3+4/2/11: Perry St farm / Is horse grazing a problem at TRW?

3/2/11

Today I was down near Thames Road Wetland for a meeting with two fellow members of Bexley Natural Environment Focus Group to discuss our collective response to the Council's draft Biodiversity Action Plan re-write.

I checked out Perry Street farm from Gascoyne Drive on the way there. There were 5 Pied Wagtail. A minimum of 133 Starlings were in and around a Bramble thicket in the middle of a field. Most of the birds could only be seen in silhouette, and there were probably others hidden from view.

Something must have spooked the Gulls roosting on the industrial redevelopoment site on Thames Rd., down near the 'Jolly Farmers' public house, as a huge 'cloud' of something like 200 birds took to the sky.

At Thames Rd Wetland there was a male Chaffinch, male Blackbird, a Robin, 3 Mallard and a couple of Coot. 3 Blue Tits seemed to be finding something to eat amongst the Reedmace seed heads.

Very close (8-10 foot) views were had of 2 brown 'Warblers', also foraging in the reedmace. They had a light eye stripe and light grey underparts. I am advised that these would have been Chiffchaffs, a new record for the site.

Long-tailed Tit and 2 Collared Doves were along By-way 105.

On the way to the 'Bear and Ragged Staff' in Crayford for a post-meeting drink with one of my BNEFG colleagues, we spotted 2 Grey Wagtails in the town-centre Riverside Gardens.

4/2/11.

Some management work at TRW today.

I had been concerned by the impact of horse-trampling in the 'Brookweed zone', noted on the 3rd. Horses aren't supposed to be on the site, but every now and again someone puts them out there. Said person(s) even renewed the barbed-wire fence that keeps them on the east side of the Wansunt. Except that there were also fresh droppings and hoof-marks along the Thames Rd bank of the larger part of the site, to the west of the Wansunt. This section is not completely fenced and therefore horses could potentially get onto Thames Rd and cause a serious accident .........

Anyway, the fact of the matter is that the Brookweed survived grazing activity by up to 3 horses last winter before I knew it was there, so I guess in the long run this process might conceivably be beneficial. But still, this is where I regret not having made the time to count and map Brookweed rosettes last season. If I'd done so I'd be in a position to start making a proper assessment. Taking a 'better safe than sorry' approach (given that I can hand-weed the Brookweed zone to reduce competition from more thuggish plants anyway), I wove bits of cut Bramble stem through the Rushes around which the Brookweed grow. Time will tell if this will work.

There's no indication that the feeding itself does anything other than take out the tops of the Rush clumps (see picture below), and this may give the Brookweed more early season light. But the trampling pressure is clearly pretty significant - and might be the main explanation for why most Brookweed appears to grow hard up against the bases of the Rushes where there is less of an impact.

Horse-trampling and Rush grazing in the 'Brookweed zone' at TRW

I also did some more work on extending a deepening my 'dune and ditch' system east of the Wansunt, part of a process of increasing cover and micro-habitat variations to encourage invertebrates and help Common Lizards colonise more of the site. As part of this endeavour I re-arranged the piles of Reedmace pulled out last year into a 'dead hedge', piling up bits of rubble at intervals to provide Lizard basking sites. The Reedmace will rot over time, but if we keep adding to the linear 'heap', a low banking will eventually be created.

Pulled Reedmace being used to create a 'dead hedge' to provide more cover for small creatures of various sorts in the exposed eastern end of the TRW

There had been around 20 Goldfinches along By-way 105 earlier in the day, and there was a female Pochard on the Cray here.

Around 28 Teal were on the water in the farm fields south of of Thames Rd Wetland.

On the way home, there were about 43 House Sparrows in the roost hedge on Thames Rd, by the 'Imagination' building, and a further 36 or so in the tree they use on Perry Street roundabout.

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!

13/7/10: Brookweed and Little Grebe amongst new records on Thames Road Wetland

More recording either side of some Cray Riverkeepers work.

On the way down to the Cray an adult Asparagus Beetle was seen on Asparagus in Eversley Avenue, and larvae on Parkside Rd.

A clump of Tansy was noted on the 'rough' off Perry St. roundabout, in the Thames Rd/Gascoyne Drive section, a new record for me here.

22 Starlings were seen on roofs on Barnes Cray Rd.

Dace and Chubb were seen in the River Cray by Footpath 106. Amongst the marginal plants recorded were Branched Bur-reed (Sparganium erectum), Reed Sweet Grass and Reed Canary Grass in flower.

Insects about along FP106 and By-way 105 included a couple of Red Admiral, Gatekeepers, Banded Demoiselles, lots of Blue-tailed Damselflies and also a Large Red Damselfly ovipositing.

Next stop was the Thames Road Wetland (TRW). On the western section of the Sewer Embankment was a Black Knapweed, which I don't recall seeing here before (but I may be wrong - I'm way behind on spreadsheeting my records to make them quickly accessible ..... ). There were Cinnabar Moth caterpillars on Common Ragwort. A Large White Butterfly was seen further along, and 2 adult and 2 juvenile Goldfinches flew onto a shrub.

Black Knapweed and Common Ragwort on the Sewer Embankment by the TRW

The TRW is glimpsed over a clump of the uncommon plant Dittander (Lepidium latifolium), a mass of which were pouring forth their frothy white flowers along the Sewer Embankment

Looking out over the Thames Road Wetland, birds on the 'lake' (the deeper, open water at the eastern end of the flooded area west of the Wansunt) were 2 adult and a couple of juvenile Coot and a new record for me on the site of Little Grebe (Dabchick), of which there were 2 adults and 3 small young.

A couple of the mildew-feeding 22-spot Ladybird species down in the TRW 'bowl' were also a new record here.

At one point I was trying to get close to a flying Dragonfly, in order to get an ID, when it was grabbed from among the Reedmace by a House Sparrow which disappeared into the Thames Rd shrub beds with it.

From this side of the site I was able to pick out 4 Gadwall somewhat hidden on a small grassy 'island'.

Wild Mignonette (Reseda lutea) was in flower on the flat, dry, ground up next to the Thames Rd fence.

Next I checked out that part of the site to the east of the River Wansunt. There were a few Purple Loosestrife in flower here, some Gypsywort and 8 Celery-leaved Crowfoot (Ranunculus sceleratus) in flower in the damp margins of the drying pool.

Dittander is now down in the bowl proper, on a corner of the easternmost pool, next to Branched Bur-reed which only seems to be at this end of the site so far, and is a new record for the 'bowl'.

Branched Bur-reed in flower on the TRW

A further new record for the site was a single Greek Dock which, oddly, was growing in the water.

A Goat's-Rue was also found down in the bowl.


The pool on the eastern fringe of the flooded area, east of the Wansunt, is shallow, its winter extent shown by the thin Rushes in the picture above

In the drying, but still quite damp mud here (with water pooling in old horse hoof-prints), yet another new site record was obtained in the shape of 15 flowering plants of Brookweed (Samolus valerandi). This is a member of the Primula family and has small, white flowers, with notched petals. This is the first time I've come across this species anywhere. It is reported to now have a rather restricted distribution in the UK, so this is a good find.

Brookweed (Samolus valerandi) on the TRW - a species completely new to me