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Saturday, June 15, 2024
The Parrett Catchment Project

Arable Reversion to Woodland

Component 12: Woodland development




This project is designed to demonstrate the reversion of land in the mid and upper catchment, currently within an intensive grassland or arable crop regime, to woodland, thus stabilising soils and enabling the build up of organic matter. This will increase soil water retention capacity and the presence of wet woodland alongside streams and rivers could also bring benefits to flood management in this part of the Parrett catchment.


At present, the available grant schemes do not match woodland implementation costs and the farmer is expected to meet the difference, in some cases this can be a substantial sum. Where these investments are for flood defence purposes and largely for the public good, landowners may be reluctant to make this contribution and then the take up may be small.




  • To demonstrate that water management and (providing there are no biodiversity constraints), environmental benefits are likely in many situations, together with possible landscape enhancement.

  • To evaluate implementation costs.

  • To measure the effectiveness of woodland in water management.


The initial proposal for this project was produced by FWAG (with support from the RSPB) and can be found on our publications page.



Research and Review of Mapping Exercises

The research report "Opportunity mapping for trees and floods" commissioned by the PCP Woodland Development Group in October 2003, identified areas where woodland establishment would have the greatest potential to reduce flooding and associated problems. The report can be downloaded on our publications page.


Three types of woodland that will help contribute to flood management were identified in the report:


  1. Riparian planting on the upper catchment

  2. Wider catchment planting, in particular in areas of high risk soils

  3. Floodplain woodland


The Woodland Group identified 1 and 2 as the most suitable options for the pilot sites. More information is outlined below.



Riparian Woodland


Purpose of planting:


  • Delaying runoff into tributaries

  • Reducing soil compaction in riparian areas by reducing area arable/intensive farming adjacent to watercourses

  • Increasing water penetration in the riparian strip

  • Wood debris in tributaries to reduce flows

  • Reduction in diffuse pollution


83% of the riparian zone is available for woodland.



Wider Catchment Woodland


Purpose of planting:


  • Reduce/delay surface run of – create more of a ‘sponge’ effect

  • Reduce soil compaction by reducing area of arable/intensive farming in catchment

  • Reduce impact of rainfall by catching precipitation in woodland canopy

  • Improve soil structure – increase rainfall penetration into soil surface

  • Increase water take up by trees (more effective in summer for deciduous trees)


54% of the wider catchment is available for woodland establishment



Floodplain Woodland

It was agreed that this was not an option for the Parrett catchment at present, for the following reasons:


  • In view of the large proportion of the lower floodplain, which has a conservation/ archaeological interest, it would be difficult to identify sites where the full width of the floodplain could be used for woodland planting

  • The need to breach existing flood banks to allow water through the floodplain is not considered a realistic option in the Somerset Levels

  • Reducing the runoff on the middle and upper reaches is felt to be a more helpful role in the

  • Parrett catchment, as by the time floodwater reaches the lower catchment, the damage is done

  • Only 13% of the floodplain would be available for woodland establishment given the conservation constraints



Case Study: Lower Severalls Farm, Crewkerne


A project coordinated by Somerset FWAG has been started at Lower Severalls Farm, Haselbury Plucknett with the co-operation of landowner Robert Pring. 1.2ha of new native, broadleaved woodland was planted during 2003/4 in a former arable field on the floodplain of the River Parrett. The woodland is being used to 'square off' meanders and is an example of a riparian woodland that can 'slow down' floodplain flow in the upper catchment. The trees were planted with approval from the Forestry Commission under the Woodland Grant Scheme and Farm Woodland Premium Scheme.







This sub project is to complement other sub projects within the Farming Water programme. The Farming Water projects are new initiatives looking to bring about changes to water management. In order to demonstrate that Farming Water does bring about change it is necessary to monitor and measure their effectiveness.




To monitor the impacts of the Farming Water Woodland Development, Arable Reversion to Grassland and Soil Management Initiatives.


There are three monitoring projects currently running:


  • Lysimeter Plots (through the Farming and Wildlife Advisory Group)

  • Turbidity Project (through the Environment Agency)

  • Compaction Study (through the Environment Agency)



Lysimeter Plots (A FWAG Demonstration Project)


Through JAF, a project has been set up that demonstrates different post harvest management of soils that have a high risk of run-off and erosion following the harvest of maize and potatoes.


The demonstration site is located on the Dillington Estate, near Ilminster, Somerset and is managed by Dr Robert Clements from the Institute of Grassland and Environment Research (IGER). The demonstration plots were set up in Summer 2003 and will be kept in place until March 2006.


Click here for more details and results of trials.



Turbidity Project (An Environment Agency led project)


The overall objective of this project is to provide a cost effective long term measure of the diffuse pollutants, suspended solids and total phosphates in a sample stretch of water, based on their correlation with turbidity. This will also provide:


  • A monitoring tool for the success of FWAG projects and other diffuse pollution prevention work

  • Estimates of the quantity of these determinants from diffuse sources to be made for use in nutrient budgets

  • Knowledge of the contribution of the total phosphate load from diffuse sources to these rivers will facilitate implementation of the Habitats Directive in the Somerset Levels and Moors SAC.


There is currently a turbidity probe installed in the River Tone near Taunton. Sample results are continuously being collected and stored on a central database. Depending on the success of the monitoring in the River Tone, it is hoped that a probe will be installed in the River Parrett in the near future.



Component 4: Creating new wetland habitats


The PCP has continued to lobby DEFRA through the Agri-Environment Review, and the Environment Agency and Flood Defence Committee have bid for £1M for habitat creation funds to assist with a land purchase or land swap.