Abteilung Ökosystemmodellierung

[["dc.bibliographiccitation.firstpage","1539"],["dc.bibliographiccitation.issue","3"],["dc.bibliographiccitation.journal","Biological Reviews"],["dc.bibliographiccitation.lastpage","1569"],["dc.bibliographiccitation.volume","92"],["dc.contributor.author","Dislich, Claudia"],["dc.contributor.author","Keyel, Alexander C."],["dc.contributor.author","Salecker, Jan"],["dc.contributor.author","Kisel, Yael"],["dc.contributor.author","Meyer, Katrin M."],["dc.contributor.author","Auliya, Mark"],["dc.contributor.author","Barnes, Andrew D."],["dc.contributor.author","Corre, Marife D."],["dc.contributor.author","Darras, Kevin"],["dc.contributor.author","Faust, Heiko"],["dc.contributor.author","Hess, Bastian"],["dc.contributor.author","Klasen, Stephan"],["dc.contributor.author","Knohl, Alexander"],["dc.contributor.author","Kreft, Holger"],["dc.contributor.author","Meijide, Ana"],["dc.contributor.author","Nurdiansyah, Fuad"],["dc.contributor.author","Otten, Fenna"],["dc.contributor.author","Pe'er, Guy"],["dc.contributor.author","Steinebach, Stefanie"],["dc.contributor.author","Tarigan, Suria"],["dc.contributor.author","Tölle, Merja H."],["dc.contributor.author","Tscharntke, Teja"],["dc.contributor.author","Wiegand, Kerstin"],["dc.date.accessioned","2017-09-07T11:44:46Z"],["dc.date.available","2017-09-07T11:44:46Z"],["dc.date.issued","2017"],["dc.description.abstract","Oil palm plantations have expanded rapidly in recent decades. This large-scale land-use change has had great ecological, economic, and social impacts on both the areas converted to oil palm and their surroundings. However, research on the impacts of oil palm cultivation is scattered and patchy, and no clear overview exists. We address this gap through a systematic and comprehensive literature review of all ecosystem functions in oil palm plantations, including several (genetic, medicinal and ornamental resources, information functions) not included in previous systematic reviews. We compare ecosystem functions in oil palm plantations to those in forests, as the conversion of forest to oil palm is prevalent in the tropics. We find that oil palm plantations generally have reduced ecosystem functioning compared to forests: 11 out of 14 ecosystem functions show a net decrease in level of function. Some functions show decreases with potentially irreversible global impacts (e.g. reductions in gas and climate regulation, habitat and nursery functions, genetic resources, medicinal resources, and information functions). The most serious impacts occur when forest is cleared to establish new plantations, and immediately afterwards, especially on peat soils. To variable degrees, specific plantation management measures can prevent or reduce losses of some ecosystem functions (e.g. avoid illegal land clearing via fire, avoid draining of peat, use of integrated pest management, use of cover crops, mulch, and compost) and we highlight synergistic mitigation measures that can improve multiple ecosystem functions simultaneously. The only ecosystem function which increases in oil palm plantations is, unsurprisingly, the production of marketable goods. Our review highlights numerous research gaps. In particular, there are significant gaps with respect to socio-cultural information functions. Further, there is a need for more empirical data on the importance of spatial and temporal scales, such as differences among plantations in different environments, of different sizes, and of different ages, as our review has identified examples where ecosystem functions vary spatially and temporally. Finally, more research is needed on developing management practices that can offset the losses of ecosystem functions. Our findings should stimulate research to address the identified gaps, and provide a foundation for more systematic research and discussion on ways to minimize the negative impacts and maximize the positive impacts of oil palm cultivation."],["dc.identifier.doi","10.1111/brv.12295"],["dc.identifier.fs","621226"],["dc.identifier.gro","3148957"],["dc.identifier.pmid","27511961"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/14337"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/5600"],["dc.language.iso","en"],["dc.notes.intern","Wiegand Crossref Import"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","final"],["dc.notes.submitter","chake"],["dc.relation","SFB 990: Ökologische und sozioökonomische Funktionen tropischer Tieflandregenwald-Transformationssysteme (Sumatra, Indonesien)"],["dc.relation","SFB 990 | B | B10: Landschaftsbezogene Bewertung der ökologischen und sozioökonomischen Funktionen von Regenwald- Transformationssystemen in Sumatra (Indonesien)"],["dc.relation.issn","1464-7931"],["dc.relation.orgunit","Abteilung Ökosystemmodellierung"],["dc.relation.orgunit","Wirtschaftswissenschaftliche Fakultät"],["dc.relation.orgunit","Abteilung Bioklimatologie"],["dc.rights","CC BY-NC 4.0"],["dc.rights.uri","https://creativecommons.org/licenses/by-nc/4.0/"],["dc.subject.gro","Elaeis guineensis"],["dc.subject.gro","biodiversity"],["dc.subject.gro","ecosystem functions"],["dc.subject.gro","ecosystem services"],["dc.subject.gro","land-use change"],["dc.subject.gro","oil palm"],["dc.subject.gro","sfb990_journalarticles"],["dc.title","A review of the ecosystem functions in oil palm plantations, using forests as a reference system"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.subtype","original_ja"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","3768"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Scientific Reports"],["dc.bibliographiccitation.volume","9"],["dc.contributor.author","Ratzmann, Gregor"],["dc.contributor.author","Zakharova, Liubov"],["dc.contributor.author","Tietjen, Britta"],["dc.date.accessioned","2019-07-09T11:50:32Z"],["dc.date.available","2019-07-09T11:50:32Z"],["dc.date.issued","2019"],["dc.description.abstract","Leaf water potential regulation is a key process in whole plant and ecosystem functioning. While low water potentials induced by open stomata may initially be associated with greater CO2 supply and a higher water flux from the rhizosphere to the canopy, they also inhibit cell growth, photosynthesis and ultimately water supply. Here, we show that plants regulate their leaf water potential in an optimal manner under given constraints using a simple leaf water status regulation model and data from a global dryland leaf water potential database. Model predictions agree strongly with observations across locations and species and are further supported by experimental data. Leaf water potentials non-linearly decline with soil water potential, underlining the shift from maximizing water supply to avoiding stress with declining water availability. Our results suggest that optimal regulation of the leaf water status under varying water supply and stress tolerance is a ubiquitous property of plants in drylands. The proposed model moreover provides a novel quantitative framework describing how plants respond to short- and long-term changes in water availability and may help elaborating models of plant and ecosystem functioning."],["dc.identifier.doi","10.1038/s41598-019-40448-2"],["dc.identifier.pmid","30842586"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/15956"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/59789"],["dc.language.iso","en"],["dc.notes.intern","Merged from goescholar"],["dc.relation.issn","2045-2322"],["dc.relation.orgunit","Abteilung Ökosystemmodellierung"],["dc.rights","CC BY 4.0"],["dc.rights.uri","https://creativecommons.org/licenses/by/4.0"],["dc.subject.ddc","570"],["dc.title","Optimal leaf water status regulation of plants in drylands"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.subtype","original_ja"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1854"],["dc.bibliographiccitation.issue","11"],["dc.bibliographiccitation.journal","Methods in Ecology and Evolution"],["dc.bibliographiccitation.lastpage","1863"],["dc.bibliographiccitation.volume","10"],["dc.contributor.author","Salecker, Jan"],["dc.contributor.author","Sciaini, Marco"],["dc.contributor.author","Meyer, Katrin M."],["dc.contributor.author","Wiegand, Kerstin"],["dc.date.accessioned","2020-12-10T18:26:41Z"],["dc.date.available","2020-12-10T18:26:41Z"],["dc.date.issued","2019"],["dc.description.abstract","1.Agent-based models find wide application in all fields of science where large scale patterns emerge from properties of individuals. Due to increasing capacities of computing resources it was possible to improve the level of detail and structural realism of next-generation models in recent years. However, this is at the expense of increased model complexity, which requires more efficient tools for model exploration, analysis and documentation that enable reproducibility, repeatability and parallelisation. NetLogo is a widely used environment for agent-based model development, but it does not provide sufficient built-in tools for extensive model exploration, such as sensitivity analyses. One tool for controlling NetLogo externally is the R-package RNetLogo. However, this package is not suited for efficient, reproducible research as it has stability and resource allocation issues, is not straightforward to be setup and used on high performance computing clusters and does not provide utilities, such as storing and exchanging metadata, in an easy way. 2.We present the R-package nlrx, which overcomes stability and resource allocation issues by running NetLogo simulations via dynamically created XML experiment files. Class objects make setting up experiments more convenient and helper functions provide many parameter exploration approaches, such as Latin Hypercube designs, Sobol sensitivity analyses or optimization approaches. Output is automatically collected in user-friendly formats and can be post-processed with provided utility functions. nlrx enables reproducibility by storing all relevant information and simulation output of experiments in one R object which can conveniently be archived and shared. 3.We provide a detailed description of the nlrx package functions and the overall workflow. We also present a use case scenario using a NetLogo model, for which we performed a sensitivity analysis and a genetic algorithm optimization. 4.The nlrx package is the first framework for documentation and application of reproducible NetLogo simulation model analysis."],["dc.description.sponsorship","Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659"],["dc.identifier.doi","10.1111/2041-210X.13286"],["dc.identifier.issn","2041-210X"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/16518"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/76155"],["dc.language.iso","en"],["dc.notes.intern","DOI Import GROB-354"],["dc.notes.intern","Merged from goescholar"],["dc.relation","SFB 990: Ökologische und sozioökonomische Funktionen tropischer Tieflandregenwald-Transformationssysteme (Sumatra, Indonesien)"],["dc.relation","SFB 990 | B | B10: Landschaftsbezogene Bewertung der ökologischen und sozioökonomischen Funktionen von Regenwald- Transformationssystemen in Sumatra (Indonesien)"],["dc.relation.issn","2041-210X"],["dc.relation.orgunit","Zentrum für Biodiversität und Nachhaltige Landnutzung"],["dc.relation.orgunit","Abteilung Ökosystemmodellierung"],["dc.rights","CC BY 4.0"],["dc.rights.uri","https://creativecommons.org/licenses/by/4.0"],["dc.subject.gro","agent-based modelling"],["dc.subject.gro","individual-based modelling"],["dc.subject.gro","reproducible workflow"],["dc.subject.gro","R package"],["dc.subject.gro","NetLogo"],["dc.subject.gro","sfb990_journalarticles"],["dc.title","The nlrx r package: A next‐generation framework for reproducible NetLogo model analyses"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.subtype","original_ja"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","e80352"],["dc.bibliographiccitation.issue","12"],["dc.bibliographiccitation.journal","PLoS ONE"],["dc.bibliographiccitation.volume","8"],["dc.contributor.author","Sabatier, Rodolphe"],["dc.contributor.author","Wiegand, Kerstin"],["dc.contributor.author","Meyer, Katrin Mareike"],["dc.date.accessioned","2017-09-07T11:44:43Z"],["dc.date.available","2017-09-07T11:44:43Z"],["dc.date.issued","2013"],["dc.description.abstract","Ecological intensification, i.e. relying on ecological processes to replace chemical inputs, is often presented as the ideal alternative to conventional farming based on an intensive use of chemicals. It is said to both maintain high yield and provide more robustness to the agroecosystem. However few studies compared the two types of management with respect to their consequences for production and robustness toward perturbation. In this study our aim is to assess productive performance and robustness toward diverse perturbations of a Cacao agroecosystem managed with two contrasting groups of strategies: one group of strategies relying on a high level of pesticides and a second relying on low levels of pesticides. We conducted this study using a dynamical model of a Cacao agroecosystem that includes Cacao production dynamics, and dynamics of three insects: a pest (the Cacao Pod Borer, Conopomorpha cramerella) and two characteristic but unspecified beneficial insects (a pollinator of Cacao and a parasitoid of the Cacao Pod Borer). Our results showed two opposite behaviors of the Cacao agroecosystem depending on its management, i.e. an agroecosystem relying on a high input of pesticides and showing low ecosystem functioning and an agroecosystem with low inputs, relying on a high functioning of the ecosystem. From the production point of view, no type of management clearly outclassed the other and their ranking depended on the type of pesticide used. From the robustness point of view, the two types of managements performed differently when subjected to different types of perturbations. Ecologically intensive systems were more robust to pest outbreaks and perturbations related to pesticide characteristics while chemically intensive systems were more robust to Cacao production and management-related perturbation."],["dc.identifier.doi","10.1371/journal.pone.0080352"],["dc.identifier.fs","599770"],["dc.identifier.gro","3148945"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/9510"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/5587"],["dc.language.iso","en"],["dc.notes.intern","Wiegand Crossref Import"],["dc.notes.status","public"],["dc.notes.submitter","chake"],["dc.relation.issn","1932-6203"],["dc.relation.orgunit","Abteilung Ökosystemmodellierung"],["dc.rights.access","openAccess"],["dc.title","Production and Robustness of a Cacao Agroecosystem: Effects of Two Contrasting Types of Management Strategies"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","no"],["dc.type.subtype","original_ja"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","e13092"],["dc.bibliographiccitation.issue","6"],["dc.bibliographiccitation.journal","Journal of Vegetation Science"],["dc.bibliographiccitation.volume","32"],["dc.contributor.affiliation","Yizhaq, Hezi; 3\r\nDepartment of Solar Energy and Environmental Physics\r\nBlaustein Institutes for Desert Research\r\nBen‐Gurion University of the Negev\r\nBe'er Sheva Israel"],["dc.contributor.affiliation","Tschinkel, Walter R.; 4\r\nDepartment of Biological Science\r\nFlorida State University\r\nTallahassee Florida USA"],["dc.contributor.author","Getzin, Stephan"],["dc.contributor.author","Yizhaq, Hezi"],["dc.contributor.author","Tschinkel, Walter R."],["dc.date.accessioned","2021-12-02T08:13:44Z"],["dc.date.available","2021-12-02T08:13:44Z"],["dc.date.issued","2021"],["dc.date.updated","2022-03-21T05:59:32Z"],["dc.description.abstract","Abstract Aims The fairy circles along the Namib Desert in southern Africa are round grassland gaps that have puzzled scientists for about 50 years. With the discovery of fairy circles in Australia in 2016, the debate on the origin of the circles has been extended to a new continent. Research interest on the topic has since then risen strongly but so has the use of the term “fairy circle”. This term has become more imprecise and, by analogy, has been applied to circular vegetation gaps or plant rings that are largely unrelated to fairy circles. For this reason, we define the concept of fairy circles by identifying their three main characteristics based on in situ field observations and soil excavations to larger‐scale spatial patterns, and regional‐scale distribution. Results Following this approach, fairy circles are defined by: (a) being “empty gaps” in grassland without a central insect‐nest structure; (b) their ability to form spatially periodic patterns, which are regular hexagonal patterns with an extraordinary degree of spatial ordering; and (c) their strongly regional distribution confined within a narrow arid climatic envelope. In these combined traits, fairy circles differ from other common vegetation gaps which, for example, always have a central insect‐nest structure and may occur across broad climatic gradients on continents. Also plant rings have their own specific characteristics that largely differ from the combined attributes of genuine fairy circles. Conclusions There are many other vegetation‐gap patterns in arid lands but if such gaps cannot jointly show the three characteristics defining the fairy circles, they should be carefully discussed on their own, rather than mixing them up with fairy circles. Our synthesis provides a new etymology for the different types of vegetation gaps and rings, aiming to guide the reader through various classes of circular plant patterns."],["dc.description.abstract","The fairy circles of Namibia are one of nature's greatest mysteries. The term “fairy circles” was established in ecology more than 20 years ago, but recently has been used interchangeably for other circular patterns that are largely unrelated. Here we summarize the main characteristics of fairy circles and show how they differ from common vegetation gaps and plant rings. image"],["dc.description.sponsorship","German Research Foundation (DFG)"],["dc.identifier.doi","10.1111/jvs.13092"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/94958"],["dc.language.iso","en"],["dc.relation.issn","1100-9233"],["dc.relation.issn","1654-1103"],["dc.relation.orgunit","Abteilung Ökosystemmodellierung"],["dc.rights","This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial‐NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made."],["dc.title","Definition of “fairy circles” and how they differ from other common vegetation gaps and plant rings"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","13"],["dc.bibliographiccitation.journal","Forstarchiv"],["dc.bibliographiccitation.lastpage","23"],["dc.bibliographiccitation.volume","84"],["dc.contributor.author","Bauling, S."],["dc.contributor.author","Saborowski, J."],["dc.contributor.author","Rühe, F."],["dc.date.accessioned","2020-12-14T12:09:20Z"],["dc.date.available","2020-12-14T12:09:20Z"],["dc.date.issued","2013"],["dc.description.abstract","Die Bestandesschätzung von Wildwiederkäuern in Waldgebieten ist oft deshalb so unsicher, weil wesentliche, den verschiedenen Berechnungsmethoden zugrunde liegende Prämissen bei ihrer Anwendung nicht ausreichend eingehalten werden. Im Solling, Niedersachsen, herrschten über 14 Jahre Rahmenbedingungen für eine Schätzung der Größe des Rotwildbestandes, die sich im Vergleich zu vielen anderen Rotwildgebieten Deutschlands als besonders günstig erwiesen. Die dortige Rotwildpopulation wurde über mehrere Jahrzehnte durch ein Gatter isoliert, sodass eine Verzerrung der Schätzwerte der Bestandesdichten durch Migrationseffekte vernachlässigt werden konnte. Wie groß der Rotwildbestand im Solling damals war, war unsicher und bislang nicht wissenschaftlich untersucht worden. Ziel der Untersuchung war es, die jährliche Rotwilddichte der Jahre 1981 bis 1994 zu schätzen. Um die Spannweite zu ermitteln, innerhalb der die geschätzte Größe des Rotwildbestandes lag, haben wir die Population in 2 Varianten auf Grundlage der Age-at-Harvest-Methode rekonstruiert: (A) mit Überlebensraten, die an frei, in relativ harscher Umwelt ohne Winterfütterung lebenden Populationen ermittelt wurden und als Mindestüberlebensraten der Sollingpopulation angenommen wurden, und (B) wegen günstigerer Umweltbedingungen im Solling mit deutlich höheren Werten, die als maximale Überlebensraten des dortigen Rotwildbestandes betrachtet werden. Die auf Basis der Variante A geschätzte Rotwilddichte (± SDF) sank von 14,54 ± 1,53 Stück pro 100 ha im Jahr 1981 um 56,05 % auf 6,39 ± 0,79 Stück pro 100 ha im Jahr 1994 herab. Im Mittel von 1981 bis 1994 betrug sie 8,32 ± 0,78 Stück pro 100 ha. Die Variante B schätzte die Bestandesdichte im selben Zeitraum auf durchschnittlich 5,11 ± 0,16 Stück pro 100 ha und damit um mehr als ein Drittel niedriger als Variante A. Die Spannweite zwischen den Schätzwerten beider Varianten innerhalb eines jeden der 14 Jahre zeigt, dass die damalige Zieldichte der Rotwildbewirtschaftung, 3 bis 4 Stück pro 100 ha, in 12 von 14 Jahren augenscheinlich verfehlt und in den übrigen 2 Jahren (1989 und 1994) nur unter Annahme extrem niedriger natürlicher Sterblichkeit erreicht wurde. Zur natürlichen Sterblichkeit von Rotwild in Mitteleuropa besteht dringender Forschungsbedarf."],["dc.description.abstract","Estimating the abundance of wild ruminants in woodland is often uncertain because essential assumptions of the applied methods are not kept sufficiently. For over 14 years, the conditions for assessing the population size of red deer in the Solling, a low mountain range in Lower Saxony, Germany, proved to be particularly favourable if compared to other red deer management areas in Germany. The red deer population of the Solling lived, for many decades, in a leak-proof enclosure 25,000 ha in size. Thus, a bias of the estimates of abundance of this isolated population through migration effects could be neglected. How big the red deer population of the Solling was at that time was uncertain and has to date not been studied scientifically. The aim of this study was to assess the annual red deer population density of the years 1981 to 1994. To determine the range of the estimated size of the red deer population, the population was reconstructed in 2 models, both on the basis of the age-at-harvest method: (A) using survival rates of red deer populations, which lived in a harsh environment without winter feeding, they are understood as the minimal survival rates of the Solling red deer population, and (B) using considerably higher survival rates due to the more favourable environmental conditions in the Solling, they are understood as the maximal survival rates of the Solling population. The red deer population density (± SE) estimated with model A decreased from 14.54 ± 1.53 head per 100 ha in 1981 by 56.05% to 6.39 ± 0.79 head per 100 ha in 1994. From 1981 to 1994 it averaged 8.32 ± 0.78 head per 100 ha. For the same time period model B estimated the red deer population density to be 5.11 ± 0.16 head per 100 ha on average and thus by over a third lower of what was estimated by using model A. The span between the 2 density values of both variants shows that the then aim-density of red deer management, 3 to 4 head per 100 ha, was missed in 12 of 14 years and was only achieved in the remaining 2 years (1989 and 1994) by assuming an extremely low natural mortality. Research on natural mortality of central European red deer populations is urgently needed."],["dc.identifier.doi","10.4432/0300-4112-84-13"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/79051"],["dc.language.iso","de"],["dc.relation.orgunit","Abteilung Ökosystemmodellierung"],["dc.relation.orgunit","Abteilung Wildtierwissenschaften"],["dc.subject.gro","Rothirsch"],["dc.subject.gro","Populationsrekonstruktion"],["dc.subject.gro","Populationsdichte"],["dc.subject.gro","Kohortenanalyse"],["dc.title","Schätzung der Rotwilddichte (Cervus elaphus L.) im Solling mit der Age-at-Harvest-Methode"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","229"],["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","Perspectives in Plant Ecology, Evolution and Systematics"],["dc.bibliographiccitation.lastpage","242"],["dc.bibliographiccitation.volume","7"],["dc.contributor.author","Wiegand, Kerstin"],["dc.contributor.author","Saltz, David"],["dc.contributor.author","Ward, David"],["dc.date.accessioned","2017-09-07T11:44:40Z"],["dc.date.available","2017-09-07T11:44:40Z"],["dc.date.issued","2005"],["dc.description.abstract","The coexistence of woody and grassy plants in savannas has often been attributed to a rooting-niche separation (two-layer hypothesis). Water was assumed to be the limiting resource for both growth forms and grasses were assumed to extract water from the upper soil layer and trees and bushes from the lower layers. Woody plant encroachment (i.e. an increase in density of woody plants often unpalatable to domestic livestock) is a serious problem in many savannas and is believed to be the result of overgrazing in ‘two-layer systems’. Recent research has questioned the universality of both the two-layer hypothesis and the hypothesis that overgrazing is the cause of woody plant encroachment. We present an alternative hypothesis explaining both tree–grass coexistence and woody plant encroachment in arid savannas. We propose that woody plant encroachment is part of a cyclical succession between open savanna and woody dominance and is driven by two factors: rainfall that is highly variable in space and time, and inter-tree competition. In this case, savanna landscapes are composed of many patches (a few hectares in size) in different states of transition between grassy and woody dominance, i.e. we hypothesize that arid savannas are patch-dynamic systems. We summarize patterns of tree distribution observed in an arid savanna in Namibia and show that these patterns are in agreement with the patch-dynamic savanna hypothesis. We discuss the applicability of this hypothesis to fire-dominated savannas, in which rainfall variability is low and fire drives spatial heterogeneity. We conclude that field studies are more likely to contribute to a general understanding of tree–grass coexistence and woody plant encroachment if they consider both primary (rain and nutrients) and secondary (fire and grazing) determinants of patch properties across different savannas."],["dc.identifier.doi","10.1016/j.ppees.2005.10.001"],["dc.identifier.gro","3148947"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/5590"],["dc.language.iso","en"],["dc.notes.intern","Wiegand Crossref Import"],["dc.notes.status","final"],["dc.notes.submitter","chake"],["dc.relation.issn","1433-8319"],["dc.relation.orgunit","Abteilung Ökosystemmodellierung"],["dc.subject.gro","Fire"],["dc.subject.gro","Grazing"],["dc.subject.gro","Honeycomb rippling model"],["dc.subject.gro","Inter-tree competition"],["dc.subject.gro","Spatio-temporal rainfall variation"],["dc.subject.gro","Tree-grass coexistence"],["dc.title","A patch-dynamics approach to savanna dynamics and woody plant encroachment – Insights from an arid savanna"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","no"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","397"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Methods in Ecology and Evolution"],["dc.bibliographiccitation.lastpage","404"],["dc.bibliographiccitation.volume","3"],["dc.contributor.author","Getzin, Stephan"],["dc.contributor.author","Wiegand, Kerstin"],["dc.contributor.author","Schöning, Ingo"],["dc.date.accessioned","2017-09-07T11:52:28Z"],["dc.date.available","2017-09-07T11:52:28Z"],["dc.date.issued","2011"],["dc.description.abstract","1. Structural diversity and niche differences within habitats are important for stabilizing species coexistence. However, land-use change leading to environmental homogenization is a major cause for the dramatic decline of biodiversity under global change. The difficulty in assessing large-scale biodiversity losses urgently requires new technological advances to evaluate land-use impact on diversity timely andefficiently across space. 2. While cost-effective aerial images have been suggested for potential biodiversity assessments in forests, correlation of canopy object variables such as gaps with plant or animal diversity has so far not been demonstrated using these images. 3. Here,we show that aerial images of canopy gaps can be used to assess floristic biodiversity of the forest understorey. This approach is made possible because we employed cutting-edge unmanned aerial vehicles and very high-resolution images (7 cm pixel)1) of the canopy properties. Wedemon- strate that detailed, spatially implicit information on gap shape metrics is sufficient to reveal strong dependency between disturbance patterns and plant diversity (R2 up to 0{\\AE}74). This is feasible because opposing disturbance patterns such as aggregated and dispersed tree retention directly cor- respond to different functional and dispersal traits of species and ultimately to different species diversities. 4. Our findings can be used as a coarse-filter approach to conservation in forests wherever light strongly limits regeneration and biodiversity."],["dc.identifier.doi","10.1111/j.2041-210x.2011.00158.x"],["dc.identifier.gro","3148921"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/5560"],["dc.language.iso","en"],["dc.notes.intern","Wiegand Crossref Import"],["dc.notes.status","public"],["dc.notes.submitter","chake"],["dc.relation.issn","2041-210X"],["dc.relation.orgunit","Abteilung Ökosystemmodellierung"],["dc.rights.uri","http://doi.wiley.com/10.1002/tdm_license_1.1"],["dc.subject.gro","Biodiversity"],["dc.subject.gro","Coarse-filter approach"],["dc.subject.gro","Forest understorey"],["dc.subject.gro","Gap shape complexity index"],["dc.subject.gro","Unmanned aerial vehicles"],["dc.title","Assessing biodiversity in forests using very high-resolution images and unmanned aerial vehicles"],["dc.title.alternative","Assessing biodiversity in forests"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","no"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","2318"],["dc.bibliographiccitation.issue","9"],["dc.bibliographiccitation.journal","Environmental Toxicology and Chemistry"],["dc.bibliographiccitation.lastpage","2327"],["dc.bibliographiccitation.volume","41"],["dc.contributor.affiliation","Reiner, Dominik; 1\r\nDepartment of Ecosystem Modelling\r\nUniversity of Göttingen\r\nGöttingen Germany"],["dc.contributor.affiliation","Grimm, Volker; 2\r\nDepartment of Ecological Modelling\r\nHelmholtz Centre for Environmental Research—UFZ\r\nLeipzig Germany"],["dc.contributor.affiliation","Groeneveld, Jürgen; 2\r\nDepartment of Ecological Modelling\r\nHelmholtz Centre for Environmental Research—UFZ\r\nLeipzig Germany"],["dc.contributor.affiliation","Wiegand, Kerstin; 1\r\nDepartment of Ecosystem Modelling\r\nUniversity of Göttingen\r\nGöttingen Germany"],["dc.contributor.author","Reiner, Dominik"],["dc.contributor.author","Grimm, Volker"],["dc.contributor.author","Groeneveld, Jürgen"],["dc.contributor.author","Wiegand, Kerstin"],["dc.contributor.author","Spangenberg, Matthias C."],["dc.date.accessioned","2022-08-29T08:11:24Z"],["dc.date.available","2022-08-29T08:11:24Z"],["dc.date.issued","2022-09"],["dc.date.updated","2022-11-11T13:13:52Z"],["dc.description.abstract","Honeybees (Apis mellifera) are important pollinators for wild plants as well as for crops, but honeybee performance is threatened by several stressors including varroa mites, gaps in foraging supply, and pesticides. The consequences of bee colony longtime exposure to multiple stressors are not well understood. The vast number of possible stressor combinations and necessary study duration require research comprising field, laboratory, and simulation experiments. We simulated long-term exposure of a honeybee colony to the insecticide imidacloprid and to varroa mites carrying the deformed wing virus in landscapes with different temporal gaps in resource availability as single stressors and in combinations. Furthermore, we put a strong emphasis on chronic lethal, acute sublethal, and acute lethal effects of imidacloprid on honeybees. We have chosen conservative published values to parameterize our model (e.g., highest reported imidacloprid contamination). As expected, combinations of stressors had a stronger negative effect on bee performance than each single stressor alone, and effect sizes were larger after 3 years of exposure than after the first year. Imidacloprid-caused reduction in bee performance was almost exclusively due to chronic lethal effects because the thresholds for acute effects were rarely met in simulations. In addition, honeybee colony extinctions were observed by the last day of the first year but more pronounced on the last days of the second and third simulation year. In conclusion, our study highlights the need for more long-term studies on chronic lethal effects of pesticides on honeybees. Environ Toxicol Chem 2022;41:2318-2327. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC."],["dc.description.sponsorship","Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659"],["dc.identifier.doi","10.1002/etc.5420"],["dc.identifier.pmid","35771006"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/113266"],["dc.language.iso","en"],["dc.relation.eissn","1552-8618"],["dc.relation.issn","0730-7268"],["dc.relation.issn","1552-8618"],["dc.relation.orgunit","Abteilung Ökosystemmodellierung"],["dc.rights","CC BY-NC 4.0"],["dc.title","Chronic and Acute Effects of Imidacloprid on a Simulated BEEHAVE Honeybee Colony"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.subtype","original_ja"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","563"],["dc.bibliographiccitation.issue","7"],["dc.bibliographiccitation.journal","Basic and Applied Ecology"],["dc.bibliographiccitation.lastpage","571"],["dc.bibliographiccitation.volume","11"],["dc.contributor.author","Meyer, Katrin M."],["dc.contributor.author","Schiffers, Katja H."],["dc.contributor.author","Muenkemueller, Tamara"],["dc.contributor.author","Schaedler, Martin"],["dc.contributor.author","Calabrese, Justin M."],["dc.contributor.author","Basset, Alberto"],["dc.contributor.author","Breulmann, Marc"],["dc.contributor.author","Duquesne, Sabine"],["dc.contributor.author","Hidding, Bert"],["dc.contributor.author","Huth, Andreas"],["dc.contributor.author","Schoeb, Christian"],["dc.contributor.author","van de Voorde, Tess F. J."],["dc.date.accessioned","2018-11-07T08:47:07Z"],["dc.date.available","2018-11-07T08:47:07Z"],["dc.date.issued","2010"],["dc.description.abstract","When investigating complex ecological dynamics at the population or community level, we necessarily need to abstract and aggregate ecological information. The way in which information is aggregated may be crucial for the outcome of the study. In this paper, we suggest that in addition to the traditional spatial, temporal and organizational levels, we need a more flexible framework linking ecological processes, study objects and types of aggregation. We develop such a framework and exemplify the most commonly used types of aggregation and their potential influence on identifiable drivers of community dynamics. We also illustrate strategies to narrow down the range of possible aggregation types for a particular study. With this approach, we hope (i) to clarify the function of aggregation types as related to traditional ecological levels and (ii) to raise the awareness of how important a deliberate way of aggregating ecological information is for a sound and reliable outcome of any empirical or theoretical ecological study."],["dc.identifier.doi","10.1016/j.baae.2010.08.001"],["dc.identifier.isi","000286795300002"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/20866"],["dc.language.iso","en"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.issn","1439-1791"],["dc.relation.orgunit","Abteilung Ökosystemmodellierung"],["dc.subject.gro","Body size class"],["dc.subject.gro","Functional type"],["dc.subject.gro","Genotype"],["dc.subject.gro","Organizational level"],["dc.subject.gro","Pattern-process relationship"],["dc.subject.gro","Phenotype"],["dc.subject.gro","Scales"],["dc.subject.gro","Species"],["dc.subject.gro","Study design"],["dc.subject.gro","Trophic guild"],["dc.title","Predicting population and community dynamics: The type of aggregation matters"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]