TY - JOUR A1 - Blaum, Niels A1 - Tietjen, Britta A1 - Rossmanith, Eva T1 - The impact of livestock husbandry on small- and medium-sized carnivores in Kalahari savannah rangelands N2 - We analyzed relative sensitivities of small- and medium-sized carnivores to livestock husbandry (stocking rates and predator control) in Kalahari, South Africa, rangelands at a regional scale. We monitored small carnivores using track counts on 22 Kalahari farms across a land-use gradient ranging from low to high stocking rates and also interviewed each farm manager to identify farmers" perception of small carnivores as potential predators for livestock. We recorded 12 species of small- and medium-sized carnivores across 22 Kalahari farms. Stocking rate was the most important driving variable for local carnivore abundance. Abundance of all species was lowest on farms where stocking rate was high. Most farm managers perceived medium-sized carnivores, in particular, African wildcat (Felis silvestris lybica), black-backed jackal (Canis mesomelas), and caracal (Caracal caracal), as potential predators of livestock. Multiple regression analysis shows that black-backed jackal, African wildcat, and caracal were negatively affected by predator control measures, whereas bat-eared fox (Otocyon megalotis), cape fox (Vulpes chama), and small-spotted genet (Genetta genetta) were positively affected. Our results show a need for expanding research and conservation activities toward small- and medium-sized carnivores in southern African savannah rangelands. We, therefore, suggest developing a monitoring program combining passive tracking with indigenous knowledge of local Khoisan Bushmen to monitor carnivore populations, and we recommend additional predator removal experiments that manipulate predator densities. Y1 - 2009 UR - http://www.wildlifejournals.org/perlserv/?request=index-html&ct=1 U6 - https://doi.org/10.2193/2008-034 SN - 0022-541X ER - TY - JOUR A1 - Tews, Jörg A1 - Blaum, Niels A1 - Jeltsch, Florian T1 - Structural and animal species diversity in arid and semi-arid savannas of the southern Kalahari Y1 - 2004 ER - TY - JOUR A1 - Ullmann, Wiebke A1 - Fischer, Christina A1 - Pirhofer-Walzl, Karin A1 - Kramer-Schadt, Stephanie A1 - Blaum, Niels T1 - Spatiotemporal variability in resources affects herbivore home range formation in structurally contrasting and unpredictable agricultural landscapes JF - Landscape ecology N2 - We investigated whether a given landscape structure affects the level of home range size adaptation in response to resource variability. We tested whether increasing resource variability forces herbivorous mammals to increase their home ranges. In 2014 and 2015 we collared 40 European brown hares (Lepus europaeus) with GPS-tags to record hare movements in two regions in Germany with differing landscape structures. We examined hare home range sizes in relation to resource availability and variability by using the normalized difference vegetation index as a proxy. Hares in simple landscapes showed increasing home range sizes with increasing resource variability, whereas hares in complex landscapes did not enlarge their home range. Animals in complex landscapes have the possibility to include various landscape elements within their home ranges and are more resilient against resource variability. But animals in simple landscapes with few elements experience shortcomings when resource variability becomes high. The increase in home range size, the movement related increase in energy expenditure, and a decrease in hare abundances can have severe implications for conservation of mammals in anthropogenic landscapes. Hence, conservation management could benefit from a better knowledge about fine-scaled effects of resource variability on movement behaviour. KW - Resource variability KW - Resource availability KW - Home range size KW - European brown hare KW - GPS tracking KW - Telemetry KW - Lepus europaeus Y1 - 2018 U6 - https://doi.org/10.1007/s10980-018-0676-2 SN - 0921-2973 SN - 1572-9761 VL - 33 IS - 9 SP - 1505 EP - 1517 PB - Springer CY - Dordrecht 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 - 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 - 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 - Stanton, Richard A. A1 - Boone, Wesley W. A1 - Soto-Shoender, Jose A1 - Fletcher, Robert J. A1 - Blaum, Niels A1 - McCleery, Robert A. T1 - Shrub encroachment and vertebrate diversity BT - a global meta-analysis JF - Global ecology and biogeography : a journal of macroecology N2 - Aim: Across the planet, grass-dominated biomes are experiencing shrub encroachment driven by atmospheric CO2 enrichment and land-use change. By altering resource structure and availability, shrub encroachment may have important impacts on vertebrate communities. We sought to determine the magnitude and variability of these effects across climatic gradients, continents, and taxa, and to learn whether shrub thinning restores the structure of vertebrate communities. Location: Worldwide. Time period: Contemporary. Major taxa studied: Terrestrial vertebrates. Methods: We estimated relationships between percentage shrub cover and the structure of terrestrial vertebrate communities (species richness, Shannon diversity and community abundance) in experimentally thinned and unmanipulated shrub-encroached grass-dominated biomes using systematic review and meta-analyses of 43 studies published from 1978 to 2016. We modelled the effects of continent, biome, mean annual precipitation, net primary productivity and the normalized difference vegetation index (NDVI) on the relationship between shrub cover and vertebrate community structure. Results: Species richness, Shannon diversity and total abundance had no consistent relationship with shrub encroachment and experimental thinning did not reverse encroachment effects on vertebrate communities. However, some effects of shrub encroachment on vertebrate communities differed with net primary productivity, amongst vertebrate groups, and across continents. Encroachment had negative effects on vertebrate diversity at low net primary productivity. Mammalian and herpetofaunal diversity decreased with shrub encroachment. Shrub encroachment also had negative effects on species richness and total abundance in Africa but positive effects in North America. Main conclusions: Biodiversity conservation and mitigation efforts responding to shrub encroachment should focus on low-productivity locations, on mammals and herpetofauna, and in Africa. However, targeted research in neglected regions such as central Asia and India will be needed to fill important gaps in our knowledge of shrub encroachment effects on vertebrates. Additionally, our findings provide an impetus for determining the mechanisms associated with changes in vertebrate diversity and abundance in shrub-encroached grass-dominated biomes. KW - biodiversity KW - global change KW - grasslands KW - grazing KW - pastoral abandonment KW - savannas KW - shrub encroachment KW - shrub thinning KW - species richness KW - woody encroachment Y1 - 2017 U6 - https://doi.org/10.1111/geb.12675 SN - 1466-822X SN - 1466-8238 VL - 27 IS - 3 SP - 368 EP - 379 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Reinhard, Johanna E. A1 - Geissler, Katja A1 - Blaum, Niels T1 - Short-term responses of darkling beetles (Coleoptera:Tenebrionidae) to the effects of fire and grazing in savannah rangeland JF - Insect Conservation and Diversity N2 - Fire and grazing shape biodiversity in savannah landscapes. In land use management, knowing the effects of fire and grazing on biodiversity are important in order to ensure environmental sustainability. Beetles specifically are indicators of the biodiversity response to fire and grazing. A grazing exclusion and burning experiment in a split-plot design was used in order to investigate the interacting effects of fire and wildlife grazing on biomass, diversity, and species composition of darkling beetles (Coleoptera, Tenebrionidae) over time after fire. Darkling beetle species richness and diversity were responding in a three-way-interaction to fire, grazing, and time after fire, whereby biomass of darkling beetles remained unaffected and species compositional changes were attributed to seasonal changes of time only. Fire on ungrazed plots had a negative effect on species diversity and richness 2 weeks and 6 months post fire, whereas fire on grazed plots had no impact on species diversity and richness. Grazing only lowered species diversity and richness 6 months after fire treatments. Results suggest that grazing overrides the effects of fire and that the similar effects caused by fire and grazing are due to niche and assemblage simplification of the habitat. KW - Arid ecosystems KW - arid rangeland KW - beetles KW - herbivory KW - insect diversity KW - land use KW - management Y1 - 2018 U6 - https://doi.org/10.1111/icad.12324 SN - 1752-458X SN - 1752-4598 VL - 12 IS - 1 SP - 39 EP - 48 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Lohmann, Dirk A1 - Tietjen, Britta A1 - Blaum, Niels A1 - Joubert, David F. A1 - Jeltsch, Florian T1 - Shifting thresholds and changing degradation patterns: climate change effects on the simulated long-term response of a semi-arid savanna to grazing JF - Journal of applied ecology : an official journal of the British Ecological Society N2 - 1. The complex, nonlinear response of dryland systems to grazing and climatic variations is a challenge to management of these lands. Predicted climatic changes will impact the desertification of drylands under domestic livestock production. Consequently, there is an urgent need to understand the response of drylands to grazing under climate change. 2. We enhanced and parameterized an ecohydrological savanna model to assess the impacts of a range of climate change scenarios on the response of a semi-arid African savanna to grazing. We focused on the effects of temperature and CO2 level increase in combination with changes in inter- and intra-annual precipitation patterns on the long-term dynamics of three major plant functional types. 3. We found that the capacity of the savanna to sustain livestock grazing was strongly influenced by climate change. Increased mean annual precipitation and changes in intra-annual precipitation pattern have the potential to slightly increase carrying capacities of the system. In contrast, decreased precipitation, higher interannual variation and temperature increase are leading to a severe decline of carrying capacities owing to losses of the perennial grass biomass. 4. Semi-arid rangelands will be at lower risk of shrub encroachment and encroachment will be less intense under future climatic conditions. This finding holds in spite of elevated levels of atmospheric CO2 and irrespective of changes in precipitation pattern, because of the drought sensitivity of germination and establishment of encroaching species. 5. Synthesis and applications. Changes in livestock carrying capacities, both positive and negative, mainly depend on the highly uncertain future rainfall conditions. However, independent of the specific changes, shrub encroachment becomes less likely and in many cases less severe. Thus, managers of semi-arid rangelands should shift their focus from woody vegetation towards perennial grass species as indicators for rangeland degradation. Furthermore, the resulting reduced competition from woody vegetation has the potential to facilitate ecosystem restoration measures such as re-introduction of desirable plant species that are only little promising or infeasible under current climatic conditions. On a global scale, the reductions in standing biomass resulting from altered degradation dynamics of semi-arid rangelands can have negative impacts on carbon sequestration. KW - CO2 increase KW - demographic bottleneck KW - ecohydrology KW - grid-based simulation model KW - livestock KW - precipitation pattern KW - savanna resilience KW - shrub encroachment KW - soil moisture KW - sustainable rangeland management Y1 - 2012 U6 - https://doi.org/10.1111/j.1365-2664.2012.02157.x SN - 0021-8901 VL - 49 IS - 4 SP - 814 EP - 823 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Rossmanith, Eva A1 - Blaum, Niels A1 - Höntsch, Kerstin A1 - Jeltsch, Florian T1 - Sex-related parental care strategies in the lesser spotted woodpecker "Picoides minor" : of flexible mothers and dependable fathers N2 - We investigated sex-specific parental care behaviour of lesser spotted woodpeckers Picoides minor in the low mountain range Taunus, Germany. Observed parental care included incubation, nest sanitation as well as brooding and feeding of nestlings. Contributions of the two sexes to parental care changed in progress of the breeding period. During incubation and the first half of the nestling period, parental care was divided equally between partners. However, in the late nestling stage, we found males to feed their nestlings irrespective of brood size while females considerably decreased feeding rate with the number of nestlings. This behaviour culminated in desertion of small broods by females shortly before fledging. The fact that even deserted nests were successful indicates that males were able to compensate for the females' absence. Interestingly, the mating of one female with two males with separate nests could be found in the population, which confirms earlier findings of polyandry in the lesser spotted woodpecker. We conclude that biparental care is not essential in the later stage and one partner can reduce effort and thus costs of parental care, at least in small broods where the mate is able to compensate for that behaviour. Reduced care and desertion appears only in females, which might be caused by a combination of two traits: First, females might suffer higher costs of investment in terms of mortality and secondly, male-biased sex ratio in the population generally leads to higher mating probabilities for females in the following breeding season. The occurrence of polyandry seems to be a result of these conditions. Y1 - 2009 UR - http://www3.interscience.wiley.com/journal/118513172/home U6 - https://doi.org/10.1111/j.1600-048X.2008.04353.x SN - 0908-8857 ER -