Aquatic systems and landscape ontogeny – temporal and spatial perspectives

Aim: to illustrate the extent to which the functioning of contemporary aquatic ecosystems reflects a variety of processes, including their landscape position, and the extent to which these processes and interactions have changed over varying timescales as a result of natural and anthropogenic forcing.

Responsible: John Anderson

Form and duration of course: residential, intensive (4-5 days)

Location: to be decided

Date: December 2002

The structure and functioning of aquatic ecosystems reflects a number of different factors – internal - autogenic - processes, direct climate (meteorological) forcing and (indirect) responses of surface water chemistry to soil and vegetation processes (i.e. their location in landscape). The extent to which allogenic or autogenic processes are predominant in controlling community structure depends on a variety of factors, but the degree to which their importance has changed can only be addressed by considering a variety data types (both contemporary and palaeoecological).

Anthropogenic processes today affect the great majority of the world’s biomes. However, the timescale, rate and extent of our alteration of ecosystem processes and landscapes varies in both space and time. While much of North America and NW Europe are instantly recognisable as cultural landscapes, change in these two areas occurred over different timescales (~200 versus 5000 years): what are the implications of these different rates of change for biogeochemical processes and community change? Rapid change is now occurring in the Tropics but palaeoecological data indicate that in some areas, anthropogenic alteration requires us to reconsider our use of word "pristine" in relation to these problems.

Land management changes (deforestation and agricultural development) have had fundamental effects on catchment hydrology and biogeochemical cycles and hence nutrient transfer from land to water. Importantly, given the limited timescale of contemporary process studies, it can be difficult to clearly separate natural from anthropogenic-dominated processes. However, palaeoecological records can be used both to extend the temporal perspective of these natural and anthropogenic processes and their interaction, as well as to clarify the extent to which inherent natural variability of systems has been altered as a result of disturbance.

This residential course will focus on both contemporary linkages between catchments and aquatic systems (here defined as streams, lakes, estuaries and coastal embayments) and as well our attempts to quantify ecological change at a variety of timescales. Our attempts to quantify past and present fluxes of material (nutrients, minerogenic matter) at the catchment scale and the affect of these changes on e.g., internal nutrient cycling, anoxia and aquatic biota will be illustrated.

The course will address questions fundamental to our understanding of aquatic ecosystem functioning, such as the role of climatic variability, their position in landscape and their interaction/response to terrestrial changes during the Holocene. Emphasis will be placed on contemporary issues and process studies as well as conceptual issues surrounding the use, interpretation and technical aspects of using palaeoecological records as a tool for studying past and present ecological change.

The course will address questions such as:

• To what extent is the anthropogenic alteration of biogeochemical cycles a function of landscape location compared to the intensity and type of disturbance?

• How do contemporary rates of material transfer from terrestrial to aquatic ecosystems compare with historical estimates derived form the sediment record? Are there fundamental technical aspects that limit cross-system/methodological comparisons?

• How does the response of communities vary in relation to rapid (pulse) and chronic, long-term (press) disturbance?

• To what extent do changes in aquatic systems lag those in terrestrial catchment processes?

• To what extent has ecosystem variability been altered by anthropogenic disturbance?

• How can we use palaeoecological records to address questions concerning rates of material transfer at catchment and regional scales?

• How similar are the long-term changes observed in lakes to those that occurred in coastal water?

• What are the technical limits to reconstructing past community change in terrestrial and aquatic systems?

New PhD students will also be encouraged to present a brief synopsis of their projects, while those who are further into their course of study will be asked to make a brief presentation of their results to date. It is envisaged that these presentations will be followed by group discussions.

Technical details

Course convenor: N. John Anderson (Department of Geography, University of Copenhagen)

Invited lecturers (to date):

Bent Odgaard (GEUS)

Daniel R. Engstrom (Science Museum, University of Minnesota)

John A. Dearing (Dept of Geography, University of Liverpool)

Daniel J. Conley (DMU)

And more to come/follow