TY  - JOUR
A1  - Langhammer, Maria
A1  - Grimm, Volker
T1  - Mitigating bioenergy-driven biodiversity decline
BT  - a modelling approach with the European brown hare
JF  - Ecological modelling : international journal on ecological modelling and engineering and systems ecolog
N2  - The cultivation of energy crops leads to direct and indirect land use changes that impair the biodiversity of the agricultural landscape. In our study, we analyse the effects of mitigation measures on the European brown hare (Lepus europaeus), which is directly affected by ongoing land use change and has experienced widespread decline throughout Europe since the 1960s. Therefore, we developed a spatially explicit and individual-based ecological model to study the effects of different landscape configurations and compositions on hare population development. As an input, we used two 4 x 4 km large model landscapes, which were generated by a landscape generator based on real field sizes and crop proportions and differed in average field size and crop composition. The crops grown annually are evaluated in terms of forage suitability, breeding suitability and crop richness for the hare. In six mitigation scenarios, we investigated the effects of a 10 % increase in the following measures: (1) mixed silphie, (2) miscanthus, (3) grass-clover ley, (4) alfalfa, (5) set-aside, and (6) general crop richness. All mitigation measures had significant effects on hare population development. Compared to the base scenario, the relative change in hare abundance ranged from a factor of 0.56 in the grass-clover ley scenario to-0.16 in the miscanthus scenario. The mitigation measures of mixed silphie, grass-clover ley and increased crop richness led to distinct increases in hare abundance in both landscapes ( > 0.3). The results show that both landscape configuration and composition have a significant effect on hare population development, which responds particularly strongly to compositional changes. The increase in crop diversity, e.g., through the cultivation of alternative energy crops such as mixed silphie and grass-clover ley, proves to be beneficial for the brown hare.
KW  - agent-based modelling
KW  - mitigation measures
KW  - agriculture
KW  - European brown
KW  - hare
KW  - land-use change
KW  - Lepus europaeus
Y1  - 2020
U6  - https://doi.org/10.1016/j.ecolmodel.2019.108914
SN  - 0304-3800
SN  - 1872-7026
VL  - 416
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Rosenkranz, Ruben
A1  - Schildgen, Taylor F.
A1  - Wittmann, Hella
A1  - Spiegel, Cornelia
T1  - Coupling erosion and topographic development in the rainiest place on Earth
BT  - Reconstructing the Shillong Plateau uplift history with in-situ cosmogenic Be-10
JF  - Earth & planetary science letters
N2  - The uplift of the Shillong Plateau, in northeast India between the Bengal floodplain and the Himalaya Mountains, has had a significant impact on regional precipitation patterns, strain partitioning, and the path of the Brahmaputra River. Today, the plateau receives the highest measured yearly rainfall in the world and is tectonically active, having hosted one of the strongest intra-plate earthquakes ever recorded. Despite the unique tectonic and climatic setting of this prominent landscape feature, its exhumation and surface uplift history are poorly constrained. We collected 14 detrital river sand and 3 bedrock samples from the southern margin of the Shillong Plateau to measure erosion rates using the terrestrial cosmogenic nuclide 10Be. The calculated bedrock erosion rates range from 2.0 to 5.6 m My−1, whereas catchment average erosion rates from detrital river sands range from 48 to 214 m My−1. These rates are surprisingly low in the context of steep, tectonically active slopes and extreme rainfall. Moreover, the highest among these rates, which occur on the low-relief plateau surface, appear to have been affected by anthropogenic land-use change. To determine the onset of surface uplift, we coupled the catchment averaged erosion rates with topographic analyses of the plateau's southern margin. We interpolated an inclined, pre-incision surface from minimally eroded remnants along the valley interfluves and calculated the eroded volume of the valleys carved beneath the surface. The missing volume was then divided by the volume flux derived from the erosion rates to obtain the onset of uplift. The results of this calculation, ranging from 3.0 to 5.0 Ma for individual valleys, are in agreement with several lines of stratigraphic evidence from the Brahmaputra and Bengal basin that constrain the onset of topographic uplift, specifically the onset of flexural loading and the transgression from deltaic to marine deposition. Ultimately, our data corroborate the hypothesis that surface uplift was decoupled from the onset of rapid exhumation, which occurred several millions of years earlier.
KW  - river profile analysis
KW  - land-use change
KW  - Be-10
KW  - orographic rainfall
KW  - erosion
Y1  - 2017
U6  - https://doi.org/10.1016/j.epsl.2017.11.047
SN  - 0012-821X
SN  - 1385-013X
VL  - 483
SP  - 39
EP  - 51
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Tabares Jimenez, Ximena del Carmen
A1  - Zimmermann, Heike Hildegard
A1  - Dietze, Elisabeth
A1  - Ratzmann, Gregor
A1  - Belz, Lukas
A1  - Vieth-Hillebrand, Andrea
A1  - Dupont, Lydie
A1  - Wilkes, Heinz
A1  - Mapani, Benjamin
A1  - Herzschuh, Ulrike
T1  - Vegetation state changes in the course of shrub encroachment in an African savanna since about 1850 CE and their potential drivers
JF  - Ecology and evolution
N2  - Shrub encroachment has far-reaching ecological and economic consequences in many ecosystems worldwide. Yet, compositional changes associated with shrub encroachment are often overlooked despite having important effects on ecosystem functioning. We document the compositional change and potential drivers for a northern Namibian Combretum woodland transitioning into a Terminalia shrubland. We use a multiproxy record (pollen, sedimentary ancient DNA, biomarkers, compound-specific carbon (delta C-13) and deuterium (delta D) isotopes, bulk carbon isotopes (delta(13)Corg), grain size, geochemical properties) from Lake Otjikoto at high taxonomical and temporal resolution. We provide evidence that state changes in semiarid environments may occur on a scale of one century and that transitions between stable states can span around 80 years and are characterized by a unique vegetation composition. We demonstrate that the current grass/woody ratio is exceptional for the last 170 years, as supported by n-alkane distributions and the delta C-13 and delta(13)Corg records. Comparing vegetation records to environmental proxy data and census data, we infer a complex network of global and local drivers of vegetation change. While our delta D record suggests physiological adaptations of woody species to higher atmospheric pCO(2) concentration and drought, our vegetation records reflect the impact of broad-scale logging for the mining industry, and the macrocharcoal record suggests a decrease in fire activity associated with the intensification of farming. Impact of selective grazing is reflected by changes in abundance and taxonomical composition of grasses and by an increase of nonpalatable and trampling-resistant taxa. In addition, grain-size and spore records suggest changes in the erodibility of soils because of reduced grass cover. Synthesis. We conclude that transitions to an encroached savanna state are supported by gradual environmental changes induced by management strategies, which affected the resilience of savanna ecosystems. In addition, feedback mechanisms that reflect the interplay between management legacies and climate change maintain the encroached state.
KW  - climate change
KW  - fossil pollen
KW  - land-use change
KW  - savanna ecology
KW  - sedimentary ancient DNA
KW  - state and transition
KW  - tree-grass interactions
Y1  - 2019
U6  - https://doi.org/10.1002/ece3.5955
SN  - 2045-7758
VL  - 10
IS  - 2
SP  - 962
EP  - 979
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Manning, Pete
A1  - Gossner, Martin M.
A1  - Bossdorf, Oliver
A1  - Allan, Eric
A1  - Zhang, Yuan-Ye
A1  - Prati, Daniel
A1  - Blüthgen, Nico
A1  - Boch, Steffen
A1  - Böhm, Stefan
A1  - Börschig, Carmen
A1  - Hölzel, Norbert
A1  - Jung, Kirsten
A1  - Klaus, Valentin H.
A1  - Klein, Alexandra Maria
A1  - Kleinebecker, Till
A1  - Krauss, Jochen
A1  - Lange, Markus
A1  - Müller, Jörg
A1  - Pasalic, Esther
A1  - Socher, Stephanie A.
A1  - Tschapka, Marco
A1  - Türke, Manfred
A1  - Weiner, Christiane
A1  - Werner, Michael
A1  - Gockel, Sonja
A1  - Hemp, Andreas
A1  - Renner, Swen C.
A1  - Wells, Konstans
A1  - Buscot, Francois
A1  - Kalko, Elisabeth K. V.
A1  - Linsenmair, Karl Eduard
A1  - Weisser, Wolfgang W.
A1  - Fischer, Markus
T1  - Grassland management intensification weakens the associations among the diversities of multiple plant and animal taxa
JF  - Ecology : a publication of the Ecological Society of America
N2  - Land-use intensification is a key driver of biodiversity change. However, little is known about how it alters relationships between the diversities of different taxonomic groups, which are often correlated due to shared environmental drivers and trophic interactions. Using data from 150 grassland sites, we examined how land-use intensification (increased fertilization, higher livestock densities, and increased mowing frequency) altered correlations between the species richness of 15 plant, invertebrate, and vertebrate taxa. We found that 54% of pairwise correlations between taxonomic groups were significant and positive among all grasslands, while only one was negative. Higher land-use intensity substantially weakened these correlations(35% decrease in rand 43% fewer significant pairwise correlations at high intensity), a pattern which may emerge as a result of biodiversity declines and the breakdown of specialized relationships in these conditions. Nevertheless, some groups (Coleoptera, Heteroptera, Hymenoptera and Orthoptera) were consistently correlated with multidiversity, an aggregate measure of total biodiversity comprised of the standardized diversities of multiple taxa, at both high and lowland-use intensity. The form of intensification was also important; increased fertilization and mowing frequency typically weakened plant-plant and plant-primary consumer correlations, whereas grazing intensification did not. This may reflect decreased habitat heterogeneity under mowing and fertilization and increased habitat heterogeneity under grazing. While these results urge caution in using certain taxonomic groups to monitor impacts of agricultural management on biodiversity, they also suggest that the diversities of some groups are reasonably robust indicators of total biodiversity across a range of conditions.
KW  - Biodiversity indicators
KW  - correlation
KW  - fertilization
KW  - grassland management
KW  - grazing
KW  - land-use change
KW  - land-use intensity
KW  - mowing
KW  - multidiversity
KW  - multitrophic interactions
Y1  - 2015
U6  - https://doi.org/10.1890/14-1307.1
SN  - 0012-9658
SN  - 1939-9170
VL  - 96
IS  - 6
SP  - 1492
EP  - 1501
PB  - Wiley
CY  - Washington
ER  - 
TY  - JOUR
A1  - Gevers, Jana
A1  - Hoye, Toke Thomas
A1  - Topping, Chris John
A1  - Glemnitz, Michael
A1  - Schroeder, Boris
T1  - Biodiversity and the mitigation of climate change through bioenergy  impacts of increased maize cultivation on farmland wildlife
JF  - Global change biology : Bioenergy
N2  - The public promotion of renewable energies is expected to increase the number of biogas plants and stimulate energy crops cultivation (e. g. maize) in Germany. In order to assess the indirect effects of the resulting land-use changes on biodiversity, we developed six land-use scenarios and simulated the responses of six farmland wildlife species with the spatially explicit agent-based model system ALMaSS. The scenarios differed in composition and spatial configuration of arable crops. We implemented scenarios where maize for energy production replaced 15% and 30% of the area covered by other cash crops. Biogas maize farms were either randomly distributed or located within small or large aggregation clusters. The animal species investigated were skylark (Alauda arvensis), grey partridge (Perdix perdix), European brown hare (Lepus europaeus), field vole (Microtus agrestis), a linyphiid spider (Erigone atra) and a carabid beetle (Bembidion lampros). The changes in crop composition had a negative effect on the population sizes of skylark, partridge and hare and a positive effect on the population sizes of spider and beetle and no effect on the population size of vole. An aggregated cultivation of maize amplified these effects for skylark. Species responses to changes in the crop composition were consistent across three differently structured landscapes. Our work suggests that with the compliance to some recommendations, negative effects of biogas-related land-use change on the populations of the six representative farmland species can largely be avoided.
KW  - agriculture
KW  - ALMaSS
KW  - biogas
KW  - farmland biodiversity
KW  - land-use change
KW  - maize
KW  - spatially explicit agent-based modeling
Y1  - 2011
U6  - https://doi.org/10.1111/j.1757-1707.2011.01104.x
SN  - 1757-1693
VL  - 3
IS  - 6
SP  - 472
EP  - 482
PB  - Wiley-Blackwell
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Huber, Robert
A1  - Rigling, Andreas
A1  - Bebi, Peter
A1  - Brand, Fridolin Simon
A1  - Briner, Simon
A1  - Buttler, Alexandre
A1  - Elkin, Che
A1  - Gillet, Francois
A1  - Gret-Regamey, Adrienne
A1  - Hirschi, Christian
A1  - Lischke, Heike
A1  - Scholz, Roland Werner
A1  - Seidl, Roman
A1  - Spiegelberger, Thomas
A1  - Walz, Ariane
A1  - Zimmermann, Willi
A1  - Bugmann, Harald
T1  - Sustainable land use in Mountain Regions under global change synthesis across scales and disciplines
JF  - Ecology and society : a journal of integrative science for resilience and sustainability
N2  - Mountain regions provide essential ecosystem goods and services (EGS) for both mountain dwellers and people living outside these areas. Global change endangers the capacity of mountain ecosystems to provide key services. The Mountland project focused on three case study regions in the Swiss Alps and aimed to propose land-use practices and alternative policy solutions to ensure the provision of key EGS under climate and land-use changes. We summarized and synthesized the results of the project and provide insights into the ecological, socioeconomic, and political processes relevant for analyzing global change impacts on a European mountain region. In Mountland, an integrative approach was applied, combining methods from economics and the political and natural sciences to analyze ecosystem functioning from a holistic human-environment system perspective. In general, surveys, experiments, and model results revealed that climate and socioeconomic changes are likely to increase the vulnerability of the EGS analyzed. We regard the following key characteristics of coupled human-environment systems as central to our case study areas in mountain regions: thresholds, heterogeneity, trade-offs, and feedback. Our results suggest that the institutional framework should be strengthened in a way that better addresses these characteristics, allowing for (1) more integrative approaches, (2) a more network-oriented management and steering of political processes that integrate local stakeholders, and (3) enhanced capacity building to decrease the identified vulnerability as central elements in the policy process. Further, to maintain and support the future provision of EGS in mountain regions, policy making should also focus on project-oriented, cross-sectoral policies and spatial planning as a coordination instrument for land use in general.
KW  - adaptive management
KW  - climate change
KW  - ecosystem services
KW  - experiments
KW  - interdisciplinary research
KW  - land-use change
KW  - modeling
KW  - transdisciplinary research
Y1  - 2013
U6  - https://doi.org/10.5751/ES-05499-180336
SN  - 1708-3087
VL  - 18
IS  - 3
PB  - Resilience Alliance
CY  - Wolfville
ER  - 
TY  - THES
A1  - Haßler, Sibylle Kathrin
T1  - Saturated hydraulic conductivity in the humid tropics : sources of variability, implications for monitoring and effects on near-surface hydrological flow paths
T1  - Quellen der Variabilität der gesättigten hydraulischen Leitfähigkeit in den humiden Tropen, ihre Bedeutung für die Beprobung der Leitfähigkeit und ihre Auswirkungen auf bodennahe hydrologische Fließpfade
N2  - Large areas in the humid tropics are currently undergoing land-use change. The decrease of tropical rainforest, which is felled for land clearing and timber production, is countered by increasing areas of tree plantations and secondary forests. These changes are known to affect the regional water cycle as a result of plant-specific water demand and by influencing key soil properties which determine hydrological flow paths. One of these key properties sensitive to land-use change is the saturated hydraulic conductivity (Ks) as it governs vertical percolation of water within the soil profile. Low values of Ks in a certain soil depth can form an impeding layer and lead to perched water tables and the development of predominantly lateral flow paths such as overland flow. These processes can induce nutrient redistribution, erosion and soil degradation and thus affect ecosystem services and human livelihoods. Due to its sensitivity to land-use change, Ks is commonly used to assess the associated changes in hydrological flow paths. The objective of this dissertation was to assess the effect of land-use change on hydrological flow paths by analysing Ks as indicator variable. Sources of Ks variability, their implications for Ks monitoring and the relationship between Ks and near-surface hydrological flow paths in the context of land-use change were studied. The research area was located in central Panama, a country widely experiencing the abovementioned changes in land use. Ks is dependent on both static, soil-inherent properties such as particle size and clay mineralogy and dynamic, land use-dependent properties such as organic carbon content. By conducting a pair of studies with one of these influences held constant in each, the importance of static and dynamic properties for Ks was assessed. Applying a space-for-time approach to sample Ks under secondary forests of different age classes on comparable soils, a recovery of Ks from the former pasture use was shown to require more than eight years. The process was limited to the 0−6 cm sampling depth and showed large variability among replicates. A wavelet analysis of a Ks transect crossing different soil map units under comparable land cover, old-growth tropical rainforest, showed large small-scale variability, which was attributed to biotic influences, as well as a possible but non-conclusive influence of soil types. The two results highlight the importance of dynamic, land use-dependent influences on Ks. Monitoring studies can help to quantify land use-induced change of Ks, but there is a variety of sampling designs which differ in efficiency of estimating mean Ks. A comparative study of four designs and their suitability for Ks monitoring is used to give recommendations about designing a Ks monitoring scheme. Quantifying changes in spatial means of Ks for small catchments with a rotational stratified sampling design did not prove to be more efficient than Simple Random Sampling. The lack of large-scale spatial structure prevented benefits of stratification, and large small-scale variability resulting from local biotic processes and artificial effects of destructive sampling caused a lack of temporal consistency in the re-sampling of locations, which is part of the rotational design. The relationship between Ks and near-surface hydrological flow paths is of critical importance when assessing the consequences of land-use change in the humid tropics. The last part of this dissertation aimed at disclosing spatial relationships between Ks and overland flow as influenced by different land cover types. The effects of Ks on overland-flow generation were spatially variable, different between planar plots and incised flowlines and strongly influenced by land-cover characteristics. A simple comparison of Ks values and rainfall intensities was insufficient to describe the observed pattern of overland flow. Likewise, event flow in the stream was apparently not directly related to overland flow response patterns within the catchments. The study emphasises the importance of combining pedological, hydrological, meteorological and botanical measurements to comprehensively understand the land use-driven change in hydrological flow paths. In summary, Ks proved to be a suitable parameter for assessing the influence of land-use change on soils and hydrological processes. The results illustrated the importance of land cover and spatial variability of Ks for decisions on sampling designs and for interpreting overland-flow generation. As relationships between Ks and overland flow were shown to be complex and dependent on land cover, an interdisciplinary approach is required to comprehensively understand the effects of land-use change on soils and near-surface hydrological flow paths in the humid tropics.
N2  - Tropische Regionen sind einem andauernden Landnutzungswandel unterworfen. Einerseits wird tropischer Regenwald für Holz- und Flächengewinnung abgeholzt, andererseits fallen Flächen im Zuge der Urbanisierung brach. Diese werden zum Teil mit Nutzholz-Plantagen aufgeforstet, zum Teil entwickelt sich auf ihnen natürlicher Sekundärwald. Änderungen in der Landnutzung beeinflussen Bodeneigenschaften und dadurch implizit den Wasserkreislauf der Region. Eine dieser wichtigen landnutzungsabhängigen Bodeneigenschaften ist die gesättigte hydraulische Leitfähigkeit oder Permeabilität, die maßgeblich die Versickerungsrate im Boden bestimmt. Eine niedrige Permeabilität hemmt die (vertikale) Versickerung und kann dazu führen, dass laterale hydrologische Fließpfade wie z.B. Oberflächenabfluss aktiviert werden. Dadurch wird sowohl die Bodenerosion und Nährstoffverlagerung verstärkt als auch die Auffüllung des Grundwasserspeichers verringert. In welchem Maße jedoch die Änderung der Permeabilität während des Landnutzungswandels eine Änderung der hydrologischen Fließpfade nach sich zieht, ist noch unzureichend erforscht. Die Zielstellung der vorliegenden Dissertation war, mit Hilfe der Permeabilität als Indikatorvariable die Auswirkungen des Landnutzungswandels auf bodennahe hydrologische Fließpfade zu beurteilen. Dabei sollten die Quellen der Variabilität der Permeabilität anhand des Einflusses von Bodentyp und Landnutzung eingeschätzt, diese Variabilität in das Design einer Probenahmestrategie für die Permeabilität integriert und die Auswirkungen dieser Einflüsse auf die Aktivierung lateraler Fließpfade untersucht werden. Die Studien wurden in Panama durchgeführt, da dieses Land stark vom Landnutzungswandel betroffen ist, eine gute Forschungsinfrastruktur aufweist und sich durch die hohen Niederschläge des tropischen Klimas Änderungen im Wasserkreislauf besonders stark auswirken. Zwei Teilstudien zu den Quellen der Variabilität der Permeabilität lieferten Hinweise auf einen möglichen Einfluss des Bodentyps, der jedoch durch den lokal stärkeren Einfluss der Landnutzung überprägt wurde. Auf regionaler Skala wurde die Erholung der Permeabilität unter Sekundärwald nach einer vorhergehenden Weidenutzung belegt. Beide Studien deuteten auf einen maßgeblichen Einfluss der Landnutzung und der räumlichen Struktur der Permeabilität auf die untersuchten Prozesse hin. Für die effiziente Abschätzung zeitlicher Veränderungen der Permeabilität, wie sie im Zuge des Landnutzungswandels auftritt, ist die Einbeziehung dieser räumlichen Strukturen in das Design einer Probenahmestrategie für die Permeabilität von großer Bedeutung, wie in einem Vergleich vier verschiedener Designs gezeigt wurde. Der Zusammenhang zwischen der Permeabilität und der Entstehung von Oberflächenabfluss konnte nicht durch einfache Ansätze, wie dem Vergleich der Permeabilität mit Regenintensitäten oder der Betrachtung des Gebietsabflusses, erklärt werden. Vielmehr scheint ein komplexes Zusammenspiel aus meteorologischen, biologischen, bodenkundlichen und hydrologischen Faktoren zu wirken. So wurde die räumliche Struktur des Oberflächenabflusses im Untersuchungsgebiet vermutlich durch eine Kombination aus Landnutzungs- und Permeabilitäts-Einflüssen bedingt, zu deren Aufklärung weitere notwendige Messungen vorgeschlagen werden. Zusammengefasst konnte anhand der Permeabilität der Einfluss des Landnutzungswandels auf die hydrologischen Fließpfade gut aufgezeigt werden. Eine besondere Bedeutung kommt hierbei der Betrachtung der landnutzungsabhängigen räumlichen Struktur der Permeabilität zu. Für die Prozessaufklärung der Aktivierung lateraler Fließpfade müssen jedoch Messungen aus verschiedenen Disziplinen kombiniert werden.
KW  - Bodenhydrologie
KW  - Landnutzungswandel
KW  - Tropen
KW  - Probenahmestrategie
KW  - hydrologische Fließpfade
KW  - Soil hydrology
KW  - land-use change
KW  - tropics
KW  - monitoring
KW  - hydrological flow paths
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-66864
ER  -