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Key findings to date

A selection of the key findings of the Turf2Surf project are listed below.

Soil-vegetation-atmosphere

  • Annual net primary productivity (ANPP) in the Conwy sits below the mean UK levels on average. Rates within habitats are comparable
  • Annual net primary productivity:
    • Is predictable from simple soil metrics (NO3, pH and Total-P) on one unified gradient irrespective of soil, habitat or climate
    • Foliar nutrient ratios are not good indicators of nutrient limitation as plants are well adapted to their environments
    • Photosynthesis rates are not good indicators of overall ANPP due to other traits and ecological processes which down-regulate i.e. production is sink not source controlled.
    • A new soil-P method is better able to identify plant-available-P than total-P
  • Carbon turnover in soil
    • C turnover in soils is C limited as soil available C:N:P is always below microbial C:N:P of 70:7:1
    • In arable systems available C:N ratios < 5 leads to phosphorus limitation of C turnover
    • C turnover in deep soils is highly responsive to change in C,N and P availability
  • Wetlands are completely consistent with other soils in their behaviour across the C:N:P gradient. Anoxia does not change the relationship.

Riparian and river network

  • Clear differences in C/N/P ratios between landscapes, largely along an established ecological gradient and reflect land cover and geology
  • Complex picture of nutrient losses spatially and temporally through events: dilution, mobilisation, seasonal and flow influences can all be detected
  • Definition of riparian zone depends on issue to be considered

Instream processes

Uplands:

  • Aquatic DOM production, related to N and P
  • Aquatic DOM decomposition/respiration, related to C lability
  • DOM concentration same down system, but transformation occurs
  • P begins to limit algal growth only at 11 ug P/l, CNP additions stimulate algal growth

Lowlands:

  • N and P – sources and hydrological processes dominate dynamics
  • Fine scale dynamics important for abiotic-biotic interactions (e.g. Si and P limits during bloom development)
  • For flux estimation to sea, reach-scale losses important, but not subtle abiotic-biotic coupling not needed

River Estuarine Transition Zone

  • Estuarine turbidity maximum (ETM) created by landward advection of SPM resuspended from intertidal flats.
  • In upper estuary, flood tide velocities > ebb tide velocities (common in meso/macrotidal estuaries) but due to density stratification on the flood tide, flood turbulence < ebb turbulence (new). Suppression of turbulence limits resuspension of SPM by the flood tide – decreases landward transport of SPM especially of larger flocs (new).
  • Aggregation and sedimentation of flocs in ETM at HW in the tidally influenced river.
  • Large flocs resuspended on ebb tide,  ETM re-created and advected seawards.
  • Results in floc size fractionation – large flocs move seawards into main estuary, small flocs move landwards into tidally influenced river (new).
  • Particulate nutrient and pathogen concentration peaks map on to SPM concentration peaks (new).
  • RETZ and estuarine solutes driven by river, whilst RETZ and estuarine particulates driven by sea.

Integrated assessment and modelling

  • aNPP is key explanatory variable of plant biodiversity
  • River flow is very important in terms of nutrient distribution in estuaries;
  • Wetter winters will flush nutrients to the sea, drier summers will increase trapping;
  • Sources dominate instream N and P dynamics, ratios and concentrations except in clean, upland systems (where N, P prime DOM production);
  • Lowlands - instream processing is a secondary effect on N and P dynamics, though reach scale losses important for accurate flux determination, and N and P prime DOM production

Data from the Conwy

Did you know that river level data for six site on the Conwy catchment will become available in early 2017?

It will accessible via the Centre for Ecology and Hydrology's Environmental Information Platform.

Turf2Surf on the EIP

Published work

A significant number of papers have been published as a result of Turf2Surf research, and they continue to be published. A recent example is available here -

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