TY - JOUR A1 - Lischeid, Gunnar A1 - Kalettka, Thomas A1 - Merz, Christoph A1 - Steidl, Jörg T1 - Monitoring the phase space of ecosystems: Concept and examples from the Quillow catchment, Uckermark JF - Ecological indicators : integrating monitoring, assessment and management N2 - Ecosystem research benefits enormously from the fact that comprehensive data sets of high quality, and covering long time periods are now increasingly more available. However, facing apparently complex interdependencies between numerous ecosystem components, there is urgent need rethinking our approaches in ecosystem research and applying new tools of data analysis. The concept presented in this paper is based on two pillars. Firstly, it postulates that ecosystems are multiple feedback systems and thus are highly constrained. Consequently, the effective dimensionality of multivariate ecosystem data sets is expected to be rather low compared to the number of observables. Secondly, it assumes that ecosystems are characterized by continuity in time and space as well as between entities which are often treated as distinct units. Implementing this concept in ecosystem research requires new tools for analysing large multivariate data sets. This study presents some of them, which were applied to a comprehensive water quality data set from a long-term monitoring program in Northeast Germany in the Uckermark region, one of the LTER-D (Long Term Ecological Research network, Germany) sites. Short-term variability of the kettle hole water samples differed substantially from that of the stream water samples, suggesting different processes generating the dynamics in these two types of water bodies. However, again, this seemed to be due to differing intensities of single processes rather than to completely different processes. We feel that research aiming at elucidating apparently complex interactions in ecosystems could make much more efficient use from now available large monitoring data sets by implementing the suggested concept and using corresponding innovative tools of system analysis. (C) 2015 Elsevier Ltd. All rights reserved. KW - Ecosystem research KW - Monitoring KW - Concept KW - Effective dimensionality KW - Continuity KW - Visualization Y1 - 2016 U6 - https://doi.org/10.1016/j.ecolind.2015.10.067 SN - 1470-160X SN - 1872-7034 VL - 65 SP - 55 EP - 65 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Lischeid, Gunnar A1 - Kalettka, Thomas T1 - Grasping the heterogeneity of kettle hole water quality in Northeast Germany JF - Hydrobiologia : acta hydrobiologica, hydrographica, limnologica et protistologica N2 - In the young moraine landscape in Northeast Germany, small glacially created ponds, the so-called kettle holes, are very abundant. They exhibit large spatial heterogeneity, seemingly rendering each kettle hole unique. However, this would not be consistent with any scientific approach. Thus, a classification scheme has been developed for kettle holes in Northeast Germany based on morphology, hydrodynamics and connection to stream networks of the kettle holes as well as size, topography and land use of the respective catchment. These indices are assumed to be related both to water quality as well as to biological issues of the kettle holes. Starting in the mid-1990s, an extensive monitoring program has been established in the federal state of Brandenburg, Germany. In this study, a subset comprising 1,316 samples from 79 kettle holes was analysed, where 21 parameters had been determined. Sampling intervals varied widely, and were between bi-weekly and three-monthly at most sites. A nonlinear principal component analysis was performed. The first four components explained 90% of the variance. These components seem to provide quantitative measures of phosphorus release from the sediments during hypoxic periods, agricultural solute input, algae primary production, and geogenic compounds. This allowed differentiating between the natural and anthropogenic impact factors on water quality. In addition, scores of single components were related to properties of the kettle holes and their environments. The results contribute to a better understanding of biological and biogeochemical processes and can be used to verify the effects of conservation and management strategies for kettle holes. KW - Kettle holes KW - Water quality KW - Monitoring KW - Land use KW - Isomap Y1 - 2012 U6 - https://doi.org/10.1007/s10750-011-0764-7 SN - 0018-8158 SN - 1573-5117 VL - 689 IS - 1 SP - 63 EP - 77 PB - Springer CY - Dordrecht ER -