@article{TuckerBoehningGaeseFaganetal.2018, author = {Tucker, Marlee A. and Boehning-Gaese, Katrin and Fagan, William F. and Fryxell, John M. and Van Moorter, Bram and Alberts, Susan C. and Ali, Abdullahi H. and Allen, Andrew M. and Attias, Nina and Avgar, Tal and Bartlam-Brooks, Hattie and Bayarbaatar, Buuveibaatar and Belant, Jerrold L. and Bertassoni, Alessandra and Beyer, Dean and Bidner, Laura and van Beest, Floris M. and Blake, Stephen and Blaum, Niels and Bracis, Chloe and Brown, Danielle and de Bruyn, P. J. Nico and Cagnacci, Francesca and Calabrese, Justin M. and Camilo-Alves, Constanca and Chamaille-Jammes, Simon and Chiaradia, Andre and Davidson, Sarah C. and Dennis, Todd and DeStefano, Stephen and Diefenbach, Duane and Douglas-Hamilton, Iain and Fennessy, Julian and Fichtel, Claudia and Fiedler, Wolfgang and Fischer, Christina and Fischhoff, Ilya and Fleming, Christen H. and Ford, Adam T. and Fritz, Susanne A. and Gehr, Benedikt and Goheen, Jacob R. and Gurarie, Eliezer and Hebblewhite, Mark and Heurich, Marco and Hewison, A. J. Mark and Hof, Christian and Hurme, Edward and Isbell, Lynne A. and Janssen, Rene and Jeltsch, Florian and Kaczensky, Petra and Kane, Adam and Kappeler, Peter M. and Kauffman, Matthew and Kays, Roland and Kimuyu, Duncan and Koch, Flavia and Kranstauber, Bart and LaPoint, Scott and Leimgruber, Peter and Linnell, John D. C. and Lopez-Lopez, Pascual and Markham, A. Catherine and Mattisson, Jenny and Medici, Emilia Patricia and Mellone, Ugo and Merrill, Evelyn and Mourao, Guilherme de Miranda and Morato, Ronaldo G. and Morellet, Nicolas and Morrison, Thomas A. and Diaz-Munoz, Samuel L. and Mysterud, Atle and Nandintsetseg, Dejid and Nathan, Ran and Niamir, Aidin and Odden, John and Oliveira-Santos, Luiz Gustavo R. and Olson, Kirk A. and Patterson, Bruce D. and de Paula, Rogerio Cunha and Pedrotti, Luca and Reineking, Bjorn and Rimmler, Martin and Rogers, Tracey L. and Rolandsen, Christer Moe and Rosenberry, Christopher S. and Rubenstein, Daniel I. and Safi, Kamran and Said, Sonia and Sapir, Nir and Sawyer, Hall and Schmidt, Niels Martin and Selva, Nuria and Sergiel, Agnieszka and Shiilegdamba, Enkhtuvshin and Silva, Joao Paulo and Singh, Navinder and Solberg, Erling J. and Spiegel, Orr and Strand, Olav and Sundaresan, Siva and Ullmann, Wiebke and Voigt, Ulrich and Wall, Jake and Wattles, David and Wikelski, Martin and Wilmers, Christopher C. and Wilson, John W. and Wittemyer, George and Zieba, Filip and Zwijacz-Kozica, Tomasz and Mueller, Thomas}, title = {Moving in the Anthropocene}, series = {Science}, volume = {359}, journal = {Science}, number = {6374}, publisher = {American Assoc. for the Advancement of Science}, address = {Washington}, issn = {0036-8075}, doi = {10.1126/science.aam9712}, pages = {466 -- 469}, year = {2018}, abstract = {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.}, language = {en} } @article{LuftNeumannItzerottetal.2016, author = {Luft, Laura and Neumann, C. and Itzerott, S. and Lausch, A. and Doktor, D. and Freude, M. and Blaum, Niels and Jeltsch, Florian}, title = {Digital and real-habitat modeling of Hipparchia statilinus based on hyper spectral remote sensing data}, series = {International journal of environmental science and technology}, volume = {13}, journal = {International journal of environmental science and technology}, publisher = {Springer}, address = {New York}, issn = {1735-1472}, doi = {10.1007/s13762-015-0859-1}, pages = {187 -- 200}, year = {2016}, abstract = {The abandonment of military areas leads to succession processes affecting valuable open-land habitats and is considered to be a major threat for European butterflies. We assessed the ability of hyper spectral remote sensing data to spatially predict the occurrence of one of the most endangered butterfly species (Hipparchia statilinus) in Brandenburg (Germany) on the basis of habitat characteristics at a former military training area. Presence-absence data were sampled on a total area of 36 km(2), and N = 65 adult individuals of Hipparchia statilinus could be detected. The floristic composition within the study area was modeled in a three-dimensional ordination space. Occurrence probabilities for the target species were predicted as niches between ordinated floristic gradients by using Regression Kriging of Indicators. Habitat variance could be explained by up to 81 \% with spectral variables at a spatial resolution of 2 x 2 m by transferring PLSR models to imagery. Ordinated ecological niche of Hipparchia statilinus was tested against environmental predictor variables. N = 6 variables could be detected to be significantly correlated with habitat preferences of Hipparchia statilinus. They show that Hipparchia statilinus can serve as a valuable indicator for the evaluation of the conservation status of Natura 2000 habitat type 2330 (inland dunes with open Corynephorus and Agrostis grasslands) protected by the Habitat Directive (Council Directive 92/43/EEC). The authors of this approach, conducted in August 2013 at Doberitzer Heide Germany, aim to increase the value of remote sensing as an important tool for questions of biodiversity research and conservation.}, language = {en} } @article{StieglerPahlGuillenetal.2023, author = {Stiegler, Jonas and Pahl, Janice and Guillen, Rafael Arce and Ullmann, Wiebke and Blaum, Niels}, title = {The heat is on}, series = {Frontiers in Ecology and Evolution}, volume = {11}, journal = {Frontiers in Ecology and Evolution}, publisher = {Frontiers Media}, address = {Lausanne}, issn = {2296-701X}, doi = {10.3389/fevo.2023.1193861}, pages = {10}, year = {2023}, abstract = {Climate conditions severely impact the activity and, consequently, the fitness of wildlife species across the globe. Wildlife can respond to new climatic conditions, but the pace of human-induced change limits opportunities for adaptation or migration. Thus, how these changes affect behavior, movement patterns, and activity levels remains unclear. In this study, we investigate how extreme weather conditions affect the activity of European hares (Lepus europaeus) during their peak reproduction period. When hares must additionally invest energy in mating, prevailing against competitors, or lactating, we investigated their sensitivities to rising temperatures, wind speed, and humidity. To quantify their activity, we used the overall dynamic body acceleration (ODBA) calculated from tri-axial acceleration measurements of 33 GPS-collared hares. Our analysis revealed that temperature, humidity, and wind speed are important in explaining changes in activity, with a strong response for high temperatures above 25 \& DEG;C and the highest change in activity during temperature extremes of over 35 \& DEG;C during their inactive period. Further, we found a non-linear relationship between temperature and activity and an interaction of activity changes between day and night. Activity increased at higher temperatures during the inactive period (day) and decreased during the active period (night). This decrease was strongest during hot tropical nights. At a stage of life when mammals such as hares must substantially invest in reproduction, the sensitivity of females to extreme temperatures was particularly pronounced. Similarly, both sexes increased their activity at high humidity levels during the day and low wind speeds, irrespective of the time of day, while the effect of humidity was stronger for males. Our findings highlight the importance of understanding the complex relationships between extreme weather conditions and mammal behavior, critical for conservation and management. With ongoing climate change, extreme weather events such as heat waves and heavy rainfall are predicted to occur more often and last longer. These events will directly impact the fitness of hares and other wildlife species and hence the population dynamics of already declining populations across Europe.}, language = {en} } @article{GeisslerHeblackUuguluetal.2019, author = {Geißler, Katja and Heblack, Jessica and Uugulu, Shoopala and Wanke, Heike and Blaum, Niels}, title = {Partitioning of Water Between Differently Sized Shrubs and Potential Groundwater Recharge in a Semiarid Savanna in Namibia}, series = {Frontiers in Plant Science}, volume = {10}, journal = {Frontiers in Plant Science}, publisher = {Frontiers Media}, address = {Lausanne}, issn = {1664-462X}, doi = {10.3389/fpls.2019.01411}, pages = {13}, year = {2019}, abstract = {Introduction: Many semiarid regions around the world are presently experiencing significant changes in both climatic conditions and vegetation. This includes a disturbed coexistence between grasses and bushes also known as bush encroachment, and altered precipitation patterns with larger rain events. Fewer, more intense precipitation events might promote groundwater recharge, but depending on the structure of the vegetation also encourage further woody encroachment. Materials and Methods: In this study, we investigated how patterns and sources of water uptake of Acacia mellifera (blackthorn), an important encroaching woody plant in southern African savannas, are associated with the intensity of rain events and the size of individual shrubs. The study was conducted at a commercial cattle farm in the semiarid Kalahari in Namibia (MAP 250 mm/a). We used soil moisture dynamics in different depths and natural stable isotopes as markers of water sources. Xylem water of fifteen differently sized individuals during eight rain events was extracted using a Scholander pressure bomb. Results and Discussion: Results suggest the main rooting activity zone of A. mellifera in 50 and 75 cm soil depth but a reasonable water uptake from 10 and 25 cm. Any apparent uptake pattern seems to be driven by water availability, not time in the season. Bushes prefer the deeper soil layers after heavier rain events, indicating some evidence for the classical Walter's two-layer hypothesis. However, rain events up to a threshold of 6 mm/day cause shallower depths of use and suggest several phases of intense competition with perennial grasses. The temporal uptake pattern does not depend on shrub size, suggesting a fast upwards water flow inside. d2H and d18O values in xylem water indicate that larger shrubs rely less on upper and very deep soil water than smaller shrubs. It supports the hypothesis that in environments where soil moisture is highly variable in the upper soil layers, the early investment in a deep tap-root to exploit deeper, more reliable water sources could reduce the probability of mortality during the establishment phase. Nevertheless, independent of size and time in the season, bushes do not compete with potential groundwater recharge. In a savanna encroached by A. mellifera, groundwater will most likely be affected indirectly.}, language = {en} } @article{NoonanTuckerFlemingetal.2018, author = {Noonan, Michael J. and Tucker, Marlee A. and Fleming, Christen H. and Akre, Thomas S. and Alberts, Susan C. and Ali, Abdullahi H. and Altmann, Jeanne and Antunes, Pamela Castro and Belant, Jerrold L. and Beyer, Dean and Blaum, Niels and Boehning-Gaese, Katrin and Cullen Jr, Laury and de Paula, Rogerio Cunha and Dekker, Jasja and Drescher-Lehman, Jonathan and Farwig, Nina and Fichtel, Claudia and Fischer, Christina and Ford, Adam T. and Goheen, Jacob R. and Janssen, Rene and Jeltsch, Florian and Kauffman, Matthew and Kappeler, Peter M. and Koch, Flavia and LaPoint, Scott and Markham, A. Catherine and Medici, Emilia Patricia and Morato, Ronaldo G. and Nathan, Ran and Oliveira-Santos, Luiz Gustavo R. and Olson, Kirk A. and Patterson, Bruce D. and Paviolo, Agustin and Ramalho, Emiliano Estero and Rosner, Sascha and Schabo, Dana G. and Selva, Nuria and Sergiel, Agnieszka and da Silva, Marina Xavier and Spiegel, Orr and Thompson, Peter and Ullmann, Wiebke and Zieba, Filip and Zwijacz-Kozica, Tomasz and Fagan, William F. and Mueller, Thomas and Calabrese, Justin M.}, title = {A comprehensive analysis of autocorrelation and bias in home range estimation}, series = {Ecological monographs : a publication of the Ecological Society of America.}, volume = {89}, journal = {Ecological monographs : a publication of the Ecological Society of America.}, number = {2}, publisher = {Wiley}, address = {Hoboken}, issn = {0012-9615}, doi = {10.1002/ecm.1344}, pages = {21}, year = {2018}, abstract = {Home range estimation is routine practice in ecological research. While advances in animal tracking technology have increased our capacity to collect data to support home range analysis, these same advances have also resulted in increasingly autocorrelated data. Consequently, the question of which home range estimator to use on modern, highly autocorrelated tracking data remains open. This question is particularly relevant given that most estimators assume independently sampled data. Here, we provide a comprehensive evaluation of the effects of autocorrelation on home range estimation. We base our study on an extensive data set of GPS locations from 369 individuals representing 27 species distributed across five continents. We first assemble a broad array of home range estimators, including Kernel Density Estimation (KDE) with four bandwidth optimizers (Gaussian reference function, autocorrelated-Gaussian reference function [AKDE], Silverman's rule of thumb, and least squares cross-validation), Minimum Convex Polygon, and Local Convex Hull methods. Notably, all of these estimators except AKDE assume independent and identically distributed (IID) data. We then employ half-sample cross-validation to objectively quantify estimator performance, and the recently introduced effective sample size for home range area estimation ( N̂ area ) to quantify the information content of each data set. We found that AKDE 95\% area estimates were larger than conventional IID-based estimates by a mean factor of 2. The median number of cross-validated locations included in the hold-out sets by AKDE 95\% (or 50\%) estimates was 95.3\% (or 50.1\%), confirming the larger AKDE ranges were appropriately selective at the specified quantile. Conversely, conventional estimates exhibited negative bias that increased with decreasing N̂ area. To contextualize our empirical results, we performed a detailed simulation study to tease apart how sampling frequency, sampling duration, and the focal animal's movement conspire to affect range estimates. Paralleling our empirical results, the simulation study demonstrated that AKDE was generally more accurate than conventional methods, particularly for small N̂ area. While 72\% of the 369 empirical data sets had >1,000 total observations, only 4\% had an N̂ area >1,000, where 30\% had an N̂ area <30. In this frequently encountered scenario of small N̂ area, AKDE was the only estimator capable of producing an accurate home range estimate on autocorrelated data.}, language = {en} } @article{KuechlyMuellerReinfelderetal.2011, author = {Kuechly, Helga Ursula and Mueller, Julia Sophie and Reinfelder, Vanessa Luisa and Wiedemann, Stephan and Blaum, Niels}, title = {Rodent-mediated dispersal of Acacia seeds in Kalahari savannah rangelands - implications for bush encroachment}, series = {African journal of ecology}, volume = {49}, journal = {African journal of ecology}, number = {1}, publisher = {Wiley-Blackwell}, address = {Malden}, issn = {0141-6707}, doi = {10.1111/j.1365-2028.2010.01230.x}, pages = {119 -- 121}, year = {2011}, language = {en} } @article{ThieleJeltschBlaum2008, author = {Thiele, T. and Jeltsch, Florian and Blaum, Niels}, title = {Importance of woody vegetation for foraging site selection in the Southern Pied Babbler (Turdoides bicolor) under two different land use regimes}, issn = {0140-1963}, year = {2008}, language = {en} } @article{TewsBlaumJeltsch2004, author = {Tews, J{\"o}rg and Blaum, Niels and Jeltsch, Florian}, title = {Structural and animal species diversity in arid and semi-arid savannas of the southern Kalahari}, year = {2004}, language = {en} } @article{BlaumEngemanWasiolkaetal.2008, author = {Blaum, Niels and Engeman, Richard M. and Wasiolka, Bernd and Rossmanith, Eva}, title = {Indexing small mammalian carnivores in the southern Kalahari, South Africa}, issn = {1035-3712}, year = {2008}, abstract = {Monitoring animal populations in changing environments is crucial to wildlife conservation and management, but restrictions in resources are a recurring problem for wildlife managers and researchers throughout Africa. Land-use- induced shrub encroachment in Kalahari savannah rangelands has led to fragmentation of the landscape. Mammalian carnivores are particularly vulnerable to local extinction in fragmented landscapes, but their low numbers and their often nocturnal and secretive habits make them difficult to monitor. In this study, we tested the applicability of a passive tracking method and compared two measurement methods and index calculations for monitoring small carnivores across a grazing gradient in the southern Kalahari. During the four years of monitoring in a five-year period, we used the knowledge of indigenous Khoisan Bushmen for the identification of carnivore tracks on 640 sand transects (5 m x 250 m). Our results showed that this simple and inexpensive observation method enabled detailed monitoring of 10 small carnivore species across the grazing gradient. A binary index calculated an index based on presence/absence of a species' tracks on each transect, whereas the track intrusion index used the number of track intrusions to each transect for each species in its calculations. For less common species, the two indices were similar in trend and magnitude, because the number of intrusions to each transect was typically 1 or 0. Usually, the two indices showed relatively strong correlations. However, species with patchy distributions of higher numbers presented difficulties for the binary index to monitor trends, but not for the track intrusion index.}, language = {en} } @article{PoppDomptailBlaumetal.2009, author = {Popp, Alexander and Domptail, Stephanie and Blaum, Niels and Jeltsch, Florian}, title = {Landuse experience does not qualify for adaptation to climate change}, issn = {0304-3800}, doi = {10.1016/j.ecolmodel.2008.11.015}, year = {2009}, abstract = {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.}, language = {en} }