Welche Rolle spielt die endozoochore Ausbreitung von Pflanzen durch wildlebende Säugetiere? Untersuchungen in zwei brandenburgischen Waldgebieten

HEINKEN, T.; HANSPACH, H.; SCHAUMANN, F.: How important is endozoochorous seed dispersal by wild mammals in centrat European forests?- Hercynia N.F. 34 (2001): 237-259. In two forest areas in Brandenburg (NE Germany) endozoochorous dispersal of plants by wild herbivorous and omnivorous mammals with a !arge home range was investigated. Feces of roe deer (Capreolus capreolus), fallow deer (Cervus dama), hare (Lepus europaeus) and wild boar (Sus scrofa) were collected throughout a vegetation period. Seeds from the feces collected each month were germinated in a greenhouse. The results were compared with the forest vegetation of both investigated areas. The mean contents of germinable seeds within the feces of herbivorous mammals were 20 to 40 times higher than those of wild boar, which apparently ingest only small amounts of seeds in their diet. Taking the population densities and defecation rates into consideration, it is evident that roe and fallow deer disperse high numbers of seeds, whereas wild boar and hare only carry small amounts. Altogether, 65 plant species were detected endozoochorously, 13 of these (among others Milium effusum, Moehringia trinervia and Ranunculus ficaria) for the first time. Due to their choice of diet, the spectrum of species dispersed by roe deer was smaller than the spectra of the other animals investigated. Though the investigated feces were collected within the forest areas, feces of roe deer contained no characteristic forest species, and only small amounts were detected in those of the other wild mammals. In the mesic forest habitat of the Brieselang, the herbivores dispersed almost exclusively annual species from ruderal vegetation, arable land and trampled areas. In the acidic forest habitat of the Krämer, they dispersed in particular species which occur both in oligotrophic grasslands and forests. In general, almost all diaspores dispersed by the herbivorous mammals were small ( <1mg), as they are less likely to be damaged during the chewing procedure. Wild boar also defecate live seeds of !arger diaspores, among them several cultivated plants. Several of the species dominating the acidic, and most dominating the mesic, forest stand are obviously dispersed endozoochorously either only very seldom or not at all by the investigated mammals. This is probably because their diaspores arenot able to survive the passage through the gut, due to their )arge size as weil as the fact that they are only produced in small numbers. The results confirm the assumption of low dispersal potentials of forest floor species and may be generally applied to centrat European forest habitats. Thus, at least by endozoochory, roe and fallow deer, hare and wild boar play only a small roJe in long-distance dispersal of forest species. Their importance may be greater in the dispersal of plant species of the open landscape.Die Hercynia publiziert Originalbeiträge mit dem Schwerpunkt Ökologie (mit ihren vielseitigen Aspekten der Biodiversität), Botanik, Zoologie, Geologie und Geografie, den anwendungsorientierten Bereichen des Natur- und Umweltschutzes, sowie der Land- und Forstwirtschaft

From coppice to high forest – vegetation change and mesophication in acidic mixed oak forests in the southeastern lowlands of Lower Saxony during 25 years

Die Wiederholung älterer Vegetationsaufnahmen auf gut relokalisierbaren Probeflächen zeigte in mitteleuropäischen Waldökosystemen oft starke Veränderungen der Vegetation als Ergebnis verschiedener Umwelteinwirkungen. Gegenstand dieser Untersuchung sind bodensaure, histo-risch vorwiegend als bäuerliche Niederwälder bewirtschaftete Eichen-Mischwälder des Betulo-Quercetum auf sandigen Partien der Geestplatten südlich des Aller-Urstromtals. Vierzehn eigene, in den Jahren 1990 und 1991 angefertigte Vegetationsaufnahmen in neun Waldgebieten wurden im Jahr 2015 wiederholt. Veränderungen in der Struktur und Bewirtschaftung gaben Anlass, die Nutzungsgeschichte der Bestände seit Ende des 18. Jahrhunderts anhand von historischen Kar-ten und durch Befragung von Lokalhistorikern, Waldbesitzern und Förstern zu dokumentieren. Folgende zwei Hypothesen bilden die Grundlage der Studie: (1) Bestandesschluss nach Aufgabe der historischen Niederwaldnutzung führte zu einem Rückgang lichtliebender Pflanzenarten. (2) Stickstoffdeposition aus der Luft hatte auf den relativ nährstoffarmen, grundwasserfernen Standorten die Zunahme von stickstoffliebenden Pflanzen und mesophilen Waldarten zur Folge. Anhand veränderter Häufigkeiten in den 14 Vegetationsaufnahmen wurden „Gewinner- und Verliererarten“ ermittelt; außerdem wurden Artenzahlen und mittlere Ellenberg-Zeigerwerte der rezenten und historischen Vegetationsaufnahmen verglichen. Im Verlauf von 25 Jahren waren alle Flächen, von denen neun historisch alte Wälder und fünf Aufforstungen oder Vorwälder auf ehemaligen Heide- und Ackerflächen waren, noch Eichen-Mischwälder des Betulo-Quercetum. Fast alle der acht noch 1990/91 niederwaldartigen Bestände hatten diesen Charakter verloren, indem bei Durchforstung nur ein Eichenstamm mehrstämmi-ger Stockausschläge belassen wurde. Insgesamt nahmen Birken als Pioniergehölze ab, und die Strauchschicht wurde u.a. durch die Zunahme der neophytischen Spätblühenden Traubenkirsche dichter. In Übereinstimmung mit Hypothese 1 konnte eine Entwicklung zu schattentoleranterer 120 Vegetation nachgewiesen werden; viele ehemals vorhandene Lichtzeiger – vor allem charakteristische Arten der Birken-Eichenwälder– gingen zurück oder verschwanden. Die mittleren Lichtzahlen der Flächen nahmen ab und die mittleren Feuchtezahlen infolge des ausgeglicheneren Bestandesklimas zu. Auch Hypothese 2 konnte bestätigt werden, denn eine Reihe von Stickstoffzeigern und mesophilen Waldarten nahm zu. Dies brachte eine Zunahme von obligaten Waldarten auf Kosten von auch auf mageren Offenlandstandorten verbreiteten Arten sowie bei den Zeigerwerten eine Erhöhung der mittleren Stickstoffzahlen mit sich. Neben Stickstoffeinträgen dürfte die Regeneration der Standorte durch geringere Biomasseentnahme hierfür eine Rolle spielen. Diese Entwicklungen sind in jüngerer Zeit auch in anderen Regionen Mitteleuropas nachgewiesen worden, doch war der Zeitraum seit der Erstaufnahme dort meist deutlich länger. Die Geschwindigkeit der Veränderungen überrascht daher. Die Ergebnisse unterstreichen, dass die Birken- Eichenwälder der Region nicht der potenziell natürlichen Vegetation entsprechen, sondern kulturgeschichtlich interessante Nutzungsrelikte sind. Eine weitere Bewirtschaftung als Eichenwald und ein beispielhafter Erhalt niederwaldartiger Nutzung ist wünschenswert; eine Erhaltung bzw. Wiederherstellung des früheren Vegetationszustands ist aber angesichts fortwährender Stickstoffeinträge und fehlenden Nährstoffentzugs unrealistisch.Resurveying historical permanent or quasi-permanent vegetation plots in Central European forest ecosystems often revealed strong vegetation changes over the past decades due to different environmental drivers. Subject of this study were acidic mixed oak forests (Betulo-Quercetum) on sandy soils on glacial deposits south of the Aller glacial valley (Lower Saxony, Germany), most of which have been historically used as coppice forests. Fourteen own relevés from the years 1990 and 1991 were resurveyed in 2015. Changes in structure and forest management gave reason to document the land use history of the forest stands since the second half of the 18th century, using historical maps and questioning of local historians, land owners and foresters. The following hypotheses were tested: (1) Canopy closure after abandonment of historical land use led to a decrease of heliophilous plant species. (2) Airborne nitrogen deposition led to an increase of nitrophilous plant species and mesophilous forest species on the relatively nutrientpoor and dry sites. Using frequency and cover changes winner and loser species were identified. Also species numbers as well as mean Ellenberg indicator values for actual and historical relevés were compared. During 25 years all stands, of which nine were ancient forests and five afforestations or pioneer forests on former heathland or farmland, were still mixed oak forests belonging to the Betulo- Quercetum. However, nearly all of the eight stands still recognizable as coppice forest in 1990/91 had lost this character due to conversion to high forest by cutting of side shoots from trunks. Altogether birch as pioneer tree decreased and the shrub canopy became denser, partly due to the spread of the neophyte Prunus serotina. In agreement with existing literature and hypothesis (1) a shift towards more shade-tolerant communities was proved. Light indicators, among them many characteristic plant species of acidic mixed oak forests, decreased or disappeared. This resulted not only in a decrease of mean Ellenberg light values, but also an increase of moisture values of Thilo Heinken: Vom bodensauren Niederwald zum mesophilen Hochwald – Vegetationsveränderungen in Eichenmischwäldern im Flachland südlich der Aller im Verlauf von 25 Jahren 121 the plots due to a more mesic microclimate. Also hypothesis (2) was confirmed, as a number of nitrogen indicators and mesophilous forest species increased, indicating a ‘mesophication’ of the studied forests. This resulted in an increase of strict forest species at the expense of species which also occur on nutrient-poor sites in the open land, and of mean nutrient values of the plots. Besides nitrogen deposition a soil recovery process due to a lower biomass removal may play a role for this effect. All trends have been recently described in other regions of Central Europe, but the time span between the first census and the resurvey was mostly much longer in these studies. The speed of vegetation change is thus surprising. The results emphasize that mixed oak forests do not correspond with the potential natural vegetation, but are interesting relicts of former landuse in cultural heritage terms. In the future a management as oak forest and an exemplary conservation of coppice forest stands is desirable, but a conservation or restoration of the former vegetation state is not realistic, given the continuous nitrogen deposition and missing removal of nutrients

Estudio de las reacciones diagnósticas del embarazo : Variaciones del hierro no hemínico, en el estado de gravidez

Índice - Estudio del método y la determinación de su sensibilidad con distintas concentraciones de sal férrica - Sensibilidad del método para una solución determinada de hierro. - Sensibilidad del método con un suero. - Variaciones fisiológicas del hierro no hemínico en mujeres no embarazadas - Variaciones del hierro en suero de mujeres embarazadas - Estudio cooperativo - Conclusiones - BibliografíaTesis digitalizada en SEDICI gracias a la Biblioteca Central de la Facultad de Ciencias Exactas (UNLP).Facultad de Ciencias Exacta

Gut microbiota functions: metabolism of nutrients and other food components

The diverse microbial community that inhabits the human gut has an extensive metabolic repertoire that is distinct from, but complements the activity of mammalian enzymes in the liver and gut mucosa and includes functions essential for host digestion. As such, the gut microbiota is a key factor in shaping the biochemical profile of the diet and, therefore, its impact on host health and disease. The important role that the gut microbiota appears to play in human metabolism and health has stimulated research into the identification of specific microorganisms involved in different processes, and the elucidation of metabolic pathways, particularly those associated with metabolism of dietary components and some host-generated substances. In the first part of the review, we discuss the main gut microorganisms, particularly bacteria, and microbial pathways associated with the metabolism of dietary carbohydrates (to short chain fatty acids and gases), proteins, plant polyphenols, bile acids, and vitamins. The second part of the review focuses on the methodologies, existing and novel, that can be employed to explore gut microbial pathways of metabolism. These include mathematical models, omics techniques, isolated microbes, and enzyme assays

Estudio de las reacciones diagnósticas del embarazo : Variaciones del hierro no hemínico, en el estado de gravidez

Índice - Estudio del método y la determinación de su sensibilidad con distintas concentraciones de sal férrica - Sensibilidad del método para una solución determinada de hierro. - Sensibilidad del método con un suero. - Variaciones fisiológicas del hierro no hemínico en mujeres no embarazadas - Variaciones del hierro en suero de mujeres embarazadas - Estudio cooperativo - Conclusiones - BibliografíaTesis digitalizada en SEDICI gracias a la Biblioteca Central de la Facultad de Ciencias Exactas (UNLP).Doctor en Bioquímica y FarmaciaUniversidad Nacional de La PlataFacultad de Ciencias Exacta

Microbiome Modelling Toolbox 2.0: efficient, tractable modelling of microbiome communities

Motivation: Constraint-Based Reconstruction and Analysis (COBRA) is a widely used approach for the interrogation and stratification of microbiome samples, yet applications to large-scale cohorts are hampered by limited scalability and efficiency of simulations. Results: We substantially improved the computation speed and scalability of a previous implementation for the construction and interrogation of personalized constraint-based microbiome models as well as implemented additional functionalities for analysis and visualization. Availability and implementation: Microbiome Modelling Toolbox and tutorials are freely available as part of the COBRA Toolbox at https://git.io/microbiomeModelingToolbox

Responses of competitive understorey species to spatial environmental gradients inaccurately explain temporal changes

Understorey plant communities play a key role in the functioning of forest ecosystems. Under favourable environmental conditions, competitive understorey species may develop high abundances and influence important ecosystem processes such as tree regeneration. Thus, understanding and predicting the response of competitive understorey species as a function of changing environmental conditions is important for forest managers. In the absence of sufficient temporal data to quantify actual vegetation changes, space-for-time (SFT) substitution is often used, i.e. studies that use environmental gradients across space to infer vegetation responses to environmental change over time. Here we assess the validity of such SFT approaches and analysed 36 resurvey studies from ancient forests with low levels of recent disturbances across temperate Europe to assess how six competitive understorey plant species respond to gradients of overstorey cover, soil conditions, atmospheric N deposition and climatic conditions over space and time. The combination of historical and contemporary surveys allows (i) to test if observed contemporary patterns across space are consistent at the time of the historical survey, and, crucially, (ii) to assess whether changes in abundance over time given recorded environmental change match expectations from patterns recorded along environmental gradients in space. We found consistent spatial relationships at the two periods: local variation in soil variables and overstorey cover were the best predictors of individual species’ cover while interregional variation in coarse-scale variables, i.e. N deposition and climate, was less important. However, we found that our SFT approach could not accurately explain the large variation in abundance changes over time. We thus recommend to be cautious when using SFT substitution to infer species responses to temporal changes.</p

Fine spatial pattern of an epiphytic lichen species is affected by habitat conditions in two forest types in the Iberian Mediterranean region

Persistence and abundance of species is determined by habitat availability and the ability to disperse and colonize habitats at contrasting spatial scales. Favourable habitat fragments are also heterogeneous in quality, providing differing opportunities for establishment and affecting the population dynamics of a species. Based on these principles, we suggest that the presence and abundance of epiphytes may reflect their dispersal ability, which is primarily determined by the spatial structure of host trees, but also by host quality. To our knowledge there has been no explicit test of the importance of host tree spatial pattern for epiphytes in Mediterranean forests. We hypothesized that performance and host occupancy in a favourable habitat depend on the spatial pattern of host trees, because this pattern affects the dispersal ability of each epiphyte and it also determines the availability of suitable sites for establishment. We tested this hypothesis using new point pattern analysis tools and generalized linear mixed models to investigate the spatial distribution and performance of the epiphytic lichen Lobaria pulmonaria, which inhabits two types of host trees (beeches and Iberian oaks). We tested the effects on L. pulmonaria distribution of tree size, spatial configuration, and host tree identity. We built a model including tree size, stand structure, and several neighbourhood predictors to understand the effect of host tree on L. pulmonaria. We also investigated the relative importance of spatial patterning on the presence and abundance of the species, independently of the host tree configuration. L. pulmonaria distribution was highly dependent on habitat quality for successful establishment, i.e., tree species identity, tree diameter, and several forest stand structure surrogates. For beech trees, tree diameter was the main factor influencing presence and cover of the lichen, although larger lichen-colonized trees were located close to focal trees, i.e., young trees. However, oak diameter was not an important factor, suggesting that bark roughness at all diameters favoured lichen establishment. Our results indicate that L. pulmonaria dispersal is not spatially restricted, but it is dependent on habitat quality. Furthermore, new spatial analysis tools suggested that L. pulmonaria cover exhibits a distinct pattern, although the spatial pattern of tree position and size was random