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Thursday, 4 November 2010

October and early November Thames Road Wetland management work

TRW management activity 7th, 14th, 20th, 28th October and 4th November 2010

With my 'Site Manager' hat on, here's a round up of recent management work on the site, and the reasons for the various actions taken.

The main group activity on these dates was Greater Reedmace removal. The reasons for this were:

- to ensure the survival of other emergent plants, and to allow increases in some of them, such as Common Reed, and to prevent the water areas becoming too much of a Greater Reedmace monoculture
- to prevent encroachment onto the area occupied by the rare Brookweed
- to recover areas of shallow open water and muddy margins for (additional species of) Dragonflies and Damselflies
- to create more 'reed edge' microhabitat for foraging waterbirds
- to prevent the build up of excessive amounts of Reedmace litter in certain shallow areas, so as to slow/prevent succession to bog and then dry land, which would be more difficult to remedy later

Most of the work was concentrated on a shallow pool at the east end of the site, on the east side of the River Wansunt, which had been almost entirely taken over by Greater Reedmace.

The method used was pulling, as it was correctly surmised that this would bring up root and some of the rhizome carrying new shoots. (It works better where the water is deeper - i.e. the plants have had their feet in liquid mud all year, and less well in shallower areas where the water level has fallen below the soil surface for part of the year). It was felt that this would deliver better and longer term control than other options. Late last winter we had scythed off top growth, and horse grazing had had the same practical effect, but the Reedmace quickly caught up with untouched stands through regrowth from the base. The seed heads were breaking up at the time, so that the myriad seeds were getting in our eyes, noses and mouths. There is also a need to do this work when birds are not breeding. The RSPB's Reedbed Management handbook doesn't say anything much about Reedmace control, and Googling Reedmace control or management didn't turn up a great deal either. But searching 'Reedmace pulling' revealed the fact that a lot of other conservation groups around the country were going to be using the same technique at the same time of year, and this had increased my confidence in taking this approach.

Getting started - Cray Riverkeeper Volunteers Boss Ashe Hurst, Angelle and daughter Stephanie begin to make inroads into a 'wall' of Greater Reedmace

The cleared area gets larger

View from the sewer pipe embankment, looking towards Thames Rd. Cleared area visible left of centre. Removed Reedmace being piled up on the right.

Views from opposite directions showing the extent of the cleared area in mid November

We won't have got all the root out in this restored open water area, so there will be a need to go in again early next year to remove as much as possible of any regrowth.

Reedmace removal from around Common Reed (right centre) and Reed Sweet Grass (front right)

Reedmace removal from in and around a stand of Sedge at the north-west corner of the site

Another of my priorities was the creation of bare ground next to the current area of Brookweed, and weeding (mainly removing Creeping Buttercup and seedlings of Teasel) to favour the establishment of new plants of this species, which is very rare in London. Seed from the existing plants was scattered in this 'new' area in an initial attempt to increase the number of plants and double the 'footprint' of the colony. Brookweed appears to do best around the bases of these clumps of Rushes.

A further intiative is the digging of winding ditches (and creation of adjacent ridges from the spoil) in the flat, very open and sparsely vegetated north east corner of the site. The purpose of this is to create microhabitat heterogeneity and cover, especially for thermophilic (heat-loving) and burrowing invertebrates. It is also hoped that it will enable Common Lizards colonise more of the site. The work has been hard and slow-going because of the heavily compacted, extremely stony nature of the spoil that was dumped on this area.

If there are any readers out there who would like to get involved with hands-on management work here, please get in touch!

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