4,809 research outputs found
Können Käfer Klimawald? Herausforderungen und Chancen für Artenvielfalt im Wald der Zukunft
No full textTree species richness, tree identity and non-native tree proportion affect arboreal spider diversity, abundance and biomass
No full textBiodiversität contra Corona – Was hat der Erhalt von Arten und ihren Lebensräumen mit der Covid-19 Pandemie zu tun?
No full textNon-native Douglas fir promotes epigeal spider density, but has a mixed effect on functional diversity
No full textAbstract With climate change altering ecosystems worldwide, forest management in Europe is increasingly relying on more adaptable non-native tree species, such as Douglas fir ( Pseudotsuga menziesii ). However, the ecological consequences of the increased utilization of Douglas fir on arthropod diversity and ecosystem functioning are not fully known. Here we assessed how non-native Douglas fir as well as large- and small-scale differences in the environmental context, affect epigeal spider abundance, biomass, taxonomic and functional diversity, and community structure in Central European forests. Our study sites were divided into two regions with large differences in environmental conditions, with seven replicates of five stand types, including monocultures of native European beech ( Fagus sylvatica ), non-native Douglas fir and native Norway spruce ( Picea abies ), as well as two-species mixtures of European beech and each of the conifers. Contrary to our expectations, Douglas fir promoted small-scale spider diversity, and abundance and biomass (activity density). On the other hand, it decreased spider functional divergence and altered spider community structure. Microhabitat characteristics had opposing effects on spider diversity and activity density, with more open stands harboring a more diverse but less abundant spider community. Overall, our findings suggest that increasing Douglas fir utilization at the expense of Norway spruce does not necessarily decrease the diversity of epigeal arthropods and may even promote local spider diversity and activity density. However, care needs to be taken in terms of biodiversity conservation because typical forest spider species and their functional divergence were more strongly associated with native beech than with coniferous stands.Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659Georg-August-Universität Göttingen http://dx.doi.org/10.13039/50110000338
Tree Species Richness Strengthens Relationships between Ants and the Functional Composition of Spider Assemblages in a Highly Diverse Forest
No full textNon-native tree species (Pseudotsuga menziesii) strongly decreases predator biomass and abundance in mixed-species plantations of a tree diversity experiment
No full textCommunities of ground-living spiders in deciduous forests: Does tree species diversity matter?
Full text linkSchuldt A, Fahrenholz N, Brauns M, Migge-Kleian S, Platner C, Schaefer M. Communities of ground-living spiders in deciduous forests: Does tree species diversity matter? BIODIVERSITY AND CONSERVATION. 2008;17(5):1267-1284.The relationships between species diversity and ecosystem functions are in the focus of recent ecological research. However, until now the influence of species diversity on ecosystem processes such as decomposition or mineral cycling is not well understood. In deciduous forests, spiders are an integral part of the forest floor food web. In the present study, patterns of spider diversity and community structure are related to diversity of deciduous forest stands in the Hainich National Park (Thuringia). In 2005, pitfall trapping and quantitative forest floor sampling were conducted in nine plots of forest stands with one (Diversity Level 1), three (DL 2) and five (DL 3) major deciduous tree species. Species richness, measured with both methods, as well as spider abundance in forest floor samples were highest in stands with medium diversity (DL 2) and lowest in pure beech stands (DL 1). The Shannon-Wiener index and spider numbers in pitfall traps decreased from DL 1 to DL 3, while the Shannon-Wiener index in forest floor samples increased in the opposite direction. Spider community composition differed more strongly between single plots than between diversity levels. Altogether, no general relationship between increasing tree species diversity and patterns of diversity and abundance in spider communities was found. It appears that there is a strong influence of single tree species dominating a forest stand and modifying structural habitat characteristics such as litter depth and herb cover which are important for ground-living spiders
Scale-dependent diversity patterns. affect spider assemblages of two contrasting forest ecosystems
No full textSpiders are important generalist predators in forests. However, differences in assemblage structure and diversity can have consequences for their functional impact. Such differences are particularly evident across latitudes, and their analysis can help to generate a better understanding of region-specific characteristics of predator assemblages. Here, we analyse the relationships between species richness, family richness and functional diversity (FD) as well as alpha- and beta-components of epigeic spider diversity in semi-natural temperate and subtropical forest sites. As expected, within-plot and overall spider species and family richness were higher in the subtropical plots. In contrast, local FD within plots was similar between sites, and differences in FD only became evident at larger spatial scales due to higher species turnover in the subtropical forests. Our study indicates that the functional effects of predator assemblages can change across spatial scales. We discuss how differences in richness and functional diversity between contrasting forest ecosystems can depend on environmental heterogeneity and the effects of species filters acting at local scales. The high turnover observed in the species-rich subtropical forests also requires a more regional perspective for the conservation of the overall diversity and the ecological functions of predators than in less diverse forests, as strategies need to account for the large spatial heterogeneity among plots. (C) 2013 Elsevier Masson SAS. All rights reserved
Spatio-temporal patterns and potential trade-offs in the promotion of aphid and seed predation in agroforestry systems
Full text linkAbstract Agricultural intensification and simplification compromise biodiversity and can destabilize populations of important ecosystem service providers. By promoting invertebrate and vertebrate predators that deliver important ecosystem services such as pest and weed control, agroforestry systems may reconcile ecological benefits and agriculture productivity, making them a promising land-use system for the transition towards sustainable agriculture. However, the spatio-temporal regulation of ecosystem services and potential disservices provided by predators in agroforestry systems remains poorly studied. We compared aphid, weed seed, and crop seed predation in the crop rows between temperate alley cropping systems and open croplands without trees. In addition, we analyzed the extent to which effects of tree rows extended into the crop rows at two different time periods in spring. Aphid predation was higher at sampling locations close to the tree rows. Seed predation was spatially more variable but showed, similar to aphid predation, particularly low rates in open croplands. The distance-dependence of aphid and crop seed predation changed in magnitude across sampling periods, while weed seed predation was more temporally constant. Moreover, crop seeds were consumed nearly twice as much as weed seeds, indicating varying food preferences among invertebrate and vertebrate seed predators and a potential trade-off between ecosystem services and disservices. Our results suggest that alley cropping agroforestry benefits pest and weed control. However, differences in spatio-temporal patterns of aphid and seed predation indicate varying dependencies of different predator groups on the tree rows, while high crop seed predation suggests a concurrent promotion of a disservice. Our study emphasizes that understanding the spatial and temporal patterns of predation-related ecosystem services and disservices is needed to develop management practices promoting natural pest control and reducing the amount of plant protection products used in agriculture. Therefore, knowing how and when to support beneficial organisms and at the same time control pests is key for the development of sustainable agricultural systems.German Federal Ministry of Education and ResearchGeorg-August-Universität Göttingen http://dx.doi.org/10.13039/50110000338
A distributed archival network for process-oriented autonomic long-term digital preservation
Full text linkThe rapidly growing production of digital data, together with their increasing importance and essential demands for their longevity, urgently require systems that provide reliable long-term preservation of digital objects.
These systems have to ensure guaranteed availability, integrity, authenticity, and interpretability over the course of the preservation, where the preservation period may last for several years, for instance in business or scientific applications, the lifetime of a human in medical applications, up to potentially unlimited time-spans for preservation in cultural heritage digital libraries. This means that all kinds of technical problems (network, software or hardware failures) need to be reliably handled and that the evolution of data formats is supported. At the same time, systems need to scale with the volume of data to be archived. Thus, long-term digital preservation systems have to be inherently distributed to allow content to be replicated. Institutions with long-term archiving needs for the preservation of digital data, have to collaborate in order to build a highly reliable and available, geographically distributed Internet-based digital archiving system. By employing distributed systems technologies be it for the creation of a small cooperating network of few institutions with limited resources, or a large network with many nodes providing combined potentially vast amounts of globally distributed resources, the challenges lie in the autonomic, efficient, and fault-tolerant use of these resources without a centralized global coordinator.
We present novel concepts for a distributed long-term preservation system for digital data, with a focus on long-term preservation as required by archives, museums, research communities, or the corporate sector. These concepts are the result of combining distributed, autonomic, and process oriented computing, with requirements from the digital preservation community regarding special system, user, and metadata functionality. Originating from this fusion, our novel concepts are the main ingredients of the described system model, consisting of a data model, and different processes. At the data level, support is provided for complex data objects, management of collections, annotations, and arbitrary links between digital objects. At process level, our proposed archiving system model supports automated processes that provide dynamic replication, consistency checks, and automated recovery of the archived digital objects utilizing autonomic behavior governed by preservation policies without any centralized coordinator in a fully distributed network. This allows for an efficient and fault-tolerant use of the resources provided in the network.
Further, we present a prototype implementation of the DISTARNET (DISTributed ARchival NETwork) System, a distributed long-term digital preservation solution, which utilizes the described novel concepts. While implementing the described data model and processes, our implementation is additionally governed by considerations such as fault-tolerance on the node level, maintainability and extendability, and long-term use of the system, which all flow into the described system architecture, and resulting implementation.
Subsequently, we then perform an evaluation of the implemented prototype and the underlying concepts, with the use of realistic scenarios. The evaluation consists of two parts. In the first part, we define and employ a benchmark geared towards triple stores, in which we evaluate the feasibility and the constraints of using triple stores for RDF-based metadata storage and management in the context of long-term preservation systems. In the second part, we perform a qualitative and quantitative evaluation of the DISTARNET system prototype implementation. The former looking at the correct execution of the developed processes, and the later looking at the performance of the system regarding the overall archiving storage capacity and scalability of the system
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