TY - JOUR A1 - Jeltsch, Florian T1 - Ökologische Forschungen an der Unteren Havel BT - ein Ausblick JF - Brandenburgische Umwelt-Berichte : BUB ; Schriftenreihe der Mathematisch-Naturwissenschaftlichen Fakultät der Universität Potsdam Y1 - 2003 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-4100 SN - 1434-2375 SN - 1611-9339 VL - 13 SP - 138 EP - 139 ER - TY - JOUR A1 - Jeltsch, Florian T1 - Wechselbeziehungen zwischen Artendiversität und struktureller Diversität : modellgestützte Untersuchungen am Beispiel einer semiariden Savanne Y1 - 2002 ER - TY - JOUR A1 - Wichmann, Matthias A1 - Jeltsch, Florian A1 - Dean, Richard A1 - Moloney, Kirk A. A1 - Wissel, Christian T1 - Weather does matter : simulating population dynamics of tawny eagle (Aquila rapax) under various rainfall scenarios Y1 - 2002 ER - TY - JOUR A1 - Jeltsch, Florian A1 - Wiegand, T. A1 - Hanski, I. A1 - Grimm, Volker T1 - Using pattern-oriented modeling for revealing hidden information : a key for reconciling ecological theory and application Y1 - 2003 ER - TY - JOUR A1 - Eccard, Jana A1 - Dean, W. Richard J. A1 - Wichmann, Matthias A1 - Huttunen, S. M A1 - Eskelinen, Eeva-Liisa A1 - Moloney, Kirk A. A1 - Jeltsch, Florian T1 - Use of large Acacia trees by the cavity dwelling Black-tailed Tree Rat in the southern Kalahari N2 - Recent extensive harvesting of large, often dead Acacia trees in and savanna of southern Africa is cause for concern about the conservation status of the arid savanna and its animal community. We mapped vegetation and nests of the Black-tailed Tree Rat Thallomy's nigricauda to assess the extent to which the rats depend on particular tree species and on the existence of dead, standing trees. The study was conducted in continuous Acacia woodland on the southern and eastern edge of the Kalahari, South Africa. Trees in which there were tree rat nests were compared with trees of similar size and vigour to identify the characteristics of nest sites. Spatial analysis of tree rat distribution was conducted using Ripley's-L function. We found that T nigricauda was able to utilize all available tree species, as long as trees were large and old enough so that cavities were existing inside the stem. The spatial distribution of nest trees did not show clumping at the investigated scale, and we therefore reject the notion of the rats forming colonies when inhabiting continuous woodlands. The selection of a particular tree as a nest site was furthermore depending on the close proximity of the major food plant, Acacia mellifera. This may limit the choice of suitable nest sites. since A. mellifera was less likely to grow within a vegetation patch containing a large trees than in patches without large trees. Y1 - 2006 UR - http://www.sciencedirect.com/science/journal/01401963 U6 - https://doi.org/10.1016/j.jaridenv.2005.06.019 SN - 0140-1963 ER - TY - JOUR A1 - Bergholz, Kolja A1 - May, Felix A1 - Ristow, Michael A1 - Giladi, Itamar A1 - Ziv, Yaron A1 - Jeltsch, Florian T1 - Two Mediterranean annuals feature high within-population trait variability and respond differently to a precipitation gradient JF - Basic and applied ecology : Journal of the Gesellschaft für Ökologie N2 - Intraspecific trait variability plays an important role in species adaptation to climate change. However, it still remains unclear how plants in semi-arid environments respond to increasing aridity. We investigated the intraspecific trait variability of two common Mediterranean annuals (Geropogon hybridus and Crupina crupinastrum) with similar habitat preferences. They were studied along a steep precipitation gradient in Israel similar to the maximum predicted precipitation changes in the eastern Mediterranean basin (i.e. -30% until 2100). We expected a shift from competitive ability to stress tolerance with decreasing precipitation and tested this expectation by measuring key functional traits (canopy and seed release height, specific leaf area, N-and P-leaf content, seed mass). Further, we evaluated generative bet-hedging strategies by different seed traits. Both species showed different responses along the precipitation gradient. C. crupinastrum exhibited only decreased plant height toward saridity, while G. hybridus showed strong trends of generative adaptation to aridity. Different seed trait indices suggest increased bet-hedging of G. hybridus in arid environments. However, no clear trends along the precipitation gradient were observed in leaf traits (specific leaf area and leaf N-/P-content) in both species. Moreover, variance decomposition revealed that most of the observed trait variation (>> 50%) is found within populations. The findings of our study suggest that responses to increased aridity are highly species-specific and local environmental factors may have a stronger effect on intraspecific trait variation than shifts in annual precipitation. We therefore argue that trait-based analyses should focus on precipitation gradients that are comparable to predicted precipitation changes and compare precipitation effects to effects of local environmental factors. (C) 2017 Gesellschaft fur Okologie. Published by Elsevier GmbH. All rights reserved. KW - Climate change KW - Functional ecology KW - Plant height KW - Drought stress KW - Rainfall gradient KW - Trait-environment relationship KW - Local adaptation KW - Phenotypic plasticity Y1 - 2017 U6 - https://doi.org/10.1016/j.baae.2017.11.001 SN - 1439-1791 SN - 1618-0089 VL - 25 SP - 48 EP - 58 PB - Elsevier CY - Jena ER - TY - JOUR A1 - Kruse, Stefan A1 - Wieczorek, Mareike A1 - Jeltsch, Florian A1 - Herzschuh, Ulrike T1 - Treeline dynamics in Siberia under changing climates as inferred from an individual-based model for Larix JF - Ecological modelling : international journal on ecological modelling and engineering and systems ecolog KW - Forest change KW - IBM KW - ODD model description KW - Larix gmelinii KW - Permafrost ecosystem KW - Time-lag effects Y1 - 2016 U6 - https://doi.org/10.1016/j.ecolmodel.2016.08.003 SN - 0304-3800 SN - 1872-7026 VL - 338 SP - 101 EP - 121 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Treydte, Anna C. A1 - Grant, Rina C. C. A1 - Jeltsch, Florian T1 - Tree size and herbivory determine below-canopy grass quality and species composition in savannahs N2 - Large single-standing trees are rapidly declining in savannahs, ecosystems supporting a high diversity of large herbivorous mammals. Savannah trees are important as they support both a unique flora and fauna. The herbaceous layer in particular responds to the structural and functional properties of a tree. As shrubland expands stem thickening occurs and large trees are replaced by smaller trees. Here we examine whether small trees are as effective in providing advantages for grasses growing beneath their crowns as large trees are. The role of herbivory in this positive tree- grass interaction is also investigated. We assessed soil and grass nutrient content, structural properties, and herbaceous species composition beneath trees of three size classes and under two grazing regimes in a South African savannah. We found that grass leaf content (N and P) beneath the crowns of particularly large (ca. 3.5 m) and very large trees (ca. 9 m) was as much as 40% greater than the same grass species not growing under a tree canopy, whereas nutrient contents of grasses did not differ beneath small trees (< 2.3 m). Moderate herbivory enhanced these effects slightly. Grass species composition differed beneath and beyond the tree canopy but not between tree size classes. As large trees significantly improve the grass nutrient quality for grazers in contrast to smaller trees, the decline of the former should be halted. The presence of trees further increases grass species diversity and patchiness by favouring shade- tolerant species. Both grazing wildlife and livestock will benefit from the presence of large trees because of their structural and functional importance for savannahs. Y1 - 2009 UR - http://www.springerlink.com/content/100125 U6 - https://doi.org/10.1007/s10531-009-9694-3 SN - 0960-3115 ER - TY - GEN A1 - Bergholz, Kolja A1 - Kober, Klarissa A1 - Jeltsch, Florian A1 - Schmidt, Kristina A1 - Weiß, Lina T1 - Trait means or variance BT - What determines plant species' local and regional occurrence in fragmented dry grasslands? T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - One of the few laws in ecology is that communities consist of few common and many rare taxa. Functional traits may help to identify the underlying mechanisms of this community pattern, since they correlate with different niche dimensions. However, comprehensive studies are missing that investigate the effects of species mean traits (niche position) and intraspecific trait variability (ITV, niche width) on species abundance. In this study, we investigated fragmented dry grasslands to reveal trait-occurrence relationships in plants at local and regional scales. We predicted that (a) at the local scale, species occurrence is highest for species with intermediate traits, (b) at the regional scale, habitat specialists have a lower species occurrence than generalists, and thus, traits associated with stress-tolerance have a negative effect on species occurrence, and (c) ITV increases species occurrence irrespective of the scale. We measured three plant functional traits (SLA = specific leaf area, LDMC = leaf dry matter content, plant height) at 21 local dry grassland communities (10 m × 10 m) and analyzed the effect of these traits and their variation on species occurrence. At the local scale, mean LDMC had a positive effect on species occurrence, indicating that stress-tolerant species are the most abundant rather than species with intermediate traits (hypothesis 1). We found limited support for lower specialist occurrence at the regional scale (hypothesis 2). Further, ITV of LDMC and plant height had a positive effect on local occurrence supporting hypothesis 3. In contrast, at the regional scale, plants with a higher ITV of plant height were less frequent. We found no evidence that the consideration of phylogenetic relationships in our analyses influenced our findings. In conclusion, both species mean traits (in particular LDMC) and ITV were differently related to species occurrence with respect to spatial scale. Therefore, our study underlines the strong scale-dependency of trait-abundance relationships. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1151 KW - LMA KW - niche width KW - plant functional trait KW - scale-dependency KW - species abundance KW - trait-environment relationship Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-519905 SN - 1866-8372 SP - 3357 EP - 3365 ER - TY - JOUR A1 - Bergholz, Kolja A1 - Kober, Klarissa A1 - Jeltsch, Florian A1 - Schmidt, Kristina A1 - Weiß, Lina T1 - Trait means or variance BT - What determines plant species' local and regional occurrence in fragmented dry grasslands? JF - Ecology and evolution N2 - One of the few laws in ecology is that communities consist of few common and many rare taxa. Functional traits may help to identify the underlying mechanisms of this community pattern, since they correlate with different niche dimensions. However, comprehensive studies are missing that investigate the effects of species mean traits (niche position) and intraspecific trait variability (ITV, niche width) on species abundance. In this study, we investigated fragmented dry grasslands to reveal trait-occurrence relationships in plants at local and regional scales. We predicted that (a) at the local scale, species occurrence is highest for species with intermediate traits, (b) at the regional scale, habitat specialists have a lower species occurrence than generalists, and thus, traits associated with stress-tolerance have a negative effect on species occurrence, and (c) ITV increases species occurrence irrespective of the scale. We measured three plant functional traits (SLA = specific leaf area, LDMC = leaf dry matter content, plant height) at 21 local dry grassland communities (10 m × 10 m) and analyzed the effect of these traits and their variation on species occurrence. At the local scale, mean LDMC had a positive effect on species occurrence, indicating that stress-tolerant species are the most abundant rather than species with intermediate traits (hypothesis 1). We found limited support for lower specialist occurrence at the regional scale (hypothesis 2). Further, ITV of LDMC and plant height had a positive effect on local occurrence supporting hypothesis 3. In contrast, at the regional scale, plants with a higher ITV of plant height were less frequent. We found no evidence that the consideration of phylogenetic relationships in our analyses influenced our findings. In conclusion, both species mean traits (in particular LDMC) and ITV were differently related to species occurrence with respect to spatial scale. Therefore, our study underlines the strong scale-dependency of trait-abundance relationships. KW - LMA KW - niche width KW - plant functional trait KW - scale-dependency KW - species abundance KW - trait-environment relationship Y1 - 2020 U6 - https://doi.org/10.1002/ece3.7287 SN - 2045-7758 VL - 11 IS - 7 SP - 3357 EP - 3365 PB - John Wiley & Sons, Inc. ER - TY - JOUR A1 - Jeltsch, Florian A1 - Moloney, Kirk A. A1 - Schurr, Frank Martin A1 - Köchy, Martin A1 - Schwager, Monika T1 - The state of plant population modelling in light of environmental change N2 - Plant population modelling has been around since the 1970s, providing a valuable approach to understanding plant ecology from a mechanistic standpoint. It is surprising then that this area of research has not grown in prominence with respect to other approaches employed in modelling plant systems. In this review, we provide an analysis of the development and role of modelling in the field of plant population biology through an exploration of where it has been, where it is now and, in our opinion, where it should be headed. We focus, in particular, on the role plant population modelling could play in ecological forecasting, an urgent need given current rates of regional and global environmental change. We suggest that a critical element limiting the current application of plant population modelling in environmental research is the trade-off between the necessary resolution and detail required to accurately characterize ecological dynamics pitted against the goal of generality, particularly at broad spatial scales. In addition to suggestions how to overcome the current shortcoming of data on the process-level we discuss two emerging strategies that may offer a way to overcome the described limitation: (1) application of a modern approach to spatial scaling from local processes to broader levels of interaction and (2) plant functional-type modelling. Finally we outline what we believe to be needed in developing these approaches towards a 'science of forecasting'. Y1 - 2008 U6 - https://doi.org/10.1016/j.ppees.2007.11.004 SN - 1433-8319 ER - TY - JOUR A1 - Thulke, Hans-Hermann A1 - Tischendorf, L. A1 - Staubach, C. A1 - Selhorst, T. A1 - Jeltsch, Florian A1 - Müller, T. A1 - Schlüter, H. A1 - Wissel, Christian T1 - The spatio-temporal dynamics of a post-vaccination recovery of rabies in foxes and emergency vaccination planning Y1 - 2000 ER - TY - JOUR A1 - Teckentrup, Lisa A1 - Kramer-Schadt, Stephanie A1 - Jeltsch, Florian T1 - The risk of ignoring fear: underestimating the effects of habitat loss and fragmentation on biodiversity JF - Landscape ecology KW - Predator-prey interactions KW - Fragmentation KW - Habitat loss KW - Landscape of fear KW - Biodiversity KW - Community Y1 - 2019 U6 - https://doi.org/10.1007/s10980-019-00922-8 SN - 0921-2973 SN - 1572-9761 VL - 34 IS - 12 SP - 2851 EP - 2868 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Weiß, Lina A1 - Jeltsch, Florian T1 - The response of simulated grassland communities to the cessation of grazing JF - Ecological modelling : international journal on ecological modelling and engineering and systems ecolog N2 - Changes in land-use are supposed to be among the severest prospective threats to plant diversity worldwide. In semi-natural temperate grasslands, the cessation of traditional land use like livestock grazing is considered to be one of the most important drivers of the diversity loss witnessed within the last decades. Despite of the enormous number of studies on successional pathways following grazing abandonment there is no general pattern of how grassland communities are affected in terms of diversity, trait composition and pace of succession. To gain a comprehensive picture is difficult given the heterogeneity of environments and the time and effort needed for long-term investigations. We here use a proven individual- and trait-based grassland community model to analyze short- and long-term consequences of grazing abandonment under different assumptions of resource availability, pre-abandonment grazing intensity and regional isolation of communities. Grazing abandonment led to a decrease of plant functional type (PFT) diversity in all but two scenarios in the long-term. In short-term we also found an increase or no change in Shannon diversity for several scenarios. With grazing abandonment we overall found an increase in maximum plant mass, clonal integration and longer lateral spread, a decrease in rosette plant types and in stress tolerant plants, as well as an increase in grazing tolerant and a decrease in grazing avoiding plant types. Observed changes were highly dependent on the regional configuration of communities, prevalent resource conditions and land use intensity before abandonment. While long-term changes took around 10-20 years in resource rich conditions, new equilibria established in resource poor conditions only after 30-40 years. Our results confirm the potential threats caused by recent land-use changes and the assumption that oligotrophic communities are more resistant than mesotrophic communities also for long-term abandonment. Moreover, results revealed that species-rich systems are not per se more resistant than species-poor grasslands. (C) 2015 Elsevier B.V. All rights reserved. KW - Diversity KW - Individual-based model KW - Land use intensity KW - Seed immigration KW - Abandonment KW - Resistance Y1 - 2015 U6 - https://doi.org/10.1016/j.ecolmodel.2015.02.002 SN - 0304-3800 SN - 1872-7026 VL - 303 SP - 1 EP - 11 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Fer, Istem A1 - Tietjen, Britta A1 - Jeltsch, Florian A1 - Wolff, Christian Michael T1 - The influence of El Nino-Southern Oscillation regimes on eastern African vegetation and its future implications under the RCP8.5 warming scenario JF - Biogeosciences N2 - The El Nino-Southern Oscillation (ENSO) is the main driver of the interannual variability in eastern African rainfall, with a significant impact on vegetation and agriculture and dire consequences for food and social security. In this study, we identify and quantify the ENSO contribution to the eastern African rainfall variability to forecast future eastern African vegetation response to rainfall variability related to a predicted intensified ENSO. To differentiate the vegetation variability due to ENSO, we removed the ENSO signal from the climate data using empirical orthogonal teleconnection (EOT) analysis. Then, we simulated the ecosystem carbon and water fluxes under the historical climate without components related to ENSO teleconnections. We found ENSO-driven patterns in vegetation response and confirmed that EOT analysis can successfully produce coupled tropical Pacific sea surface temperature-eastern African rainfall teleconnection from observed datasets. We further simulated eastern African vegetation response under future climate change as it is projected by climate models and under future climate change combined with a predicted increased ENSO intensity. Our EOT analysis highlights that climate simulations are still not good at capturing rainfall variability due to ENSO, and as we show here the future vegetation would be different from what is simulated under these climate model outputs lacking accurate ENSO contribution. We simulated considerable differences in eastern African vegetation growth under the influence of an intensified ENSO regime which will bring further environmental stress to a region with a reduced capacity to adapt effects of global climate change and food security. Y1 - 2017 U6 - https://doi.org/10.5194/bg-14-4355-2017 SN - 1726-4170 SN - 1726-4189 VL - 14 SP - 4355 EP - 4374 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Fer, Istem A1 - Tietjen, Britta A1 - Jeltsch, Florian A1 - Wolff, Christian Michael T1 - The influence of El Nino-Southern Oscillation regimes on eastern African vegetation and its future implications under the RCP8.5 warming scenario JF - Biogeosciences N2 - The El Nino-Southern Oscillation (ENSO) is the main driver of the interannual variability in eastern African rainfall, with a significant impact on vegetation and agriculture and dire consequences for food and social security. In this study, we identify and quantify the ENSO contribution to the eastern African rainfall variability to forecast future eastern African vegetation response to rainfall variability related to a predicted intensified ENSO. To differentiate the vegetation variability due to ENSO, we removed the ENSO signal from the climate data using empirical orthogonal teleconnection (EOT) analysis. Then, we simulated the ecosystem carbon and water fluxes under the historical climate without components related to ENSO teleconnections. We found ENSO-driven patterns in vegetation response and confirmed that EOT analysis can successfully produce coupled tropical Pacific sea surface temperature-eastern African rainfall teleconnection from observed datasets. We further simulated eastern African vegetation response under future climate change as it is projected by climate models and under future climate change combined with a predicted increased ENSO intensity. Our EOT analysis highlights that climate simulations are still not good at capturing rainfall variability due to ENSO, and as we show here the future vegetation would be different from what is simulated under these climate model outputs lacking accurate ENSO contribution. We simulated considerable differences in eastern African vegetation growth under the influence of an intensified ENSO regime which will bring further environmental stress to a region with a reduced capacity to adapt effects of global climate change and food security. Y1 - 2017 U6 - https://doi.org/10.5194/bg-14-4355-2017 SN - 1726-4170 SN - 1726-4189 VL - 14 IS - 18 SP - 4355 EP - 4374 PB - Copernicus CY - Katlenburg-Lindau ER - TY - GEN A1 - Fer, Istem A1 - Tietjen, Britta A1 - Jeltsch, Florian A1 - Wolff, Christian Michael T1 - The influence of El Nino-Southern Oscillation regimes on eastern African vegetation and its future implications under the RCP8.5 warming scenario N2 - The El Nino-Southern Oscillation (ENSO) is the main driver of the interannual variability in eastern African rainfall, with a significant impact on vegetation and agriculture and dire consequences for food and social security. In this study, we identify and quantify the ENSO contribution to the eastern African rainfall variability to forecast future eastern African vegetation response to rainfall variability related to a predicted intensified ENSO. To differentiate the vegetation variability due to ENSO, we removed the ENSO signal from the climate data using empirical orthogonal teleconnection (EOT) analysis. Then, we simulated the ecosystem carbon and water fluxes under the historical climate without components related to ENSO teleconnections. We found ENSO-driven patterns in vegetation response and confirmed that EOT analysis can successfully produce coupled tropical Pacific sea surface temperature-eastern African rainfall teleconnection from observed datasets. We further simulated eastern African vegetation response under future climate change as it is projected by climate models and under future climate change combined with a predicted increased ENSO intensity. Our EOT analysis highlights that climate simulations are still not good at capturing rainfall variability due to ENSO, and as we show here the future vegetation would be different from what is simulated under these climate model outputs lacking accurate ENSO contribution. We simulated considerable differences in eastern African vegetation growth under the influence of an intensified ENSO regime which will bring further environmental stress to a region with a reduced capacity to adapt effects of global climate change and food security. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 394 Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-403853 ER - TY - JOUR A1 - Synodinos, Alexis D. A1 - Tietjen, Britta A1 - Lohmann, Dirk A1 - Jeltsch, Florian T1 - The impact of inter-annual rainfall variability on African savannas changes with mean rainfall JF - Journal of theoretical biology N2 - Savannas are mixed tree-grass ecosystems whose dynamics are predominantly regulated by resource competition and the temporal variability in climatic and environmental factors such as rainfall and fire. Hence, increasing inter-annual rainfall variability due to climate change could have a significant impact on savannas. To investigate this, we used an ecohydrological model of stochastic differential equations and simulated African savanna dynamics along a gradient of mean annual rainfall (520–780 mm/year) for a range of inter-annual rainfall variabilities. Our simulations produced alternative states of grassland and savanna across the mean rainfall gradient. Increasing inter-annual variability had a negative effect on the savanna state under dry conditions (520 mm/year), and a positive effect under moister conditions (580–780 mm/year). The former resulted from the net negative effect of dry and wet extremes on trees. In semi-arid conditions (520 mm/year), dry extremes caused a loss of tree cover, which could not be recovered during wet extremes because of strong resource competition and the increased frequency of fires. At high mean rainfall (780 mm/year), increased variability enhanced savanna resilience. Here, resources were no longer limiting and the slow tree dynamics buffered against variability by maintaining a stable population during ‘dry’ extremes, providing the basis for growth during wet extremes. Simultaneously, high rainfall years had a weak marginal benefit on grass cover due to density-regulation and grazing. Our results suggest that the effects of the slow tree and fast grass dynamics on tree-grass interactions will become a major determinant of the savanna vegetation composition with increasing rainfall variability. KW - Rainfall variability KW - Savanna-grassland bistability KW - Stochastic differential equations KW - Coexistence mechanisms KW - Fire Y1 - 2017 U6 - https://doi.org/10.1016/j.jtbi.2017.10.019 SN - 0022-5193 SN - 1095-8541 VL - 437 SP - 92 EP - 100 PB - Elsevier Ltd. CY - London ER - TY - JOUR A1 - Rotics, Shay A1 - Kaatz, Michael A1 - Resheff, Yehezkel S. A1 - Turjeman, Sondra Feldman A1 - Zurell, Damaris A1 - Sapir, Nir A1 - Eggers, Ute A1 - Flack, Andrea A1 - Fiedler, Wolfgang A1 - Jeltsch, Florian A1 - Wikelski, Martin A1 - Nathan, Ran T1 - The challenges of the first migration: movement and behaviour of juvenile vs. adult white storks with insights regarding juvenile mortality JF - Journal of animal ecology : a journal of the British Ecological Society N2 - 1. Migration conveys an immense challenge, especially for juvenile birds coping with enduring and risky journeys shortly after fledging. Accordingly, juveniles exhibit considerably lower survival rates compared to adults, particularly during migration. Juvenile white storks (Ciconia ciconia), which are known to rely on adults during their first fall migration presumably for navigational purposes, also display much lower annual survival than adults. 2. Using detailed GPS and body acceleration data, we examined the patterns and potential causes of age-related differences in fall migration properties of white storks by comparing first-year juveniles and adults. We compared juvenile and adult parameters of movement, behaviour and energy expenditure (estimated from overall dynamic body acceleration) and placed this in the context of the juveniles’ lower survival rate. 3. Juveniles used flapping flight vs. soaring flight 23% more than adults and were estimated to expend 14% more energy during flight. Juveniles did not compensate for their higher flight costs by increased refuelling or resting during migration. When juveniles and adults migrated together in the same flock, the juvenile flew mostly behind the adult and was left behind when they separated. Juveniles showed greater improvement in flight efficiency throughout migration compared to adults which appears crucial because juveniles exhibiting higher flight costs suffered increased mortality. 4. Our findings demonstrate the conflict between the juveniles’ inferior flight skills and their urge to keep up with mixed adult–juvenile flocks. We suggest that increased flight costs are an important proximate cause of juvenile mortality in white storks and likely in other soaring migrants and that natural selection is operating on juvenile variation in flight efficiency. KW - flight KW - flight efficiency KW - juvenile mortality KW - migration KW - white stork Y1 - 2016 U6 - https://doi.org/10.1111/1365-2656.12525 SN - 0021-8790 SN - 1365-2656 VL - 85 SP - 938 EP - 947 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Tews, Jörg A1 - Blaum, Niels A1 - Jeltsch, Florian T1 - Structural and animal species diversity in arid and semi-arid savannas of the southern Kalahari Y1 - 2004 ER - TY - JOUR A1 - Zurell, Damaris A1 - Jeltsch, Florian A1 - Dormann, Carsten F. A1 - Schröder-Esselbach, Boris T1 - Static species distribution models in dynamically changing systems : how good can predictions really be? N2 - SDM performance varied for different range dynamics. Prediction accuracies decreased when abrupt range shifts occurred as species were outpaced by the rate of climate change, and increased again when a new equilibrium situation was realised. When ranges contracted, prediction accuracies increased as the absences were predicted well. Far- dispersing species were faster in tracking climate change, and were predicted more accurately by SDMs than short- dispersing species. BRTs mostly outperformed GLMs. The presence of a predator, and the inclusion of its incidence as an environmental predictor, made BRTs and GLMs perform similarly. Results are discussed in light of other studies dealing with effects of ecological traits and processes on SDM performance. Perspectives are given on further advancements of SDMs and for possible interfaces with more mechanistic approaches in order to improve predictions under environmental change. Y1 - 2009 UR - http://www3.interscience.wiley.com/journal/117966123/home?CRETRY=1&SRETRY=0 U6 - https://doi.org/10.1111/j.1600-0587.2009.05810.x SN - 0906-7590 ER - TY - JOUR A1 - Jeltsch, Florian A1 - Moloney, Kirk A. T1 - Spatially-explicit vegetation models : what have we learned ? Y1 - 2001 ER - TY - JOUR A1 - Moloney, Kirk A. A1 - Jeltsch, Florian T1 - Space matters : novel developments in plant ecology through spatial modelling Y1 - 2008 U6 - https://doi.org/10.1016/j.ppees.2007.12.002 SN - 1433-8319 ER - TY - JOUR A1 - Schäfer, Merlin A1 - Menz, Stephan A1 - Jeltsch, Florian A1 - Zurell, Damaris T1 - sOAR: a tool for modelling optimal animal life-history strategies in cyclic environments JF - Ecography : pattern and diversity in ecology ; research papers forum N2 - Periodic environments determine the life cycle of many animals across the globe and the timing of important life history events, such as reproduction and migration. These adaptive behavioural strategies are complex and can only be fully understood (and predicted) within the framework of natural selection in which species adopt evolutionary stable strategies. We present sOAR, a powerful and user-friendly implementation of the well-established framework of optimal annual routine modelling. It allows determining optimal animal life history strategies under cyclic environmental conditions using stochastic dynamic programming. It further includes the simulation of population dynamics under the optimal strategy. sOAR provides an important tool for theoretical studies on the behavioural and evolutionary ecology of animals. It is especially suited for studying bird migration. In particular, we integrated options to differentiate between costs of active and passive flight into the optimal annual routine modelling framework, as well as options to consider periodic wind conditions affecting flight energetics. We provide an illustrative example of sOAR where food supply in the wintering habitat of migratory birds significantly alters the optimal timing of migration. sOAR helps improving our understanding of how complex behaviours evolve and how behavioural decisions are constrained by internal and external factors experienced by the animal. Such knowledge is crucial for anticipating potential species’ response to global environmental change. Y1 - 2017 U6 - https://doi.org/10.1111/ecog.03328 SN - 0906-7590 SN - 1600-0587 VL - 41 IS - 3 SP - 551 EP - 557 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Jeltsch, Florian A1 - Hansen, Frank A1 - Thulke, Hans-Hermann T1 - Simulationsmodelle zur Planung von Strategien in der Bekämpfung von Wildtiererkrankungen Y1 - 2003 ER - TY - JOUR A1 - Tietjen, Britta A1 - Zehe, Erwin A1 - Jeltsch, Florian T1 - Simulating plant water availability in dry lands under climate change : a generic model of two soil layers N2 - Dry lands are exposed to a highly variable environment and face a high risk of degradation. The effects of climate change are likely to increase this risk; thus a profound knowledge of the system dynamics is crucial for evaluating management options. This applies particularly for the interactions between water and vegetation, which exhibit strong feedbacks. To evaluate these feedbacks and the effects of climate change on soil moisture dynamics, we developed a generic, process-based, spatially explicit soil moisture model of two soil layers, which can be coupled with vegetation models. A time scale relevant for ecological processes can be simulated without difficulty, and the model avoids complex parameterization with data that are unavailable for most regions of the world. We applied the model to four sites in Israel along a precipitation and soil type gradient and assessed the effects of climate change by comparing possible climatic changes with present climate conditions. The results show that in addition to temperature, the total amount of precipitation and its intra-annual variability are an important driver of soil moisture patterns. This indicates that particularly with regard to climate change, the approach of many ecological models that simulate water dynamics on an annual base is far too simple to make reliable predictions. Thus, the introduced model can serve as a valuable tool to improve present ecological models of dry lands because of its focus on the applicability and transferability. Y1 - 2009 UR - http://www.agu.org/journals/wr/ U6 - https://doi.org/10.1029/2007WR006589 SN - 0043-1397 ER - TY - JOUR A1 - Jeltsch, Florian A1 - Weber, G. E. A1 - Moloney, Kirk A. T1 - Simulated long-term vegetation response to alternative stocking strategies in savanna rangelands Y1 - 2000 ER - TY - JOUR A1 - Lohmann, Dirk A1 - Tietjen, Britta A1 - Blaum, Niels A1 - Joubert, David F. A1 - Jeltsch, Florian T1 - Shifting thresholds and changing degradation patterns: climate change effects on the simulated long-term response of a semi-arid savanna to grazing JF - Journal of applied ecology : an official journal of the British Ecological Society N2 - 1. The complex, nonlinear response of dryland systems to grazing and climatic variations is a challenge to management of these lands. Predicted climatic changes will impact the desertification of drylands under domestic livestock production. Consequently, there is an urgent need to understand the response of drylands to grazing under climate change. 2. We enhanced and parameterized an ecohydrological savanna model to assess the impacts of a range of climate change scenarios on the response of a semi-arid African savanna to grazing. We focused on the effects of temperature and CO2 level increase in combination with changes in inter- and intra-annual precipitation patterns on the long-term dynamics of three major plant functional types. 3. We found that the capacity of the savanna to sustain livestock grazing was strongly influenced by climate change. Increased mean annual precipitation and changes in intra-annual precipitation pattern have the potential to slightly increase carrying capacities of the system. In contrast, decreased precipitation, higher interannual variation and temperature increase are leading to a severe decline of carrying capacities owing to losses of the perennial grass biomass. 4. Semi-arid rangelands will be at lower risk of shrub encroachment and encroachment will be less intense under future climatic conditions. This finding holds in spite of elevated levels of atmospheric CO2 and irrespective of changes in precipitation pattern, because of the drought sensitivity of germination and establishment of encroaching species. 5. Synthesis and applications. Changes in livestock carrying capacities, both positive and negative, mainly depend on the highly uncertain future rainfall conditions. However, independent of the specific changes, shrub encroachment becomes less likely and in many cases less severe. Thus, managers of semi-arid rangelands should shift their focus from woody vegetation towards perennial grass species as indicators for rangeland degradation. Furthermore, the resulting reduced competition from woody vegetation has the potential to facilitate ecosystem restoration measures such as re-introduction of desirable plant species that are only little promising or infeasible under current climatic conditions. On a global scale, the reductions in standing biomass resulting from altered degradation dynamics of semi-arid rangelands can have negative impacts on carbon sequestration. KW - CO2 increase KW - demographic bottleneck KW - ecohydrology KW - grid-based simulation model KW - livestock KW - precipitation pattern KW - savanna resilience KW - shrub encroachment KW - soil moisture KW - sustainable rangeland management Y1 - 2012 U6 - https://doi.org/10.1111/j.1365-2664.2012.02157.x SN - 0021-8901 VL - 49 IS - 4 SP - 814 EP - 823 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Rossmanith, Eva A1 - Blaum, Niels A1 - Höntsch, Kerstin A1 - Jeltsch, Florian T1 - Sex-related parental care strategies in the lesser spotted woodpecker "Picoides minor" : of flexible mothers and dependable fathers N2 - We investigated sex-specific parental care behaviour of lesser spotted woodpeckers Picoides minor in the low mountain range Taunus, Germany. Observed parental care included incubation, nest sanitation as well as brooding and feeding of nestlings. Contributions of the two sexes to parental care changed in progress of the breeding period. During incubation and the first half of the nestling period, parental care was divided equally between partners. However, in the late nestling stage, we found males to feed their nestlings irrespective of brood size while females considerably decreased feeding rate with the number of nestlings. This behaviour culminated in desertion of small broods by females shortly before fledging. The fact that even deserted nests were successful indicates that males were able to compensate for the females' absence. Interestingly, the mating of one female with two males with separate nests could be found in the population, which confirms earlier findings of polyandry in the lesser spotted woodpecker. We conclude that biparental care is not essential in the later stage and one partner can reduce effort and thus costs of parental care, at least in small broods where the mate is able to compensate for that behaviour. Reduced care and desertion appears only in females, which might be caused by a combination of two traits: First, females might suffer higher costs of investment in terms of mortality and secondly, male-biased sex ratio in the population generally leads to higher mating probabilities for females in the following breeding season. The occurrence of polyandry seems to be a result of these conditions. Y1 - 2009 UR - http://www3.interscience.wiley.com/journal/118513172/home U6 - https://doi.org/10.1111/j.1600-048X.2008.04353.x SN - 0908-8857 ER - TY - JOUR A1 - Esther, Alexandra A1 - Groeneveld, Juergen A1 - Enright, Neal J. A1 - Miller, Ben P. A1 - Lamont, Byron B. A1 - Perry, George L. W. A1 - Blank, F. Benjamin A1 - Jeltsch, Florian T1 - Sensitivity of plant functional types to climate change : classification tree analysis of a simulation model N2 - Question: The majority of studies investigating the impact of climate change on local plant communities ignores changes in regional processes, such as immigration from the regional seed pool. Here we explore: (i) the potential impact of climate change on composition of the regional seed pool, (ii) the influence of changes in climate and in the regional seed pool on local community structure, and (iii) the combinations of life history traits, i.e. plant functional types (PFTs), that are most affected by environmental changes. Location: Fire-prone, Mediterranean-type shrublands in southwestern Australia. Methods: Spatially explicit simulation experiments were conducted at the population level under different rainfall and fire regime scenarios to determine the effect of environmental change on the regional seed pool for 38 PFTs. The effects of environmental and seed immigration changes on local community dynamics were then derived from community-level experiments. Classification tree analyses were used to investigate PFT- specific vulnerabilities to climate change. Results: The classification tree analyses revealed that responses of PFTs to climate change are determined by specific trait characteristics. PFT-specific seed production and community patterns responded in a complex manner to climate change. For example, an increase in annual rainfall caused an increase in numbers of dispersed seeds for some PFTs, but decreased PFT diversity in the community. Conversely, a simulated decrease in rainfall reduced the number of dispersed seeds and diversity of PFTs. Conclusions: PFT interactions and regional processes must be considered when assessing how local community structure will be affected by environmental change. Y1 - 2010 UR - http://www3.interscience.wiley.com/journal/121642345/home U6 - https://doi.org/10.1111/j.1654-1103.2009.01155.x SN - 1100-9233 ER - TY - JOUR A1 - Jeltsch, Florian A1 - Groeneveld, Jürgen A1 - Wissel, Christian A1 - Wucherer, W. A1 - Dimeyeva, L. T1 - Seed dispersal by cattle may cause shrub encroachment of Grewia flava on southern Kalahari rangelands Y1 - 2005 SN - 3-86537-386-0 ER - TY - JOUR A1 - Jeltsch, Florian A1 - Wiegand, K. A1 - Ward, D. T1 - Seed dispersal by cattle may cause shrub encroachment of Grewia flava on southern Kalahari rangelands Y1 - 2004 ER - TY - JOUR A1 - Jeltsch, Florian A1 - Tews, Jörg A1 - Schurr, Frank Martin T1 - Seed dispersal by cattle may cause shrub encroachment of Grewia flava on southern Kalahari rangelands N2 - Shrub encroachment, i.e. the increase in woody plant cover, is a major concern for livestock farming in southern Kalahari savannas. We developed a grid-based computer model simulating the population dynamics of Grewia flava, a common, fleshy-fruited encroaching shrub. In the absence of large herbivores, seeds of Grewia are largely deposited in the sub-canopy of Acacia erioloba. Cattle negate this dispersal limitation by browsing on the foliage of Grewia and dispersing seeds into the grassland matrix. In this study we first show that model predictions of Grewia cover dynamics are realistic by comparing model output with shrub cover estimates obtained from a time series of aerial photographs. Subsequently, we apply a realistic range of intensity of cattle-induced seed dispersal combined with potential precipitation and fire scenarios. Based on the simulation results we suggest that cattle may facilitate shrub encroachment of Grewia. The results show that the severity of shrub encroachment is governed by the intensity of seed dispersal. For a high seed dispersal intensity without fire (equivalent to a high stocking rate) the model predicts 56% shrub cover and 85% cell cover after 100 yr. With fire both recruitment and shrub cover are reduced, which may, under moderate intensities, prevent shrub encroachment. Climate change scenarios with two-fold higher frequencies of drought and wet years intensified shrub encroachment rates, although long-term mean of precipitation remained constant. As a management recommendation we suggest that shrub encroachment on rangelands may be counteracted by frequent fires and controlling cattle movements to areas with a high proportion of fruiting Grewia shrubs Y1 - 2004 ER - TY - CHAP A1 - Rossmanith, Eva A1 - Blaum, Niels A1 - Keil, Manfred A1 - Langerwisch, F. A1 - Meyer, Jork A1 - Popp, Alexander A1 - Schmidt, Michael A1 - Schultz, Christoph A1 - Schwager, Monika A1 - Vogel, Melanie A1 - Wasiolka, Bernd A1 - Jeltsch, Florian T1 - Scaling up local population dynamics to regional scales BT - an integrated approach N2 - In semi-arid savannas, unsustainable land use can lead to degradation of entire landscapes, e.g. in the form of shrub encroachment. This leads to habitat loss and is assumed to reduce species diversity. In BIOTA phase 1, we investigated the effects of land use on population dynamics on farm scale. In phase 2 we scale up to consider the whole regional landscape consisting of a diverse mosaic of farms with different historic and present land use intensities. This mosaic creates a heterogeneous, dynamic pattern of structural diversity at a large spatial scale. Understanding how the region-wide dynamic land use pattern affects the abundance of animal and plant species requires the integration of processes on large as well as on small spatial scales. In our multidisciplinary approach, we integrate information from remote sensing, genetic and ecological field studies as well as small scale process models in a dynamic region-wide simulation tool.
Interdisziplinäres Zentrum für Musterdynamik und Angewandte Fernerkundung Workshop vom 9. - 10. Februar 2006. Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-7320 N1 - [Poster] ER - TY - JOUR A1 - Popp, Alexander A1 - Vogel, Melanie A1 - Blaum, Niels A1 - Jeltsch, Florian T1 - Scaling up ecohydrological processes : role of surface water flow in water-limited landscapes N2 - In this study, we present a stochastic landscape modeling approach that has the power to transfer and integrate existing information on vegetation dynamics and hydrological processes from the small scale to the landscape scale. To include microscale processes like ecohydrological feedback mechanisms and spatial exchange like surface water flow, we derive transition probabilities from a fine-scale simulation model. We applied two versions of the landscape model, one that includes and one that disregards spatial exchange of water to the situation of a sustainably used research farm and communally used and degraded rangeland in semiarid Namibia. Our simulation experiments show that including spatial exchange of overland flow among vegetation patches into our model is a precondition to reproduce vegetation dynamics, composition, and productivity, as well as hydrological processes at the landscape scale. In the model version that includes spatial exchange of water, biomass production at light grazing intensities increases 2.24-fold compared to the model without overland flow. In contrast, overgrazing destabilizes positive feedbacks through vegetation and hydrology and decreases the number of hydrological sinks in the model with overland flow. The buffer capacity of these hydrological sinks disappears and runoff increases. Here, both models predicted runoff losses from the system and artificial droughts occurring even in years with good precipitation. Overall, our study reveals that a thorough understanding of overland flow is an important precondition for improving the management of semiarid and arid rangelands with distinct topography. Y1 - 2009 UR - http://www.agu.org/journals/jg/ U6 - https://doi.org/10.1029/2008jg000910 SN - 0148-0227 ER - TY - JOUR A1 - Giladi, Itamar A1 - May, Felix A1 - Ristow, Michael A1 - Jeltsch, Florian A1 - Ziv, Yaron T1 - Scale-dependent species-area and species-isolation relationships: a review and a test study from a fragmented semi-arid agro-ecosystem JF - Journal of biogeography N2 - Aim Patterns that relate species richness with fragment area (the species-area relationship, SAR) and with isolation (the species-isolation relationship, SIR) are well documented. However, those that relate species density - the number of species within a standardized area - with fragment area (D-SAR) or isolation (D-SIR) have not been sufficiently explored, despite the potential for such an analysis to disentangle the underlying mechanisms of SARs and SIRs. Previous spatial theory predicts that a significant D-SAR or D-SIR is unlikely to emerge in taxa with high dispersal limitation, such as plants. Furthermore, a recent model predicts that the detection and the significance of D-SARs or D-SIRs may decrease with grain size. We combined a literature review with grain size-dependent sampling in a fragmented landscape to evaluate the prevalence and grain size-dependent nature of D-SARs and D-SIRs in plants. Location Worldwide (review) and a semi-arid agro-ecosystem in Israel (case study). Methods We combined an extensive literature review of 31 D-SAR studies of plants in fragmented landscapes with an empirical study in which we analysed grain size-dependent D-SARs and D-SIRs using a grain size-dependent hierarchical sampling of species density and species richness in a fragmented, semi-arid agro-ecosystem. Results We found that significantly increasing D-SARs are rare in plant studies. Furthermore, we found that the detection of a significant D-SAR is often possible only after the data have been stratified by species, habitat or landscape characteristics. The results from our case study indicated that the significance and the slopes of both D-SARs and D-SIRs increase as grain size decreases. Main conclusions These results call for a careful consideration of scale while analysing and interpreting the responses of species richness and species density to fragmentation. Our results suggest that grain size-dependent analyses of D-SARs and D-SIRs may help to disentangle the mechanisms that generate SARs and SIRs and may enable early detection of the effects of fragmentation on plant biodiversity. KW - species density KW - isolation KW - scale-dependence KW - habitat fragmentation KW - extinction debt KW - Conservation biogeography KW - species-area relationship KW - island ecology KW - habitat islands KW - island biogeography theory Y1 - 2014 U6 - https://doi.org/10.1111/jbi.12299 SN - 0305-0270 SN - 1365-2699 VL - 41 IS - 6 SP - 1055 EP - 1069 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Giladi, Itamar A1 - Ziv, Yaron A1 - May, Felix A1 - Jeltsch, Florian T1 - Scale-dependent determinants of plant species richness in a semi-arid fragmented agro-ecosystem JF - Journal of vegetation science N2 - Aims: (1) Understanding how the relationship between species richness and its determinants depends on the interaction between scales at which the response and explanatory variables are measured. (2) Quantifying the relative contributions of local, intermediate and large-scale determinants of species richness in a fragmented agro-ecosystem. (3) Testing the hypothesis that the relative contribution of these determinants varies with the grain size at which species richness is measured. Location: A fragmented agro-ecosystem in the Southern Judea Lowland, Israel, within a desert-Mediterranean transition zone. Methods: Plant species richness was estimated using hierarchical nested sampling in 81 plots, positioned in 38 natural vegetation patches within an agricultural matrix (mainly wheat fields) among three land units along a sharp precipitation gradient. Explanatory variables included position along that gradient, patch area, patch isolation, habitat heterogeneity and overall plant density. We used general linear models and hierarchical partitioning of variance to test and quantify the effect of each explanatory variable on species richness at four grain sizes (0.0625, 1, 25 and 225m(2)). Results: Species richness was mainly affected by position along a precipitation gradient and overall plant density, and to a lesser extent by habitat heterogeneity. It was also significantly affected by patch area and patch isolation, but only for small grain sizes. The contribution of each explanatory variable to explained variance in species richness varied with grain size, i.e. scale-dependent. The influence of geographic position and habitat heterogeneity on species richness increased with grain size, while the influence of plant density decreased with grain size. Main conclusions: Species richness is determined by the combined effect of several scale-dependent determinants. Ability to detect an effect and effect size of each determinant varies with the scale (grain size) at which it is measured. The combination of a multi-factorial approach and multi-scale sampling reveals that conclusions drawn from studies that ignore these dimensions are restricted and potentially misleading. KW - Habitat fragmentation KW - Hierarchical partitioning of variance KW - Multi-grain sampling KW - Scale-dependence KW - Species density KW - Uniform sampling Y1 - 2011 U6 - https://doi.org/10.1111/j.1654-1103.2011.01309.x SN - 1100-9233 VL - 22 IS - 6 SP - 983 EP - 996 PB - Wiley-Blackwell CY - Malden ER - TY - JOUR A1 - Schiffers, Katja A1 - Tielboerger, Katja A1 - Tietjen, Britta A1 - Jeltsch, Florian T1 - Root plasticity buffers competition among plants theory meets experimental data JF - Ecology : a publication of the Ecological Society of America N2 - Morphological plasticity is a striking characteristic of plants in natural communities. In the context of foraging behavior particularly, root plasticity has been documented for numerous species. Root plasticity is known to mitigate competitive interactions by reducing the overlap of the individuals' rhizospheres. But despite its obvious effect on resource acquisition, plasticity has been generally neglected in previous empirical and theoretical studies estimating interaction intensity among plants. In this study, we developed a semi-mechanistic model that addresses this shortcoming by introducing the idea of compensatory growth into the classical-zone-of influence (ZOI) and field-of-neighborhood (FON) approaches. The model parameters describing the belowground plastic sphere of influence (PSI) were parameterized using data from an accompanying field experiment. Measurements of the uptake of a stable nutrient analogue at distinct distances to the neighboring plants showed that the study species responded plastically to belowground competition by avoiding overlap of individuals' rhizospheres. An unexpected finding was that the sphere of influence of the study species Bromus hordeaceus could be best described by a unimodal function of distance to the plant's center and not with a continuously decreasing function as commonly assumed. We employed the parameterized model to investigate the interplay between plasticity and two other important factors determining the intensity of competitive interactions: overall plant density and the distribution of individuals in space. The simulation results confirm that the reduction of competition intensity due to morphological plasticity strongly depends on the spatial structure of the competitive environment. We advocate the use of semi-mechanistic simulations that explicitly consider morphological plasticity to improve our mechanistic understanding of plant interactions. KW - Bromus hordeaceus KW - competition intensity KW - morphological plasticity KW - nutrient analogues KW - plant density KW - PSI (plastic sphere of influence) KW - zone-of-influence model Y1 - 2011 SN - 0012-9658 VL - 92 IS - 3 SP - 610 EP - 620 PB - Wiley CY - Washington ER - TY - JOUR A1 - May, Felix A1 - Grimm, Volker A1 - Jeltsch, Florian T1 - Reversed effects of grazing on plant diversity : the role of below-ground competition and size symmetry N2 - Grazing is known as one of the key factors for diversity and community composition in grassland ecosystems, but the response of plant communities towards grazing varies remarkably between sites with different environmental conditions. It is generally accepted that grazing increases plant diversity in productive environments, while it tends to reduce diversity in unproductive habitats (grazing reversal hypothesis). Despite empirical evidence for this pattern the mechanistic link between modes of plant-plant competition and grazing response at the community level still remains poorly understood. Root-competition in particular has rarely been included in theoretical studies, although it has been hypothesized that variations in productivity and grazing regime can alter the relative importance of shoot- and root-competition. We therefore developed an individual-based model based on plant functional traits to investigate the response of a grassland community towards grazing. Models of different complexity, either incorporating only shoot competition or with distinct shoot- and root-competition, were used to study the interactive effects of grazing, resource availability, and the mode of competition (size-symmetric or asymmetric). The pattern predicted by the grazing reversal hypothesis (GRH) can only be explained by our model if shoot- and root-competition are explicitly considered and if size asymmetry of above- and symmetry of below-ground competition is assumed. For this scenario, the model additionally reproduced empirically observed plant trait responses: erect and large plant functional types (PFTs) dominated without grazing, while frequent grazing favoured small PFTs with a rosette growth form. We conclude that interactions between shoot- and root-competition and size symmetry/asymmetry of plant-plant interactions are crucial in order to understand grazing response under different habitat productivities. Our results suggest that future empirical trait surveys in grassland communities should include root traits, which have been largely ignored in previous studies, in order to improve predictions of plants" responses to grazing. Y1 - 2009 UR - http://www3.interscience.wiley.com/journal/118531693/home U6 - https://doi.org/10.1111/j.1600-0706.2009.17724.x SN - 0030-1299 ER - TY - JOUR A1 - Moloney, Kirk A. A1 - Holzapfel, Claus A1 - Tielbörger, Katja A1 - Jeltsch, Florian A1 - Schurr, Frank Martin T1 - Rethinking the common garden in invasion research N2 - In common garden experiments, a number of genotypes are raised in a common environment in order to quantify the genetic component of phenotypic variation. Common gardens are thus ideally suited for disentangling how genetic and environmental factors contribute to the success of invasive species in their new non-native range. Although common garden experiments are increasingly employed in the study of invasive species, there has been little discussion about how these experiments should be designed for greatest utility. We argue that this has delayed progress in developing a general theory of invasion biology. We suggest a minimum optimal design (MOD) for common garden studies that target the ecological and evolutionary processes leading to phenotypic differentiation between native and invasive ranges. This involves four elements: (A) multiple, strategically sited garden locations, involving at the very least four gardens (2 in the native range and 2 in the invaded range); (B) careful consideration of the genetic design of the experiment; (C) standardization of experimental protocols across all gardens; and (D) care to ensure the biosafety of the experiment. Our understanding of the evolutionary ecology of biological invasions will be greatly enhanced by common garden studies, if and only if they are designed in a more systematic fashion, incorporating at the very least the MOD suggested here. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/14338319 U6 - https://doi.org/10.1016/j.ppees.2009.05.002 SN - 1433-8319 ER - TY - GEN A1 - Weise, Hanna A1 - Auge, Harald A1 - Baessler, Cornelia A1 - Bärlund, Ilona A1 - Bennett, Elena M. A1 - Berger, Uta A1 - Bohn, Friedrich A1 - Bonn, Aletta A1 - Borchardt, Dietrich A1 - Brand, Fridolin A1 - Jeltsch, Florian A1 - Joshi, Jasmin Radha A1 - Grimm, Volker T1 - Resilience trinity BT - Safeguarding ecosystem functioning and services across three different time horizons and decision contexts T2 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Ensuring ecosystem resilience is an intuitive approach to safeguard the functioning of ecosystems and hence the future provisioning of ecosystem services (ES). However, resilience is a multi-faceted concept that is difficult to operationalize. Focusing on resilience mechanisms, such as diversity, network architectures or adaptive capacity, has recently been suggested as means to operationalize resilience. Still, the focus on mechanisms is not specific enough. We suggest a conceptual framework, resilience trinity, to facilitate management based on resilience mechanisms in three distinctive decision contexts and time-horizons: 1) reactive, when there is an imminent threat to ES resilience and a high pressure to act, 2) adjustive, when the threat is known in general but there is still time to adapt management and 3) provident, when time horizons are very long and the nature of the threats is uncertain, leading to a low willingness to act. Resilience has different interpretations and implications at these different time horizons, which also prevail in different disciplines. Social ecology, ecology and engineering are often implicitly focussing on provident, adjustive or reactive resilience, respectively, but these different notions of resilience and their corresponding social, ecological and economic tradeoffs need to be reconciled. Otherwise, we keep risking unintended consequences of reactive actions, or shying away from provident action because of uncertainties that cannot be reduced. The suggested trinity of time horizons and their decision contexts could help ensuring that longer-term management actions are not missed while urgent threats to ES are given priority. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1444 KW - concepts KW - ecosystems KW - ecosystem services provisioning KW - management KW - resilience Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-515284 SN - 1866-8372 IS - 4 ER - TY - JOUR A1 - Weise, Hanna A1 - Auge, Harald A1 - Baessler, Cornelia A1 - Bärlund, Ilona A1 - Bennett, Elena M. A1 - Berger, Uta A1 - Bohn, Friedrich A1 - Bonn, Aletta A1 - Borchardt, Dietrich A1 - Brand, Fridolin A1 - Jeltsch, Florian A1 - Joshi, Jasmin Radha A1 - Grimm, Volker T1 - Resilience trinity BT - safeguarding ecosystem functioning and services across three different time horizons and decision contexts JF - Oikos N2 - Ensuring ecosystem resilience is an intuitive approach to safeguard the functioning of ecosystems and hence the future provisioning of ecosystem services (ES). However, resilience is a multi-faceted concept that is difficult to operationalize. Focusing on resilience mechanisms, such as diversity, network architectures or adaptive capacity, has recently been suggested as means to operationalize resilience. Still, the focus on mechanisms is not specific enough. We suggest a conceptual framework, resilience trinity, to facilitate management based on resilience mechanisms in three distinctive decision contexts and time-horizons: 1) reactive, when there is an imminent threat to ES resilience and a high pressure to act, 2) adjustive, when the threat is known in general but there is still time to adapt management and 3) provident, when time horizons are very long and the nature of the threats is uncertain, leading to a low willingness to act. Resilience has different interpretations and implications at these different time horizons, which also prevail in different disciplines. Social ecology, ecology and engineering are often implicitly focussing on provident, adjustive or reactive resilience, respectively, but these different notions of resilience and their corresponding social, ecological and economic tradeoffs need to be reconciled. Otherwise, we keep risking unintended consequences of reactive actions, or shying away from provident action because of uncertainties that cannot be reduced. The suggested trinity of time horizons and their decision contexts could help ensuring that longer-term management actions are not missed while urgent threats to ES are given priority. KW - concepts KW - ecosystems KW - ecosystem services provisioning KW - management KW - resilience Y1 - 2020 U6 - https://doi.org/10.1111/oik.07213 SN - 0030-1299 SN - 1600-0706 VL - 129 IS - 4 SP - 445 EP - 456 PB - Wiley-Blackwell CY - Oxford ER - TY - JOUR A1 - Köchy, Martin A1 - Mathaj, Martin A1 - Jeltsch, Florian A1 - Malkinson, Dan T1 - Resilience of stocking capacity to changing climate in arid to Mediterranean landscapes N2 - Small livestock is an important resource for rural human populations in dry climates. How strongly will climate change affect the capacity of the rangeland? We used hierarchical modelling to scale quantitatively the growth of shrubs and annual plants, the main food of sheep and goats, to the landscape extent in the eastern Mediterranean region. Without grazing, productivity increased in a sigmoid way with mean annual precipitation. Grazing reduced productivity more strongly the drier the landscape. At a point just under the stocking capacity of the vegetation, productivity declined precipitously with more intense grazing due to a lack of seed production of annuals. We repeated simulations with precipitation patterns projected by two contrasting IPCC scenarios. Compared to results based on historic patterns, productivity and stocking capacity did not differ in most cases. Thus, grazing intensity remains the stronger impact on landscape productivity in this dry region even in the future. Y1 - 2008 UR - http://www.springerlink.com/content/gj0567116q770036/ U6 - https://doi.org/10.1007/s10113-008-0048-6 ER - TY - GEN A1 - Köchy, Martin A1 - Mathaj, Martin A1 - Jeltsch, Florian A1 - Malkinson, Dan T1 - Resilience of stocking capacity to changing climate in arid to Mediterranean landscapes N2 - Small livestock is an important resource for rural human populations in dry climates. How strongly will climate change affect the capacity of the rangeland? We used hierarchical modelling to scale quantitatively the growth of shrubs and annual plants, the main food of sheep and goats, to the landscape extent in the eastern Mediterranean region. Without grazing, productivity increased in a sigmoid way with mean annual precipitation. Grazing reduced productivity more strongly the drier the landscape. At a point just under the stocking capacity of the vegetation, productivity declined precipitously with more intense grazing due to a lack of seed production of annuals. We repeated simulations with precipitation patterns projected by two contrasting IPCC scenarios. Compared to results based on historic patterns, productivity and stocking capacity did not differ in most cases. Thus, grazing intensity remains the stronger impact on landscape productivity in this dry region even in the future. N2 - Kleinvieh ist eine wichtige Lebensgrundlage für die Landbevölkerung in trockenen Regionen. Wie stark wird sich der Klimawandel auf die Tragfähigkeit der Weideflächen auswirken? Wir benutzten hierarchische Modellierung, um das Wachstum von Sträuchern und einjährigen Kräutern, das wichtigste Futter für Ziegen und Schafe, quantitativ auf die Fläche von Landschaften in der östlichen Mittelmeerregion zu dimensionieren. Die Produktivität ohne Beweidung stieg sigmoidal mit dem mittleren Jahresniederschlag. Je trockener die Landschaft, desto stärker verminderte Beweidung die Produktion. An einem Punkt knapp unter der Tragfähigkeit der Vegetation, sank die Produktion stark mit zunehmender Beweidung, weil die Samenproduktion der Kräuter zu gering war. Wir wiederholten die Simulationen mit Niederschlagsverteilungsmustern gemäß zweier gegensätzlicher IPCC-Szenarien. Zukünftige Produktivität und Tragfähigkeit unterschieden sich in den meisten Fällen nicht von Ergebnissen auf Grund von historischer Niederschlagsverteilung. Allerdings war die zukünftige Produktivität in trockenen Habitaten der semiariden und trocken-mediterranen Regionen niedriger. Somit hat auch in Zukunft die Besatzdichte die größere Auswirkung auf die Produktivität dieser trockenen Landschaft als das Klima. "This abstract is provided by the authors, and is for convenience of the users only. The author certifies that the translation faithfully represents the official version in the language of the journal, which is the published Abstract of record and is the only Abstract to be used for reference and citation." T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 066 KW - topography KW - spatially explicit model KW - climate change KW - Middle East KW - stocking capacity Y1 - 2008 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-18720 ER - TY - GEN A1 - Synodinos, Alexios D. A1 - Eldridge, David A1 - Geißler, Katja A1 - Jeltsch, Florian A1 - Lohmann, Dirk A1 - Midgley, Guy A1 - Blaum, Niels T1 - Remotely sensed canopy height reveals three pantropical ecosystem states BT - a comment T2 - Ecology : a publication of the Ecological Society of America Y1 - 2017 U6 - https://doi.org/10.1002/ecy.1997 SN - 0012-9658 SN - 1939-9170 VL - 99 IS - 1 SP - 231 EP - 234 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Burkart, Michael A1 - Alsleben, Katja A1 - Lachmuth, Susanne A1 - Schumacher, Juliane A1 - Hofmann, Ralf A1 - Jeltsch, Florian A1 - Schurr, Frank Martin T1 - Recruitment requirements of the rare and threatened Juncus atratus N2 - The long-term persistence of populations and species depends on the successful recruitment of individuals. The generative recruitment of plants may be limited by a lack of suitable germination and establishment conditions. Establishment limitation may especially be caused by the competitive effect of surrounding dense vegetation, which is believed to restrict the recruitment success of many plant species to small open patches ('safe sites'). We conducted experiments to clarify the roles of germination and seedling establishment as limiting processes in the recruitment of Juncus atratus Krock., a rare and threatened herbaceous perennial river corridor plant in Central Europe. Light intensity had a positive effect on germination. However, some seedlings emerged even in total darkness and the germination rate at 1% light intensity was more than half of that at 60% light intensity. Seedling establishment in the field after 10 weeks was 30% on bare ground, but it was close to zero in grassland. Establishment in the growth chamber after 8 weeks was close to 75% for seedlings that germinated underwater, but only about 35% for seedlings that germinated afloat. Furthermore, establishment decreased with flooding duration on bare ground, but increased with flooding duration in grassland. These data indicate that establishment, rather than germination, is a critical life stage in Central European populations off. atratus. They furthermore indicate that the competition of surrounding vegetation for water limits seedling establishment under field conditions without flooding, largely restricting establishment success to bare ground habitats. In contrast, grassland is more suitable for the recruitment off. atratus than bare ground under prolonged flooding. Grassland may facilitate the establishment off. atratus seedlings during long- lasting floods by supplying oxygen to the soil through aerenchyma. The shift from competition to facilitation in grassland occurred after 30 days of flooding, i.e. within the ontogeny of individual plants. The specific recruitment requirements off. arrows may be a main cause of its rarity in modern Central Europe. In order to prevent regional extinction off. atratus, we suggest maintaining or re-establishing natural hydrodynamics in the species' habitats. Y1 - 2010 UR - http://www.sciencedirect.com/science/journal/03672530 U6 - https://doi.org/10.1016/j.flora.2009.08.003 SN - 0367-2530 ER - TY - JOUR A1 - Tielbörger, Katja A1 - Kadmon, Ronen A1 - Müller, Monika A1 - Jeltsch, Florian T1 - Raum-zeitliche Populationsdynamik von einjährigen Wüstenpflanzen Y1 - 2000 ER - TY - JOUR A1 - Pagel, Jörn A1 - Anderson, Barbara J. A1 - Cramer, Wolfgang A1 - Fox, Richard A1 - Jeltsch, Florian A1 - Roy, David B. A1 - Thomas, Chris D. A1 - Schurr, Frank Martin T1 - Quantifying range-wide variation in population trends from local abundance surveys and widespread opportunistic occurrence records JF - Methods in ecology and evolution : an official journal of the British Ecological Society N2 - 2. We present a hierarchical model that integrates observations from multiple sources to estimate spatio-temporal abundance trends. The model links annual population densities on a spatial grid to both long-term count data and to opportunistic occurrence records from a citizen science programme. Specific observation models for both data types explicitly account for differences in data structure and quality. 3. We test this novel method in a virtual study with simulated data and apply it to the estimation of abundance dynamics across the range of a butterfly species (Pyronia tithonus) in Great Britain between 1985 and 2004. The application to simulated and real data demonstrates how the hierarchical model structure accommodates various sources of uncertainty which occur at different stages of the link between observational data and the modelled abundance, thereby it accounts for these uncertainties in the inference of abundance variations. 4. We show that by using hierarchical observation models that integrate different types of commonly available data sources, we can improve the estimates of variation in species abundances across space and time. This will improve our ability to detect regional trends and can also enhance the empirical basis for understanding range dynamics. KW - atlas data KW - Bayesian statistics KW - biogeography KW - butterflies KW - citizen science programme KW - conservation biology KW - count data KW - macroecology KW - state-space model Y1 - 2014 U6 - https://doi.org/10.1111/2041-210X.12221 SN - 2041-210X SN - 2041-2096 VL - 5 IS - 8 SP - 751 EP - 760 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Jeltsch, Florian A1 - Hansen, Frank A1 - Tackmann, K. A1 - Staubach, C. A1 - Thulke, Hans-Hermann T1 - Processes leading to a spatial aggregation of Echinococcus multilocularis in its natural intermediate host Microtus arvalis N2 - The small fox tapeworm (Echinococcus multilocularis) shows a heterogeneous spatial distribution in the intermediate host (Microtus arvalis). To identify the ecological processes responsible for this heterogeneity, we developed a spatially explicit simulation model. The model combines individual-based (foxes, Vulpes vulpes) and grid- based (voles) techniques to simulate the infections in both intermediate and definite host. If host populations are homogeneously mixed, the model reproduces field data for parasite prevalence only for a limited number of parameter combinations. As ecological parameters inevitably vary to a certain degree, we discarded the homogeneous mixing model as insufficient to gain insight into the ecology of the fox tapeworm cycle. We analysed five different model scenarios, each focussing on an ecological process that might be responsible for the heterogeneous spatial distribution of E multilocularis in the intermediate host. Field studies revealed that the prevalence ratio between intermediate and definite host remains stable over a wide range of ecological conditions. Thus, by varying the parameters in simulation experiments, we used the robustness of the agreement between field data and model output as quality criterion for the five scenarios. Only one of the five scenarios was found to reproduce the prevalence ratio over a sufficient range of parameter combinations. In the accentuated scenario most tapeworm eggs die due to bad environmental conditions before they cause infections in the intermediate host. This scenario is supported by the known sensitivity of tapeworm eggs to high temperatures and dry conditions. The identified process is likely to lead to a heterogeneous availability of infective eggs and thus to a clumped distribution of infected intermediate hosts. In conclusion, areas with humid conditions and low temperatures must be pointed out as high risk areas for human exposure to E. multilocularis eggs as well. (C) 2004 on behalf of Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved Y1 - 2004 ER - TY - JOUR A1 - Lohmann, Dirk A1 - Tietjen, Britta A1 - Blaum, Niels A1 - Joubert, David Francois A1 - Jeltsch, Florian T1 - Prescribed fire as a tool for managing shrub encroachment in semi-arid savanna rangelands JF - Journal of arid environments N2 - Savanna rangelands worldwide are threatened by shrub encroachment, i.e. the increase of woody plant species at the cost of perennial grasses, causing a strong decline in the productivity of domestic livestock production. Although recent studies indicate that fire might be of great importance for semi-arid and arid savanna dynamics, it is largely not applied in the management of semi-arid rangelands especially with regard to woody plant control. We used the eco-hydrological savanna model EcoHyD to simulate the effects of different fire management strategies on semi-arid savanna vegetation and to assess their longterm suitability for semi-arid rangeland management. Simulation results show that prescribed fires, timed to kill tree seedlings prevented shrub encroachment for a broad range of livestock densities while the possible maximum long-term cattle densities on the simulated semi-arid rangeland in Namibia increased by more than 30%. However, when grazing intensity was too high, fire management failed in preventing shrub encroachment. Our findings indicate that with regard to fire management a clear distinction between mesic and more arid savannas is necessary: While the frequency of fires is of relevance for mesic savannas, we recommend a fire management focussing on the timing of fire for semi-arid and arid savannas. (C) 2014 Elsevier Ltd. All rights reserved. KW - Acacia mellifera KW - Bush encroachment KW - Dry land degradation KW - Rangeland management KW - Simulation model KW - Southern Africa Y1 - 2014 U6 - https://doi.org/10.1016/j.jaridenv.2014.04.003 SN - 0140-1963 SN - 1095-922X VL - 107 SP - 49 EP - 56 PB - Elsevier CY - London ER -