Wurzelverlauf von Buchen (Fagus sylvatica) unter Rückegassen

Das Befahren von Waldböden im Zuge der mechanisierten Holzernte führt häufig zu deutlich erkennbaren Fahrspuren. Damit einher gehen Verdichtung und Belüftungsstörung des Bodens mit einer Reduktion der Feinwurzeldichte. Es stellt sich die Frage, ob eine Fahrspur im Wald als ein für Pflanzen toter Raum angesehen werden muss und ob es Bäumen möglich ist, den Raum zwischen den beiden Fahrspuren zu nutzen Um dies herauszufinden, wurde der Wurzelverlauf mehrerer am Rand einer Rückegasse stehender Bäume (Fagus sylvatica) in einem Waldgebiet auf Löß geprägter Braunerde untersucht. Die Wurzelanläufe der Bäume dienten bei der Wurzelfreilegung als Anfangspunkt. Mit diversen Kleinwerkzeugen wurde der Wurzelraum unter der Rückegasse vom Stammfuß bis zur Wurzelspitze einer jeden Wurzel freigelegt. Mit Hilfe eines Schnurgerüstes wurden die Tiefen der Wurzeln, deren Lage sowie deren Zustand und Anzahl, Dicke und Verzweigung vermessen und dokumentiert. In den Rückegassen gab es lebende Grobwurzeln, aber auch deutliche Verdichtungsanzeichen (Rostflecken, Bleichzonen). Der Einfluss der Fahrspuren ist deutlich zu erkennen. Viele Wurzeln verkümmerten in den Spuren, andere verweigerten den Wuchs in sie hinein und wählten einen Weg parallel zur Fahrspur. Wieder andere wuchsen unter der Spur hindurch, kamen im Mittelstreifen empor und drangen bei der zweiten Spur wieder tiefer in den Boden. Auffällig war ebenfalls die hohe Anzahl an Wurzeln, die nicht in den verdichteten Boden gingen, sondern in der neu gebildeten Humus-/ Laubschicht wuchsen. Somit lässt sich festhalten, dass eine Rückegasse, bzw. eine Fahrspur, kein toter Raum für Baumwurzeln ist, aber eine durchaus starke Behinderung darstellt. Die Bäume nutzen Möglichkeiten, der Verdichtung auszuweichen (Humusschicht, Parallelwuchs) oder sind kräftig genug sie zu überwinden und den Mittelstreifen als Lebensraum zu erobern

Auswirkungen von Bodenperforation und Kalkung auf Bodeneigenschaften von Rückegassen in einem Buchenbestand des Sollings

Einhergehend mit der Befahrung des Waldes durch tonnenschwere Forstmaschinen, kann es auf Rückegassen zu erheblichen Schäden am Waldboden in Form von Strukturveränderungen kommen. Die resultierende Bodenverformung und -verdichtung bewirkt Veränderungen von Bodeneigenschaften, u.a. des Porensystems, welche sich in einer Uniformierung der Poren bei gleichzeitigem Rückgang des Porenvolumens sowie der Porenkontinuität äußern (1). Infolge der Strukturveränderungen ist es insbesondere der modifizierte Gashaushalt, der sich auf vielfältige Prozesse auswirkt und die Lebensraumfunktion des Waldbodens verringert (2). Von erheblicher Bedeutung ist die Frage nach der natürlichen Regenerationsfähigkeit verdichteter Waldböden unter Rückegassen. Seitens des RÜWOLA-Projektes wird in einem Feldversuch auf einem Lösslehmstandort im Solling (Braunerde) geprüft, ob mit dem Verfahren der Bodenperforation und der Kombination weiterer Maßnahmen wie Kalkung, eine Technik zur Verfügung steht, die es ermöglicht, regenerative Prozesse im Boden zu initiieren bzw. zu beschleunigen. Drei Jahre nach Anlage von Lochstanzungen wurden Schürfgruben quer zu den Fahrspuren gegraben, die Stanzlöcher freigelegt und mittels verschiedener Methoden die Auswirkungen auf Bodeneigenschaften geprüft. Unter Verwendung der KA 5 (3) erfolgte ein direkter Vergleich zwischen Fahrspur und Mittelstreifen sowie eine detaillierte Untersuchung der Stanzlöcher mit Hilfe eines Zählrahmens (u.a. Durchwurzelung). Des Weiteren fanden Infiltrationsversuche, Bestimmung mikrobieller Biomasse (CFE-Methode), saurer Phosphataseaktivität und physikalischer Kenngrößen (z.B. TRD, GPV) statt. Die Ergebnisse verdeutlichen, dass Unterschiede zwischen Fahrspur und Mittelstreifen insbesondere bzgl. Eigenschaften der Bodenstruktur und der Durchwurzelung gegeben sind. Kontraste bestehen ebenfalls im Vergleich der Stanzlöcher und dem umgebenden, ungestanzten Bodenareal. Die Summe der betrachteten Parameter weist auf eine mögliche Wirkung der Maßnahmenkombination „Lochstanzung + Kalkung“ hin. Bodenperforation scheint auch zu erhöhter Verdunstung und Drainage beizutragen, wohingegen die Ergebnisse der Stechzylinderproben eher als indifferent zu beurteilen sind

Time Pressure Modulates Electrophysiological Correlates of Early Visual Processing

BACKGROUND: Reactions to sensory events sometimes require quick responses whereas at other times they require a high degree of accuracy-usually resulting in slower responses. It is important to understand whether visual processing under different response speed requirements employs different neural mechanisms. METHODOLOGY/PRINCIPAL FINDINGS: We asked participants to classify visual patterns with different levels of detail as real-world or non-sense objects. In one condition, participants were to respond immediately, whereas in the other they responded after a delay of 1 second. As expected, participants performed more accurately in delayed response trials. This effect was pronounced for stimuli with a high level of detail. These behavioral effects were accompanied by modulations of stimulus related EEG gamma oscillations which are an electrophysiological correlate of early visual processing. In trials requiring speeded responses, early stimulus-locked oscillations discriminated real-world and non-sense objects irrespective of the level of detail. For stimuli with a higher level of detail, oscillatory power in a later time window discriminated real-world and non-sense objects irrespective of response speed requirements. CONCLUSIONS/SIGNIFICANCE: Thus, it seems plausible to assume that different response speed requirements trigger different dynamics of processing

Temporal scale‐dependence of plant–pollinator networks

The study of mutualistic interaction networks has led to valuable insights into ecological and evolutionary processes. However, our understanding of network structure may depend upon the temporal scale at which we sample and analyze network data. To date, we lack a comprehensive assessment of the temporal scale-dependence of network structure across a wide range of temporal scales and geographic locations. If network structure is temporally scale-dependent, networks constructed over different temporal scales may provide very different perspectives on the structure and composition of species interactions. Furthermore, it remains unclear how various factors – including species richness, species turnover, link rewiring and sampling effort – act in concert to shape network structure across different temporal scales. To address these issues, we used a large database of temporally-resolved plant–pollinator networks to investigate how temporal aggregation from the scale of one day to multiple years influences network structure. In addition, we used structural equation modeling to explore the direct and indirect effects of temporal scale, species richness, species turnover, link rewiring and sampling effort on network structural properties. We find that plant–pollinator network structure is strongly temporally-scale dependent. This general pattern arises because the temporal scale determines the degree to which temporal dynamics (i.e. phenological turnover of species and links) are included in the network, in addition to how much sampling effort is put into constructing the network. Ultimately, the temporal scale-dependence of our plant–pollinator networks appears to be mostly driven by species richness, which increases with sampling effort, and species turnover, which increases with temporal extent. In other words, after accounting for variation in species richness, network structure is increasingly shaped by its underlying temporal dynamics. Our results suggest that considering multiple temporal scales may be necessary to fully appreciate the causes and consequences of interaction network structure.Fil: Schwarz, Benjamin. Albert Ludwigs University of Freiburg; AlemaniaFil: Vazquez, Diego P.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; ArgentinaFil: Cara Donna, Paul J.. Chicago Botanic Garden; Estados UnidosFil: Knight, Tiffany M.. German Centre for Integrative Biodiversity Research; AlemaniaFil: Benadi, Gita. Albert Ludwigs University of Freiburg; AlemaniaFil: Dormann, Carsten F.. Albert Ludwigs University of Freiburg; AlemaniaFil: Gauzens, Benoit. German Centre for Integrative Biodiversity Research; AlemaniaFil: Motivans, Elena. German Centre for Integrative Biodiversity Research; AlemaniaFil: Resasco, Julian. University of Colorado; Estados UnidosFil: Blüthgen, Nico. Universitat Technische Darmstadt; AlemaniaFil: Burkle, Laura A.. Montana State University; AlemaniaFil: Fang, Qiang. Henan University of Science and Technology; ChinaFil: Kaiser Bunbury, Christopher N.. University of Exeter; Reino UnidoFil: Alarcón, Ruben. California State University; Estados UnidosFil: Bain, Justin A.. Chicago Botanic Garden; Estados UnidosFil: Chacoff, Natacha Paola. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; ArgentinaFil: Huang, Shuang Quan. Central China Normal University; ChinaFil: LeBuhn, Gretchen. San Francisco State University; Estados UnidosFil: MacLeod, Molly. Rutgers University; Estados UnidosFil: Petanidou, Theodora. Univversity of the Aegean; Estados UnidosFil: Rasmussen, Claus. University Aarhus; DinamarcaFil: Simanonok, Michael P.. Montana State University; Estados UnidosFil: Thompson, Amibeth H.. German Centre for Integrative Biodiversity Research; AlemaniaFil: Fründ, Jochen. Albert Ludwigs University of Freiburg; Alemani

Psychophysics with children: Investigating the effects of attentional lapses on threshold estimates

When assessing the perceptual abilities of children, researchers tend to use psychophysical techniques designed for use with adults. However, children’s poorer attentiveness might bias the threshold estimates obtained by these methods. Here, we obtained speed discrimination threshold estimates in 6- to 7-year-old children in UK Key Stage 1 (KS1), 7- to 9-year-old children in Key Stage 2 (KS2), and adults using three psychophysical procedures: QUEST, a 1-up 2-down Levitt staircase, and Method of Constant Stimuli (MCS). We estimated inattentiveness using responses to “easy” catch trials. As expected, children had higher threshold estimates and made more errors on catch trials than adults. Lower threshold estimates were obtained from psychometric functions fit to the data in the QUEST condition than the MCS and Levitt staircases, and the threshold estimates obtained when fitting a psychometric function to the QUEST data were also lower than when using the QUEST mode. This suggests that threshold estimates cannot be compared directly across methods. Differences between the procedures did not vary significantly with age group. Simulations indicated that inattentiveness biased threshold estimates particularly when threshold estimates were computed as the QUEST mode or the average of staircase reversals. In contrast, thresholds estimated by post-hoc psychometric function fitting were less biased by attentional lapses. Our results suggest that some psychophysical methods are more robust to attentiveness, which has important implications for assessing the perception of children and clinical groups

Relative Stability of Core Groups in Pollination Networks in a Biodiversity Hotspot over Four Years

Plants and their pollinators form pollination networks integral to the evolution and persistence of species in communities. Previous studies suggest that pollination network structure remains nested while network composition is highly dynamic. However, little is known about temporal variation in the structure and function of plant-pollinator networks, especially in species-rich communities where the strength of pollinator competition is predicted to be high. Here we quantify temporal variation of pollination networks over four consecutive years in an alpine meadow in the Hengduan Mountains biodiversity hotspot in China. We found that ranked positions and idiosyncratic temperatures of both plants and pollinators were more conservative between consecutive years than in non-consecutive years. Although network compositions exhibited high turnover, generalized core groups – decomposed by a k-core algorithm – were much more stable than peripheral groups. Given the high rate of turnover observed, we suggest that identical plants and pollinators that persist for at least two successive years sustain pollination services at the community level. Our data do not support theoretical predictions of a high proportion of specialized links within species-rich communities. Plants were relatively specialized, exhibiting less variability in pollinator composition at pollinator functional group level than at the species level. Both specialized and generalized plants experienced narrow variation in functional pollinator groups. The dynamic nature of pollination networks in the alpine meadow demonstrates the potential for networks to mitigate the effects of fluctuations in species composition in a high biodiversity area

The 3-Hydroxy-2-Butanone Pathway Is Required for Pectobacterium carotovorum Pathogenesis

Pectobacterium species are necrotrophic bacterial pathogens that cause soft rot diseases in potatoes and several other crops worldwide. Gene expression data identified Pectobacterium carotovorum subsp. carotovorum budB, which encodes the α-acetolactate synthase enzyme in the 2,3-butanediol pathway, as more highly expressed in potato tubers than potato stems. This pathway is of interest because volatiles produced by the 2,3-butanediol pathway have been shown to act as plant growth promoting molecules, insect attractants, and, in other bacterial species, affect virulence and fitness. Disruption of the 2,3-butanediol pathway reduced virulence of P. c. subsp. carotovorum WPP14 on potato tubers and impaired alkalinization of growth medium and potato tubers under anaerobic conditions. Alkalinization of the milieu via this pathway may aid in plant cell maceration since Pectobacterium pectate lyases are most active at alkaline pH

Forest biodiversity, ecosystem functioning and the provision of ecosystem services

Forests are critical habitats for biodiversity and they are also essential for the provision of a wide range of ecosystem services that are important to human well-being. There is increasing evidence that biodiversity contributes to forest ecosystem functioning and the provision of ecosystem services. Here we provide a review of forest ecosystem services including biomass production, habitat provisioning services, pollination, seed dispersal, resistance to wind storms, fire regulation and mitigation, pest regulation of native and invading insects, carbon sequestration, and cultural ecosystem services, in relation to forest type, structure and diversity. We also consider relationships between forest biodiversity and multifunctionality, and trade-offs among ecosystem services. We compare the concepts of ecosystem processes, functions and services to clarify their definitions. Our review of published studies indicates a lack of empirical studies that establish quantitative and causal relationships between forest biodiversity and many important ecosystem services. The literature is highly skewed; studies on provisioning of nutrition and energy, and on cultural services, delivered by mixed-species forests are under-represented. Planted forests offer ample opportunity for optimising their composition and diversity because replanting after harvesting is a recurring process. Planting mixed-species forests should be given more consideration as they are likely to provide a wider range of ecosystem services within the forest and for adjacent land uses. This review also serves as the introduction to this special issue of Biodiversity and Conservation on various aspects of forest biodiversity and ecosystem services

Mutation analysis of 18 nephronophthisis associated ciliopathy disease genes using a DNA pooling and next generation sequencing strategy

Background Nephronophthisis associated ciliopathies (NPHP-AC) comprise a group of autosomal recessive cystic kidney diseases that includes nephronophthisis (NPHP), Senior-Loken syndrome (SLS), Joubert syndrome (JBTS), and Meckel-Gruber syndrome (MKS). To date, causative mutations in NPHP-AC have been described for 18 different genes, rendering mutation analysis tedious and expensive. To overcome the broad genetic locus heterogeneity, a strategy of DNA pooling with consecutive massively parallel resequencing (MPR) was devised.Methods In 120 patients with severe NPHP-AC phenotypes, five pools of genomic DNA with 24 patients each were prepared which were used as templates in order to PCR amplify all 376 exons of 18 NPHP-AC genes (NPHP1, INVS, NPHP3, NPHP4, IQCB1, CEP290, GLIS2, RPGRIP1L, NEK8, TMEM67, INPP5E, TMEM216, AHI1, ARL13B, CC2D2A, TTC21B, MKS1, and XPNPEP3). PCR products were then subjected to MPR on an Illumina Genome-Analyser and mutations were subsequently assigned to their respective mutation carrier via CEL I endonuclease based heteroduplex screening and confirmed by Sanger sequencing.Results For proof of principle, DNA from patients with known mutations was used and detection of 22 out of 24 different alleles (92% sensitivity) was demonstrated. MPR led to the molecular diagnosis in 30/120 patients (25%) and 54 pathogenic mutations (27 novel) were identified in seven different NPHP-AC genes. Additionally, in 24 patients only single heterozygous variants of unknown significance were found.Conclusions The combined approach of DNA pooling followed by MPR strongly facilitates mutation analysis in broadly heterogeneous single gene disorders. The lack of mutations in 75% of patients in this cohort indicates further extensive heterogeneity in NPHP-AC