TY - JOUR A1 - Grimm, Volker A1 - Berger, Uta A1 - Bastiansen, Finn A1 - Eliassen, Sigrunn A1 - Ginot, Vincent A1 - Giske, Jarl A1 - Goss-Custard, John A1 - Grand, Tamara A1 - Heinz, Simone K. A1 - Huse, Geir A1 - Huth, Andreas A1 - Jepsen, Jane U. A1 - Jorgensen, Christian A1 - Mooij, Wolf M. A1 - Mueller, Birgit A1 - Piou, Cyril A1 - Railsback, Steven Floyd A1 - Robbins, Andrew M. A1 - Robbins, Martha M. A1 - Rossmanith, Eva A1 - Rueger, Nadja A1 - Strand, Espen A1 - Souissi, Sami A1 - Stillman, Richard A. A1 - Vabo, Rune A1 - Visser, Ute A1 - DeAngelis, Donald L. T1 - A standard protocol for describing individual-based and agent-based models JF - Ecological modelling : international journal on ecological modelling and engineering and systems ecolog N2 - Simulation models that describe autonomous individual organisms (individual based models, IBM) or agents (agent-based models, ABM) have become a widely used tool, not only in ecology, but also in many other disciplines dealing with complex systems made up of autonomous entities. However, there is no standard protocol for describing such simulation models, which can make them difficult to understand and to duplicate. This paper presents a proposed standard protocol, ODD, for describing IBMs and ABMs, developed and tested by 28 modellers who cover a wide range of fields within ecology. This protocol consists of three blocks (Overview, Design concepts, and Details), which are subdivided into seven elements: Purpose, State variables and scales, Process overview and scheduling, Design concepts, Initialization, Input, and Submodels. We explain which aspects of a model should be described in each element, and we present an example to illustrate the protocol in use. In addition, 19 examples are available in an Online Appendix. We consider ODD as a first step for establishing a more detailed common format of the description of IBMs and ABMs. Once initiated, the protocol will hopefully evolve as it becomes used by a sufficiently large proportion of modellers. (c) 2006 Elsevier B.V. All rights reserved. KW - individual-based model KW - agent-based model KW - model description KW - scientific communication KW - standardization Y1 - 2006 U6 - https://doi.org/10.1016/j.ecolmodel.2006.04.023 SN - 0304-3800 VL - 198 SP - 115 EP - 126 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Langhammer, Maria A1 - Thober, Jule A1 - Lange, Martin A1 - Frank, Karin A1 - Grimm, Volker T1 - Agricultural landscape generators for simulation models BT - a review of existing solutions and an outline of future directions JF - Ecological modelling : international journal on ecological modelling and engineering and systems ecolog N2 - There is an increasing need for an assessment of the impacts of land use and land use change (LUCC). In this context, simulation models are valuable tools for investigating the impacts of stakeholder actions or policy decisions. Agricultural landscape generators (ALGs), which systematically and automatically generate realistic but simplified representations of land cover in agricultural landscapes, can provide the input for LUCC models. We reviewed existing ALGs in terms of their objectives, design and scope. We found eight ALGs that met our definition. They were based either on generic mathematical algorithms (pattern-based) or on representations of ecological or land use processes (process-based). Most ALGs integrate only a few landscape metrics, which limits the design of the landscape pattern and thus the range of applications. For example, only a few specific farming systems have been implemented. We conclude that existing ALGs contain useful approaches that can be used for specific purposes, but ideally generic modular ALGs are developed that can be used for a wide range of scenarios, regions and model types. We have compiled features of such generic ALGs and propose a possible software architecture. Considerable joint efforts are required to develop such generic ALGs, but the benefits in terms of a better understanding and development of more efficient agricultural policies would be high. KW - Agricultural landscape KW - Field pattern KW - Agricultural landscape generator KW - Landscape simulator KW - Neutral landscape model KW - Process-based model Y1 - 2019 U6 - https://doi.org/10.1016/j.ecolmodel.2018.12.010 SN - 0304-3800 SN - 1872-7026 VL - 393 SP - 135 EP - 151 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Jeltsch, Florian A1 - Tews, Jörg A1 - Brose, Ulrich A1 - Grimm, Volker A1 - Tielbörger, Katja A1 - Wichmann, Matthias A1 - Schwager, Monika T1 - Animal species diversity driven by habitat heterogeneity/diversity : the importance of keystone structures N2 - In a selected literature survey we reviewed studies on the habitat heterogeneity-animal species diversity relationship and evaluated whether there are uncertainties and biases in its empirical support. We reviewed 85 publications for the period 1960-2003. We screened each publication for terms that were used to define habitat heterogeneity, the animal species group and ecosystem studied, the definition of the structural variable, the measurement of vegetation structure and the temporal and spatial scale of the study. The majority of studies found a positive correlation between habitat heterogeneity/diversity and animal species diversity. However, empirical support for this relationship is drastically biased towards studies of vertebrates and habitats under anthropogenic influence. In this paper we show that ecological effects of habitat heterogeneity may vary considerably between species groups depending on whether structural attributes are perceived as heterogeneity or fragmentation. Possible effects may also vary relative to the structural variable measured. Based upon this, we introduce a classification framework that may be used for across-studies comparisons. Moreover, the effect of habitat heterogeneity for one species group may differ in relation to the spatial scale. In several studies, however, different species groups are closely linked to 'keystone structures' that determine animal species diversity by their presence. Detecting crucial keystone structures of the vegetation has profound implications for nature conservation and biodiversity management. Y1 - 2004 ER - TY - JOUR A1 - Radchuk, Viktoriia A1 - Johst, Karin A1 - Groeneveld, Jürgen A1 - Turlure, Camille A1 - Grimm, Volker A1 - Schtickzelle, Nicolas T1 - Appropriate resolution in time and model structure for population viability analysis: Insights from a butterfly metapopulation JF - : an international journal N2 - The importance of a careful choice of the appropriate scale for studying ecological phenomena has been stressed repeatedly. However, issues of spatial scale in metapopulation dynamics received much more attention compared to temporal scale. Moreover, multiple calls were made to carefully choose the appropriate model structure for Population Viability Analysis (PVA). We assessed the effect of using coarser resolution in time and model structure on population dynamics. For this purpose, we compared outcomes of two PVA models differing in their time step: daily individual-based model (dIBM) and yearly stage-based model (ySBM), loaded with empirical data on a well-known metapopulation of the butterfly Boloria eunomia. Both models included the same environmental drivers of population dynamics that were previously identified as being the most important for this species. Under temperature change scenarios, both models yielded the same qualitative scenario ranking, but they quite substantially differed quantitatively with dIBM being more pessimistic in absolute viability measures. We showed that these differences stemmed from inter-individual heterogeneity in dIBM allowing for phenological shifts of individual appearance. We conclude that a finer temporal resolution and an individual-based model structure allow capturing the essential mechanisms necessary to go beyond mere PVA scenario ranking. We encourage researchers to carefully chose the temporal resolution and structure of their model aiming at (1) depicting the processes important for (meta)population dynamics of the species and (2) implementing the environmental change scenarios expected for their study system in the future, using the temporal resolution at which such changes are predicted to operate. KW - Temporal grain KW - Model complexity KW - Model comparison KW - Population dynamics KW - Individual-based model KW - Stage-based model Y1 - 2014 U6 - https://doi.org/10.1016/j.biocon.2013.12.004 SN - 0006-3207 SN - 1873-2917 VL - 169 SP - 345 EP - 354 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Becher, Matthias A. A1 - Grimm, Volker A1 - Thorbek, Pernille A1 - Horn, Juliane A1 - Kennedy, Peter J. A1 - Osborne, Juliet L. T1 - BEEHAVE: a systems model of honeybee colony dynamics and foraging to explore multifactorial causes of colony failure JF - Journal of applied ecology : an official journal of the British Ecological Society N2 - BEEHAVE offers a valuable tool for researchers to design and focus field experiments, for regulators to explore the relative importance of stressors to devise management and policy advice and for beekeepers to understand and predict varroa dynamics and effects of management interventions. We expect that scientists and stakeholders will find a variety of applications for BEEHAVE, stimulating further model development and the possible inclusion of other stressors of potential importance to honeybee colony dynamics. KW - Apis mellifera KW - colony decline KW - cross-level interactions KW - feedbacks KW - foraging KW - modelling KW - multiple stressors KW - multi-agent simulation KW - predictive systems ecology KW - Varroa destructor Y1 - 2014 U6 - https://doi.org/10.1111/1365-2664.12222 SN - 0021-8901 SN - 1365-2664 VL - 51 IS - 2 SP - 470 EP - 482 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Rossmanith, Eva A1 - Grimm, Volker A1 - Blaum, Niels A1 - Jeltsch, Florian T1 - Behavioural flexibility in the mating system buffers population extinction: lessons from the Lesser Spotted Woodpecker (Picoides minor) N2 - In most stochastic models addressing the persistence of small populations, environmental noise is included by imposing a synchronized effect of the environment on all individuals. However, buffer mechanisms are likely to exist that may counteract this synchronization to some degree. We have studied whether the flexibility in the mating system, which has been observed in some bird species, is a potential mechanism counteracting the synchronization of environmental fluctuations. Our study organism is the lesser spotted woodpecker Picoides minor (Linnaeus), a generally monogamous species. However, facultative polyandry, where one female mates with two males with separate nests, was observed in years with male-biased sex ratio. We constructed an individual-based model from data and observations of a population in Taunus, Germany. We tested the impact of three behavioural scenarios on population persistence: (1) strict monogamy; (2) polyandry without costs; and (3) polyandry assuming costs in terms of lower survival and reproductive success for secondary males. We assumed that polyandry occurs only in years with male-biased sex ratio and only for females with favourable breeding conditions. Even low rates of polyandry had a strong positive effect on population persistence. The increase of persistence with carrying capacity was slower in the monogamous scenario, indicating strong environmental noise. In the polyandrous scenarios, the increase of persistence was stronger, indicating a buffer mechanism. In the polyandrous scenarios, populations had a higher mean population size, a lower variation in number of individuals, and recovered faster after a population breakdown. Presuming a realistic polyandry rate and costs for polyandry, there was still a strong effect of polyandry on persistence. The results show that polyandry and in general flexibility in mating systems is a buffer mechanism that can significantly reduce the impact of environmental and demographic noise in small populations. Consequently, we suggest that even behaviour that seems to be exceptional should be considered explicitly when predicting the persistence of populations Y1 - 2006 U6 - https://doi.org/10.1111/j.1365-2656.2006.01074.x ER - TY - JOUR A1 - Radchuk, Viktoriia A1 - Johst, Karin A1 - Gröneveld, Juergen A1 - Grimm, Volker A1 - Schtickzelle, Nicolas T1 - Behind the scenes of population viability modeling predicting butterfly metapopulation dynamics under climate change JF - Ecological modelling : international journal on ecological modelling and engineering and systems ecolog N2 - Studies explaining the choice of model structure for population viability analysis (PVA) are rare and no such study exists for butterfly species, a focal group for conservation. Here, we describe in detail the development of a model to predict population viability of a glacial relict butterfly species, Boloria eunomia, under climate change. We compared four alternative formulations of an individual-based model, differing in the environmental factors acting on the survival of immature life stages: temperature (only temperature impact), weather (temperature, precipitation, and sunshine), temperature and parasitism, and weather and parasitism. Following pattern-oriented modeling, four observed patterns were used to contrast these models: one qualitative (response of population size to habitat parameters) and three quantitative ones describing population dynamics during eight years (mean and variability of population size, and magnitude of the temporal autocorrelation in yearly population growth rates). The four model formulations were not equally able to depict population dynamics under current environmental conditions; the model including only temperature was selected as the most parsimonious model sufficiently well reproducing the empirical patterns. We used all four model formulations to test a range of climate change scenarios that were characterized by changes in both mean and variability of the weather variables. All models predicted adverse effects of climate change and resulted in the same ranking of mean climate change scenarios. However, models differed in their absolute values of population viability measures, underlining the need to explicitly choose the most appropriate model formulation and avoid arbitrary usage of environmental drivers in a model. We conclude that further applications of pattern-oriented modeling to butterfly and other species are likely to help in identifying the key factors impacting the viability of certain taxa, which, ultimately, will aid and speed up informed management decisions for endangered species under climate change. KW - Individual-based model KW - Population viability analysis KW - Glacial relict species KW - Life cycle KW - Boloria eunomia KW - Pattern-oriented modeling KW - Model structure Y1 - 2013 U6 - https://doi.org/10.1016/j.ecolmodel.2013.03.014 SN - 0304-3800 VL - 259 IS - 2 SP - 62 EP - 73 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Cortes-Avizanda, Ainara A1 - Jovani, Roger A1 - Antonio Donazar, Jose A1 - Grimm, Volker T1 - Bird sky networks: How do avian scavengers use social information to find carrion? JF - Ecology : a publication of the Ecological Society of America N2 - The relative contribution of personal and social information to explain individual and collective behavior in different species and contexts is an open question in animal ecology. In particular, there is a major lack of studies combining theoretical and empirical approaches to test the relative relevance of different hypothesized individual behaviors to predict empirical collective patterns. We used an individual-based model to confront three hypotheses about the information transfer between social scavengers (Griffon Vultures, Gyps fulvus) when searching for carrion: (1) Vultures only use personal information during foraging ("nonsocial" hypothesis); (2) they create long chains of vultures by following both other vultures that are flying towards carcasses and vultures that are following other vultures that are flying towards carcasses ("chains of vultures" hypothesis); and (3) vultures are only attracted by other vultures that are sinking vertically to a carcass ("local enhancement" hypothesis). The chains of vultures hypothesis has been used in existing models, but never been confronted with field data. Testing is important, though, because these hypotheses could have different management implications. The model was parameterized to mimic the behavior and the densities of both Griffon Vultures and carcasses in a 10 000-km(2) study area in northeastern Spain. We compared the number of vultures attending simulated carcasses with those attending 25 continuously monitored experimental carcasses in the field. Social hypotheses outperformed the nonsocial hypothesis. The chains of vultures hypothesis overestimated the number of vultures feeding on carcasses; the local enhancement hypothesis fitted closely to the empirical data. Supported by our results, we discuss mechanistic and adaptive considerations that reveal that local enhancement may be the key social mechanism behind collective foraging in this and likely other avian scavengers and/or social birds. It also highlights the current need for more studies confronting alternative models of key behaviors with empirical patterns in order to understand how collective behavior emerges in animal societies. KW - carrion resources KW - foraging KW - group-living KW - pulsed resources KW - sociality KW - Spain KW - vultures Y1 - 2014 SN - 0012-9658 SN - 1939-9170 VL - 95 IS - 7 SP - 1799 EP - 1808 PB - Wiley CY - Washington ER - TY - THES A1 - Grimm, Volker T1 - Bottom-up Simulation Modelling in Ecology : Strategies and Examples Y1 - 2002 ER - TY - JOUR A1 - Gergs, Andre A1 - Zenker, Armin A1 - Grimm, Volker A1 - Preuss, Thomas G. T1 - Chemical and natural stressors combined from cryptic effects to population extinction JF - Scientific reports N2 - In addition to natural stressors, populations are increasingly exposed to chemical pollutants released into the environment. We experimentally demonstrate the loss of resilience for Daphnia magna populations that are exposed to a combination of natural and chemical stressors even though effects on population size of a single stressor were cryptic, i.e. hard to detect statistically. Data on Daphnia population demography and along with model-based exploration of our predator-prey system revealed that direct trophic interactions changed the population size-structure and thereby increased population vulnerability to the toxicant which acts in a size selective manner. Moreover, population vulnerability to the toxicant increases with predator size and predation intensity whereas indirect trait-mediated interactions via predator kairomones may buffer chemical effects to a certain extent. Our study demonstrates that population size can be a poor endpoint for risk assessments of chemicals and that ignoring disturbance interactions can lead to severe underestimation of extinction risk. Y1 - 2013 U6 - https://doi.org/10.1038/srep02036 SN - 2045-2322 VL - 3 IS - 2 PB - Nature Publ. Group CY - London ER -