TY - JOUR A1 - Pfestorf, H. A1 - Weiss, L. A1 - Müller, J. A1 - Boch, Steffen A1 - Socher, S. A. A1 - Prati, Daniel A1 - Schöning, Ingo A1 - Weisser, W. A1 - Fischer, M. A1 - Jeltsch, Florian T1 - Community mean traits as additional indicators to monitor effects of land-use intensity On grassland plant diversity JF - Perspectives in plant ecology, evolution and systematics N2 - 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. KW - Biodiversity Exploratories KW - Biological conservation KW - (Semi-natural) Grasslands KW - Plant functional traits KW - Indicators KW - Land-use intensity Y1 - 2013 U6 - https://doi.org/10.1016/j.ppees.2012.10.003 SN - 1433-8319 VL - 15 IS - 1 SP - 1 EP - 11 PB - Elsevier CY - Jena ER - TY - JOUR A1 - May, Felix A1 - Giladi, Itamar A1 - Ristow, Michael A1 - Ziv, Yaron A1 - Jeltsch, Florian T1 - Plant functional traits and community assembly along interacting gradients of productivity and fragmentation JF - Perspectives in plant ecology, evolution and systematics N2 - Quantifying the association of plant functional traits to environmental gradients is a promising approach for understanding and projecting community responses to land use and climatic changes. Although habitat fragmentation and climate are expected to affect plant communities interactively, there is a lack of empirical studies addressing trait associations to fragmentation in different climatic regimes. In this study, we analyse data on the key functional traits: specific leaf area (SLA), plant height, seed mass and seed number. First, we assess the evidence for the community assembly mechanisms habitat filtering and competition at different spatial scales, using several null-models and a comprehensive set of community-level trait convergence and divergence indices. Second, we analyse the association of community-mean traits with patch area and connectivity along a south-north productivity gradient. We found clear evidence for trait convergence due to habitat filtering. In contrast, the evidence for trait divergence due to competition fundamentally depended on the null-model used. When the null-model controlled for habitat filtering, there was only evidence for trait divergence at the smallest sampling scale (0.25 m x 0.25 m). All traits varied significantly along the S-N productivity gradient. While plant height and SLA were consistently associated with fragmentation, the association of seed mass and seed number with fragmentation changed along the S-N gradient. Our findings indicate trait convergence due to drought stress in the arid sites and due to higher productivity in the mesic sites. The association of plant traits to fragmentation is likely driven by increased colonization ability in small and/or isolated patches (plant height, seed number) or increased persistence ability in isolated patches (seed mass). Our study provides the first empirical test of trait associations with fragmentation along a productivity gradient. We conclude that it is crucial to study the interactive effects of different ecological drivers on plant functional traits. KW - Connectivity KW - Drought-stress KW - Habitat filtering KW - Limiting similarity KW - Null models KW - Plant height KW - Seed mass KW - Seed number KW - Specific leaf area (SLA) Y1 - 2013 U6 - https://doi.org/10.1016/j.ppees.2013.08.002 SN - 1433-8319 VL - 15 IS - 6 SP - 304 EP - 318 PB - Elsevier CY - Jena ER - TY - JOUR A1 - Seifan, Merav A1 - Seifan, Tal A1 - Schiffers, Katja A1 - Jeltsch, Florian A1 - Tielboerger, Katja T1 - Beyond the competition-colonization trade-off - linking multiple trait response to disturbance characteristics JF - The American naturalist : a bi-monthly journal devoted to the advancement and correlation of the biological sciences N2 - 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. KW - competition resistance trade-off KW - functional types KW - intermediate disturbance hypothesis KW - plant communities KW - species assemblies Y1 - 2013 U6 - https://doi.org/10.1086/668844 SN - 0003-0147 VL - 181 IS - 2 SP - 151 EP - 160 PB - Univ. of Chicago Press CY - Chicago ER - TY - JOUR A1 - Buchmann, Carsten M. A1 - Schurr, Frank Martin A1 - Nathan, Ran A1 - Jeltsch, Florian T1 - Habitat loss and fragmentation affecting mammal and bird communities-The role of interspecific competition and individual space use JF - Ecological informatics : an international journal on ecoinformatics and computational ecolog N2 - Fragmentation and loss of habitat are major threats to animal communities and are therefore important to conservation. Due to the complexity of the interplay of spatial effects and community processes, our mechanistic understanding of how communities respond to such landscape changes is still poor. Modelling studies have mostly focused on elucidating the principles of community response to fragmentation and habitat loss at relatively large spatial and temporal scales relevant to metacommunity dynamics. Yet, it has been shown that also small scale processes, like foraging behaviour, space use by individuals and local resource competition are also important factors. However, most studies that consider these smaller scales are designed for single species and are characterized by high model complexity. Hence, they are not easily applicable to ecological communities of interacting individuals. To fill this gap, we apply an allometric model of individual home range formation to investigate the effects of habitat loss and fragmentation on mammal and bird communities, and, in this context, to investigate the role of interspecific competition and individual space use. Results show a similar response of both taxa to habitat loss. Community composition is shifted towards higher frequency of relatively small animals. The exponent and the 95%-quantile of the individual size distribution (ISD, described as a power law distribution) of the emerging communities show threshold behaviour with decreasing habitat area. Fragmentation per se has a similar and strong effect on mammals, but not on birds. The ISDs of bird communities were insensitive to fragmentation at the small scales considered here. These patterns can be explained by competitive release taking place in interacting animal communities, with the exception of bird's buffering response to fragmentation, presumably by adjusting the size of their home ranges. These results reflect consequences of higher mobility of birds compared to mammals of the same size and the importance of considering competitive interaction, particularly for mammal communities, in response to landscape fragmentation. Our allometric approach enables scaling up from individual physiology and foraging behaviour to terrestrial communities, and disentangling the role of individual space use and interspecific competition in controlling the response of mammal and bird communities to landscape changes. KW - Allometry KW - Body size KW - Fractal landscapes KW - Foraging movement KW - Individual-based model KW - Locomotion costs Y1 - 2013 U6 - https://doi.org/10.1016/j.ecoinf.2012.11.015 SN - 1574-9541 VL - 14 SP - 90 EP - 98 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Jeltsch, Florian A1 - Blaum, Niels A1 - Brose, Ulrich A1 - Chipperfield, Joseph D. A1 - Clough, Yann A1 - Farwig, Nina A1 - Geissler, Katja A1 - Graham, Catherine H. A1 - Grimm, Volker A1 - Hickler, Thomas A1 - Huth, Andreas A1 - May, Felix A1 - Meyer, Katrin M. A1 - Pagel, Jörn A1 - Reineking, Björn A1 - Rillig, Matthias C. A1 - Shea, Katriona A1 - Schurr, Frank Martin A1 - Schroeder, Boris A1 - Tielbörger, Katja A1 - Weiss, Lina A1 - Wiegand, Kerstin A1 - Wiegand, Thorsten A1 - Wirth, Christian A1 - Zurell, Damaris T1 - How can we bring together empiricists and modellers in functional biodiversity research? JF - Basic and applied ecology : Journal of the Gesellschaft für Ökologie N2 - Improving our understanding of biodiversity and ecosystem functioning and our capacity to inform ecosystem management requires an integrated framework for functional biodiversity research (FBR). However, adequate integration among empirical approaches (monitoring and experimental) and modelling has rarely been achieved in FBR. We offer an appraisal of the issues involved and chart a course towards enhanced integration. A major element of this path is the joint orientation towards the continuous refinement of a theoretical framework for FBR that links theory testing and generalization with applied research oriented towards the conservation of biodiversity and ecosystem functioning. We further emphasize existing decision-making frameworks as suitable instruments to practically merge these different aims of FBR and bring them into application. This integrated framework requires joint research planning, and should improve communication and stimulate collaboration between modellers and empiricists, thereby overcoming existing reservations and prejudices. The implementation of this integrative research agenda for FBR requires an adaptation in most national and international funding schemes in order to accommodate such joint teams and their more complex structures and data needs. KW - Biodiversity theory KW - Biodiversity experiments KW - Conservation management KW - Decision-making KW - Ecosystem functions and services KW - Forecasting KW - Functional traits KW - Global change KW - Monitoring programmes KW - Interdisciplinarity Y1 - 2013 U6 - https://doi.org/10.1016/j.baae.2013.01.001 SN - 1439-1791 VL - 14 IS - 2 SP - 93 EP - 101 PB - Elsevier CY - Jena ER - TY - CHAP A1 - Sapir, N. A1 - Rotics, S. A1 - Kaatz, M. A1 - Davidson, S. A1 - Zurell, Damaris A1 - Eggers, U. A1 - Jeltsch, Florian A1 - Nathan, R. A1 - Wikelski, M. T1 - Multi-year tracking of white storks (Ciconia ciconia) how the environment shapes the movement and behavior of a soaring-gliding inter-continental migrant T2 - Integrative and comparative biology Y1 - 2013 SN - 1540-7063 VL - 53 IS - 3 SP - E189 EP - E189 PB - Oxford Univ. Press CY - Cary ER - TY - JOUR A1 - Sarmento, Juliano Sarmento A1 - Jeltsch, Florian A1 - Thuiller, Wilfried A1 - Higgins, Steven A1 - Midgley, Guy F. A1 - Rebelo, Anthony G. A1 - Rouget, Mathieu A1 - Schurr, Frank Martin T1 - Impacts of past habitat loss and future climate change on the range dynamics of South African Proteaceae JF - Diversity & distributions : a journal of biological invasions and biodiversity N2 - Aim To assess how habitat loss and climate change interact in affecting the range dynamics of species and to quantify how predicted range dynamics depend on demographic properties of species and the severity of environmental change. Location South African Cape Floristic Region. Methods We use data-driven demographic models to assess the impacts of past habitat loss and future climate change on range size, range filing and abundances of eight species of woody plants (Proteaceae). The species-specific models employ a hybrid approach that simulates population dynamics and long-distance dispersal on top of expected spatio-temporal dynamics of suitable habitat. Results Climate change was mainly predicted to reduce range size and range filling (because of a combination of strong habitat shifts with low migration ability). In contrast, habitat loss mostly decreased mean local abundance. For most species and response measures, the combination of habitat loss and climate change had the most severe effect. Yet, this combined effect was mostly smaller than expected from adding or multiplying effects of the individual environmental drivers. This seems to be because climate change shifts suitable habitats to regions less affected by habitat loss. Interspecific variation in range size responses depended mostly on the severity of environmental change, whereas responses in range filling and local abundance depended mostly on demographic properties of species. While most surviving populations concentrated in areas that remain climatically suitable, refugia for multiple species were overestimated by simply overlying habitat models and ignoring demography. Main conclusions Demographic models of range dynamics can simultaneously predict the response of range size, abundance and range filling to multiple drivers of environmental change. Demographic knowledge is particularly needed to predict abundance responses and to identify areas that can serve as biodiversity refugia under climate change. These findings highlight the need for data-driven, demographic assessments in conservation biogeography. KW - biodiversity refugia KW - CFR Proteaceae KW - climate change KW - demographic properties KW - habitat loss KW - local abundances KW - process-based range models KW - range filling KW - range size KW - species distribution models Y1 - 2013 U6 - https://doi.org/10.1111/ddi.12011 SN - 1366-9516 VL - 19 IS - 4 SP - 363 EP - 376 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - May, Felix A1 - Giladi, Itamar A1 - Ristow, Michael A1 - Ziv, Yaron A1 - Jeltsch, Florian T1 - Metacommunity, mainland-island system or island communities? : assessing the regional dynamics of plant communities in a fragmented landscape JF - Ecography : pattern and diversity in ecology ; research papers forum N2 - Understanding the regional dynamics of plant communities is crucial for predicting the response of plant diversity to habitat fragmentation. However, for fragmented landscapes the importance of regional processes, such as seed dispersal among isolated habitat patches, has been controversially debated. Due to the stochasticity and rarity of among-patch dispersal and colonization events, we still lack a quantitative understanding of the consequences of these processes at the landscape-scale. In this study, we used extensive field data from a fragmented, semi-arid landscape in Israel to parameterize a multi-species incidence-function model. This model simulates species occupancy pattern based on patch areas and habitat configuration and explicitly considers the locations and the shapes of habitat patches for the derivation of patch connectivity. We implemented an approximate Bayesian computation approach for parameter inference and uncertainty assessment. We tested which of the three types of regional dynamics - the metacommunity, the mainland-island, or the island communities type - best represents the community dynamics in the study area and applied the simulation model to estimate the extinction debt in the investigated landscape. We found that the regional dynamics in the patch-matrix study landscape is best represented as a system of highly isolated island' communities with low rates of propagule exchange among habitat patches and consequently low colonization rates in local communities. Accordingly, the extinction rates in the local communities are the main drivers of community dynamics. Our findings indicate that the landscape carries a significant extinction debt and in model projections 33-60% of all species went extinct within 1000 yr. Our study demonstrates that the combination of dynamic simulation models with field data provides a promising approach for understanding regional community dynamics and for projecting community responses to habitat fragmentation. The approach bears the potential for efficient tests of conservation activities aimed at mitigating future losses of biodiversity. Y1 - 2013 U6 - https://doi.org/10.1111/j.1600-0587.2012.07793.x SN - 0906-7590 VL - 36 IS - 7 SP - 842 EP - 853 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Lauterbach, D. A1 - Roemermann, C. A1 - Jeltsch, Florian A1 - Ristow, Michael T1 - Factors driving plant rarity in dry grasslands on different spatial scales: a functional trait approach JF - BIODIVERSITY AND CONSERVATION N2 - In European dry grasslands land-use changes affect plant species performance and frequency. Potential driving forces are eutrophication and habitat fragmentation. The importance of these factors is presumably scale dependent. We used a functional trait approach to detect processes that influence species frequency and endangerment on different spatial scales. We tested for associations between functional traits and (1) frequency and (2) degree of endangerment on local, regional and national scales. We focussed on five selected traits that describe the life-history of plant species and that are related to competition, dispersal ability and habitat specificity. Trait data on plant height, SLA, plant coverage, peak of flowering and diaspore mass were measured for 28 perennials from common to rare and endangered to non-endangered on 59 dry grassland sites in north-eastern Germany. Multiple regression models revealed that species frequency is positively and species endangerment negatively related to plant height, plant coverage and SLA on more than one spatial scale. On the local scale, diaspore mass has a negative effect on species frequency. More frequent and less endangered species show a later peak of flowering on nationwide and regional scales. We concluded that competition traits are more important on larger scales, whereas dispersal traits are more important for species frequency on the smaller scale. On national and regional scales, eutrophication and habitat loss may be the main drivers of species threat, whereas on the local scale fragmentation plays a crucial role for the performance of dry grassland species. KW - Species frequency KW - Species endangerment KW - Fragmentation KW - Eutrophication KW - SLA Y1 - 2013 U6 - https://doi.org/10.1007/s10531-013-0455-y SN - 0960-3115 VL - 22 IS - 10 SP - 2337 EP - 2352 PB - SPRINGER CY - DORDRECHT ER - TY - JOUR A1 - Jeltsch, Florian A1 - Bonte, Dries A1 - Peer, Guy A1 - Reineking, Björn A1 - Leimgruber, Peter A1 - Balkenhol, Niko A1 - Schröder-Esselbach, Boris A1 - Buchmann, Carsten M. A1 - Müller, Thomas A1 - Blaum, Niels A1 - Zurell, Damaris A1 - Böhning-Gaese, Katrin A1 - Wiegand, Thorsten A1 - Eccard, Jana A1 - Hofer, Heribert A1 - Reeg, Jette A1 - Eggers, Ute A1 - Bauer, Silke T1 - Integrating movement ecology with biodiversity research - exploring new avenues to address spatiotemporal biodiversity dynamics Y1 - 2013 UR - http://download.springer.com/static/pdf/827/art%253A10.1186%252F2051-3933-1- 6.pdf?auth66=1394891271_f1a4cb74d6be42ee3f8872ef2ca22c24&ext=.pdf U6 - https://doi.org/10.1186/2051-3933-1-6 ER - TY - JOUR A1 - Schwager, Monika A1 - Covas, Rita A1 - Blaum, Niels A1 - Jeltsch, Florian T1 - Limitations of population models in predicting climate change effects : a simulation study of sociable weavers in southern Africa Y1 - 2008 UR - http://www3.interscience.wiley.com/journal/118531693/home U6 - https://doi.org/10.1111/j.0030-1299.2008.16464.x SN - 0030-1299 ER - TY - JOUR A1 - Zurell, Damaris A1 - Berger, Uta A1 - Cabral, Juliano Sarmento A1 - Jeltsch, Florian A1 - Meynard, Christine N. A1 - Muenkemueller, Tamara A1 - Nehrbass, Nana A1 - Pagel, Jörn A1 - Reineking, Bjoern A1 - Schroeder, Boris A1 - Grimm, Volker T1 - The virtual ecologist approach : simulating data and observers N2 - Ecologists carry a well-stocked toolbox with a great variety of sampling methods, statistical analyses and modelling tools, and new methods are constantly appearing. Evaluation and optimisation of these methods is crucial to guide methodological choices. Simulating error-free data or taking high-quality data to qualify methods is common practice. Here, we emphasise the methodology of the 'virtual ecologist' (VE) approach where simulated data and observer models are used to mimic real species and how they are 'virtually' observed. This virtual data is then subjected to statistical analyses and modelling, and the results are evaluated against the 'true' simulated data. The VE approach is an intuitive and powerful evaluation framework that allows a quality assessment of sampling protocols, analyses and modelling tools. It works under controlled conditions as well as under consideration of confounding factors such as animal movement and biased observer behaviour. In this review, we promote the approach as a rigorous research tool, and demonstrate its capabilities and practical relevance. We explore past uses of VE in different ecological research fields, where it mainly has been used to test and improve sampling regimes as well as for testing and comparing models, for example species distribution models. We discuss its benefits as well as potential limitations, and provide some practical considerations for designing VE studies. Finally, research fields are identified for which the approach could be useful in the future. We conclude that VE could foster the integration of theoretical and empirical work and stimulate work that goes far beyond sampling methods, leading to new questions, theories, and better mechanistic understanding of ecological systems. Y1 - 2010 UR - http://www3.interscience.wiley.com/cgi-bin/issn?DESCRIPTOR=PRINTISSN&VALUE=0030-1299 U6 - https://doi.org/10.1111/j.1600-0706.2009.18284.x SN - 0030-1299 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 - 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 - 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 - JOUR A1 - Wasiolka, Bernd A1 - Jeltsch, Florian A1 - Henschel, Joh A1 - Blaum, Niels T1 - Space use of the spotted sand lizard (Pedioplanis l. lineoocellata) under different degradation states N2 - Although the effects of grazing-induced savannah degradation on animal diversity are well documented, knowledge of how they affect space use or responding behaviour remains poor. In this study, we analysed space use of the spotted sand lizard (Pedioplanis l. lineoocellata) in degraded versus nondegraded habitats of southern Kalahari savannah habitats. Lizards were radio tracked, daily movement distances recorded and home range sizes calculated. In degraded Kalahari savannah habitats where plant diversity and perennial grass cover are low but shrub cover high, P. lineoocellata moves larger distances (40.88 +/- 6.42 m versus 27.43 +/- 5.08 m) and occupies larger home ranges (646.64 +/- 244.84 m(2) versus 209.15 +/- 109.84 m(2)) than in nondegraded habitats (high plant diversity, high perennial grass cover and low shrub cover). We assume that this increase in daily movement distances and home range sizes is a behavioural plasticity to limited food resources in degraded savannah habitats. Although P. lineoocellata is able to adjust to resource-poor savannah habitats, the increase in the lizard's movement activities is likely to result in a higher predation risk. This is supported by the lower availability of protective vegetation i.e. perennial grass cover. Hence, we conclude that despite behavioural plasticity of P. lineoocellata, overgrazing has a severe negative impact on the space use of P. lineoocellata. Y1 - 2010 UR - http://www3.interscience.wiley.com/cgi-bin/issn?DESCRIPTOR=PRINTISSN&VALUE=0141-6707 U6 - https://doi.org/10.1111/j.1365-2028.2009.01085.x SN - 0141-6707 ER - TY - JOUR A1 - Treydte, Anna C. A1 - Riginos, Corinna A1 - Jeltsch, Florian T1 - Enhanced use of beneath-canopy vegetation by grazing ungulates in African savannahs N2 - 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. Y1 - 2010 UR - http://www.sciencedirect.com/science/journal/01401963 U6 - https://doi.org/10.1016/j.jaridenv.2010.07.003 SN - 0140-1963 ER - TY - JOUR A1 - Tietjen, Britta A1 - Jeltsch, Florian A1 - Zehe, Erwin A1 - Classen, Nikolaus A1 - Groengroeft, Alexander A1 - Schiffers, Katja A1 - Oldeland, Jens T1 - Effects of climate change on the coupled dynamics of water and vegetation in drylands N2 - 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. Y1 - 2010 UR - http://www3.interscience.wiley.com/journal/114209870/home U6 - https://doi.org/10.1002/Eco.70 SN - 1936-0584 ER - TY - JOUR A1 - Petru, Martina A1 - Tielbörger, Katja A1 - Belkin, Ruthie A1 - Sternberg, Marcelo A1 - Jeltsch, Florian T1 - Life history variation in an annual plant under two opposing environmental constraints along an aridity gradient N2 - Environmental gradients represent an ideal framework for studying adaptive variation in the life history of plant species. However, on very steep gradients, largely contrasting conditions at the two gradient ends often limit the distribution of the same species across the whole range of environmental conditions. Here, we study phenotypic variation in a winter annual crucifer Biscutella didyma persisting along a steep gradient of increasing rainfall in Israel. In particular, we explored whether the life history at the arid end of the gradient indicates adaptations to drought and unpredictable conditions, while adaptations to the highly competitive environment prevail at the mesic Mediterranean end. We examined several morphological and reproductive traits in four natural populations and in populations cultivated in standard common environment. Plants from arid environments were faster in phenological development, more branched in architecture and tended to maximize reproduction, while the Mediterranean plants invested mainly in vertical vegetative growth. Differences between cultivation and field in diaspore production were very large for arid populations as opposed to Mediterranean ones, indicating a larger potential to increase reproduction under favorable conditions. Our overall findings indicate two strongly opposing selective forces at the two extremes of the aridity gradient, which result in contrasting strategies within the studied annual plant species Y1 - 2006 UR - http://www3.interscience.wiley.com/journal/117966123/home U6 - https://doi.org/10.1111/j.2005.0906-7590.04310.x ER - TY - JOUR A1 - Wasiolka, Bernd A1 - Blaum, Niels A1 - Jeltsch, Florian A1 - Henschel, Joh T1 - Behavioural responses of the lizard "Pedioplanis l. lineoocellata" to overgrazing N2 - 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. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/1146609X U6 - https://doi.org/10.1016/j.actao.2008.09.009 SN - 1146-609X 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 - 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 - JOUR A1 - Esther, Alexandra A1 - Groeneveld, Jürgen A1 - Enright, Neal J. A1 - Miller, Ben P. A1 - Lamont, Byron B. A1 - Perry, George L. W. A1 - Schurr, Frank Martin A1 - Jeltsch, Florian T1 - Assessing the importance of seed immigration on coexistence of plant functional types in a species-rich ecosystem N2 - 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. Y1 - 2008 UR - http://www.sciencedirect.com/science/journal/03043800 U6 - https://doi.org/10.1016/j.ecolmodel.2008.01.014 SN - 0304-3800 ER - TY - JOUR A1 - Körner, Katrin A1 - Jeltsch, Florian T1 - Detecting general plant functional type responses in fragmented landscapes using spatially-explicit simulations Y1 - 2008 UR - http://www.sciencedirect.com/science/journal/03043800 U6 - https://doi.org/10.1016/j.ecolmodel.2007.08.002 SN - 0304-3800 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 - Popp, Alexander A1 - Domptail, Stephanie A1 - Blaum, Niels A1 - Jeltsch, Florian T1 - Landuse experience does not qualify for adaptation to climate change N2 - The need to implement sustainable resource management regimes for semi-arid and arid rangelands is acute as non- adapted grazing strategies lead to irreversible environmental problems such as desertification and associated loss of economic support to society. In these sensitive ecosystems, traditional sectoral, disciplinary approaches will not work to attain sustainability: achieving a collective vision of how to attain sustainability requires interactive efforts among disciplines in a more integrated approach. Therefore, we developed an integrated ecological-economic approach that consists of an ecological and an economic module and combines relevant processes on either level. Parameters for both modules are adjusted for an arid dwarf shrub savannah in southern Namibia. The economic module is used to analyse decisions of different virtual farmer types on annual stocking rates depending on their knowledge how the ecosystem works and climatic conditions. We used a dynamic linear optimisation model to simulate farm economics and livestock dynamics. The ecological module is used to simulate the impact of the farmers' land-use decision, derived by the economic module, on ecosystem dynamics and resulting carrying capacity of the system for livestock. Vegetation dynamics, based on the concept of State-and-transition models, and forage productivity for both modules is derived by a small- scale and spatially explicit vegetation model. This mechanistic approach guarantees that data collected and processes estimated at smaller scales are included in our application. Simulation results of the ecological module were successfully compared to simulation results of the optimisation model for a time series of 30 years. We revealed that sustainable management of semi-arid and arid rangelands relies strongly on rangeland managers' understanding of ecological processes. Furthermore, our simulation results demonstrate that the projected lower annual rainfall due to climate change adds an additional layer of risk to these ecosystems that are already prone to land degradation. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/03043800 U6 - https://doi.org/10.1016/j.ecolmodel.2008.11.015 SN - 0304-3800 ER - TY - JOUR A1 - Meyer, Jork A1 - Raudnitschka, Dorit A1 - Steinhauser, J. A1 - Jeltsch, Florian A1 - Brandl, Roland T1 - Biology and ecology of "Thallomys nigricauda" (Rodentia, Muridae) in the Thornveld savannah of South Africa Y1 - 2008 UR - http://www.sciencedirect.com/science/journal/16165047 U6 - https://doi.org/10.1016/j.mambio.2006.11.002 SN - 1616-5047 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 - 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 - Pfeifer, Marion A1 - Schatz, Bertrand A1 - Picó, F. Xavier A1 - Passalacqua, Nicodemo G. A1 - Fay, Michael F. A1 - Carey, Pete D. A1 - Jeltsch, Florian T1 - Phylogeography and genetic structure of the orchid "Himantoglossum hircinum" (L.) Spreng. across its European central-marginal gradient N2 - Aim This study aims to link demographic traits and post-glacial recolonization processes with genetic traits in Himantoglossum hircinum (L.) Spreng (Orchidaceae), and to test the implications of the central-marginal concept (CMC) in Europe. Location Twenty sites covering the entire European distribution range of this species. Methods We employed amplified fragment length polymorphism (AFLP) markers and performed a plastid microsatellite survey to assess genetic variation in 20 populations of H. hircinum located along central-marginal gradients. We measured demographic traits to assess population fitness along geographical gradients and to test for correlations between demographic traits and genetic diversity. We used genetic diversity indices and analyses of molecular variance (AMOVA) to test hypotheses of reduced genetic diversity and increased genetic differentiation and isolation from central to peripheral sites. We used Bayesian simulations to analyse genetic relationships among populations. Results Genetic diversity decreased significantly with increasing latitudinal and longitudinal distance from the distribution centre when excluding outlying populations. The AMOVA revealed significant genetic differentiation among populations (F-ST = 0.146) and an increase in genetic differentiation from the centre of the geographical range to the margins (except for the Atlantic group). Population fitness, expressed as the ratio N-R/N, decreased significantly with increasing latitudinal distance from the distribution centre. Flower production was lower in most eastern peripheral sites. The geographical distribution of microsatellite haplotypes suggests post-glacial range expansion along three major migratory pathways, as also supported by individual membership fractions in six ancestral genetic clusters (C1-C6). No correlations between genetic diversity (e.g. diversity indices, haplotype frequency) and population demographic traits were detected. Main conclusions Reduced genetic diversity and haplotype frequency in H. hircinum at marginal sites reflect historical range expansions. Spatial variation in demographic traits could not explain genetic diversity patterns. For those sites that did not fit into the CMC, the genetic pattern is probably masked by other factors directly affecting either demography or population genetic structure. These include post-glacial recolonization patterns and changes in habitat suitability due to climate change at the northern periphery. Our findings emphasize the importance of distinguishing historical effects from those caused by geographical variation in population demography of species when studying evolutionary and ecological processes at the range margins under global change. Y1 - 2009 UR - http://www3.interscience.wiley.com/journal/117963685/home U6 - https://doi.org/10.1111/j.1365-2699.2009.02168.x SN - 0305-0270 ER - TY - JOUR A1 - Blaum, Niels A1 - Seymour, Colleen A1 - Rossmanith, Eva A1 - Schwager, Monika A1 - Jeltsch, Florian T1 - Changes in arthropod diversity along a land use driven gradient of shrub cover in savanna rangelands : identifcation of suitable indicators N2 - 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. Y1 - 2009 UR - http://www.springerlink.com/content/100125 U6 - https://doi.org/10.1007/s10531-008-9498-x SN - 0960-3115 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 - Popp, Alexander A1 - Blaum, Niels A1 - Jeltsch, Florian T1 - Ecohydrological feedback mechanisms in arid rangelands : simulating the impacts of topography and land use N2 - 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. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/14391791 U6 - https://doi.org/10.1016/j.baae.2008.06.002 SN - 1439-1791 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 - 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 - Grimm, Volker A1 - Revilla, Eloy A1 - Groeneveld, Jürgen A1 - Kramer-Schadt, Stephanie A1 - Schwager, Monika A1 - Tews, Jörg A1 - Wichmann, Matthias A1 - Jeltsch, Florian T1 - Importance of buffer mechanisms for population viability analysis Y1 - 2005 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 - Wiegand, K. A1 - Schmidt, H. A1 - Jeltsch, Florian A1 - Ward, D. T1 - Linking a spatially-explicit model of acacias to GIS and remotely-sensed data Y1 - 2000 ER - TY - JOUR A1 - Jeltsch, Florian A1 - Weber, Gisela A1 - Dean, W. R. J. A1 - Milton, Sue J. A1 - VanRooyen, N. A1 - O'Connor, Terry A1 - Moloney, Kirk A. T1 - Entstehung und Bedeutung räumlicher Vegetationsstrukturen in Trockensavannen : Baum-Graskoexistenz und Artenvielfalt Y1 - 2000 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 - Tielbörger, Katja A1 - Kadmon, Ronen A1 - Müller, Monika A1 - Jeltsch, Florian T1 - Populationsdynamische Funktionen von Ausbreitung und Dormanz Y1 - 2000 ER - TY - JOUR A1 - Jeltsch, Florian A1 - Weber, Gisela A1 - Paruelo, J. A1 - Dean, W. R. J. A1 - Milton, Sue J. A1 - VanRooyen, N. T1 - Beweidung als Degradationsfaktor in ariden und semiariden Weidesystemen Y1 - 2000 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 - Jeltsch, Florian A1 - Weber, Gisela A1 - Grimm, Volker T1 - Ecological buffering mechanisms in savannas : a unifying theory of long-term tree-grass coexistence Y1 - 2000 ER - TY - JOUR A1 - Wiegand, K. A1 - Ward, D. A1 - Thulke, Hans-Hermann A1 - Jeltsch, Florian T1 - From snap-shot information to long-term population dynamics of Acacias by a simulation model Y1 - 2000 ER - TY - JOUR A1 - Wiegand, K. A1 - Jeltsch, Florian A1 - Ward, D. T1 - Do spatial effects play a role in the spatial distribution of desert dwelling Acacias? Y1 - 2000 ER - TY - JOUR A1 - Wiegand, T. A1 - Jeltsch, Florian T1 - Long-term dynamics in arid and semi-arid ecosystems : synthesis of a workshop Y1 - 2000 ER - TY - JOUR A1 - Weber, Gisela A1 - Jeltsch, Florian T1 - Long-term impacts of livestock herbivory on herbaceous and woody vegetation in semiarid savannas Y1 - 2000 ER - TY - JOUR A1 - Jeltsch, Florian A1 - Stephan, T. A1 - Wiegand, T. A1 - Weber, G. E. T1 - Arid rangeland management supported by dynamic spatially-explicit simulation models Y1 - 2001 ER - TY - JOUR A1 - Jeltsch, Florian A1 - Moloney, Kirk A. T1 - Spatially-explicit vegetation models : what have we learned ? Y1 - 2001 ER -