TY - THES A1 - Cameron, G. A1 - Sobieraj, J. A. A1 - Elsenbeer, Helmut T1 - Scale dependency in spatial patterns of saturated hydraulic conductivity N2 - This study investigates spatial patterns of Ks and tests the hypothesis of whether structural variance emerges from noise with increasing sampling precision. We analyzed point measurements of Ks along independent transects at sampling intervals of 25, 10, 1 and 0.25 m. The field area is a tropical rainforest catena (i.e. toposequence) characterized by systematic downslope changes in soil properties including color (red to yellow), mineralogy (kaolinite- illite to kaolinite) and texture (sandy clay to sand). Independent tramsects spanning the entire catena at lag intervals of 25 and 10 in reveal little to no spatial patterns in Ks; i.e. scatter plots are noisy and lack apparent spatial trends, and semivariograms suggest little to no autocorrelation in Ks. As sampling precision is increased (h = 1 and 0.25 m), spatial patterns emerge in Ks for the downslope areas, in which distinctive hydraulic boundaries in Ks correlate with relatively small-scale, topography-controlled soils with coarse textures (greater than or equal to 80% sand). For these areas, semivariograms of Ks and those of %sand and %clay exhibit similar spatial structure characterized by small nugget variances and large ranges, and nugget variance is reduced as sampling precision increases from 1 to 0.25 m. In the upslope, clay-rich locations along this toposequence, Ks exhibits few spatial patterns, irrespective of sampling scale. For these locations, scatter plots are noisy without apparent spatial trends, and semivariograms show almost complete nugget variance, suggesting little to no correlation in this hydraulic parameter at any scale. This study suggests that in the absence of coarse textures (greater than or equal to 80% sand), there is little predictability in Ks, even at sampling intervals of 0.25 m. We believe this lack of spatial structure is due to a predominance of small-scale processes such as biological activity that largely control Ks in this forested setting. (C) 2003 Elsevier B.V. All rights reserved Y1 - 2004 UR - http://www.uni-potsdam.de/u/Geooekologie/download/elsenbeer/publikationen/RG5.pdf SN - 0341-8162 ER - TY - JOUR A1 - Heller, Wilfried T1 - Ethnicity and globalisation : on the significance of ethnical categories in countries undergoing transition N2 - During the 1990s, ethnic conflict and war placed tremendous strain on a number of countries undergoing transition in Eastern and South Eastern Europe. The reasons for these conflicts can be better understood by examining the history of these countries and their ethnic groups. This paper tries to find out why this kind of conflict has arisen during transition, taking into account the fact that the affected states are now subject to globalisation processes to an unprecedented extent. The study begins with an overview of the ways in which the term ethnicity has been used in the past, and discusses several theoretical approaches to explaining ethnic conflict. Socially relevant aspects of the new critical cultural geography may also be of use. The paper concludes that a qualified, constructivist ethnicity concept could provide a better explanation of the complex phenomenon of ethnically influenced politics and ethnic conflict. The paper also discusses the process of globalisation, as this can contribute additional perspectives as well as spatially differentiated knowledge of the significance of economic, social and political structures and national and supranational institutions for different ethnic groups and their living conditions. The paper concludes by offering suggestions for reducing or preventing ethnic conflict Y1 - 2004 SN - 0016-7479 ER - TY - JOUR A1 - Oppel, Steffen A1 - Schäfer, Martin H. A1 - Schmidt, Veronika A1 - Schröder-Esselbach, Boris T1 - How much suitable habitat is left for the last known population of the Pale-Headed Brush-Finch? N2 - The Pale-headed Brush-Finch (Atlapetes pallidiceps) is threatened with extinction due to loss of habitat. The only remnant population consists of 30-35 pairs and is confined to a single valley in the Andes of southwestern Ecuador. We investigated the habitat types used by this species in order to quantify the amount of available suitable habitat. The species used semiopen habitat types featuring a mosaic of dense scrub 2-4 In tall and grassy patches. Low continuous scrub was also used in larger proportions than on average available; forest and open country were not included in territories. Suitable habitat covered 28% of the area, and 16% was still available for new brush-finch territories. We identified a minimum of seven coherent patches that could support eight further pairs of the species. The valley can thus potentially support 40-50 pairs. The occupied habitat as described here should serve as a guideline in searching for new habitat Y1 - 2004 UR - http://brandenburg.geoecology.uni-potsdam.de/users/schroeder/download/publications/ oppel_etal_condor_proofs.pdf ER - TY - JOUR A1 - Güntner, Andreas A1 - Krol, Marten S. A1 - de Arajo, José Carlos A1 - Bronstert, Axel T1 - Simple water balance modelling of surface reservoir systems in a large data-scarce semiarid region N2 - Water resources in dryland areas are often provided by numerous surface reservoirs. As a basis for securing future water supply, the dynamics of reservoir systems need to be simulated for large river basins, accounting for environmental change and an increasing water demand. For the State of Ceara in semiarid Northeast Brazil, with several thousands of reservoirs, a simple deterministic water balance model is presented. Within a cascade-type approach, the reservoirs are grouped into six classes according to storage capacity, rules for flow routing between reservoirs of different size are defined, and water withdrawal and return flow due to human water use is accounted for. While large uncertainties in model applications exist, particularly in terms of reservoir operation rules, model validation against observed reservoir storage volumes shows that the approach is a reasonable simplification to assess surface water availability in large river basins. The results demonstrate the large impact of reservoir storage on downstream flow and stress the need for a coupled simulation of runoff generation, network redistribution and water use Y1 - 2004 SN - 0262-6667 ER - TY - JOUR A1 - Godsey, S. A1 - Elsenbeer, Helmut A1 - Stallard, R. F. T1 - Overland flow generation in two lithologically distinct rainforest catchments N2 - Streams on uniformly rainforest-covered, but lithologically very diverse Barro Colorado Island in central Panamd show remarkable differences in their runoff response to rainfall. This lithological diversity is reflected in equally diverse soilscapes, and our objective was to test the hypothesis that contrasting runoff responses derive from soilscape features that control the generation of overland flow. We determined the soil saturated hydraulic conductivity (K-s) of two neighboring, but hydrologically contrasting catchments (Lutz Creek with a flashy and Conrad Trail with a delayed response to rainfall), and quantified the spatial and temporal frequency of overland flow occurrence. The median K-s values at a depth of 12.5 cm are large enough to rule out Hortonian overland flow, but a marked decrease in K-s in Lutz Creek catchment at 30 cm suggests the formation of a perched water table and the generation saturation overland flow; the decrease in K-s in the Conrad Trail catchment is more gradual, and a perched water table is expected to form only at depths below 50 cm. In Lutz Creek, overland flow was generated frequently in time and space and regardless of topographic position, including near the interfluve, with very low thresholds of storm magnitude, duration, intensity and antecedent wetness, whereas in Conrad Trail, overland flow was generated much less frequently and then only locally. We conclude that soilscape features and microtopography are important controls of overland flow generation in these catchments. Our results contribute to the growing evidence that overland flow and forests are not a priori a contradiction in terms. (C) 2004 Elsevier B.V. All rights reserved Y1 - 2004 SN - 0022-1694 ER - TY - JOUR A1 - Güntner, Andreas A1 - Bronstert, Axel T1 - Representation of landscape variability and lateral redistribution processes for large-scale hydrological modelling in semi-arid areas N2 - The spatial variability of landscape features such as topography, soils and vegetation defines the spatial pattern of hydrological state variables like soil moisture. Spatial variability thereby controls the functional behaviour of the landscape in terms of its runoff response. A consequence of spatial variability is that exchange processes between landscape patches can occur at various spatial scales ranging from the plot to the basin scale. In semi-arid areas, the lateral redistribution of surface runoff between adjacent landscape patches is an important process. For applications to large river basins of 10(4)-10(5) km(2) in size, a multi-scale landscape discretization scheme is presented in this paper. The landscape is sub-divided into modelling units within a hierarchy of spatial scale levels. By delineating areas characterized by a typical toposequence, organised and random variability of landscape characteristics is captured in the model. Using runoff-runon relationships with transition frequencies based on areal fractions of modelling units, lateral surface and subsurface water fluxes between modelling units at the hillslope scale are represented. Thus, the new approach allows for a manageable description of interactions between fine-scale landscape features for inclusion in coarse-scale models. Model applications for the State of Ceara (148,000 km(2)) in the north- east of Brazil demonstrate the importance of taking into account landscape variability and interactions between landscape patches in a semi-arid environment. Using mean landscape characteristics leads to a considerable underestimation of infiltration-excess surface runoff and total simulated runoff. Re-infiltration of surface runoff and lateral redistribution processes between landscape patches cause a reduction of runoff volumes at the basin scale and contribute to the amplification of variations in runoff volumes relative to variations in rainfall volumes for semi-arid areas. (C) 2004 Elsevier B.V. All rights reserved Y1 - 2004 SN - 0022-1694 ER - TY - JOUR A1 - Zehe, Erwin A1 - Blöschl, Günter T1 - Predictability of hydrologic response at the plot and catchment scales : the role of initial conditions N2 - [1] This paper examines the effect of uncertain initial soil moisture on hydrologic response at the plot scale (1 m(2)) and the catchment scale (3.6 km(2)) in the presence of threshold transitions between matrix and preferential flow. We adopt the concepts of microstates and macrostates from statistical mechanics. The microstates are the detailed patterns of initial soil moisture that are inherently unknown, while the macrostates are specified by the statistical distributions of initial soil moisture that can be derived from the measurements typically available in field experiments. We use a physically based model and ensure that it closely represents the processes in the Weiherbach catchment, Germany. We then use the model to generate hydrologic response to hypothetical irrigation events and rainfall events for multiple realizations of initial soil moisture microstates that are all consistent with the same macrostate. As the measures of uncertainty at the plot scale we use the coefficient of variation and the scaled range of simulated vertical bromide transport distances between realizations. At the catchment scale we use similar statistics derived from simulated flood peak discharges. The simulations indicate that at both scales the predictability depends on the average initial soil moisture state and is at a minimum around the soil moisture value where the transition from matrix to macropore flow occurs. The predictability increases with rainfall intensity. The predictability increases with scale with maximum absolute errors of 90 and 32% at the plot scale and the catchment scale, respectively. It is argued that even if we assume perfect knowledge on the processes, the level of detail with which one can measure the initial conditions along with the nonlinearity of the system will set limits to the repeatability of experiments and limits to the predictability of models at the plot and catchment scales Y1 - 2004 ER - TY - BOOK ED - Sallanz, Josef T1 - Sprechen sie romänisch? : von Minderheiten und Mehrheiten im Donaudelta ; Exkursion des Instituts für Geographie der Universität Potsdam, 8. bis 22. September 2004 Y1 - 2004 PB - Univ. CY - Potsdam ER - TY - BOOK A1 - Bronstert, Axel A1 - Thieken, Annegret A1 - Merz, Bruno A1 - Rode, Michael A1 - Menzel, Lucas T1 - Wasser- und Stofftransport in heterogenen Einzugsgebieten : Beiträge zum Tag der Hydrologie 2004, 22./ 23. März 2004 in Potsdam ; Bd. 2 Poster Y1 - 2004 SN - 3-937758-18-6 PB - ATV-DVWK CY - Hennef ER - TY - BOOK A1 - Bronstert, Axel A1 - Thieken, Annegret A1 - Merz, Bruno A1 - Rode, Michael A1 - Menzel, Lucas T1 - Wasser- und Stofftransport in heterogenen Einzugsgebieten : Beiträge zum Tag der Hydrologie 2004, 22./ 23. März 2004 in Potsdam ; Bd. 1 Vorträge Y1 - 2004 SN - 3-937758-18-6 VL - 5 PB - ATV-DVWK CY - Hennef (Sieg) ER - TY - JOUR A1 - Rolfes, Manfred T1 - Bramsche Y1 - 2004 ER - TY - JOUR A1 - Oppel, Steffen A1 - Schäfer, Martin H. A1 - Schmidt, Veronika A1 - Schröder-Esselbach, Boris T1 - Cowbird parasitism of the Pale-headed Brush-Finch Atlapetes pallidiceps: implications for conservation and managemen Y1 - 2004 UR - http://brandenburg.geoecology.uni-potsdam.de/users/schroeder/download/publications/ oppel_etal_BCI_proofs.pdf ER - TY - JOUR A1 - Oppel, Steffen A1 - Schäfer, Martin H. A1 - Schmidt, Veronika A1 - Schröder-Esselbach, Boris T1 - Habitat selection by the Pale-headed brush-finch (Atlapetes pallidiceps) in southern Ecuador: implications for conservation Y1 - 2004 UR - http://brandenburg.geoecology.uni-potsdam.de/users/schroeder/download/publications/ oppel_etal_biolcons_in_press.pdf ER - TY - JOUR A1 - Schröder-Esselbach, Boris A1 - Rudner, Michael A1 - Biedermann, Robert A1 - Kleyer, Michael T1 - Ökologische & sozio-ökonomische Bewertung von Managementsystemen für die Offenhaltung von Landschaften - ein integriertes Landschaftsmodell Y1 - 2004 UR - http://brandenburg.geoecology.uni-potsdam.de/users/schroeder/download/publications/ schroeder_etal_ufzbericht9_2004.pdf ER - TY - JOUR A1 - Schröder-Esselbach, Boris T1 - Überblick zum Block "Statistische Habitatmodelle - Status quo & aktuelle Entwicklungen" Y1 - 2004 UR - http://brandenburg.geoecology.uni-potsdam.de/users/schroeder/download/publications/ schroeder_ufzbericht9_2004.pdf ER - TY - JOUR A1 - Blume, Theresa A1 - Bauer, Andreas A1 - Bronstert, Axel T1 - Experimental techniques for the Investigation of Runoff Processes in a Small Catchment in the Chilean Andes Y1 - 2004 SN - 3-937758-18-6 ER - TY - BOOK A1 - Zehe, Erwin A1 - Bolduan, Rainer A1 - Bärdossy, Andräs A1 - Bronstert, Axel A1 - Plate, Erich T1 - Stofftransport in einem Lösseinzugsgebiet: Experimentelle Evidenz und numerische Modellierung. Y1 - 2004 SN - 3-937758-18-6 ER - TY - BOOK A1 - Buder, Margret A1 - Dreßler, Jutta A1 - Gewand, Ulrich A1 - Kaden, Klaus A1 - Lüdtke, Norbert A1 - Richter, Dieter A1 - Vogt, Jürgen A1 - Weinert, Gudrun ED - Kulke, Elmar ED - Richter, Dieter T1 - Geografie : Hauptband Klasse 7 ; Ausgabe Sachsen Y1 - 2004 SN - 3-06-040792-4 PB - Cornelsen CY - Berlin ER - TY - JOUR A1 - Burkart, Michael A1 - Hinrichsen, Arne A1 - Kühling, Matthias A1 - Oehlschläger, Susanne A1 - Wallschläger, Hans-Dieter A1 - Wiegleb, Gerhard A1 - Wolters, Steffen T1 - Einführung : Offene Sandlandschaften Mitteleuropas ; Truppenübungsplätze und Naturschutz Y1 - 2004 SN - 3-540-22449-1 ER - TY - JOUR A1 - Krause, Stefan A1 - Bauer, Andreas A1 - Morgner, Markus A1 - Bronstert, Axel T1 - Wasserhaushaltsmodellierung als Beitrag zur Erstellung eines nachhaltigen Flusseinzugsgebietsmanagements an der Unteren Havel Y1 - 2004 SN - 3-937758-18-6 ER -