Core 2: Environmental processes and ecosystem dynamics

Core Chair: Prof. A.J. Hendriks

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Mission and Aims

Human welfare ultimately depends in many ways on ecosystem functioning. Most ecosystems on earth are under the influence of physical and chemical stressors, and face a steady change of concentrations and effects of a whole suite of polluting substances. All ecosystems are exposed to considerable climate change, now and in the near future. The mission of Core 2 is to contribute significantly to the analysis of environmental change and ecosystem dynamics, and to contribute to possible solutions for connected environmental problems. The research is aiming at improvement of our understanding of the main forces that drive the dynamics of human societies, biological communities and the environment as one interactive complex system. Core programme 2 focuses on the interaction of ecosystems and their components with chemical and physical stressors on the one hand, and global climate change on the other. Considering the level of integration in this Core, most research projects focus on specific local and regional problems.

The scientific position of Core programme 2 is in between Core 1 and Core 3. The small-scale behaviour, effects and fate of micro-pollutants is the domain of Core 1. Ecotoxicology in Core 1 is mainly concerned with small-scale aspects of ecosystems (single organisms; environmental chemistry; microbiology). Core 2 is dedicated to processes and effects on a larger scale, both geographically (e.g. region; forest area; watershed) as well as ecologically (e.g. populations, communities; ecosystems; landscapes). In Core programme 3 an even larger scale is pursued, concerning global change in general, continental and global hydrological cycles, large scale greenhouse gas fluxes and global biogeochemical cycles.

Research priorities

In the SENSE Research Programme 2002 –2006 a list of Research Priorities of Core 2 has been included. In this Midterm review we present an updated description of the Core programme, which can also be tracked in the main results presented. The research activities of the Core 2 research programme are centred around three main themes. (In the re-accreditation report only two foci are mentioned, but since that time the SENSE Research School has widened its membership)

Fate of substances and their role in ecosystem functioning
Structure and functioning of populations, communities and ecosystems
A-biotic and biotic regulation of ecosystems

Focus 1: Fate of substances and their role in ecosystem functioning

The study of fundamental and applied aspects of the a-biotic environment, is mainly concentrated at WU-WIMEK, with a strong accent on soil (physics; formation; quality)and water (hydrology, groundwater, quantitative water management) (see also Core programme 1). The role of substances in ecosystem functioning is important. How do ecophysiological signals, ecosystem processes, land use and soil and water management strategies affect emissions and fate of physical, chemical and biological ‘stressors’ on regional scales? Heavy metal speciation and the role of metals and organic micro-pollutants in food webs still get attention. Eutrophication and acidification, unsolved environmental problems, are tackled now in a biogeochemical context. The tendency in ecotoxicology from the ‘single stressor’ approach to the ‘multiple stressors’ approach is obvious. Fundamental aspects of the fate of substances in soil, water and air are still important items, but in their effects on (parts of) ecosystems more and more the ‘combitox’ or ‘multiple stressors’ approach is followed. The interaction between toxic substances with physical, chemical and biological factors has become more and more important.

Focus 2: Structure and functioning of population, communities and ecosystems

Fundamental questions in ecophysiology, autecology, population dynamics and community ecology are addressed, frequently in relation to factors determining the resilience and biodiversity of communities and ecosystems under pollution, disturbance and global change. Examples are: Exploring how community dynamics may be understood from properties of individual organisms using individual based approaches such as energy budget models; exploring the interactive effects of nutrients and micropollutants on individual organisms as well as on (artificial) ecosystems (see Focus 1); modelling the dynamics of simple as well as complex communities of plankton, aquatic invertebrates and soil communities; unravelling the biotic interactions between key organisms, such as green algae, macrophytes, and the other aquatic organisms –mainly consumers- on biochemical, physiological and autecological level. In general, biodiversity issues and biogeochemical issues often decide on the type of question to be tackled. The theory of ‘catastrophic shifts in ecosystems’ (Scheffer et al. 2001) is increasingly sustained by data from the field. This bears interesting challenges for empirical testing.

Focus 3: A-biotic and biotic regulation of ecosystems

Which are the main mechanisms regulating resilience and biodiversity of ecosystems, and how is the functioning of organisms and communities affected by changes in water management, climate and the concentrations of nutrients, micro-pollutants and other stressors? Basic hydrological modelling work on watersheds remains necessary to tackle this complex question. The next upgrade is sound knowledge of biogeochemical processes; models are constructed on local, regional and larger (Core 3) scale. The next step is to define rehabilitation and restoration strategies for deteriorated ecosystems (e.g. river basins and their estuaries). A number of cross-cutting (from the individual organism, to the ecosystem, and larger units) methodologies are in full use now, and the researchers of Core 2 are substantially contributing, both to the fundamental aspects as well as to the applied aspects of this domain: Geographic Information Systems (GIS) and Remote Sensing (RS), tools which have opened possibilities for extrapolation. Environmental managers are often facing economic problems (lack of money) to bring science into practice. The development of risk assessment and uncertainty analysis opens the possibility to put the priorities where they should be. Crosscutting in a geographic context (from Core 2 up to Core 4) is the attempt to bridge the gap between the science of landscape ecology and spatial planning, which is customer focused, and design-oriented.

The disciplines involved in Core 2 can tentatively be clustered in three groups. Many of the participating groups are strong in modelling, which is generally combined with empirical work in laboratory as well as field situations. The first strong group is focused on the fundamental and applied aspects of the a-biotic environment, of soil, water and air: soil physics (Feddes, WU), soil formation (Van Breemen, WU), soil quality (Van Riemsdijk, WU) (agro)hydrology (Feddes, WU; Troch, WU). The second cluster covers the entire range of ecology, both theoretically as well as empirically, from microbiology (Huisman, UvA; De Vos, WU), to ecophysiology (Roelofs, KUN; Admiraal, UvA), autecology (Verhoef, VU; Berendse, WU), population dynamics (Huisman, UvA), community ecology (Van Straalen, VU; Scheffer, WU), ecosystem dynamics (Kooiman, VU; Scheffer, WU; Berendse, WU; Nienhuis, KUN; Roelofs, KUN), ecotoxicology (Van Straalen, VU; Admiraal, UvA), terrestrial (Berendse, WU) and aquatic ecology (Scheffer, WU; Roelofs, KUN; Nienhuis, KUN). This implies that the full scale of the biodiversity concept is covered in Core programme 2. A third cluster is concerned with applied aspects of environmental sciences, viz. hydro-ecology (De Ruiter, UU), the management of water quality (Scheffer, WU) and water quantity (Troch, WU), geo-environmental science (Dolman, VU), nature conservation (Berendse, WU), environmental biology (Roelofs, KUN), ecological restoration (Nienhuis, KUN) and Environmental Systems Analysis (Leemans, WU). Many integrative studies give witness to the power of this cooperation in SENSE.

Relations with other core programmes

Core 2 is strongly related to Core 3 which builds largely on the same disciplines. Core 3 focuses on global change issues, however, and Core 2 on processes and effects at regional and ecosystem level. In practice, water quality issues are concentrated in Core 2 whereas water quantity issues such as large scale hydrological cycles are mainly concentrated in Core 3. Likewise, large scale greenhouse gas fluxes are studied in Core 3 whereas effects of global change on ecosystems are studied in Core 2. Obviously, strong links between the Cores exist as many research groups participate in both Cores. Other strong links exist with Core 1, as in Core 2 fates and effects of micro-pollutants and nutrients are often considered simultaneously in contemporary environmental studies, while in Core 1 effects on single organisms are studied and various techniques are developed. Both with respect to Core 1 and Core 3, the intense existing network of researchers warrants an easy co-ordination of research in both cores. Fragmentation of ecosystems, habitat loss and landscape management are key items in ecological restoration and spatial planning, and a cross-cutting linkage between Cores 2, 3 and 4 is the initiative of Opdam to bridge the gap in theory and applicability between the science of landscape ecology and customer focussed spatial planning (Opdam et al. 2002).