1,720,958 research outputs found
The influence of forest types including native and non‐native tree species on soil macrofauna depends on site conditions
No full textThe ongoing climate change calls for managing forest ecosystems in temperate regions toward more drought‐resistant and climate‐resilient stands. Yet ecological consequences of management options such as planting non‐native tree species and mixing coniferous and deciduous tree species have been little studied, especially on soil animal communities, key in litter decomposition and pest control. Here, we investigated the taxonomic and trophic structure of soil macrofauna communities in five forest types including native European beech ( Fagus sylvatica ), range‐expanding Norway spruce ( Picea abies ) and non‐native Douglas fir ( Pseudotsuga menziesii ) as well as conifer‐beech mixtures across loamy and sandy sites in northern Germany. Abundance of primary decomposers (feeding predominantly on litter) was high in Douglas fir and beech forests, benefiting from less acidic soil and more favorable litter resources compared to spruce forests, while secondary decomposers (feeding predominantly on microorganisms and microbial residues) reached highest densities in spruce forests. Differences in abundance and species richness among forest types generally varied between regions and were most pronounced in Douglas fir of the sandy region. However, trophic guilds differed more between regions than between forest types, indicating that environmental factors outweigh the importance of forest type on soil macrofauna communities. The analysis of stable isotopes (δ 15 N and δ 13 C values) supported the general robustness in trophic position of macrofauna trophic guilds against variations in forest types and regions, but indicated reduced detrital shifts and food‐chain lengths in coniferous compared to European beech forests with mixtures mitigating these effects. Overall, for evaluating consequences of future forest management practices on the structure and functioning of soil animal communities, regional factors need to be considered, but in particular at loamy sites the taxonomic and trophic structure of soil macrofauna communities are resistant against changes in forest types.Deutsche Forschungsgemeinschaft https://doi.org/10.13039/501100001659Open-Access-Publikationsfonds 202
Reduced predation and energy flux in soil food webs by introduced tree species: Bottom‐up control of multitrophic biodiversity across size compartments
No full textAbstract The introduction of non‐native tree species has become a global concern and may disrupt native communities and related ecosystem functions. Soil food webs regulate organic matter decomposition and nutrient cycling in forests with their feeding activities, but evaluating consequences of the introduction of tree species on soil invertebrates is challenging due to the complex trophic structure and wide range in body size of soil invertebrates. Here, we employed an energetic food web approach and estimated the energy flux in soil food webs using a four‐node model including soil meso‐ and macrofauna decomposers and predators. We examined pure and mixed stands of native European beech ( Fagus sylvatica ), introduced Douglas fir ( Pseudotsuga menziesii ) and native range‐expanding Norway spruce ( Picea abies ) across site conditions. Compared to native forests, introduced tree species reduced total fresh mass of macrofauna predators by 92% at sandy sites but not that of decomposers, suggesting trophic downgrading in soil food webs by Douglas fir. The energy flux in mixed forests was intermediate between respective monocultures, suggesting that tree mixtures mitigate potential negative impacts of introduced tree species on food web functioning. Across size classes, soil macrofauna responded more sensitively to changes in environmental conditions than soil mesofauna. Additionally, total energy flux positively correlated with species richness, pointing to the significance of soil biodiversity for trophic functionality. The energy flux through mesofauna outweighed that through macrofauna when considering energy loss to predators, highlighting the importance of mesofauna for decomposition processes in forest soil food webs. Overall, the study emphasizes the critical role of tree species composition, site conditions and soil biodiversity in driving energy flux through soil food webs and maintaining forest ecosystem functions. Read the free Plain Language Summary for this article on the Journal blog.Zusammenfassung Die Einführung nicht‐einheimischer Baumarten ist ein globales Problem und kann einheimische Gemeinschaften und die damit verbundene Ökosystemfunktionen beeinträchtigen. Bodennahrungsnetze regulieren den Abbau organischer Stoffe und den Nährstoffkreislauf in Wäldern, jedoch sind die Auswirkungen der Einführung von nicht‐einheimischen Baumarten auf Bodeninvertebraten aufgrund der komplexen trophischen Struktur und der großen Bandbreite an Körpergrößen von Bodeninvertebraten wenig untersucht. Wir untersuchten den Energiefluss in Bodennahrungsnetzen mit einem Vier‐Knoten‐Modell, das Bodenmeso‐ und Makrofauna‐Zersetzer sowie Bodenmeso‐ und Makrofauna‐Prädatoren umfasste. Wir analysierten reine und gemischte Bestände der einheimischen europäischen Buche ( Fagus sylvatica ), der eingeführten Douglasie ( Pseudotsuga menziesii ) und der einheimischen Fichte ( Picea abies ) unter verschiedenen Standortbedingungen. Im Vergleich zu einheimischen Wäldern reduzierte die Douglasie die Gesamtmasse der Makrofauna‐Prädatoren auf sandigen Böden um 92%, jedoch nicht die der Zersetzer, was auf ein trophisches “downgrading” der Bodennahrungsnetze hindeutet. Der Energiefluss in Mischwäldern lag zwischen den jeweiligen Monokulturen, was darauf hindeutet, dass Baummischungen potenzielle negative Auswirkungen eingeführter Baumarten auf die Funktionsweise von Nahrungsnetzen abmildern. Über alle Größenklassen hinweg reagierte die Bodenmakrofauna empfindlicher auf Umweltveränderungen als die Bodenmesofauna. Zudem korrelierte der Gesamtenergiefluss positiv mit der Artenvielfalt, was die Bedeutung der Bodenbiodiversität für die trophische Funktionalität unterstreicht. Trotz der geringeren Gesamtmasse überwog der Energiefluss durch die Mesofauna den durch die Makrofauna, wenn der Energieverlust durch Prädation berücksichtigt wurde, was die Bedeutung der Mesofauna für Zersetzungsprozesse in Bodennahrungsnetzen hervorhebt. Insgesamt betont die Studie die entscheidende Rolle der Baumarten‐Zusammensetzung, der Standortbedingungen und der Bodenbiodiversität für den Energiefluss in Bodennahrungsnetzen und die Erhaltung der Waldökosystemfunktionen.Abstract The introduction of non‐native tree species has become a global concern and may disrupt native communities and related ecosystem functions. Soil food webs regulate organic matter decomposition and nutrient cycling in forests with their feeding activities, but evaluating consequences of the introduction of tree species on soil invertebrates is challenging due to the complex trophic structure and wide range in body size of soil invertebrates. Here, we employed an energetic food web approach and estimated the energy flux in soil food webs using a four‐node model including soil meso‐ and macrofauna decomposers and predators. We examined pure and mixed stands of native European beech ( Fagus sylvatica ), introduced Douglas fir ( Pseudotsuga menziesii ) and native range‐expanding Norway spruce ( Picea abies ) across site conditions. Compared to native forests, introduced tree species reduced total fresh mass of macrofauna predators by 92% at sandy sites but not that of decomposers, suggesting trophic downgrading in soil food webs by Douglas fir. The energy flux in mixed forests was intermediate between respective monocultures, suggesting that tree mixtures mitigate potential negative impacts of introduced tree species on food web functioning. Across size classes, soil macrofauna responded more sensitively to changes in environmental conditions than soil mesofauna. Additionally, total energy flux positively correlated with species richness, pointing to the significance of soil biodiversity for trophic functionality. The energy flux through mesofauna outweighed that through macrofauna when considering energy loss to predators, highlighting the importance of mesofauna for decomposition processes in forest soil food webs. Overall, the study emphasizes the critical role of tree species composition, site conditions and soil biodiversity in driving energy flux through soil food webs and maintaining forest ecosystem functions. Read the free Plain Language Summary for this article on the Journal blog.Zusammenfassung Die Einführung nicht‐einheimischer Baumarten ist ein globales Problem und kann einheimische Gemeinschaften und die damit verbundene Ökosystemfunktionen beeinträchtigen. Bodennahrungsnetze regulieren den Abbau organischer Stoffe und den Nährstoffkreislauf in Wäldern, jedoch sind die Auswirkungen der Einführung von nicht‐einheimischen Baumarten auf Bodeninvertebraten aufgrund der komplexen trophischen Struktur und der großen Bandbreite an Körpergrößen von Bodeninvertebraten wenig untersucht. Wir untersuchten den Energiefluss in Bodennahrungsnetzen mit einem Vier‐Knoten‐Modell, das Bodenmeso‐ und Makrofauna‐Zersetzer sowie Bodenmeso‐ und Makrofauna‐Prädatoren umfasste. Wir analysierten reine und gemischte Bestände der einheimischen europäischen Buche ( Fagus sylvatica ), der eingeführten Douglasie ( Pseudotsuga menziesii ) und der einheimischen Fichte ( Picea abies ) unter verschiedenen Standortbedingungen. Im Vergleich zu einheimischen Wäldern reduzierte die Douglasie die Gesamtmasse der Makrofauna‐Prädatoren auf sandigen Böden um 92%, jedoch nicht die der Zersetzer, was auf ein trophisches “downgrading” der Bodennahrungsnetze hindeutet. Der Energiefluss in Mischwäldern lag zwischen den jeweiligen Monokulturen, was darauf hindeutet, dass Baummischungen potenzielle negative Auswirkungen eingeführter Baumarten auf die Funktionsweise von Nahrungsnetzen abmildern. Über alle Größenklassen hinweg reagierte die Bodenmakrofauna empfindlicher auf Umweltveränderungen als die Bodenmesofauna. Zudem korrelierte der Gesamtenergiefluss positiv mit der Artenvielfalt, was die Bedeutung der Bodenbiodiversität für die trophische Funktionalität unterstreicht. Trotz der geringeren Gesamtmasse überwog der Energiefluss durch die Mesofauna den durch die Makrofauna, wenn der Energieverlust durch Prädation berücksichtigt wurde, was die Bedeutung der Mesofauna für Zersetzungsprozesse in Bodennahrungsnetzen hervorhebt. Insgesamt betont die Studie die entscheidende Rolle der Baumarten‐Zusammensetzung, der Standortbedingungen und der Bodenbiodiversität für den Energiefluss in Bodennahrungsnetzen und die Erhaltung der Waldökosystemfunktionen.Deutsche Forschungsgemeinschaft https://doi.org/10.13039/501100001659Open-Access-Publikationsfonds 202
The effect of Douglas-fir on biodiversity in European forests – What do we know and what do we not know?
No full texthttp://dx.doi.org/10.13039/501100010269 Bavarian Ministry of Food Agriculture and Forestr
Mixing for resilience? Evaluating the growth and drought response of beech mixed with Douglas fir or silver fir
No full textContrasting effects of native and non-native conifers on soil microbial communities in mixed European beech - conifer forests
No full texthttp://dx.doi.org/10.13039/501100004543 China Scholarship Councilhttp://dx.doi.org/10.13039/501100010269 Bayerisches Staatsministerium für Ernährung, Landwirtschaft und Forste
Changes in soil mesofauna communities with increasing proportions of Douglas-fir and silver fir in European beech forests
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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