinguish oak-hornbeam forests from scree and ravine forests.
Understanding plant-plant interactions is essential in planning and implementing effective grassland management strategies. Positive and negative interactions generally co-occur in plant communities and the net effect of these interactions may depend on the disturbance regime, including grazing. Shrubs can act as biotic refuges by physically protecting neighbouring plants from herbivores. As a result, we would expect that in pastures the diversity and flowering success of plants is higher in the close vicinity of shrubs compared to the open vegetation. Nevertheless, we can also assume a competitive trade-off cost for plants that grow together with shrubs. In this study, we assessed the small-scale effects of dwarf shrubs (30–40 cm in diameter) on species density and flowering success. Specifically, we considered three types of microsites: (i) shrub interior, (ii) edge of shrub, and (iii) open pasture (more than 2 meters away from the shrub). We surveyed these three types of microsites using 10 × 10 cm sized plots both in grazed and ungrazed meadow steppe, in central Hungary. The highest species density was found at the edge of shrubs, both in grazed and ungrazed vegetation. Meanwhile, species density did not differ significantly between shrub interiors and the open pasture. However, in grazed vegetation, species flowering success was significantly higher in shrub interiors and edges than in the open pasture; no significant trend was observed for this measure in ungrazed vegetation. In contrast to previous studies, we did not detect a competitive effect of small-sized shrubs on plants in ungrazed vegetation. Our results indicate that small-sized shrubs protect other plants from herbivores and that the edge effect plays an important role for the maintenance of small-scale species diversity in pastures. Overall, our results underline the beneficial effect of biotic refuges in pastures and we suggest that retaining a sparse population of small-sized native shrubs is advantageous from a conservation point of view.
The influence of the Eastern migration route on the Slovak flora – a comparison after 40 years
(2017)
Transport is an important source of introduction and spread of alien plants into new areas and countries. This study provides comprehensive research of selected railway localities in South-Eastern Slovakia to determine the influence of the Eastern Migration Route on the Slovak flora. Railway transshipment yards in Čierna nad Tisou, Dobrá, Velké Kapušany and Matovce were studied from 1964 to 2013; with historic data sampled 1964–1998 and recent data sampled 2012–2013. These data sets were compared to determine differences in species structure following the decreased use of the transshipment yards.
A total of 657 vascular plant taxa were recorded in all localities (566 taxa in the historic and 431 taxa in the recent data set). Native species prevailed over aliens and archaeophytes over neophytes in both time periods. The most frequent aliens were naturalised taxa, where Asiatic and European species prevailed. The most frequent families were Poaceae, Asteraceae and Brassicaceae, and while many species introduced with Russian wheat were recorded only in the past, several taxa are also recorded only recently. Hemicryptophytes were the most abundant life form. Most recorded species were competitors, reproducing by seed and pollinated by insects. Zoochory and hemerochory were the most frequent dispersal types. The proportion of species traits has not changed over time. We identified 49 threatened taxa (38 in the historic and 27 in the recent data set). The Eastern migration route significantly increases the species number of alien vascular plants in the Slovak flora. Although this route had much greater importance in the past, when the role of the Eastern Slovak trans-shipment railway yards was much higher, the studied yards remain an important gateway to Eastern Central Europe and they continue to support agestochory migration of adventive plants.
Wet grasslands once covered a large area in the lowlands of northern Germany, but have declined since several decades as a result of land use intensification. Permanent plot data from such grasslands in the region that would allow to assess the extent of changes in species composition and richness are still rare. Here, we present a re-visitation study of 52 quasi-permanent plots from the Stedinger Land area in the basin of the river Weser near Bremen, comparing quadrat data between 1948 and 2015. In 1948, the grasslands were characterized by species typical of wet, moderately fertile grasslands belonging to the Bromo-Senecionetum aquatici (Bromion racemosi), including 15 species currently classified as threatened. Until 2015, the vegetation had changed strongly: almost all indicators of wet grasslands had either declined or completely vanished, whereas more nutrient-demanding species of less wet soils had increased, especially grasses. The cumulative number of species had declined by 50%, while mean plot species richness had decreased by 64.6%, mainly resulting from the pronounced loss of many herbs. A comparison of mean Ellenberg indicator values suggested that the plots had become drier, but also more base- and nutrient-rich, most likely triggered by the intensification of land use with drainage and fertilization as well as more frequent and earlier cutting. Our study reflects the dramatic loss of plant species diversity in wet grasslands over the past 60−70 years in areas not preserved and properly managed, and it documents the need for protecting remnants of these grasslands and for restoring wet grassland areas by re-wetting, nutrient removal and the transition to a less intensive land use.