Boundary House Fen, Frilford, Saturday May 13th 2023

By Margaret - June 02, 2023

This weeks' blog was written by Sally

On Saturday, 12 Green Gymmers returned to Boundary House Fen on Frilford Heath Golf Course SSSI, which was looking very lush after the recent rainfall and the reeds and sedge were knee-high, where we met up with Rod d'Ayala, who explained the tasks for the day.

Rod explained that the first priority was to cut the reed and sedge growing on the golf course side of the leat nearest Boundary House and rake as much of this as possible. All six scythers (Margaret, Roger, Barbara, JimB, Rosie and Sally) were deployed and "leap-frogged" each other along the leat as they made rapid progress. Rod had been there the day before and already made a head start for the principal rakers, Dieuwke and Lesley, so that they had something to get on with whilst the scythers got going by following the leat that Rod had created and scything one or two widths on the near side. Rod would then be able to see better how the leat was performing. The spring which feeds the fen drains into a man made stream, which has been acting like a ditch in draining the fen. In recent years, the Green Gymmers over a number of visits have been gradually filling in the ditch with cut reed, in order to re-wet the fen and create the favourable conditions for the fen specialist plants that thrive in them. Boundary House Fen is even more special, as it is a calcareous or alkaline fen - one of a number in Oxfordshire, but is a very rare habitat - which means there is a chalk layer in the substrate through which the spring water percolates, rendering the soil slightly less acidic than normal peat fens. The plants that thrive here tend to prefer less nutrients in their diet, which is why we need to rake off any cut material to avoid it rotting down and making the soil more fertile.

The other tasks were to dig up hemlock, which is a poisonous plant famed in "Macbeth" and is a member of the carrot family. It is similar to its relative, cow parsley, but Rod explained that its main distinguishing feature is the purple-red stems and blotches on stems. We had been asked to root out this plant, which is a perennial and spreads very quickly, and we wished to avoid it taking over and encroaching onto the Fen itself. Gloves were donned to protect hands and four brave souls, James, Ursula, Helen and Joan got to work uprooting all that they could find along the hedgerow.

We were much relieved when the cry of "Break Time" clamoured and we enjoyed some tasty treats over a welcome drink. After break, the hemlock pullers then switched task to remove the non-native invasive Himalayan Balsam, which may have pretty flowers but it is causing a lot of damage by crowding out our native plants and weakening river banks. Judy Webb also joined us and said that the marsh valerian was in flower and looking very pretty! She also had a special task for JimB, our most experienced scyther, and set him to work. Unfortunately, Jim ended up being our canary for the day as he took a step too far and water went in over the top of his wellie boot! The only saving grace was that it happened just before we were about to finish our session, so he was able to dry off soon afterwards.

As the Himalayan Balsam got pulled, the scythers and rakers went back to action and added to the heaps. We soon reached the end of the leat and were then tasked by Rod to concentrate our efforts on removing as much of the sedge area as possible.

We left feeling very pleased that we had achieved a lot in such a short space of time and are looking forward to returning to the site in a few weeks' time where we will continue where we left off and hopefully see some of the lovely fen plants in flower.