The objective is to: establish the key processes operating in river marginal wetland ecosystems and their linkage to functioning; assess resilience to, and the effects of, ecosystem perturbation by anthropogenic activities including altered hydrological regime, sedimentation and fertiliser application; and link dynamic models and evaluations of the effects of anthropogenic disturbance into an overall system of functional analysis.
4 study areas have been selected: Shannon floodplain (Ireland); Torridge headwaters (UK); Bec d'Allier (confluence of Loire and Allier, France); and Giguela-Zancara headwaters of the Guadiana River (Spain)
The rationale of study area selection is that they encompass a distinct climatic and environmental gradient from the hyperoceanic conditions of west Ireland through the euoceanicity of southwest England and the continental regime of the Bec d'Allier and Loire to the highly seasonal, semiarid regime of Spain. In addition, they provide both natural (or relatively undisturbed) conditions as well as sites disturbed by a range of anthropogenic activities varying in type and intensity (as indicated).
The main impacts to be considered are: sedimentation and hydrology; nutrient enrichment and drainage; flow regulation; and groundwater extraction.
The project is organized into a range of subprojects which comprise component parts of 2 major thematic areas, each representing important groups of functions. First, ion and macroelement and hydrological dynamics in the ecosystem involving: soil processes; vegetation interactions; hydrological dynamics; and semiarid process dynamics. Second, habitat support, succession and recovery involving: vegetation analysis; habitat; invertebrate indicators; survival strategy; and controlling factors. A third thematic area is concerned with dynamic modelling.
Sites will be selected from the study areas which represent natural undisturbed conditions and a range of anthropogenic impacts which will include regulated river discharge, reduced water table and groundwater, elevated nitrogen and phosphorous loadings, heavy metal contamination and sedimentation. In the case of each perturbation there will be at least one paired control unimpacted or undisturbed site. Key sites will be targetted for detailed field investigation.
For determining the state factors driving the ecosystem the following investigations are foreseen. Hydrological and hydrogeological controls will be examined using geology, shallow drilling and geophysics to determine aquifer geometry. Surface flows and groundwater head distribution and variations will be investigated over time and with depth. Hydrochemical sampling will concentrate on nitrogen and phosphorous species and complement investigations of seasonal dynamics and ecosystem routing of nitrogen, phosphorous and carbon partitioned into plant, soil and water compartments.
Field determinations of depth, spatial and temporal patterns in redox will be used to parametize simulations of ecosystem conditions in laboratory microcosms and investigate the role of wetlands as sources, sinks or transformers of these environmentally important nutrients. Computer controlled microcosms will be used to mimic the effects of anthropogenic impacts by adjustment of redox, pH and nitrogen and phosphorous loadings. Other systems will simulate flooding cycles. Field mesocosms will be established to investigate plant interactions with nitrogen and phosphorous.
Mathematical modelling of the sites initially will use layered groundwater flow models and ion dynamic (solute transport) models adjusted where appropriate for surface water effects. Chloride modelling will be used for initial calibration ahead of nitrogen and phosphorous modelling. Enhanced solute transport and reaction models will be developed by extension into finite element modelling of integral flow systems. Abiotic flow systems will be combined with models of nitrogen and phosphorous plant soil water interactions and with those developed for energy flow and succession. Geophysical, land use and remote sensing data will be used to enlarge model scale. The resulting models assembled at different scales will be used as direct input into development of the predictive functional analysis procedure to develop not only process scale predictors but also the catchment and river basin predictors and wider control variables.
Carbon flux will be studied through primary production and controlling factors examined by linkage with hydrological, hydrochemical and soil nutrient interactions. Biomass production will be related to climatic and other environmental gradients among sites and the effects of nutrient stress and management studies. The structural characteristics of plant communities will be determined by means of standard phytosociological methods. Multivariate analysis will examine environmental relationships and the effects of ecosystem stress. Remote sensing techniques will be used to map communities and habitats over more extensive scales. Specific attention will be devoted to emergent vegetation species and their response to particular anthropogenic impacts.
The work will concentrate on the analysis of survival strategy as a means of predicting ecosystem functioning, identifying stress and measuring thresholds to change. Predictors of stress will be investigated also by reference to invertebrates, particularly chironomids and molluscs. Environmental and man induced effects on both vegetation and invertebrate indicators will be assessed against normal succession and recovery patterns. The factors which are responsible for determining overall habitat potential for selected animal species will be examined with particular reference to those covered by Annex I of the Birds Directive and provision of the Bern, Bonn and Ramsar Conventions.
Intensive field compaigns will complement regular sampling programmes.
Funding SchemeCSC - Cost-sharing contracts
3584 CS Utrecht
B15 2TT Birmingham
G12 8QQ Glasgow
1081 HV Amsterdam