@article{NoonanTuckerFlemingetal.2018, author = {Noonan, Michael J. and Tucker, Marlee A. and Fleming, Christen H. and Akre, Thomas S. and Alberts, Susan C. and Ali, Abdullahi H. and Altmann, Jeanne and Antunes, Pamela Castro and Belant, Jerrold L. and Beyer, Dean and Blaum, Niels and Boehning-Gaese, Katrin and Cullen Jr, Laury and de Paula, Rogerio Cunha and Dekker, Jasja and Drescher-Lehman, Jonathan and Farwig, Nina and Fichtel, Claudia and Fischer, Christina and Ford, Adam T. and Goheen, Jacob R. and Janssen, Rene and Jeltsch, Florian and Kauffman, Matthew and Kappeler, Peter M. and Koch, Flavia and LaPoint, Scott and Markham, A. Catherine and Medici, Emilia Patricia and Morato, Ronaldo G. and Nathan, Ran and Oliveira-Santos, Luiz Gustavo R. and Olson, Kirk A. and Patterson, Bruce D. and Paviolo, Agustin and Ramalho, Emiliano Estero and Rosner, Sascha and Schabo, Dana G. and Selva, Nuria and Sergiel, Agnieszka and da Silva, Marina Xavier and Spiegel, Orr and Thompson, Peter and Ullmann, Wiebke and Zieba, Filip and Zwijacz-Kozica, Tomasz and Fagan, William F. and Mueller, Thomas and Calabrese, Justin M.}, title = {A comprehensive analysis of autocorrelation and bias in home range estimation}, series = {Ecological monographs : a publication of the Ecological Society of America.}, volume = {89}, journal = {Ecological monographs : a publication of the Ecological Society of America.}, number = {2}, publisher = {Wiley}, address = {Hoboken}, issn = {0012-9615}, doi = {10.1002/ecm.1344}, pages = {21}, year = {2018}, abstract = {Home range estimation is routine practice in ecological research. While advances in animal tracking technology have increased our capacity to collect data to support home range analysis, these same advances have also resulted in increasingly autocorrelated data. Consequently, the question of which home range estimator to use on modern, highly autocorrelated tracking data remains open. This question is particularly relevant given that most estimators assume independently sampled data. Here, we provide a comprehensive evaluation of the effects of autocorrelation on home range estimation. We base our study on an extensive data set of GPS locations from 369 individuals representing 27 species distributed across five continents. We first assemble a broad array of home range estimators, including Kernel Density Estimation (KDE) with four bandwidth optimizers (Gaussian reference function, autocorrelated-Gaussian reference function [AKDE], Silverman's rule of thumb, and least squares cross-validation), Minimum Convex Polygon, and Local Convex Hull methods. Notably, all of these estimators except AKDE assume independent and identically distributed (IID) data. We then employ half-sample cross-validation to objectively quantify estimator performance, and the recently introduced effective sample size for home range area estimation ( N̂ area ) to quantify the information content of each data set. We found that AKDE 95\% area estimates were larger than conventional IID-based estimates by a mean factor of 2. The median number of cross-validated locations included in the hold-out sets by AKDE 95\% (or 50\%) estimates was 95.3\% (or 50.1\%), confirming the larger AKDE ranges were appropriately selective at the specified quantile. Conversely, conventional estimates exhibited negative bias that increased with decreasing N̂ area. To contextualize our empirical results, we performed a detailed simulation study to tease apart how sampling frequency, sampling duration, and the focal animal's movement conspire to affect range estimates. Paralleling our empirical results, the simulation study demonstrated that AKDE was generally more accurate than conventional methods, particularly for small N̂ area. While 72\% of the 369 empirical data sets had >1,000 total observations, only 4\% had an N̂ area >1,000, where 30\% had an N̂ area <30. In this frequently encountered scenario of small N̂ area, AKDE was the only estimator capable of producing an accurate home range estimate on autocorrelated data.}, language = {en} } @article{SchurrDeanMiltonetal.2004, author = {Schurr, Frank Martin and Dean, W. R. J. and Milton, Sue J. and Jeltsch, Florian}, title = {A conceptual model linking demography of the shrub species Grewia flava to the dynamics of Kalahari savannas}, year = {2004}, abstract = {Environmental heterogeneity is a major determinant of plant population dynamics. In semi-arid Kalahari savannas, heterogeneity is created by savanna structure, i.e. by the spatial arrangement and temporal dynamics of woody plant and open grassland microsites. We formulate a conceptual model describing the effects of savanna dynamics on the population dynamics of the animal-dispersed shrub Grewia flava. From empirical results we derive model rules describing effects of savanna structure on several processes in Grewia's life cycle. By formulating the model, we summarise existing information on Grewia demography and identify gaps in this knowledge. Despite a number of such gaps, the model can be used to make certain quantitative predictions. As an example, we apply the model to investigate the role of seed dispersal in Grewia encroachment on rangelands. Model results show that cattle promote encroachment by depositing substantial numbers of seeds in open areas, where Grewia is otherwise dispersal-limited. Finally, we draw some general conclusions about Grewia's life history and population dynamics. Under natural conditions, concentrated seed deposition under woody plants appears to be a key process causing the observed association between Grewia and other woody plants. Furthermore, low rates of recruitment and high adult survival result in slow-motion dynamics of Grewia populations. As a consequence, Grewia populations interact with savanna dynamics on long temporal and short to intermediate spatial scales.}, language = {en} } @article{ReegHeineMihanetal.2020, author = {Reeg, Jette and Heine, Simon and Mihan, Christine and McGee, Sean and Preuss, Thomas G. and Jeltsch, Florian}, title = {A graphical user interface for the plant community model IBC-grass}, series = {Plos One}, volume = {15}, journal = {Plos One}, number = {3}, publisher = {Plos 1}, address = {San Francisco}, issn = {1932-6203}, doi = {10.1371/journal.pone.0230012}, pages = {18}, year = {2020}, abstract = {Plants located adjacent to agricultural fields are important for maintaining biodiversity in semi-natural landscapes. To avoid undesired impacts on these plants due to herbicide application on the arable fields, regulatory risk assessments are conducted prior to registration to ensure proposed uses of plant protection products do not present an unacceptable risk. The current risk assessment approach for these non-target terrestrial plants (NTTPs) examines impacts at the individual-level as a surrogate approach for protecting the plant community due to the inherent difficulties of directly assessing population or community level impacts. However, modelling approaches are suitable higher tier tools to upscale individual-level effects to community level. IBC-grass is a sophisticated plant community model, which has already been applied in several studies. However, as it is a console application software, it was not deemed sufficiently user-friendly for risk managers and assessors to be conveniently operated without prior expertise in ecological models. Here, we present a user-friendly and open source graphical user interface (GUI) for the application of IBC-grass in regulatory herbicide risk assessment. It facilitates the use of the plant community model for predicting long-term impacts of herbicide applications on NTTP communities. The GUI offers two options to integrate herbicide impacts: (1) dose responses based on current standard experiments (acc. to testing guidelines) and (2) based on specific effect intensities. Both options represent suitable higher tier options for future risk assessments of NTTPs as well as for research on the ecological relevance of effects.}, language = {en} } @article{GeyerStrixnerKreftetal.2015, author = {Geyer, Juliane and Strixner, Lena and Kreft, Stefan and Jeltsch, Florian and Ibisch, Pierre L.}, title = {Adapting conservation to climate change: a case study on feasibility and implementation in Brandenburg, Germany}, series = {Regional environmental change}, volume = {15}, journal = {Regional environmental change}, number = {1}, publisher = {Springer}, address = {Heidelberg}, issn = {1436-3798}, doi = {10.1007/s10113-014-0609-9}, pages = {139 -- 153}, year = {2015}, abstract = {Conservation actions need to account for global climate change and adapt to it. The body of the literature on adaptation options is growing rapidly, but their feasibility and current state of implementation are rarely assessed. We discussed the practicability of adaptation options with conservation managers analysing three fields of action: reducing the vulnerability of conservation management, reducing the vulnerability of conservation targets (i.e. biodiversity) and climate change mitigation. For all options, feasibility, current state of implementation and existing obstacles to implementation were analysed, using the Federal State of Brandenburg, Germany, as a case study. Practitioners considered a large number of options useful, most of which have already been implemented at least in part. Those options considered broadly implemented resemble mainly conventional measures of conservation without direct relation to climate change. Managers are facing several obstacles for adapting to climate change, including political reluctance to change, financial and staff shortages in conservation administrations and conflictive EU funding schemes in agriculture. A certain reluctance to act, due to the high degree of uncertainty with regard to climate change scenarios and impacts, is widespread. A lack of knowledge of appropriate methods such as adaptive management often inhibits the implementation of adaptation options in the field of planning and management. Based on the findings for Brandenburg, we generally conclude that it is necessary to focus in particular on options that help to reduce vulnerability of conservation management itself, i.e. those that enhance management effectiveness. For instance, adaptive and proactive risk management can be applied as a no-regrets option, independently from specific climate change scenarios or impacts, strengthening action under uncertainty.}, language = {en} } @article{RomeroMujalliRochowKahletal.2021, author = {Romero-Mujalli, Daniel and Rochow, Markus and Kahl, Sandra M. and Paraskevopoulou, Sofia and Folkertsma, Remco and Jeltsch, Florian and Tiedemann, Ralph}, title = {Adaptive and nonadaptive plasticity in changing environments: Implications for sexual species with different life history strategies}, series = {Ecology and Evolution}, volume = {11}, journal = {Ecology and Evolution}, number = {11}, publisher = {John Wiley \& Sons, Inc.}, address = {New Jersey}, issn = {2045-7758}, pages = {17}, year = {2021}, abstract = {Populations adapt to novel environmental conditions by genetic changes or phenotypic plasticity. Plastic responses are generally faster and can buffer fitness losses under variable conditions. Plasticity is typically modeled as random noise and linear reaction norms that assume simple one-to- one genotype-phenotype maps and no limits to the phenotypic response. Most studies on plasticity have focused on its effect on population viability. However, it is not clear, whether the advantage of plasticity depends solely on environmental fluctuations or also on the genetic and demographic properties (life histories) of populations. Here we present an individual-based model and study the relative importance of adaptive and nonadaptive plasticity for populations of sexual species with different life histories experiencing directional stochastic climate change. Environmental fluctuations were simulated using differentially autocorrelated climatic stochasticity or noise color, and scenarios of directiona climate change. Nonadaptive plasticity was simulated as a random environmental effect on trait development, while adaptive plasticity as a linear, saturating, or sinusoidal reaction norm. The last two imposed limits to the plastic response and emphasized flexible interactions of the genotype with the environment. Interestingly, this assumption led to (a) smaller phenotypic than genotypic variance in the population (many-to- one genotype-phenotype map) and the coexistence of polymorphisms, and (b) the maintenance of higher genetic variation—compared to linear reaction norms and genetic determinism—even when the population was exposed to a constant environment for several generations. Limits to plasticity led to genetic accommodation, when costs were negligible, and to the appearance of cryptic variation when limits were exceeded. We found that adaptive plasticity promoted population persistence under red environmental noise and was particularly important for life histories with low fecundity. Populations produing more offspring could cope with environmental fluctuations solely by genetic changes or random plasticity, unless environmental change was too fast.}, language = {en} } @article{ReegStriglJeltsch2022, author = {Reeg, Jette and Strigl, Lea and Jeltsch, Florian}, title = {Agricultural buffer zone thresholds to safeguard functional bee diversity}, series = {Ecology and Evolution}, volume = {12}, journal = {Ecology and Evolution}, edition = {3}, publisher = {Wiley Online Library}, address = {Hoboken, New Jersey, USA}, issn = {2045-7758}, doi = {10.1002/ece3.8748}, pages = {1 -- 17}, year = {2022}, abstract = {Wild bee species are important pollinators in agricultural landscapes. However, population decline was reported over the last decades and is still ongoing. While agricultural intensification is a major driver of the rapid loss of pollinating species, transition zones between arable fields and forest or grassland patches, i.e., agricultural buffer zones, are frequently mentioned as suitable mitigation measures to support wild bee populations and other pollinator species. Despite the reported general positive effect, it remains unclear which amount of buffer zones is needed to ensure a sustainable and permanent impact for enhancing bee diversity and abundance. To address this question at a pollinator community level, we implemented a process-based, spatially explicit simulation model of functional bee diversity dynamics in an agricultural landscape. More specifically, we introduced a variable amount of agricultural buffer zones (ABZs) at the transition of arable to grassland, or arable to forest patches to analyze the impact on bee functional diversity and functional richness. We focused our study on solitary bees in a typical agricultural area in the Northeast of Germany. Our results showed positive effects with at least 25\% of virtually implemented agricultural buffer zones. However, higher amounts of ABZs of at least 75\% should be considered to ensure a sufficient increase in Shannon diversity and decrease in quasi-extinction risks. These high amounts of ABZs represent effective conservation measures to safeguard the stability of pollination services provided by solitary bee species. As the model structure can be easily adapted to other mobile species in agricultural landscapes, our community approach offers the chance to compare the effectiveness of conservation measures also for other pollinator communities in future.}, language = {en} } @article{BuchmannSchurrNathanetal.2011, author = {Buchmann, Carsten M. and Schurr, Frank Martin and Nathan, Ran and Jeltsch, Florian}, title = {An allometric model of home range formation explains the structuring of animal communities exploiting heterogeneous resources}, series = {Oikos}, volume = {120}, journal = {Oikos}, number = {1}, publisher = {Wiley-Blackwell}, address = {Malden}, issn = {0030-1299}, doi = {10.1111/j.1600-0706.2010.18556.x}, pages = {106 -- 118}, year = {2011}, abstract = {Understanding and predicting the composition and spatial structure of communities is a central challenge in ecology. An important structural property of animal communities is the distribution of individual home ranges. Home range formation is controlled by resource heterogeneity, the physiology and behaviour of individual animals, and their intra- and interspecific interactions. However, a quantitative mechanistic understanding of how home range formation influences community composition is still lacking. To explore the link between home range formation and community composition in heterogeneous landscapes we combine allometric relationships for physiological properties with an algorithm that selects optimal home ranges given locomotion costs, resource depletion and competition in a spatially-explicit individual-based modelling framework. From a spatial distribution of resources and an input distribution of animal body mass, our model predicts the size and location of individual home ranges as well as the individual size distribution (ISD) in an animal community. For a broad range of body mass input distributions, including empirical body mass distributions of North American and Australian mammals, our model predictions agree with independent data on the body mass scaling of home range size and individual abundance in terrestrial mammals. Model predictions are also robust against variation in habitat productivity and landscape heterogeneity. The combination of allometric relationships for locomotion costs and resource needs with resource competition in an optimal foraging framework enables us to scale from individual properties to the structure of animal communities in heterogeneous landscapes. The proposed spatially-explicit modelling concept not only allows for detailed investigation of landscape effects on animal communities, but also provides novel insights into the mechanisms by which resource competition in space shapes animal communities.}, language = {en} } @article{JeltschTewsBroseetal.2004, author = {Jeltsch, Florian and Tews, J{\"o}rg and Brose, Ulrich and Grimm, Volker and Tielb{\"o}rger, Katja and Wichmann, Matthias and Schwager, Monika}, title = {Animal species diversity driven by habitat heterogeneity/diversity : the importance of keystone structures}, year = {2004}, abstract = {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.}, language = {en} } @article{JeltschStephanWiegandetal.2001, author = {Jeltsch, Florian and Stephan, T. and Wiegand, T. and Weber, G. E.}, title = {Arid rangeland management supported by dynamic spatially-explicit simulation models}, year = {2001}, language = {en} } @article{GeyerKreftJeltschetal.2017, author = {Geyer, Juliane and Kreft, Stefan and Jeltsch, Florian and Ibisch, Pierre L.}, title = {Assessing climate change-robustness of protected area management plans-The case of Germany}, series = {PLoS one}, volume = {12}, journal = {PLoS one}, publisher = {PLoS}, address = {San Fransisco}, issn = {1932-6203}, doi = {10.1371/journal.pone.0185972}, pages = {25}, year = {2017}, abstract = {Protected areas are arguably the most important instrument of biodiversity conservation. To keep them fit under climate change, their management needs to be adapted to address related direct and indirect changes. In our study we focus on the adaptation of conservation management planning, evaluating management plans of 60 protected areas throughout Germany with regard to their climate change-robustness. First, climate change-robust conservation management was defined using 11 principles and 44 criteria, which followed an approach similar to sustainability standards. We then evaluated the performance of individual management plans concerning the climate change-robustness framework. We found that climate change-robustness of protected areas hardly exceeded 50 percent of the potential performance, with most plans ranking in the lower quarter. Most Natura 2000 protected areas, established under conservation legislation of the European Union, belong to the sites with especially poor performance, with lower values in smaller areas. In general, the individual principles showed very different rates of accordance with our principles, but similarly low intensity. Principles with generally higher performance values included holistic knowledge management, public accountability and acceptance as well as systemic and strategic coherence. Deficiencies were connected to dealing with the future and uncertainty. Lastly, we recommended the presented principles and criteria as essential guideposts that can be used as a checklist for working towards more climate change-robust planning.}, language = {en} } @article{EstherGroeneveldEnrightetal.2008, author = {Esther, Alexandra and Groeneveld, J{\"u}rgen and Enright, Neal J. and Miller, Ben P. and Lamont, Byron B. and Perry, George L. W. and Schurr, Frank Martin and Jeltsch, Florian}, title = {Assessing the importance of seed immigration on coexistence of plant functional types in a species-rich ecosystem}, issn = {0304-3800}, doi = {10.1016/j.ecolmodel.2008.01.014}, year = {2008}, abstract = {Modelling and empirical studies have shown that input from the regional seed pool is essential to maintain local species diversity. However, most of these studies have concentrated on simplified, if not neutral, model systems, and focus on a limited subset of species or on aggregated measures of diversity only (e.g., species richness or Shannon diversity). Thus they ignore more complex species interactions and important differences between species. To gain a better understanding of how seed immigration affects community structure at the local scale in real communities we conducted computer simulation experiments based on plant functional types (PFTs) for a species-rich, fire-prone Mediterranean-type shrubland in Western Australia. We developed a spatially explicit simulation model to explore the community dynamics of 38 PFTs, defined by seven traits - regeneration mode, seed production, seed size, maximum crown diameter, drought tolerance, dispersal mode and seed bank type - representing 78 woody species. Model parameterisation is based on published and unpublished data on the population dynamics of shrub species collected over 18 years. Simulation experiments are based on two contrasting seed immigration scenarios: (1) the 'equal seed input number' scenario, where the number of immigrant seeds is the same for all PFTs, and (2) the 'equal seed input mass' scenario, where the cumulative mass of migrating seeds is the same for all PFTs. Both scenarios were systematically tested and compared for different overall seed input values. Without immigration the local community drifts towards a state with only 13 coexisting PFTs. With increasing immigration rates in terms of overall mass of seeds the simulated number of coexisting PFTs and Shannon diversity quickly approaches values observed in the field. The equal seed mass scenario resulted in a more diverse community than did the seed number scenario. The model successfully approximates the frequency distributions (relative densities) of all individual plant traits except seed size for scenarios associated with equal seed input mass and high immigration rate. However, no scenario satisfactorily approximated the frequency distribution for all traits in combination. Our results show that regional seed input can explain the more aggregated measures of local community structure, and some, but not all, aspects of community composition. This points to the possible importance of other (untested) processes and traits (e.g., dispersal vectors) operating at the local scale. Our modelling framework can readily allow new factors to be systematically investigated, which is a major advantage compared to previous simulation studies, as it allows us to find structurally realistic models, which can address questions pertinent to ecological theory and to conservation management.}, language = {en} } @article{RossmanithGrimmBlaumetal.2006, author = {Rossmanith, Eva and Grimm, Volker and Blaum, Niels and Jeltsch, Florian}, title = {Behavioural flexibility in the mating system buffers population extinction: lessons from the Lesser Spotted Woodpecker (Picoides minor)}, doi = {10.1111/j.1365-2656.2006.01074.x}, year = {2006}, abstract = {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}, language = {en} } @article{WasiolkaBlaumJeltschetal.2009, author = {Wasiolka, Bernd and Blaum, Niels and Jeltsch, Florian and Henschel, Joh}, title = {Behavioural responses of the lizard "Pedioplanis l. lineoocellata" to overgrazing}, issn = {1146-609X}, doi = {10.1016/j.actao.2008.09.009}, year = {2009}, abstract = {We studied the effects of overgrazing on the foraging behaviour of the lizard Pedioplanis l. lineoocellata (Spotted Sand Lizard), a sit-and-wait forager, in habitats of differing vegetation states to determine the effects of habitat degradation on this species. At high grazing intensity where vegetation cover and diversity is low, the lizard P. lineoocellata moves more frequently, spends more time moving and covers larger distances than in habitats where vegetation cover and diversity is high. These behavioural changes in movement patterns can be explained by less abundant prey in habitats with low vegetation cover and diversity. Although morphology, phylogeny and physiology of P. lineoocellata should constrain the change in foraging behaviour, the species has modified its foraging strategy from sit- and-wait to actively foraging. We assume that this behavioural flexibility of P. lineoocellata is a buffer mechanism enabling the species to use and survive in degraded (unfavourable) habitats.}, language = {en} } @article{JeltschWeberParueloetal.2000, author = {Jeltsch, Florian and Weber, Gisela and Paruelo, J. and Dean, W. R. J. and Milton, Sue J. and VanRooyen, N.}, title = {Beweidung als Degradationsfaktor in ariden und semiariden Weidesystemen}, year = {2000}, language = {de} } @article{SeifanSeifanSchiffersetal.2013, author = {Seifan, Merav and Seifan, Tal and Schiffers, Katja and Jeltsch, Florian and Tielboerger, Katja}, title = {Beyond the competition-colonization trade-off - linking multiple trait response to disturbance characteristics}, series = {The American naturalist : a bi-monthly journal devoted to the advancement and correlation of the biological sciences}, volume = {181}, journal = {The American naturalist : a bi-monthly journal devoted to the advancement and correlation of the biological sciences}, number = {2}, publisher = {Univ. of Chicago Press}, address = {Chicago}, issn = {0003-0147}, doi = {10.1086/668844}, pages = {151 -- 160}, year = {2013}, abstract = {Disturbances' role in shaping communities is well documented but highly disputed. We suggest replacing the overused two-trait trade-off approach with a functional group scheme, constructed from combinations of four key traits that represent four classes of species' responses to disturbances. Using model results and field observations from sites affected by two highly different disturbances, we demonstrated that popular dichotomous trade-offs are not sufficient to explain community dynamics, even if some emerge under certain conditions. Without disturbances, competition was only sufficient to predict species survival but not relative success, which required some escape mechanism (e.g., long-term dormancy). With highly predictable and large-scale disturbances, successful species showed a combination of high individual tolerance to disturbance and, more surprisingly, high competitive ability. When disturbances were less predictable, high individual tolerance and long-term seed dormancy were favored, due to higher environmental uncertainty. Our study demonstrates that theories relying on a small number of predefined trade-offs among traits (e.g., competition-colonization trade-off) may lead to unrealistic results. We suggest that the understanding of disturbance-community relationships can be significantly improved by employing sets of relevant trait assemblies instead of the currently common approach in which trade-offs are assumed in advance.}, language = {en} } @article{NathanMonkArlinghausetal.2022, author = {Nathan, Ran and Monk, Christopher T. and Arlinghaus, Robert and Adam, Timo and Al{\´o}s, Josep and Assaf, Michael and Baktoft, Henrik and Beardsworth, Christine E. and Bertram, Michael G. and Bijleveld, Allert and Brodin, Tomas and Brooks, Jill L. and Campos-Candela, Andrea and Cooke, Steven J. and Gjelland, Karl O. and Gupte, Pratik R. and Harel, Roi and Hellstrom, Gustav and Jeltsch, Florian and Killen, Shaun S. and Klefoth, Thomas and Langrock, Roland and Lennox, Robert J. and Lourie, Emmanuel and Madden, Joah R. and Orchan, Yotam and Pauwels, Ine S. and Riha, Milan and R{\"o}leke, Manuel and Schl{\"a}gel, Ulrike and Shohami, David and Signer, Johannes and Toledo, Sivan and Vilk, Ohad and Westrelin, Samuel and Whiteside, Mark A. and Jaric, Ivan}, title = {Big-data approaches lead to an increased understanding of the ecology of animal movement}, series = {Science}, volume = {375}, journal = {Science}, number = {6582}, publisher = {American Assoc. for the Advancement of Science}, address = {Washington}, issn = {0036-8075}, doi = {10.1126/science.abg1780}, pages = {734 -- +}, year = {2022}, abstract = {Understanding animal movement is essential to elucidate how animals interact, survive, and thrive in a changing world. Recent technological advances in data collection and management have transformed our understanding of animal "movement ecology" (the integrated study of organismal movement), creating a big-data discipline that benefits from rapid, cost-effective generation of large amounts of data on movements of animals in the wild. These high-throughput wildlife tracking systems now allow more thorough investigation of variation among individuals and species across space and time, the nature of biological interactions, and behavioral responses to the environment. Movement ecology is rapidly expanding scientific frontiers through large interdisciplinary and collaborative frameworks, providing improved opportunities for conservation and insights into the movements of wild animals, and their causes and consequences.}, language = {en} } @article{MeyerRaudnitschkaSteinhauseretal.2008, author = {Meyer, Jork and Raudnitschka, Dorit and Steinhauser, J. and Jeltsch, Florian and Brandl, Roland}, title = {Biology and ecology of "Thallomys nigricauda" (Rodentia, Muridae) in the Thornveld savannah of South Africa}, issn = {1616-5047}, doi = {10.1016/j.mambio.2006.11.002}, year = {2008}, language = {en} } @article{NiCaoJeltschetal.2014, author = {Ni, Jian and Cao, Xianyong and Jeltsch, Florian and Herzschuh, Ulrike}, title = {Biome distribution over the last 22,000 yr in China}, series = {Palaeogeography, palaeoclimatology, palaeoecology : an international journal for the geo-sciences}, volume = {409}, journal = {Palaeogeography, palaeoclimatology, palaeoecology : an international journal for the geo-sciences}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0031-0182}, doi = {10.1016/j.palaeo.2014.04.023}, pages = {33 -- 47}, year = {2014}, abstract = {Patterns of past vegetation changes over time and space can help facilitate better understanding of the interactions among climate, ecosystem, and human impact. Biome changes in China over the last 22,000 yr (calibrated radiocarbon date, a BP) were numerically reconstructed by using a standard approach of pollen-plant functional type-biome assignment (biomization). The biomization procedure involves pollen data from 2434 surface sites and 228 fossil sites with a high quality of pollen count and C-14 dating, 51 natural and three anthropogenic plant functional types (PFTs), as well as 19 natural and one anthropogenic biome. Surface pollen-based reconstruction of modern natural biome patterns is in good agreement (74.4\%) with actual vegetation distribution in China. However, modem large-scale anthropogenic biome reconstruction has not been successful based on the current setup of three anthropogenic PFTs (plantation, secondary, and disturbed PFT) because of the limitation of non-species level pollen identification and the difficulty in the clear assignment of disturbed PFTs. The non-anthropogenic biome distributions of 44 time slices at 500-year intervals show large-scale discrepant and changed vegetation patterns from the last glacial maximum (LGM) to the Holocene throughout China. From 22 ka BP to 19 ka BP, temperate grassland, xerophytic shrubland, and desert dominated northern China, whereas cold or cool forests flourished in central China. Warm-temperate evergreen forests were restricted to far southern China, and tropical forests were absent During 18.5 ka BP to 12 ka BP, cold, cool, and dry biomes extended to some parts of northern, westem, and eastern China. Warm-temperate evergreen and mixed forests gradually expanded to occupy the whole of southern China. A slight northward shift of forest biomes occurred from 15 ka BP to 12 lea BP. During 11.5 ka BP to 9 ka BP, temperate grassland and shrubland gradually stretched to northern and western China. Cold and cool forests widely expanded into northern and central China, as well as in the northern margin of South China along with temperate deciduous forest. Since the early mid-Holocene (approximately 8.5 ka BP to 5.5 ka BP), all forest biomes shifted northward at the expense of herbaceous and shrubby biomes. Simultaneously, cold and cool forest biomes occupied the marginal areas of the Tibetan Plateau and the high mountains in western China. During the middle to late Holocene, from 5 ka to the present, temperate grassland and xerophytic shrubland expanded to the south and east, whereas temperate deciduous forests slightly shifted southward. After 3 lea BP, forest biomes were absent in western China and on the Tibetan plateau surface. Dramatic biome shifts from the LGM to the Holocene were observed in the forest-grassland ecotone and transitional zones between temperate and subtropical climates, between subtropical and tropical regions, and in the mountainous margins of the eastern Tibetan Plateau. Evidence showed more human disturbances during the late Holocene. More pollen records and historical documents are therefore further needed to understand fully the human disturbance-induced large-scale forest changes. In addition, more classifications of anthropogenic biome or land cover, more distinct assignment of pollen taxa to anthropogenic PFTs, and more effective numerical and/or mechanistic techniques in building large-scale human disturbances are required. (C) 2014 Elsevier B.V. All rights reserved.}, language = {en} } @article{BlaumSeymourRossmanithetal.2009, author = {Blaum, Niels and Seymour, Colleen and Rossmanith, Eva and Schwager, Monika and Jeltsch, Florian}, title = {Changes in arthropod diversity along a land use driven gradient of shrub cover in savanna rangelands : identifcation of suitable indicators}, issn = {0960-3115}, doi = {10.1007/s10531-008-9498-x}, year = {2009}, abstract = {Shrub encroachment linked to heavy grazing has dramatically changed savanna landscapes, and is a major form of rangeland degradation. Our understanding of how shrub encroachment affects arthropod communities is poor, however. Here, we investigate the effects of shrub encroachment on abundance and diversity of ground-dwelling (wingless) arthropods at varying levels of shrub cover in the southern Kalahari. We also ascertain if invertebrate assemblage composition changes with habitat structure and identify which aspects of habitat structure (e.g., grass cover, herbaceous plant cover, shrub density) correlate most strongly with these changes. Ant, scorpion and dung beetle abundance increased with shrub cover, whereas grasshoppers and solifuges declined. Spider and beetle abundance exhibited hump-shaped relationships with shrub cover. RTU richness within orders either mirrored abundances, or exhibited no trend. Shrub density was the habitat component most correlated with similarities between invertebrate assemblages. Ground-dwelling arthropods showed clear shifts in species assemblage composition at a similarity level of 65\% according to shrub density. Changes in indicator species showed that within the Tenebrionidae (darkling beetles), certain species respond positively to shrub thickening, replacing other species within the Family. Small-bodied, wingless Scarabaeidae (dung beetles) tended to increase with increased shrub density and three species emerged as significant indicators of more thickened habitats, although this might be a response to greater dung availability, rather than habitat structure itself. We conclude that because ground- dwelling invertebrates showed such clear responses in species assemblage composition, they present excellent candidates for use as indicator species in further studies into bush encroachment.}, language = {en} } @article{GeyerKieferKreftetal.2011, author = {Geyer, Juliane and Kiefer, Iris and Kreft, Stefan and Chavez, Veronica and Salafsky, Nick and Jeltsch, Florian and Ibisch, Pierre L.}, title = {Classification of climate-change-induced stresses on biological diversity}, series = {Conservation biology : the journal of the Society for Conservation Biology}, volume = {25}, journal = {Conservation biology : the journal of the Society for Conservation Biology}, number = {4}, publisher = {Wiley-Blackwell}, address = {Malden}, issn = {0888-8892}, doi = {10.1111/j.1523-1739.2011.01676.x}, pages = {708 -- 715}, year = {2011}, abstract = {Conservation actions need to account for and be adapted to address changes that will occur under global climate change. The identification of stresses on biological diversity (as defined in the Convention on Biological Diversity) is key in the process of adaptive conservation management. We considered any impact of climate change on biological diversity a stress because such an effect represents a change (negative or positive) in key ecological attributes of an ecosystem or parts of it. We applied a systemic approach and a hierarchical framework in a comprehensive classification of stresses to biological diversity that are caused directly by global climate change. Through analyses of 20 conservation sites in 7 countries and a review of the literature, we identified climate-change-induced stresses. We grouped the identified stresses according to 3 levels of biological diversity: stresses that affect individuals and populations, stresses that affect biological communities, and stresses that affect ecosystem structure and function. For each stress category, we differentiated 3 hierarchical levels of stress: stress class (thematic grouping with the coarsest resolution, 8); general stresses (thematic groups of specific stresses, 21); and specific stresses (most detailed definition of stresses, 90). We also compiled an overview of effects of climate change on ecosystem services using the categories of the Millennium Ecosystem Assessment and 2 additional categories. Our classification may be used to identify key climate-change-related stresses to biological diversity and may assist in the development of appropriate conservation strategies. The classification is in list format, but it accounts for relations among climate-change-induced stresses.}, language = {en} } @article{JeltschTews2004, author = {Jeltsch, Florian and Tews, J{\"o}rg}, title = {Climate change impacts woody plant population dynamics in arid savanna}, year = {2004}, language = {en} } @article{SeifanSeifanJeltschetal.2012, author = {Seifan, Merav and Seifan, Tal and Jeltsch, Florian and Tielboerger, Katja}, title = {Combined disturbances and the role of their spatial and temporal properties in shaping community structure}, series = {Perspectives in plant ecology, evolution and systematics}, volume = {14}, journal = {Perspectives in plant ecology, evolution and systematics}, number = {3}, publisher = {Elsevier}, address = {Jena}, issn = {1433-8319}, doi = {10.1016/j.ppees.2011.11.003}, pages = {217 -- 229}, year = {2012}, abstract = {Disturbances are characteristic for many ecosystems. However, we still lack generalizations concerning their role in shaping communities, particularly when disturbances co-occur. To study such effects, we used a novel modeling approach that is unrestricted by a priori tradeoffs among specific plant traits, except for those generated by allocation principles. Thus, trait combinations were emergent properties associated with biotic and abiotic constraints. Specifically, we asked which traits dominate under specific disturbance regimes, whether single and combined disturbance regimes promote similar trait tradeoffs and how complex disturbance regimes affect species richness and functional diversity. Overall, disturbances' temporal properties governed the outcome of combined disturbances and were a stronger assortative force than spatial disturbance properties: low temporal predictability decreased seed-dispersability and dormancy, but increased competitive ability and disturbance tolerance. Evidence for tradeoffs between different colonization modes and between dormancy and disturbance tolerance were found, while surprisingly, the widely accepted colonization-competition tradeoff was not generated. Diversity was highest at intermediate disturbance intensity, but decreased monotonically with increasing unpredictability. In accordance with our results, future models should avoid restrictive assumptions about tradeoffs to generate robust and more general predictions about the role of disturbances for community dynamics.}, language = {en} } @article{GeisslerFiedlerNietal.2019, author = {Geissler, Katja and Fiedler, Sebastian and Ni, Jian and Herzschuh, Ulrike and Jeltsch, Florian}, title = {Combined effects of grazing and climate warming drive shrub dominance on the Tibetan Plateau}, series = {The Rangeland journal}, volume = {41}, journal = {The Rangeland journal}, number = {5}, publisher = {CSIRO Publishing}, address = {Collingwood}, issn = {1036-9872}, doi = {10.1071/RJ19027}, pages = {425 -- 439}, year = {2019}, abstract = {Encroachment of shrubs into the unique pastoral grassland ecosystems of the Tibetan Plateau has significant impact on ecosystem services, especially forage production. We developed a process-based ecohydrological model to identify the relative importance of the main drivers of shrub encroachment for the alpine meadows within the Qinghai province. Specifically, we explored the effects of summer livestock grazing (intensity and type of livestock) together with the effects of climate warming, including interactions between herbaceous and woody vegetation and feedback loops between soil, water and vegetation. Under current climatic conditions and a traditional herd composition, an increasing grazing intensity above a threshold value of 0.32 +/- 0.10 large stock units (LSU) ha(-1) day(-1) changes the vegetation composition from herbaceous towards a woody and bare soil dominated system. Very high grazing intensity (above 0.8 LSU ha(-1) day(-1)) leads to a complete loss of any vegetation. Under warmer conditions, the vegetation showed a higher resilience against livestock farming. This resilience is enhanced when the herd has a higher browser : grazer ratio. A cooler climate has a shrub encroaching effect, whereas warmer conditions increase the cover of the herbaceous vegetation. This effect was primarily due to season length and an accompanied competitive loss of slower growing shrubs, rather than evaporative water loss leading to less soil water in deeper soil layers for deeper rooting shrubs. If climate warming is driving current shrub encroachment, we conclude it is only indirectly so. It would be manifest by an advancing shrubline and could be regarded as a climatic escape of specific shrub species such as Potentilla fruticosa. Under the recent high intensity of grazing, only herding by more browsing animals can potentially prevent both shrub encroachment and the complete loss of herbaceous vegetation.}, language = {en} } @article{TeckentrupGrimmKramerSchadtetal.2018, author = {Teckentrup, Lisa and Grimm, Volker and Kramer-Schadt, Stephanie and Jeltsch, Florian}, title = {Community consequences of foraging under fear}, series = {Ecological modelling : international journal on ecological modelling and engineering and systems ecolog}, volume = {383}, journal = {Ecological modelling : international journal on ecological modelling and engineering and systems ecolog}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0304-3800}, doi = {10.1016/j.ecolmodel.2018.05.015}, pages = {80 -- 90}, year = {2018}, abstract = {Non-consumptive effects of predators within ecosystems can alter the behavior of individual prey species, and have cascading effects on other trophic levels. In this context, an understanding of non-consumptive predator effects on the whole prey community is crucial for predicting community structure and composition, hence biodiversity patterns. We used an individual-based, spatially-explicit modelling approach to investigate the consequences of landscapes of fear on prey community metrics. The model spans multiple hierarchical levels from individual home range formation based on food availability and perceived predation risk to consequences on prey community structure and composition. This mechanistic approach allowed us to explore how important factors such as refuge availability and foraging strategy under fear affect prey community metrics. Fear of predators affected prey space use, such as home range formation. These adaptations had broader consequences for the community leading to changes in community structure and composition. The strength of community responses to perceived predation risk was driven by refuge availability in the landscape and the foraging strategy of prey animals. Low refuge availability in the landscape strongly decreased diversity and total biomass of prey communities. Additionally, body mass distributions in prey communities facing high predation risk were shifted towards small prey animals. With increasing refuge availability the consequences of non-consumptive predator effects were reduced, diversity and total biomass of the prey community increased. Prey foraging strategies affected community composition. Under medium refuge availability, risk-averse prey communities consisted of many small animals while risk-taking prey communities showed a more even body mass distribution. Our findings reveal that non-consumptive predator effects can have important implications for prey community diversity and should therefore be considered in the context of conservation and nature management.}, language = {en} } @article{PfestorfWeissMuelleretal.2013, author = {Pfestorf, H. and Weiss, L. and M{\"u}ller, J. and Boch, Steffen and Socher, S. A. and Prati, Daniel and Sch{\"o}ning, Ingo and Weisser, W. and Fischer, M. and Jeltsch, Florian}, title = {Community mean traits as additional indicators to monitor effects of land-use intensity On grassland plant diversity}, series = {Perspectives in plant ecology, evolution and systematics}, volume = {15}, journal = {Perspectives in plant ecology, evolution and systematics}, number = {1}, publisher = {Elsevier}, address = {Jena}, issn = {1433-8319}, doi = {10.1016/j.ppees.2012.10.003}, pages = {1 -- 11}, year = {2013}, abstract = {Semi-natural grasslands, biodiversity hotspots in Central-Europe, suffer from the cessation of traditional land-use. Amount and intensity of these changes challenge current monitoring frameworks typically based on classic indicators such as selected target species or diversity indices. Indicators based on plant functional traits provide an interesting extension since they reflect ecological strategies at individual and ecological processes at community levels. They typically show convergent responses to gradients of land-use intensity over scales and regions, are more directly related to environmental drivers than diversity components themselves and enable detecting directional changes in whole community dynamics. However, probably due to their labor- and cost intensive assessment in the field, they have been rarely applied as indicators so far. Here we suggest overcoming these limitations by calculating indicators with plant traits derived from online accessible databases. Aiming to provide a minimal trait set to monitor effects of land-use intensification on plant diversity we investigated relationships between 12 community mean traits, 2 diversity indices and 6 predictors of land-use intensity within grassland communities of 3 different regions in Germany (part of the German 'Biodiversity Exploratory' research network). By standardization of traits and diversity measures, use of null models and linear mixed models we confirmed (i) strong links between functional community composition and plant diversity, (ii) that traits are closely related to land-use intensity, and (iii) that functional indicators are equally, or even more sensitive to land-use intensity than traditional diversity indices. The deduced trait set consisted of 5 traits, i.e., specific leaf area (SLA), leaf dry matter content (LDMC), seed release height, leaf distribution, and onset of flowering. These database derived traits enable the early detection of changes in community structure indicative for future diversity loss. As an addition to current monitoring measures they allow to better link environmental drivers to processes controlling community dynamics.}, language = {en} } @article{SonnemannPfestorfJeltschetal.2015, author = {Sonnemann, Ilja and Pfestorf, Hans and Jeltsch, Florian and Wurst, Susanne}, title = {Community-Weighted Mean Plant Traits Predict Small Scale Distribution of Insect Root Herbivore Abundance}, series = {PLoS one}, volume = {10}, journal = {PLoS one}, number = {10}, publisher = {PLoS}, address = {San Fransisco}, issn = {1932-6203}, doi = {10.1371/journal.pone.0141148}, pages = {14}, year = {2015}, abstract = {Small scale distribution of insect root herbivores may promote plant species diversity by creating patches of different herbivore pressure. However, determinants of small scale distribution of insect root herbivores, and impact of land use intensity on their small scale distribution are largely unknown. We sampled insect root herbivores and measured vegetation parameters and soil water content along transects in grasslands of different management intensity in three regions in Germany. We calculated community-weighted mean plant traits to test whether the functional plant community composition determines the small scale distribution of insect root herbivores. To analyze spatial patterns in plant species and trait composition and insect root herbivore abundance we computed Mantel correlograms. Insect root herbivores mainly comprised click beetle (Coleoptera, Elateridae) larvae (43\%) in the investigated grasslands. Total insect root herbivore numbers were positively related to community-weighted mean traits indicating high plant growth rates and biomass (specific leaf area, reproductive-and vegetative plant height), and negatively related to plant traits indicating poor tissue quality (leaf C/N ratio). Generalist Elaterid larvae, when analyzed independently, were also positively related to high plant growth rates and furthermore to root dry mass, but were not related to tissue quality. Insect root herbivore numbers were not related to plant cover, plant species richness and soil water content. Plant species composition and to a lesser extent plant trait composition displayed spatial autocorrelation, which was not influenced by land use intensity. Insect root herbivore abundance was not spatially autocorrelated. We conclude that in semi-natural grasslands with a high share of generalist insect root herbivores, insect root herbivores affiliate with large, fast growing plants, presumably because of availability of high quantities of food. Affiliation of insect root herbivores with large, fast growing plants may counteract dominance of those species, thus promoting plant diversity.}, language = {en} } @article{JeltschMoloneySchwageretal.2011, author = {Jeltsch, Florian and Moloney, Kirk A. and Schwager, Monika and K{\"o}rner, Katrin and Blaum, Niels}, title = {Consequences of correlations between habitat modifications and negative impact of climate change for regional species survival}, series = {Agriculture, ecosystems \& environment : an international journal for scientific research on the relationship of agriculture and food production to the biosphere}, volume = {145}, journal = {Agriculture, ecosystems \& environment : an international journal for scientific research on the relationship of agriculture and food production to the biosphere}, number = {1}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0167-8809}, doi = {10.1016/j.agee.2010.12.019}, pages = {49 -- 58}, year = {2011}, abstract = {While several empirical and theoretical studies have clearly shown the negative effects of climate or landscape changes on population and species survival only few of them addressed combined and correlated consequences of these key environmental drivers. This also includes positive landscape changes such as active habitat management and restoration to buffer the negative effects of deteriorating climatic conditions. In this study, we apply a conceptual spatial modelling approach based on functional types to explore the effects of both positive and negative correlations between changes in habitat and climate conditions on the survival of spatially structured populations. We test the effect of different climate and landscape change scenarios on four different functional types that represent a broad spectrum of species characterised by their landscape level carrying capacity, the local population turnover rates at the patch level (K-strategies vs. r-strategies) and dispersal characterstics. As expected, simulation results show that correlated landscape and climatic changes can accelerate (in case of habitat loss or degradation) or slow down (in case of habitat gain or improvement) regional species extinction. However, the strength of the combined changes depends on local turnover at the patch level, the overall landscape capacity of the species, and its specific dispersal characteristics. Under all scenarios of correlated changes in habitat and climate conditions we found the highest sensitivity for functional types representing species with a low landscape capacity but a high population growth rate and a strong density regulation causing a high turnover at the local patch level. The relative importance of habitat loss or habitat degradation, in combination with climate deterioration, differed among the functional types. However, an increase in regional capacity revealed a similar response pattern: For all types, habitat improvement led to higher survival times than habitat gain, i.e. the establishment of new habitat patches. This suggests that improving local habitat quality at a regional scale is a more promising conservation strategy under climate change than implementing new habitat patches. This conceptual modelling study provides a general framework to better understand and support the management of populations prone to complex environmental changes.}, language = {en} } @article{JeltschHansenTackmannetal.2003, author = {Jeltsch, Florian and Hansen, Frank and Tackmann, K. and Wissel, Christian and Thulke, Hans-Hermann}, title = {Controlling Echinococcus multilocularis - ecological implications of field trials}, year = {2003}, language = {en} } @article{PfestorfKoernerSonnemannetal.2016, author = {Pfestorf, Hans and K{\"o}rner, Katrin and Sonnemann, Ilja and Wurst, Susanne and Jeltsch, Florian}, title = {Coupling experimental data with individual-based modelling reveals differential effects of root herbivory on grassland plant co-existence along a resource gradient}, series = {Journal of vegetation science}, volume = {27}, journal = {Journal of vegetation science}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {1100-9233}, doi = {10.1111/jvs.12357}, pages = {269 -- 282}, year = {2016}, abstract = {QuestionThe empirical evidence of root herbivory effects on plant community composition and co-existence is contradictory. This originates from difficulties connected to below-ground research and confinement of experimental studies to a small range of environmental conditions. Here we suggest coupling experimental data with an individual-based model to overcome the limitations inherent in either approach. To demonstrate this, we investigated the consequences of root herbivory, as experimentally observed on individual plants, on plant competition and co-existence in a population and community context under different root herbivory intensities (RHI), fluctuating and constant root herbivore activity and grazing along a resource gradient. LocationBerlin, Germany, glasshouse; Potsdam, Germany, high performance cluster computer. MethodsThe well-established community model IBC-Grass was adapted to allow for a flexible species parameterization and to include annual species. Experimentally observed root herbivory effects on performance of eight common grassland plant species were incorporated into the model by altering plant growth rates. We then determined root herbivore effects on plant populations, competitive hierarchy and consequences for co-existence and community diversity. ResultsRoot herbivory reduced individual biomass, but temporal fluctuation allowed for compensation of herbivore effects. Reducing resource availability strongly shifted competitive hierarchies, with, however, more similar hierarchies along the gradient under root herbivory, pointing to reduced ecological species differences. Consequently, negative effects on co-existence and diversity prevailed, with the exception of a few positive effects on co-existence of selected species pairs. Temporal fluctuation alleviated but did not remove negative root herbivore effects, despite of the stronger influence of intra- compared to interspecific competition. Grazing in general augmented co-existence. Most interestingly, grazing interacted with RHI and resource availability by promoting positive effects of root herbivory. ConclusionsThrough integrating experimental data on the scale of individual plants with a simulation model we verified that root herbivory could affect plant competition with consequences for species co-existence. Our approach demonstrates the benefit that accrues when empirical and modelling approaches are brought more closely together, and that gathering data on distinct processes and under specific conditions, combined with appropriate models, can be used to answer challenging research questions in a more general way.}, language = {en} } @article{SchiffersSchurrTielboergeretal.2008, author = {Schiffers, Katja and Schurr, Frank Martin and Tielb{\"o}rger, Katja and Urbach, Carsten and Moloney, Kirk A. and Jeltsch, Florian}, title = {Dealing with virtual aggregation : a new index for analysing heterogeneous point patterns}, issn = {0906-7590}, doi = {10.1111/j.0906-7590.2008.05374.x}, year = {2008}, language = {en} } @article{SoutoVeigaGroeneveldEnrightetal.2022, author = {Souto-Veiga, Rodrigo and Groeneveld, Juergen and Enright, Neal J. and Fontaine, Joseph B. and Jeltsch, Florian}, title = {Declining pollination success reinforces negative climate and fire change impacts in a serotinous, fire-killed plant}, series = {Plant ecology : an international journal}, volume = {223}, journal = {Plant ecology : an international journal}, number = {7}, publisher = {Springer}, address = {Dordrecht}, issn = {1385-0237}, doi = {10.1007/s11258-022-01244-7}, pages = {863 -- 881}, year = {2022}, abstract = {Climate change projections predict that Mediterranean-type ecosystems (MTEs) are becoming hotter and drier and that fires will become more frequent and severe. While most plant species in these important biodiversity hotspots are adapted to hot, dry summers and recurrent fire, the Interval Squeeze framework suggests that reduced seed production (demographic shift), reduced seedling establishment after fire (post fire recruitment shift), and reduction in the time between successive fires (fire interval shift) will threaten fire killed species under climate change. One additional potential driver of accelerated species decline, however, has not been considered so far: the decrease in pollination success observed in many ecosystems worldwide has the potential to further reduce seed accumulation and thus population persistence also in these already threatened systems. Using the well-studied fire-killed and serotinous shrub species Banksia hookeriana as an example, we apply a new spatially implicit population simulation model to explore population dynamics under past (1988-2002) and current (2003-2017) climate conditions, deterministic and stochastic fire regimes, and alternative scenarios of pollination decline. Overall, model results suggest that while B. hookeriana populations were stable under past climate conditions, they will not continue to persist under current (and prospective future) climate. Negative effects of climatic changes and more frequent fires are reinforced by the measured decline in seed set leading to further reduction in the mean persistence time by 12-17\%. These findings clearly indicate that declining pollination rates can be a critical factor that increases further the pressure on the persistence of fire-killed plants. Future research needs to investigate whether other fire-killed species are similarly threatened, and if local population extinction may be compensated by recolonization events, facilitating persistence in spatially structured meta-communities.}, language = {en} } @article{KoernerJeltsch2008, author = {K{\"o}rner, Katrin and Jeltsch, Florian}, title = {Detecting general plant functional type responses in fragmented landscapes using spatially-explicit simulations}, issn = {0304-3800}, doi = {10.1016/j.ecolmodel.2007.08.002}, year = {2008}, language = {en} } @article{LohmannFalkGeissleretal.2014, author = {Lohmann, Dirk and Falk, Thomas and Geissler, Katja and Blaum, Niels and Jeltsch, Florian}, title = {Determinants of semi-arid rangeland management in a land reform setting in Namibia}, series = {Journal of arid environments}, volume = {100}, journal = {Journal of arid environments}, publisher = {Elsevier}, address = {London}, issn = {0140-1963}, doi = {10.1016/j.jaridenv.2013.10.005}, pages = {23 -- 30}, year = {2014}, abstract = {To assess the ecological and economic implications of the redistributive land reform in semi-arid Namibia, we investigated to what extent land reform beneficiaries adjust herd size and herd composition according to environmental (rainfall, vegetation) and economic variables (herd size, financial assets, running costs). We performed model-based role-plays with Namibian land reform beneficiaries, simulating 10 years of rangeland management. Our study revealed that the farmers surveyed mainly manage their herds according to their economic situation (herd size and account balance) but do not take environmental variability (rainfall and vegetation) into account. Further, our results indicate that, due to financial pressure, farmers are not able to apply their desired management strategies, and that owners of small farms face a higher risk of economic failure. However, farmers apply rather conservative and constant stocking rates and will thus, given the current economic limitations, likely not contribute to semi-arid savanna degradation. We conclude that land reform beneficiaries need support to be able to apply straightforward and efficient management strategies. This could be achieved by facilitating cooperation between small farming businesses and by supporting initial investment in productive cattle herds at the time of redistribution of the land.}, language = {en} } @article{LuftNeumannItzerottetal.2016, author = {Luft, Laura and Neumann, C. and Itzerott, S. and Lausch, A. and Doktor, D. and Freude, M. and Blaum, Niels and Jeltsch, Florian}, title = {Digital and real-habitat modeling of Hipparchia statilinus based on hyper spectral remote sensing data}, series = {International journal of environmental science and technology}, volume = {13}, journal = {International journal of environmental science and technology}, publisher = {Springer}, address = {New York}, issn = {1735-1472}, doi = {10.1007/s13762-015-0859-1}, pages = {187 -- 200}, year = {2016}, abstract = {The abandonment of military areas leads to succession processes affecting valuable open-land habitats and is considered to be a major threat for European butterflies. We assessed the ability of hyper spectral remote sensing data to spatially predict the occurrence of one of the most endangered butterfly species (Hipparchia statilinus) in Brandenburg (Germany) on the basis of habitat characteristics at a former military training area. Presence-absence data were sampled on a total area of 36 km(2), and N = 65 adult individuals of Hipparchia statilinus could be detected. The floristic composition within the study area was modeled in a three-dimensional ordination space. Occurrence probabilities for the target species were predicted as niches between ordinated floristic gradients by using Regression Kriging of Indicators. Habitat variance could be explained by up to 81 \% with spectral variables at a spatial resolution of 2 x 2 m by transferring PLSR models to imagery. Ordinated ecological niche of Hipparchia statilinus was tested against environmental predictor variables. N = 6 variables could be detected to be significantly correlated with habitat preferences of Hipparchia statilinus. They show that Hipparchia statilinus can serve as a valuable indicator for the evaluation of the conservation status of Natura 2000 habitat type 2330 (inland dunes with open Corynephorus and Agrostis grasslands) protected by the Habitat Directive (Council Directive 92/43/EEC). The authors of this approach, conducted in August 2013 at Doberitzer Heide Germany, aim to increase the value of remote sensing as an important tool for questions of biodiversity research and conservation.}, language = {en} } @article{MayGiladiZivetal.2012, author = {May, Felix and Giladi, Itamar and Ziv, Yaron and Jeltsch, Florian}, title = {Dispersal and diversity - unifying scale-dependent relationships within the neutral theory}, series = {Oikos}, volume = {121}, journal = {Oikos}, number = {6}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {0030-1299}, doi = {10.1111/j.1600-0706.2011.20078.x}, pages = {942 -- 951}, year = {2012}, abstract = {The response of species diversity to dispersal capability is inherently scale-dependent: increasing dispersal capability is expected to increase diversity at the local scale, while decreasing diversity at the metacommunity scale. However, these expectations are based on model formulations that neglect dispersal limitation and species segregation at the local scale. We developed a unifying framework of dispersaldiversity relationships and tested the generality of these expectations. For this purpose we used a spatially-explicit neutral model with various combinations of survey area (local scale) and landscape size (metacommunity scale). Simulations were conducted using landscapes of finite and of conceptually infinite size. We analyzed the scale-dependence of dispersal-diversity relationships for exponentially-bounded versus fat-tailed dispersal kernels, several levels of speciation rate and contrasting assumptions on recruitment at short dispersal distances. We found that the ratio of survey area to landscape size is a major determinant of dispersaldiversity relationships. With increasing survey-to-landscape area ratio the dispersaldiversity relationship switches from monotonically increasing through a U-shaped pattern (with a local minimum) to a monotonically decreasing pattern. Therefore, we provide a continuous set of dispersaldiversity relationships, which contains the response shapes reported previously as extreme cases. We suggest the mean dispersal distance with the minimum of species diversity (minimizing dispersal distance) for a certain scenario as a key characteristic of dispersaldiversity relationships. We show that not only increasing mean dispersal distances, but also increasing variances of dispersal can enhance diversity at the local scale, given a diverse species pool at the metacommunity scale. In conclusion, the response of diversity to variations of dispersal capability at spatial scales of interest, e.g. conservation areas, can differ more widely than expected previously. Therefore, land use and conservation activities, which manipulate dispersal capability, need to consider the landscape context and potential species pools carefully.}, language = {en} } @article{WieczorekKruseEppetal.2017, author = {Wieczorek, Mareike and Kruse, Stefan and Epp, Laura Saskia and Kolmogorov, Alexei and Nikolaev, Anatoly N. and Heinrich, Ingo and Jeltsch, Florian and Pestryakova, Luidmila Agafyevna and Zibulski, Romy and Herzschuh, Ulrike}, title = {Dissimilar responses of larch stands in northern Siberia to increasing temperatures-a field and simulation based study}, series = {Ecology : a publication of the Ecological Society of America}, volume = {98}, journal = {Ecology : a publication of the Ecological Society of America}, publisher = {Wiley}, address = {Hoboken}, issn = {0012-9658}, doi = {10.1002/ecy.1887}, pages = {2343 -- 2355}, year = {2017}, abstract = {Arctic and alpine treelines worldwide differ in their reactions to climate change. A northward advance of or densification within the treeline ecotone will likely influence climate-vegetation feedback mechanisms. In our study, which was conducted in the Taimyr Depression in the North Siberian Lowlands, w present a combined field-and model-based approach helping us to better understand the population processes involved in the responses of the whole treeline ecotone, spanning from closed forest to single-tree tundra, to climate warming. Using information on stand structure, tree age, and seed quality and quantity from seven sites, we investigate effects of intra-specific competition and seed availability on the specific impact of recent climate warming on larch stands. Field data show that tree density is highest in the forest-tundra, and average tree size decreases from closed forest to single-tree tundra. Age-structure analyses indicate that the trees in the closed forest and forest-tundra have been present for at least similar to 240 yr. At all sites except the most southerly ones, past establishment is positively correlated with regional temperature increase. In the single-tree tundra, however, a change in growth form from krummholz to erect trees, beginning similar to 130 yr ago, rather than establishment date has been recorded. Seed mass decreases from south to north, while seed quantity increases. Simulations with LAVESI (Larix Vegetation Simulator) further suggest that relative density changes strongly in response to a warming signal in the forest-tundra while intra-specific competition limits densification in the closed forest and seed limitation hinders densification in the single-tree tundra. We find striking differences in strength and timing of responses to recent climate warming. While forest-tundra stands recently densified, recruitment is almost non-existent at the southern and northern end of the ecotone due to autecological processes. Palaeo-treelines may therefore be inappropriate to infer past temperature changes at a fine scale. Moreover, a lagged treeline response to past warming will, via feedback mechanisms, influence climate change in the future.}, language = {en} } @article{WiegandJeltschWard2000, author = {Wiegand, K. and Jeltsch, Florian and Ward, D.}, title = {Do spatial effects play a role in the spatial distribution of desert dwelling Acacias?}, year = {2000}, language = {en} } @article{WichmannJeltschDeanetal.2002, author = {Wichmann, Matthias and Jeltsch, Florian and Dean, Richard and Moloney, Kirk A. and Wissel, Christian}, title = {Does climate change in arid savanna affect the population persistence of raptors?}, year = {2002}, language = {en} } @article{SchwagerJohstJeltsch2006, author = {Schwager, Monika and Johst, Karin and Jeltsch, Florian}, title = {Does red noise increase or decrease extinction risk? Single extreme events versus series of unfavorable conditions}, year = {2006}, abstract = {Recent theoretical studies have shown contrasting effects of temporal correlation of environmental fluctuations ( red noise) on the risk of population extinction. It is still debated whether and under which conditions red noise increases or decreases extinction risk compared with uncorrelated ( white) noise. Here, we explain the opposing effects by introducing two features of red noise time series. On the one hand, positive autocorrelation increases the probability of series of poor environmental conditions, implying increasing extinction risk. On the other hand, for a given time period, the probability of at least one extremely bad year ("catastrophe") is reduced compared with white noise, implying decreasing extinction risk. Which of these two features determines extinction risk depends on the strength of environmental fluctuations and the sensitivity of population dynamics to these fluctuations. If extreme ( catastrophic) events can occur ( strong noise) or sensitivity is high ( overcompensatory density dependence), then temporal correlation decreases extinction risk; otherwise, it increases it. Thus, our results provide a simple explanation for the contrasting previous findings and are a crucial step toward a general understanding of the effect of noise color on extinction risk}, language = {en} } @article{PoppBlaumJeltsch2009, author = {Popp, Alexander and Blaum, Niels and Jeltsch, Florian}, title = {Ecohydrological feedback mechanisms in arid rangelands : simulating the impacts of topography and land use}, issn = {1439-1791}, doi = {10.1016/j.baae.2008.06.002}, year = {2009}, abstract = {The interaction between ecological and hydrological processes is particularly important in arid and semi-arid regions. Often the interaction between these processes is not completely understood and they are studied separately. We developed a grid-based computer model simulating the dynamics of the four most common vegetation types (perennial grass, annuals, dwarf shrubs and shrubs) and related hydrological processes in the region studied. Eco-hydrological interactions gain importance in rangelands with increasing slope, where vegetation cover obstructs run-off and decreases evaporation from the soil. Overgrazing can influence these positive feedback mechanisms. In this study, we first show that model predictions of cover and productivity of the vegetation types are realistic by comparing them with estimates obtained from field surveys. Then, we apply a realistic range in slope angle combined with two land use regimes (light versus heavy grazing intensity). Our simulation results reveal that hydrological processes and associated productivity are strongly affected by slope, whereas the magnitude of this impact depends on overgrazing. Under low stocking rates, undisturbed vegetation is maintained and run-off and evaporation remain low on flat plains and gentle slope. On steep slopes, run-off and evaporation become larger, while water retention potential decreases, which leads to reduced productivity. Overgrazing, however, reduces vegetation cover and biomass production and the landscape"s ability to conserve water decreases even on flat plains and gentle slopes. Generally, the abundance of perennial grasses and shrubs decreases with increasing slope and grazing. Dominance is shifted towards shrubs and annuals. As a management recommendation we suggest that different vegetation growth forms should not only be regarded as forage producers but also as regulators of ecosystem functioning. Particularly on sloping range lands, a high percentage of cover by perennial vegetation insures that water is retained in the system.}, language = {en} } @article{JeltschWeberGrimm2000, author = {Jeltsch, Florian and Weber, Gisela and Grimm, Volker}, title = {Ecological buffering mechanisms in savannas : a unifying theory of long-term tree-grass coexistence}, year = {2000}, language = {en} } @article{TietjenJeltschZeheetal.2010, author = {Tietjen, Britta and Jeltsch, Florian and Zehe, Erwin and Classen, Nikolaus and Groengroeft, Alexander and Schiffers, Katja and Oldeland, Jens}, title = {Effects of climate change on the coupled dynamics of water and vegetation in drylands}, issn = {1936-0584}, doi = {10.1002/Eco.70}, year = {2010}, abstract = {Drylands worldwide are exposed to a highly variable environment and face a high risk of degradation. The effects of global climate change such as altered precipitation patterns and increased temperature leading to reduced water availability will likely increase this risk. At the same time, an elevated atmospheric CO2 level could mitigate the effects of reduced water availability by increasing the water use efficiency of plants. To prevent degradation of drylands, it is essential to understand the underlying processes that affect water availability and vegetation cover. Since water and vegetation are strongly interdependent in water-limited ecosystems, changes can lead to highly non- linear effects. We assess these effects by developing an ecohydrological model of soil moisture and vegetation cover. The water component of the model simulates the daily dynamics of surface water and water contents in two soil layers. Vegetation is represented by two functional types: shrubs and grasses. These compete for soil water and strongly influence hydrological processes. We apply the model to a Namibian thornbush savanna and evaluate the separate and combined effects of decreased annual precipitation, increased temperature, more variable precipitation and elevated atmospheric CO2 on soil moisture and on vegetation cover. The results show that two main factors control the response of plant types towards climate change, namely a change in water availability and a change in water allocation to a specific plant type. Especially, reduced competitiveness of grasses can lead to a higher risk of shrub encroachment in these systems.}, language = {en} } @article{RomeroMujalliJeltschTiedemann2019, author = {Romero-Mujalli, Daniel and Jeltsch, Florian and Tiedemann, Ralph}, title = {Elevated mutation rates are unlikely to evolve in sexual species, not even under rapid environmental change}, series = {BMC Evolutionary Biology}, volume = {19}, journal = {BMC Evolutionary Biology}, publisher = {BioMed Central}, address = {London}, issn = {1471-2148}, doi = {10.1186/s12862-019-1494-0}, pages = {9}, year = {2019}, abstract = {Background Organisms are expected to respond to changing environmental conditions through local adaptation, range shift or local extinction. The process of local adaptation can occur by genetic changes or phenotypic plasticity, and becomes especially relevant when dispersal abilities or possibilities are somehow constrained. For genetic changes to occur, mutations are the ultimate source of variation and the mutation rate in terms of a mutator locus can be subject to evolutionary change. Recent findings suggest that the evolution of the mutation rate in a sexual species can advance invasion speed and promote adaptation to novel environmental conditions. Following this idea, this work uses an individual-based model approach to investigate if the mutation rate can also evolve in a sexual species experiencing different conditions of directional climate change, under different scenarios of colored stochastic environmental noise, probability of recombination and of beneficial mutations. The color of the noise mimicked investigating the evolutionary dynamics of the mutation rate in different habitats. Results The results suggest that the mutation rate in a sexual species experiencing directional climate change scenarios can evolve and reach relatively high values mainly under conditions of complete linkage of the mutator locus and the adaptation locus. In contrast, when they are unlinked, the mutation rate can slightly increase only under scenarios where at least 50\% of arising mutations are beneficial and the rate of environmental change is relatively fast. This result is robust under different scenarios of stochastic environmental noise, which supports the observation of no systematic variation in the mutation rate among organisms experiencing different habitats. Conclusions Given that 50\% beneficial mutations may be an unrealistic assumption, and that recombination is ubiquitous in sexual species, the evolution of an elevated mutation rate in a sexual species experiencing directional climate change might be rather unlikely. Furthermore, when the percentage of beneficial mutations and the population size are small, sexual species (especially multicellular ones) producing few offspring may be expected to react to changing environments not by adaptive genetic change, but mainly through plasticity. Without the ability for a plastic response, such species may become - at least locally - extinct.}, language = {en} } @article{TreydteRiginosJeltsch2010, author = {Treydte, Anna C. and Riginos, Corinna and Jeltsch, Florian}, title = {Enhanced use of beneath-canopy vegetation by grazing ungulates in African savannahs}, issn = {0140-1963}, doi = {10.1016/j.jaridenv.2010.07.003}, year = {2010}, abstract = {The cover of large trees in African savannahs is rapidly declining, mainly due to human land-use practices. Trees improve grass nutrient quality and contribute to species and structural diversity of savannah vegetation. However, the response of herbivores to trees as habitat features is unknown We quantified the habitat use of wild and domestic ungulates in two eastern and southern African savannahs. We assessed grazing intensities and quantified dung depositions beneath and around canopies of different sized trees. Grasses were eaten and dung was deposited twice as frequently beneath large (ca. 5 m in height) and very large trees (7-10 m) than in open grasslands. Small trees (<2.5 m) did not show this trend. Grazing intensity and dung deposition decreased with distance away from trees at both study sites. These results suggest that large trees represent essential habitat features for domestic and wild herbivores. Increased dung depositions beneath large trees may further promote the maintenance of a patchy nutrient distribution in savannahs. Small trees cannot provide the same structural and functional advantages as large trees do. We recommend that land-use practices be promoted which conserve large single-standing trees to benefit the flora and fauna of African savannahs.}, language = {en} } @article{JeltschWeberDeanetal.2000, author = {Jeltsch, Florian and Weber, Gisela and Dean, W. R. J. and Milton, Sue J. and VanRooyen, N. and O'Connor, Terry and Moloney, Kirk A.}, title = {Entstehung und Bedeutung r{\"a}umlicher Vegetationsstrukturen in Trockensavannen : Baum-Graskoexistenz und Artenvielfalt}, year = {2000}, language = {de} } @article{BergholzMayGiladietal.2017, author = {Bergholz, Kolja and May, Felix and Giladi, Itamar and Ristow, Michael and Ziv, Yaron and Jeltsch, Florian}, title = {Environmental heterogeneity drives fine-scale species assembly and functional diversity of annual plants in a semi-arid environment}, series = {Perspectives in plant ecology, evolution and systematics}, volume = {24}, journal = {Perspectives in plant ecology, evolution and systematics}, publisher = {Elsevier}, address = {Jena}, issn = {1433-8319}, doi = {10.1016/j.ppees.2017.01.001}, pages = {138 -- 146}, year = {2017}, abstract = {Spatial environmental heterogeneity is considered a fundamental factor for the maintenance of plant species richness. However, it still remains unclear whether heterogeneity may also facilitate coexistence at fine grain sizes or whether other processes, like mass effects and source sink dynamics due to dispersal, control species composition and diversity at these scales. In this study, we used two complimentary analyses to identify the role of heterogeneity within 15 m x 15 m plots for the coexistence of species-rich annual communities in a semi-arid environment along a steep precipitation gradient. Specifically, we: (a) analyzed the effect of environmental heterogeneity on species, functional and phylogenetic diversity within microsites (alpha diversity, 0.06 m(2) and 1 m(2)), across microsites (beta diversity), and diversity at the entire plot (gamma diversity); (b) further we used two null models to detect non-random trait and phylogenetic patterns in order to infer assembly processes, i.e. whether co-occurring species tend to share similar traits (trait convergence) or dissimilar traits (trait divergence). In general, our results showed that heterogeneity had a positive effect on community diversity. Specifically, for alpha diversity, the effect was significant for functional diversity, and not significant for either species or phylogenetic diversities. For beta diversity, all three measures of community diversity (species, functional, and phylogenetic) increased significantly, as they also did for gamma diversity, where functional measures were again stronger than for species or phylogenetic measures. In addition, the null model approach consistently detected trait convergence, indicating that species with similar traits tended to co-occur and had high abundances in a given microsite. While null model analysis across the phylogeny partly supported these trait findings, showing phylogenetic underdispersion at the 1m(2) grain size, surprisingly when species abundances in microsites were analyzed they were more evenly distributed across the phylogenetic tress than expected (phylogenetic overdispersion). In conclusion, our results provide compelling support that environmental heterogeneity at a relatively fine scale is an important factor for species co-existence as it positively affects diversity as well as influences species assembly. Our study underlines the need for trait-based approaches conducted at fine grain sizes in order to better understand species coexistence and community assembly. (C) 2017 Elsevier GmbH. All rights reserved.}, language = {en} } @article{SchlaegelSignerHerdeetal.2019, author = {Schl{\"a}gel, Ulrike E. and Signer, Johannes and Herde, Antje and Eden, Sophie and Jeltsch, Florian and Eccard, Jana and Dammhahn, Melanie}, title = {Estimating interactions between individuals from concurrent animal movements}, series = {Methods in ecology and evolution : an official journal of the British Ecological Society}, volume = {10}, journal = {Methods in ecology and evolution : an official journal of the British Ecological Society}, number = {8}, publisher = {Wiley}, address = {Hoboken}, issn = {2041-210X}, doi = {10.1111/2041-210X.13235}, pages = {1234 -- 1245}, year = {2019}, abstract = {Animal movements arise from complex interactions of individuals with their environment, including both conspecific and heterospecific individuals. Animals may be attracted to each other for mating, social foraging, or information gain, or may keep at a distance from others to avoid aggressive encounters related to, e.g., interference competition, territoriality, or predation. With modern tracking technology, more datasets are emerging that allow to investigate fine-scale interactions between free-ranging individuals from movement data, however, few methods exist to disentangle fine-scale behavioural responses of interacting individuals when these are highly individual-specific. In a framework of step-selection functions, we related movements decisions of individuals to dynamic occurrence distributions of other individuals obtained through kriging of their movement paths. Using simulated data, we tested the method's ability to identify various combinations of attraction, avoidance, and neutrality between individuals, including asymmetric (i.e. non-mutual) behaviours. Additionally, we analysed radio-telemetry data from concurrently tracked small rodents (bank vole, Myodes glareolus) to test whether our method could detect biologically plausible behaviours. We found that our method was able to successfully detect and distinguish between fine-scale interactions (attraction, avoidance, neutrality), even when these were asymmetric between individuals. The method worked best when confounding factors were taken into account in the step-selection function. However, even when failing to do so (e.g. due to missing information), interactions could be reasonably identified. In bank voles, responses depended strongly on the sexes of the involved individuals and matched expectations. Our approach can be combined with conventional uses of step-selection functions to tease apart the various drivers of movement, e.g. the influence of the physical and the social environment. In addition, the method is particularly useful in studying interactions when responses are highly individual-specific, i.e. vary between and towards different individuals, making our method suitable for both single-species and multi-species analyses (e.g. in the context of predation or competition).}, language = {en} } @article{WeissSchalowJeltschetal.2019, author = {Weiss, Lina and Schalow, Linda and Jeltsch, Florian and Geissler, Katja}, title = {Experimental evidence for root competition effects on community evenness in one of two phytometer species}, series = {Journal of plant ecology}, volume = {12}, journal = {Journal of plant ecology}, number = {2}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {1752-9921}, doi = {10.1093/jpe/rty021}, pages = {281 -- 291}, year = {2019}, abstract = {Aims Plant-plant interactions, being positive or negative, are recognized to be key factors in structuring plant communities. However, it is thought that root competition may be less important than shoot competition due to greater size symmetry belowground. Because direct experimental tests on the importance of root competition are scarce, we aim at elucidating whether root competition may have direct or indirect effects on community structure. Indirect effects may occur by altering the overall size asymmetry of competition through root-shoot competitive interactions. Methods We used a phytometer approach to examine the effects of root, shoot and total competition intensity and importance on evenness of experimental plant communities. Thereby two different phytometer species, Festuca brevipila and Dianthus carthusianorum, were grown in small communities of six grassland species over three levels of light and water availability, interacting with neighbouring shoots, roots, both or not at all. Important Findings We found variation in community evenness to be best explained if root and shoot (but not total) competition were considered. However, the effects were species specific: in Dianthus communities increasing root competition increased plant community evenness, while in Festuca communities shoot competition was the driving force of this evenness response. Competition intensities were influenced by environmental conditions in Dianthus, but not in Festuca phytometer plants. While we found no evidence for root-shoot interactions for neither phytometer species root competition in Dianthus communities led to increased allocation to shoots, thereby increasing the potential ability to perform in size-asymmetric competition for light. Our experiment demonstrates the potential role of root competition in structuring plant communities.}, language = {en} } @article{JeltschWichmannJohstetal.2003, author = {Jeltsch, Florian and Wichmann, Matthias and Johst, J. and Moloney, Kirk A. and Wissel, Christian}, title = {Extinction risk in periodically fluctuating environments}, year = {2003}, language = {en} } @article{WichmannJohstSchwageretal.2005, author = {Wichmann, Matthias and Johst, Karin and Schwager, Monika and Jeltsch, Florian and Blasius, Bernd}, title = {Extinction risk, coloured noise and the scaling of variance}, year = {2005}, abstract = {The impact of temporally correlated fluctuating environments (coloured noise) on the extinction risk of populations has become a main focus in theoretical population ecology. In this study we particularly focus on the extinction risk in strongly autocorrelated environments. Here, in contrast to moderate autocorrelation, we found the extinction risk to be highly dependent on the process of noise generation, in particular on the method of variance scaling. Such variance scaling is commonly applied to avoid variance-driven biases when comparing the extinction risk for white and coloured noise. In this study we found an often-used scaling technique to lead to high variability in the resulting variances of different time series for strong auto-correlation eventually leading to deviations in the projected extinction risk. Therefore, we present an alternative method that always delivers the target variance, even in the case of strong temporal correlation. Furthermore, in contrast to the earlier method, our very intuitive method is not bound to auto-regressive processes but can be applied to all types of coloured noises. We recommend the method introduced here to be used when the target of interest is the effect of noise colour on extinction risk not obscured by any variance effects.}, language = {en} }