TY - JOUR A1 - Tucker, Marlee A. A1 - Boehning-Gaese, Katrin A1 - Fagan, William F. A1 - Fryxell, John M. A1 - Van Moorter, Bram A1 - Alberts, Susan C. A1 - Ali, Abdullahi H. A1 - Allen, Andrew M. A1 - Attias, Nina A1 - Avgar, Tal A1 - Bartlam-Brooks, Hattie A1 - Bayarbaatar, Buuveibaatar A1 - Belant, Jerrold L. A1 - Bertassoni, Alessandra A1 - Beyer, Dean A1 - Bidner, Laura A1 - van Beest, Floris M. A1 - Blake, Stephen A1 - Blaum, Niels A1 - Bracis, Chloe A1 - Brown, Danielle A1 - de Bruyn, P. J. Nico A1 - Cagnacci, Francesca A1 - Calabrese, Justin M. A1 - Camilo-Alves, Constanca A1 - Chamaille-Jammes, Simon A1 - Chiaradia, Andre A1 - Davidson, Sarah C. A1 - Dennis, Todd A1 - DeStefano, Stephen A1 - Diefenbach, Duane A1 - Douglas-Hamilton, Iain A1 - Fennessy, Julian A1 - Fichtel, Claudia A1 - Fiedler, Wolfgang A1 - Fischer, Christina A1 - Fischhoff, Ilya A1 - Fleming, Christen H. A1 - Ford, Adam T. A1 - Fritz, Susanne A. A1 - Gehr, Benedikt A1 - Goheen, Jacob R. A1 - Gurarie, Eliezer A1 - Hebblewhite, Mark A1 - Heurich, Marco A1 - Hewison, A. J. Mark A1 - Hof, Christian A1 - Hurme, Edward A1 - Isbell, Lynne A. A1 - Janssen, Rene A1 - Jeltsch, Florian A1 - Kaczensky, Petra A1 - Kane, Adam A1 - Kappeler, Peter M. A1 - Kauffman, Matthew A1 - Kays, Roland A1 - Kimuyu, Duncan A1 - Koch, Flavia A1 - Kranstauber, Bart A1 - LaPoint, Scott A1 - Leimgruber, Peter A1 - Linnell, John D. C. A1 - Lopez-Lopez, Pascual A1 - Markham, A. Catherine A1 - Mattisson, Jenny A1 - Medici, Emilia Patricia A1 - Mellone, Ugo A1 - Merrill, Evelyn A1 - Mourao, Guilherme de Miranda A1 - Morato, Ronaldo G. A1 - Morellet, Nicolas A1 - Morrison, Thomas A. A1 - Diaz-Munoz, Samuel L. A1 - Mysterud, Atle A1 - Nandintsetseg, Dejid A1 - Nathan, Ran A1 - Niamir, Aidin A1 - Odden, John A1 - Oliveira-Santos, Luiz Gustavo R. A1 - Olson, Kirk A. A1 - Patterson, Bruce D. A1 - de Paula, Rogerio Cunha A1 - Pedrotti, Luca A1 - Reineking, Bjorn A1 - Rimmler, Martin A1 - Rogers, Tracey L. A1 - Rolandsen, Christer Moe A1 - Rosenberry, Christopher S. A1 - Rubenstein, Daniel I. A1 - Safi, Kamran A1 - Said, Sonia A1 - Sapir, Nir A1 - Sawyer, Hall A1 - Schmidt, Niels Martin A1 - Selva, Nuria A1 - Sergiel, Agnieszka A1 - Shiilegdamba, Enkhtuvshin A1 - Silva, Joao Paulo A1 - Singh, Navinder A1 - Solberg, Erling J. A1 - Spiegel, Orr A1 - Strand, Olav A1 - Sundaresan, Siva A1 - Ullmann, Wiebke A1 - Voigt, Ulrich A1 - Wall, Jake A1 - Wattles, David A1 - Wikelski, Martin A1 - Wilmers, Christopher C. A1 - Wilson, John W. A1 - Wittemyer, George A1 - Zieba, Filip A1 - Zwijacz-Kozica, Tomasz A1 - Mueller, Thomas T1 - Moving in the Anthropocene BT - global reductions in terrestrial mammalian movements JF - Science N2 - Animal movement is fundamental for ecosystem functioning and species survival, yet the effects of the anthropogenic footprint on animal movements have not been estimated across species. Using a unique GPS-tracking database of 803 individuals across 57 species, we found that movements of mammals in areas with a comparatively high human footprint were on average one-half to one-third the extent of their movements in areas with a low human footprint. We attribute this reduction to behavioral changes of individual animals and to the exclusion of species with long-range movements from areas with higher human impact. Global loss of vagility alters a key ecological trait of animals that affects not only population persistence but also ecosystem processes such as predator-prey interactions, nutrient cycling, and disease transmission. Y1 - 2018 U6 - https://doi.org/10.1126/science.aam9712 SN - 0036-8075 SN - 1095-9203 VL - 359 IS - 6374 SP - 466 EP - 469 PB - American Assoc. for the Advancement of Science CY - Washington ER - TY - JOUR A1 - Scherer, Cedric A1 - Radchuk, Viktoriia A1 - Staubach, Christoph A1 - Mueller, Sophie A1 - Blaum, Niels A1 - Thulke, Hans-Hermann A1 - Kramer-Schadt, Stephanie T1 - Seasonal host life-history processes fuel disease dynamics at different spatial scales JF - Journal of animal ecology : a journal of the British Ecological Society N2 - Understanding the drivers underlying disease dynamics is still a major challenge in disease ecology, especially in the case of long-term disease persistence. Even though there is a strong consensus that density-dependent factors play an important role for the spread of diseases, the main drivers are still discussed and, more importantly, might differ between invasion and persistence periods. Here, we analysed long-term outbreak data of classical swine fever, an important disease in both wild boar and livestock, prevalent in the wild boar population from 1993 to 2000 in Mecklenburg-Vorpommern, Germany. We report outbreak characteristics and results from generalized linear mixed models to reveal what factors affected infection risk on both the landscape and the individual level. Spatiotemporal outbreak dynamics showed an initial wave-like spread with high incidence during the invasion period followed by a drop of incidence and an increase in seroprevalence during the persistence period. Velocity of spread increased with time during the first year of outbreak and decreased linearly afterwards, being on average 7.6 km per quarter. Landscape- and individual-level analyses of infection risk indicate contrasting seasonal patterns. During the persistence period, infection risk on the landscape level was highest during autumn and winter seasons, probably related to spatial behaviour such as increased long-distance movements and contacts induced by rutting and escaping movements. In contrast, individual-level infection risk peaked in spring, probably related to the concurrent birth season leading to higher densities, and was significantly higher in piglets than in reproductive animals. Our findings highlight that it is important to investigate both individual- and landscape-level patterns of infection risk to understand long-term persistence of wildlife diseases and to guide respective management actions. Furthermore, we highlight that exploring different temporal aggregation of the data helps to reveal important seasonal patterns, which might be masked otherwise. KW - classical swine fever KW - disease invasion KW - infection risk KW - pathogen persistence KW - seasonality KW - Sus scrofa KW - wild boar KW - wildlife disease Y1 - 2019 U6 - https://doi.org/10.1111/1365-2656.13070 SN - 0021-8790 SN - 1365-2656 VL - 88 IS - 11 SP - 1812 EP - 1824 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Noonan, Michael J. A1 - Fleming, Christen H. A1 - Tucker, Marlee A. A1 - Kays, Roland A1 - Harrison, Autumn-Lynn A1 - Crofoot, Margaret C. A1 - Abrahms, Briana A1 - Alberts, Susan C. A1 - Ali, Abdullahi H. A1 - Blaum, Niels T1 - Effects of body size on estimation of mammalian area requirements JF - Conservation Biology N2 - Accurately quantifying species' area requirements is a prerequisite for effective area-based conservation. This typically involves collecting tracking data on species of interest and then conducting home-range analyses. Problematically, autocorrelation in tracking data can result in space needs being severely underestimated. Based on the previous work, we hypothesized the magnitude of underestimation varies with body mass, a relationship that could have serious conservation implications. To evaluate this hypothesis for terrestrial mammals, we estimated home-range areas with global positioning system (GPS) locations from 757 individuals across 61 globally distributed mammalian species with body masses ranging from 0.4 to 4000 kg. We then applied block cross-validation to quantify bias in empirical home-range estimates. Area requirements of mammals <10 kg were underestimated by a mean approximately15%, and species weighing approximately100 kg were underestimated by approximately50% on average. Thus, we found area estimation was subject to autocorrelation-induced bias that was worse for large species. Combined with the fact that extinction risk increases as body mass increases, the allometric scaling of bias we observed suggests the most threatened species are also likely to be those with the least accurate home-range estimates. As a correction, we tested whether data thinning or autocorrelation-informed home-range estimation minimized the scaling effect of autocorrelation on area estimates. Data thinning required an approximately93% data loss to achieve statistical independence with 95% confidence and was, therefore, not a viable solution. In contrast, autocorrelation-informed home-range estimation resulted in consistently accurate estimates irrespective of mass. When relating body mass to home range size, we detected that correcting for autocorrelation resulted in a scaling exponent significantly >1, meaning the scaling of the relationship changed substantially at the upper end of the mass spectrum. KW - allometry KW - animal movement KW - area-based conservation KW - autocorrelation KW - home range KW - kernel density estimation KW - reserve design KW - scaling Y1 - 2019 VL - 34 IS - 4 PB - Wiley-Blackwell CY - Oxford ER - TY - JOUR A1 - Tabares, Ximena A1 - Mapani, Benjamin A1 - Blaum, Niels A1 - Herzschuh, Ulrike T1 - Composition and diversity of vegetation and pollen spectra along gradients of grazing intensity and precipitation in southern Africa JF - Review of palaeobotany and palynology : an international journal N2 - Understanding vegetation-modern pollen relationships is essential to provide confidence in fossil pollen reconstructions of long-term vegetation changes in savanna ecosystems. In this paper we compare the taxonomical composition and the diversity (Hill NO, N1, N2) of vegetation and modern pollen along precipitation and local grazing-intensity gradients in Namibian savannas. Modern pollen was extracted from surface soil samples collected from 5 x 5 m plots distributed along four 500 m gradients. Vegetation was surveyed in each plot. The results show a high correspondence between vegetation and pollen data in terms of composition. Precipitation and grazing explain a significant although low proportion of compositional change in the vegetation and pollen spectra. We identified pollen taxa as indicators of grazing pressure such as Limeum, Alternanthera, and particularly Tribulus. Correspondence between vegetation and pollen data in terms of taxa richness (NO) is limited, probably because of the influence of landscape heterogeneity and openness, as well as low pollen concentrations. In contrast, the effective numbers of common and dominant taxa (N1, N2) are consistent among the different datasets. We conclude that in spite of limitations, modern pollen assemblages can reflect changes in vegetation composition, richness and diversity patterns along precipitation and grazing gradients in savanna environments. (C) 2018 Elsevier B.V. All rights reserved. KW - Modern pollen-vegetation relationships KW - Hill numbers KW - Indicator species KW - Savanna ecology KW - Namibia Y1 - 2018 U6 - https://doi.org/10.1016/j.revpalbo.2018.04.004 SN - 0034-6667 SN - 1879-0615 VL - 253 SP - 88 EP - 100 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Geißler, Katja A1 - Hahn, Claudia A1 - Joubert, David A1 - Blaum, Niels T1 - Functional responses of the herbaceous plant community explain ecohydrological impacts of savanna shrub encroachment JF - Perspectives in plant ecology, evolution and systematics N2 - Major drivers of savanna shrub encroachment are climatic conditions, CO2 and unsustainable grazing management including fire prevention. Although all drivers affect ecohydrological processes, and given that water is a seasonally scarce resource in savannas, it remains largely unclear how shrub encroachment itself affects hydrological conditions that feed back into water use and community assembly of the remaining plant community. Hence, understanding direct ecohydrological effects of shrubs that may limit the recovery of the perennial herbaceous vegetation in grazed areas and promote the establishment of shrub seedlings facilitates the identification of areas that are most sensitive to further encroachment. In our trait-based approach, we determined relationships among shrub cover, soil and plant trait characteristics sensitive to water limitation in 120 plots along a shrub cover gradient. We focused on two functional response traits indicating immediate drought stress and subsequent water use for drought stress recovery with associated competition for water (midday leaf/xylem water potential and diurnally recovery rate of leaf water potential), and three functional response traits indicating long-term stress adaptation and related resource use strategies (SLA, plant height and seed release height). To understand species assembly and the associated mechanisms of resource use, we calculated community weighted mean traits, intraspecific trait variability as a proxy for the mechanism of coexistence, and mean traits at plant functional type level including 2-year-old Acacia mellifera-saplings. We found a low intraspecific trait variability in drought stress recovery rate and height suggesting that competitive exclusion via active resource acquisition (i.e. water exploitation) played a minor role for community assembly in a shrub encroaching savanna. The dominant community assembly process was passive stress avoidance via resource conservation up to stress tolerance indicated by the high variability in SLA and midday leaf water potential. Correlations of traits with soil moisture suggest a rooting niche differentiation between annual and perennial grasses and that Acacia-shrub saplings within the first 50 cm of soil already escaped the highest drought stress. Interestingly, immediate drought stress for the herbaceous community was lowest on moderately shrub encroached sites and not on grass dominated sites. Since passive stress avoidance accompanied by a distinct stress tolerance in semi-arid savannas is more important than active competition, and assuming that the low drought stress of the herbaceous community at intermediate levels of shrub cover also applies to newly emerging shrub seedlings, these areas are likely to be most sensitive to further encroachment. As such, they should be considered as focal areas for prevention management. KW - Community-weighted means KW - Drought stress KW - Intraspecific variation KW - Soil moisture KW - Stress recovery KW - Plant functional traits Y1 - 2019 U6 - https://doi.org/10.1016/j.ppees.2019.125458 SN - 1433-8319 VL - 39 PB - Elsevier CY - München ER - TY - JOUR A1 - Marquart, Arnim A1 - Goldbach, Lars A1 - Blaum, Niels T1 - Soil-texture affects the influence of termite macropores on soil water infiltration in a semi-arid savanna JF - Ecohydrology : ecosystems, land and water process interactions, ecohydrogeomorphology N2 - Subterranean termites create tunnels (macropores) for foraging that can influence water infiltration and may lead to preferential flow to deeper soil layers. This is particularly important in water limited ecosystems such as semi-arid, agriculturally utilized savannas, which are particularly prone to land degradation and shrub-encroachment. Using termite activity has been suggested as a restoration measure, but their impact on hydrology is neither universal nor yet fully understood. Here, we used highly replicated, small-scale (50 x 50 cm) rain-simulation experiments to analyse the interacting effects of either vegetation (grass dominated vs. shrub dominated sites) or soil texture (sand vs. loamy sand) and termite foraging macropores on infiltration patterns. We used Brilliant Blue FCF as colour tracer to make the flow pathways in paired experiments visible, on either termite-disturbed soil or controls without surface macropores in two semi-arid Namibian savannas (with either heterogeneous soil texture or shrub cover). On highly shrub-encroached plots in the savanna site with heterogeneous soil texture, termite macropores increased maximum infiltration depth and total amount of infiltrated water on loamy sand, but not on sandy soil. In the sandy savanna with heterogeneous shrub cover, neither termite activity nor shrub density affected the infiltration. Termite's effect on infiltration depends on the soil's hydraulic conductivity and occurs mostly under ponded conditions, intercepting run-off. In semi-arid savanna soils with a considerable fraction of fine particles, termites are likely an important factor for soil water dynamics. KW - ecosystem functioning KW - infiltration KW - macropores KW - rain-simulation KW - shrub-encroachment KW - soil texture KW - termites Y1 - 2020 U6 - https://doi.org/10.1002/eco.2249 SN - 1936-0584 SN - 1936-0592 VL - 13 IS - 8 PB - Wiley CY - Chichester ER - TY - JOUR A1 - Marquart, Arnim A1 - Eldridge, David J. A1 - Travers, Samantha K. A1 - Val, James A1 - Blaum, Niels T1 - Large shrubs partly compensate negative effects of grazing on hydrological function in a semi-arid savanna JF - Basic and applied ecology : Journal of the Gesellschaft für Ökologie N2 - Semiarid woodlands and savannas are globally important biomes that provide ecosystem goods and services such as habitat for biota and sinks for carbon, support millions of people that rely primarily on pastoralism, and supply livelihoods for about a third of the global human population. Savannas, however, are prone to degradation by overgrazing, and encroachment by woody plants, reducing their capacity to produce forage that pastoral enterprises depend on. We examined the impacts of livestock grazing and woody encroachment on soil hydrological processes, hypothesizing that heavy grazing by livestock would reduce hydrological function, whereas woody plants would increase hydrological function, therefore, partially offsetting any negative effects of overgrazing by livestock. Understanding the major drivers of soil hydrology in savanna ecosystems is important because water is a critical, yet limited resource in savannas. We found that livestock grazing reduced the early (sorptivity) and late (steady-state infiltration) stages of infiltration under both ponding and tension, and attributed this to a reduction in porosity caused by livestock trampling. Steady-state infiltration and sorptivity under ponding were greater under the canopies of woody shrubs than in open areas, partly compensating for any negative effect of grazing. Structural equation modeling revealed a direct positive effect of shrub height on hydrological functions, and an indirect effect via increases in litter cover. Our results suggest that woody plants can play important roles in driving hydrological function in savannas, counteracting the suppressive effect of livestock overgrazing on infiltration processes. Management strategies in semiarid savannas should aim to reduce trampling by livestock and retain large woody plants in order to maintain hydrological function. (C) 2019 Gesellschaft fur Okologie. Published by Elsevier GmbH. All rights reserved. KW - Hydrology KW - Soil function KW - Cattle KW - Encroachment KW - Thickening KW - Water flow KW - Invertebrate pores KW - Porosity Y1 - 2019 U6 - https://doi.org/10.1016/j.baae.2019.06.003 SN - 1439-1791 SN - 1618-0089 VL - 38 SP - 58 EP - 68 PB - Elsevier GMBH CY - München ER - TY - JOUR A1 - Hering, Robert A1 - Hauptfleisch, Morgan A1 - Geissler, Katja A1 - Marquart, Arnim A1 - Schoenen, Maria A1 - Blaum, Niels T1 - Shrub encroachment is not always land degradation BT - Insights from ground‐dwelling beetle species niches along a shrub cover gradient in a semi‐arid Namibian savanna JF - Land degradation & development N2 - Shrub encroachment in semi-arid savannas is induced by interacting effects of climate, fire suppression, and unsustainable livestock farming; it carries a severe risk of land degradation and strongly influences natural communities that provide key ecosystem functions. However, species-specific effects of shrub cover on many animal groups that act as indicators of degradation remain largely unknown. We analysed the consequences of shrub encroachment for ground-dwelling beetles in a semi-arid Namibian savanna rangeland, where beetles and vegetation were recorded along a shrub cover gradient (30%). Focusing on species niche breadths and optima, we identified two crucial shrub cover thresholds (2.9% and 10.0%), corresponding to major changes in the beetle communities with implications for savanna ecosystem functioning. Niche optima of most species were between the first and second thresholds; beyond the second threshold, saprophagous, coprophagous, and rare predatory beetles declined in numbers and diversity. This is problematic because beetles provide important ecosystem functions, such as decomposition and nutrient cycling. However, we also found that certain species were adapted to high shrub cover, thus providing examples of niche differentiation. Despite the predominantly negative effects of heavy shrub encroachment on beetle communities, shrubs in their early life stages apparently provide essential structures, which enhance habitat quality for ground-dwelling beetles. Our results demonstrate that shrub encroachment can have mixed effects on ground-dwelling beetle communities and hence on savanna ecosystem functioning. We, therefore, conclude that rangeland management and restoration should consider the complex trade-offs between species-specific effects and the level of encroachment for sustainable land use. KW - Coleoptera KW - rangeland KW - semi-arid savanna KW - shrub encroachment KW - species niche KW - threshold Y1 - 2018 U6 - https://doi.org/10.1002/ldr.3197 SN - 1085-3278 SN - 1099-145X VL - 30 IS - 1 SP - 14 EP - 24 PB - Wiley CY - Chichester ER - TY - JOUR A1 - Marquart, Arnim A1 - Eldridge, David J. A1 - Geissler, Katja A1 - Lobas, Christoph A1 - Blaum, Niels T1 - Interconnected effects of shrubs, invertebrate-derived macropores and soil texture on water infiltration in a semi-arid savanna rangeland JF - Land degradation & development N2 - Many semi arid savannas are prone to degradation, caused for example, by overgrazing or extreme climatic events, which often lead to shrub encroachment. Overgrazing by livestock affects vegetation and infiltration processes by directly altering plant composition (selective grazing) or by impacting soil physical properties (trampling). Water infiltration is controlled by several parameters, such as macropores (created by soil-burrowing animals or plant roots) and soil texture, but their effects have mostly been studied in isolation. Here we report on a study, in which we conducted infiltration experiments to analyze the interconnected effects of invertebrate-created macropores, shrubs and soil texture (sandy soil and loamy sand) on infiltration in two Namibian rangelands. Using structural equation modeling, we found a direct positive effect of shrub size on infiltration and indirectly via invertebrate macropores on both soil types. On loamy sands this effect was even stronger, but additionally, invertebrate-created macropores became relevant as a direct driver of infiltration. Our results provide new insights into the effects of vegetation and invertebrates on infiltration under different soil textures. Pastoralists should use management strategies that maintain a heterogeneous plant community that supports soil fauna to sustain healthy soil water dynamics, particularly on soils with higher loam content. Understanding the fundamental functioning of soil water dynamics in drylands is critical because these ecosystems are water-limited and support the livelihoods of many cultures worldwide. KW - hydrology KW - infiltration KW - invertebrate macropores KW - shrub-encroachment KW - soil function KW - soil texture Y1 - 2020 U6 - https://doi.org/10.1002/ldr.3598 SN - 1085-3278 SN - 1099-145X VL - 31 IS - 16 SP - 2307 EP - 2318 PB - Wiley CY - Chichester, Sussex ER - TY - JOUR A1 - Reinhard, Johanna E. A1 - Geißler, Katja A1 - Blaum, Niels T1 - Grass and ground dwelling beetle community responses to holistic and wildlife grazing management using a cross-fence comparison in Western Kalahari rangeland, Namibia JF - Journal of insect conservation : an international journal devoted to the conservation of insects and related invertebrates N2 - Savannahs are often branded by livestock grazing with resulting land degradation. Holistic management of livestock was proposed to contribute to biodiversity conservation by simulating native wildlife grazing behaviour. This study attempts the comparison of the impact of a holistic management regime to a wildlife grazing management regime on grass and ground-dwelling beetle species diversity on neighboring farms in Namibian rangeland. Results show that the response of biodiversity in species richness and composition to holistic management of livestock differs substantially from wildlife grazing with a positive impact. From a total of 39 identified species of ground-dwelling beetles (Coleoptera: Tenebrionidae, Carabidae) from 29 genera, eight species were found to be indicators for holistic management of livestock and three were found to be indicators for wildlife grazed rangeland. Observations suggest that holistic management of livestock may contribute to biodiversity conservation, but the differential effect of grazing management on species assemblages suggests that livestock grazing cannot replace native wildlife herbivory. Implications for insect conservation An adaptive management strategy such as holistic management used in this study shows the potential to support high beetle biodiversity. Holistic management of livestock thus aspects in favour for a sustainable form of grazing management for insect conservation even though it does not functionally replace grazing by native wildlife. KW - Beetle conservation KW - Land use management KW - Biodiversity KW - Insect conservation KW - Wildlife management Y1 - 2022 U6 - https://doi.org/10.1007/s10841-022-00410-6 SN - 1366-638X SN - 1572-9753 VL - 26 SP - 711 EP - 720 PB - Springer CY - Dordrecht ER -