Wissen im Netz. Botanik und Pflanzentransfer in europäischen Korrespondenznetzen des 18. Jahrhunderts

Europäische Korrespondenznetze, die Kommunikation über weite Räume und Grenzen hinweg ermöglichten, sind das Thema der Beiträge des Bandes. Nicht nur Meinungs- und Nachrichtenaustausch vollzog sich über das Medium des Briefes, auch Realien – Antiquitäten, Handelswaren, Bücher und Naturalien – wurden in diesen Transfer einbezogen und hatten in Korrespondenznetzen der Frühen Neuzeit eine hohe Bedeutung. Gerade dieser Realientransfer spielte für das in diesem Band gewählte Korrespondenzbeispiel "Botanik und Pflanzentransfer" mit der Versendung von Pflanzen und Pflanzensamen eine zentrale Rolle. Briefliche Kommunikation als Medium sozialer Verflechtung lässt sich in ihrer Bedeutung für Genese, Transfer und Ordnung von Wissen am Beispiel botanischer Ordnungssysteme ebenso nachvollziehen wie an der brieflichen Verbreitung und Nutzbarmachung des Wissens über neu entdeckte Pflanzen in Medizin und Landwirtschaft. Durch die Diskussion und Anwendung moderner netzwerkanalytischer Verfahren präsentiert der Band in interdisziplinärer Kooperation zugleich neue Wege einer systematisch-vergleichenden Erforschung der Struktur und Dynamik von Korrespondenznetzen.

Interacting effects of fertilization, mowing and grazing on plant species diversity of 1500 grasslands in Germany differ between regions

The relationship of different types of grassland use with plant species richness and composition (functional groups of herbs, legumes, and grasses) has so far been studied at small regional scales or comprising only few components of land use. We comprehensively studied the relationship between abandonment, fertilization, mowing intensity, and grazing by different livestock types on plant diversity and composition of 1514 grassland sites in three regions in North-East, Central and South-West Germany. We further considered environmental site conditions including soil type and topographical situation. Fertilized grasslands showed clearly reduced plant species diversity (−15% plant species richness, −0.1 Shannon diversity on fertilized grasslands plots of 16 m2) and changed composition (−3% proportion of herb species), grazing had the second largest effects and mowing the smallest ones. Among the grazed sites, the ones grazed by sheep had higher than average species richness (+27%), and the cattle grazed ones lower (−42%). Further, these general results were strongly modulated by interactions between the different components of land use and by regional context: land-use effects differed largely in size and sometimes even in direction between regions. This highlights the importance of comparing different regions and to involve a large number of plots when studying relationships between land use and plant diversity. Overall, our results show that great caution is necessary when extrapolating results and management recommendations to other regions.

High plant species richness indicates management-related disturbances rather than the conservation status of forests

There is a wealth of smaller-scale studies on the effects of forest management on plant diversity. However, studies comparing plant species diversity in forests with different management types and intensity, extending over different regions and forest stages, and including detailed information on site conditions are missing. We studied vascular plants on 1500 20 m × 20 m forest plots in three regions of Germany (Schwäbische Alb, Hainich-Dün, Schorfheide-Chorin). In all regions, our study plots comprised different management types (unmanaged, selection cutting, deciduous and coniferous age-class forests, which resulted from clear cutting or shelterwood logging), various stand ages, site conditions, and levels of management-related disturbances. We analyzed how overall richness and richness of different plant functional groups (trees, shrubs, herbs, herbaceous species typically growing in forests and herbaceous light-demanding species) responded to the different management types. On average, plant species richness was 13% higher in age-class than in unmanaged forests, and did not differ between deciduous age-class and selection forests. In age-class forests of the Schwäbische Alb and Hainich-Dün, coniferous stands had higher species richness than deciduous stands. Among age-class forests, older stands with large quantities of standing biomass were slightly poorer in shrub and light-demanding herb species than younger stands. Among deciduous forests, the richness of herbaceous forest species was generally lower in unmanaged than in managed forests, and it was even 20% lower in unmanaged than in selection forests in Hainich-Dün. Overall, these findings show that disturbances by management generally increase plant species richness. This suggests that total plant species richness is not suited as an indicator for the conservation status of forests, but rather indicates disturbances.

Landwirtschaft

Das Parlament begann im Herbst mit den Beratungen über die Agrarpolitik 2014-2017. – Das Referendum gegen das revidierte Tierseuchengesetz scheiterte an der Urne. – Die Turbulenzen um den kürzlich liberalisierten Milchmarkt beschäftigten die Branchenvertreter und das Parlament. – Sowohl das revidierte Tierschutzgesetz als auch das Bundesgesetz über den Verkehr mit Tieren und Pflanzen geschützter Arten wurden vom Parlament angenommen. – Eine Volksinitiative zum Schutz von Grossraubtieren wie Luchs, Bär und Wolf wurde bei der Staatskanzlei eingereicht.

Early responses of wild plant seedlings to arbuscular mycorrhizal fungi and pathogens

Abstract Many plants form associations with arbuscular mycorrhizal fungi (AMF) because they profit from improved phosphorus nutrition and from protection against pathogens. Whereas mycorrhiza-induced pathogen protection is well understood in agricultural plant species, it is rarely studied in wild plants. As many pathogens infest plants in the first days after germination, mycorrhiza-induced pathogen protection may be especially important in the first few weeks of plant establishment. Here, we investigated interacting effects of {AMF} and the seedling pathogen Pythium ultimum on the performance of six- to seven-week-old seedlings of six wild plant species of the family Asteraceae in a full factorial experiment. Plant species differed in their response to AMF, the pathogen and their interactions. {AMF} increased and the pathogen decreased plant biomass in one and three species, respectively. Two plant species were negatively affected by {AMF} in the absence, but positively or not affected in the presence of the pathogen, indicating protection by AMF. This mycorrhiza-induced pathogen protection is especially surprising as we could not detect mycorrhizal structure in the roots of any of the plants. Our results show that even seedlings without established intraradical hyphal network can profit from AMF, both in terms of growth promotion in the absence of a pathogen and pathogen protection. The function of {AMF} is highly species-specific, but tends to be similar for more closely related plant species, suggesting a phylogenetic component of mycorrhizal function. Further studies should test a wider range of plant species, as our study was restricted to one plant family, and investigate whether plants profit from early mycorrhizal benefits in the long term.

Giftiges Insektenvolk und faule, flüchtige Winde: Überlegungen zur Bildlichkeit für den politischen Radikalismus bei Jeremias Gotthelf

Jeremias Gotthelf, Anhänger eines christlichen Republikanismus, polemisierte öffentlich heftig gegen die Vertreter des politischen Radikalismus. Der Aufsatz versucht, die von ihm verwendeten Bilder (Pflanzen-, Aggregatsmetaphorik, chemische Prozesse) für den Radikalismus zu kontextualisieren. Zu diesem Zweck werden Gotthelfs Roman "Jacobs, des Handwerksgesellen, Wanderungen durch die Schweiz" (1846/47) und seine Erzählung "Doktor Dorbach, der Wühler und die Bürglenherren in der heiligen Weihnachtsnacht Anno 1847" (1849) untersucht; z.T. wird auch auf publizistische und Kalendertexte der 1840er-Jahre zurückgegriffen. Die Untersuchung legt die vielfältigen Bezügen zwischen Gotthelf und zeitgenössischen Debatten in einer viel bewegten Zeit offen.

Aluminum toxicity in a tropical montane forest ecosystem in southern Ecuador

Aluminum phytotoxicity frequently occurs in acid soils (pH < 5.5) and was therefore discussed to affect ecosystem functioning of tropical montane forests. The susceptibility to Al toxicity depends on the sensitivity of the plant species and the Al speciation in soil solution, which can vary highly depending e.g., on pH, ionic strength, and dissolved organic matter. An acidification of the ecosystem and periodic base metal deposition from Saharan dust may control plant available Al concentrations in the soil solutions of tropical montane rainforests in south Ecuador. The overall objective of my study was to assess a potential Al phytotoxicity in the tropical montane forests in south Ecuador. For this purpose, I exposed three native Al non-accumulating tree species (Cedrela odorata L., Heliocarpus americanus L., and Tabebuia chrysantha (Jacq.) G. Nicholson) to increased Al concentrations (0 – 2400 μM Al) in a hydroponic experiment, I established dose-response curves to estimate the sensitivity of the tree species to increased Al concentrations, and I investigated the mechanisms behind the observed effects induced by elevated Al concentrations. Furthermore, the response of Al concentrations and the speciation in soil solution to Ca amendment in the study area were determined. In a final step, I assessed all major Al fluxes, drivers of Al concentrations in ecosystem solutions, and indicators of Al toxicity in the tropical montane rainforest in Ecuador in order to test for indications of Al toxicity. In the hydroponic experiment, a 10 % reduction in aboveground biomass production occurred at 126 to 376 μM Al (EC10 values), probably attributable to decreased Mg concentrations in leaves and reduced potosynthesis. At 300 μM Al, increased root biomass production of T. chrysantha was observed. Phosphorus concentrations in roots of C. odorata and T. chrysantha were significantly highest in the treatment with 300 μM Al and correlated significantly with root biomass, being a likely reason for stimulated root biomass production. The degree of organic complexation of Al in the organic layer leachate, which is central to plant nutrition because of the high root density, and soil solution from the study area was very high (mean > 99 %). The resulting low free Al concentrations are not likely to affect plant growth, although the concentrations of potentially toxic Al3+ increased with soil depth due to higher total Al and lower dissolved organic matter concentrations in soil solutions. The Ca additions caused an increase of Al in the organic layer leachate, probably because Al3+ was exchanged against the added Ca2+ ions while pH remained constant. The free ion molar ratios of Ca2+:Al3+ (mean ratio ca. 400) were far above the threshold (≤ 1) for Al toxicity, because of a much higher degree of organo-complexation of Al than Ca. High Al fluxes in litterfall (8.8 – 14.2 kg ha−1 yr−1) indicate a high Al circulation through the ecosystem. The Al concentrations in the organic layer leachate were driven by the acidification of the ecosystem and increased significantly between 1999 and 2008. However, the Ca:Al molar ratios in organic layer leachate and all aboveground ecosystem solutions were above the threshold for Al toxicity. Except for two Al accumulating and one non-accumulating tree species, the Ca:Al molar ratios in tree leaves from the study area were above the Al toxicity threshold of 12.5. I conclude that toxic effects in the hydroponic experiment occurred at Al concentrations far above those in native organic layer leachate, shoot biomass production was likely inhibited by reduced Mg uptake, impairing photosynthesis, and the stimulation of root growth at low Al concentrations can be possibly attributed to improved P uptake. Dissolved organic matter in soil solutions detoxifies Al in acidic tropical forest soils and a wide distribution of Al accumulating tree species and high Al fluxes in the ecosystem do not necessarily imply a general Al phytotoxicity.