9/11/10: Thames Road Wetland report to Bexley Natural Environment Focus Group

Note: Bexley Natural Environment Focus Group is an interface between Bexley London Borough Council and representatives of conservation organisations operating in the Borough. It is attended by various Councillors and Council Officers. The Group has not previously had a report on Thames Road Wetland (TRW) hence the amount of background detail in this particular report, which I am posting here as it may be of interest to a wider audience. In any event the site is in the hands of the Council, so in the interests of public accountability, here we are .....

But first, some 'Then and now' photos that were not part of the original report:

TRW February 2008. Photograph by, and reproduced with kind permission of, Steve Thoroughgood

TRW September 2008. Photograph by, and reproduced with kind permission of, Steve Thoroughgood

TRW October 2010. View closely matching that of September 2008.


THAMES ROAD WETLAND (TRW) REPORT
to Bexley Natural Environment Focus Group

From: Chris Rose, Site Manager. 9/11/10.

SITE

Owned by Bexley Council. Managed under the auspices of (Thames21) Cray Riverkeeper Volunteers led by Ashe Hurst. I accepted the offer of the role of Site Manager in April 2010.

The site is in Crayford on the London/Kent border, by the lower reaches of the River Cray and was created in part mitigation for the Maiden Lane Roneo-Vickers development. It is an old field bounded by the River Cray to the west, Thames Rd to the north, the Dartford to Slade Green railway line to the east and an embankment with the North West Kent Sewerage pipes in it to the south. It was dug out to below the water table, so stays permanently flooded. The eastern end is transected by the canalised River Wansunt.

I have received no prior records from the developer/contractor ecologists as to species already present, water plants introduced, or what may have been trans-located here. Despite official requests, all I have been given is an outline plan showing ground-works and giving a list of the shrub species planted, so I have had to start from scratch. Steve Thoroughgood has kindly agreed to let me use, in presentations and reports, his pictures of the site from February and September 2008, relatively soon after the site was flooded and planted up, that I came across on Google Earth. The most recent GE imagery itself pre-dates the flooding.

SPECIES

The shrub plantings on parts of the Thames Road bank are largely of species not indigenous to the local area such as Guelder Rose and Wayfaring Tree, or are non-native in the case of Sambucus (tentatively) racemosa (which were supposed to be nigra). These have suffered badly from the drought earlier in the year, being on steeply-sloping gravelly ground.

There are a variety of aquatic plants, becoming dominated by Greater Reedmace, with some small patches of Phragmites australis reed bed (Bexley BAP). Ruderal plants of note are Slender Thistle, Annual Nettle and the recent non-native colonist Narrow-leaved Ragwort.

Other species here that are not especially frequent in this part of the Borough are Common Stork’s-bill, Vervain and White Melilot. The very infrequent plant Dittander occurs in large quantity on the Sewer Embankment and is spreading in the ‘bowl’. Star of Bethlehem was found this spring, but I have yet to determine whether it is the native sub-species (probably a garden escape from spoil). Brookweed (Samolus verlerandi) which I discovered in July is an important record as this may now be its only site in London.

Invertebrates will require specialist recording effort. Hairy Dragonfly, Migrant Hawker, large numbers of Blue-tailed and lesser numbers of Azure Blue Damselfly. Recent additions to the list include Roesel’s Bush Cricket, Long-winged Conehead and Wasp Spider.

Common Lizard – UK and London BAP, Grass Snake - UK and London BAP, Marsh Frogs and Common Newts are present.

Breeding birds – Moorhen (probably), Coot, Little Grebe, Reed Warbler (estimated 6-8 pairs)
Visitors – Grey Heron, Little Egret, various ducks including, most recently, a pair of Teal. Used by Black-headed Gulls from the Council Depot site in winter. Good numbers of Goldfinch are conspicuous at this time of year.

Two Water Vole (UK, London and Bexley BAP species) latrines recently found. Some Rabbit activity, but impact on vegetation small.


MANAGEMENT AND GETTING INVOLVED

This spring contractors belatedly installed hibernacula on the Thames Rd bank without prior consultation with myself or Ashe Hurst, using good quality, cleaned, second-hand bricks (rubble from Maiden Lane might have been a ‘greener’ option). Some Star of Bethlehem will have been destroyed as a result, though they were warned it was there. Previous habitat work was disrupted and had to be restored. This south-facing bank has the most extreme temperature variations, so it is questionable whether hibernacula should have been sited here anyway.

Recent work has involved Reedmace-pulling to create and restore open shallow water. The aim is to retain overall vegetation diversity, increase the amount of Common Reed, submergents and non-reedy emergents such as Starwort and Water Mint, and to increase the variety of Odonata.

Careful ‘weeding’ has been done around the Brookweed to remove Teasel seedlings and some Creeping Buttercup. An adjacent area has had the soil level re-profiled, most of the Buttercup removed and bare ground created. Seed has been harvested from existing plants and scattered in this new area, particularly around the clumps of Rush that Brookweed appears to like growing at the foot of, in a bid to increase the number of plants and size of the area colonised. Further such work will be conducted when other operations in this area have been completed.

On the flat, compacted, gravelly north-east corner of the site, sinuous ditches and ‘dunes’ are being created to provide micro-habitat heterogeneityfor thermophilic and burrowing invertebrates.

To increase the Common Lizard population and enable it to colonise more of the site, corridors of appropriate cover will be created where little exists, and some areas of rank vegetation are being opened up. Cut vegetation has been heaped to create Grass Snake egg-laying sites.

Litter is a continuous, but fairly modest problem. There has been some unauthorised horse grazing, but this may actually help diversify the vegetation on some parts of the site. It is not clear if or how this process might be safely and legitimately facilitated and managed in future.

My intention is to involve members of specialist societies in order to properly record more difficult species groups, and to input management advice. They may also be a source of further volunteer labour. T21 has, however, recently handed down a significant increase in Health and Safety paperwork, which could constrain options. A formal site management plan is in preparation.

Any readers of this report who have interesting records from this site, who would like a guided tour or who would like to help with the management work are invited to contact me.

Occasional reports and photographs regarding the TRW site can be found here:
http://capitalnaturebexley.blogspot.com/
http://www.flickr.com/photos/45169058@N03/

MY DETAILS: Chris Rose ...... chrisrose@gn.apc.org

Brought up locally. First class honours degree and an MSc in zoological science, Bristol University. Self-taught field botanist. Also have many years of experience of horticulture and cultivated plants. Recommenced recording all kinds of wildlife – particularly in the north and east of the Borough – in 2004, after a twenty year break.

Member of London Natural History Society, the South London Botanical Institute, Kent Botanical Recording Group and the Kent Reptile and Amphibian Group. In October 2010 helped set up a formal London Amphibian and Reptile Group and became both Reptile Officer and South East London Officer (covering the Boroughs of Bexley, Bromley, Croydon, Greenwich, Lambeth, Lewisham and Southwark). Joined the Bexley Natural Environment Focus Group in September 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!

9/10/10: Erith miscellany includes Southern Green Shieldbug and Jasmine

Continuing my roundabout route home from Crossness, I took in a number of streets in Erith, London Borough of Bexley, that I had not botanised before.

The Sandcliff Road flora included Pellitory-of-the-wall, Green Alkanet, Annual Mercury, Herb Robert, Yarrow, Nipplewort and a single Wild Carrot, the last of these on a bank behind old factories.

Common Cat's-ear and White Clover were in a grass verge on Wheatstone Rd.

My first ever Southern Green Shieldbug (Nezara viridula) - possibly a 4th instar nymph according to LNHS expert Tristan Bantock - was found on Urtica dioica by the fence of a rough grassy area next to disused factories off Sandcliff Rd, by Footpath 18. TQ 50631 78353. A recent arrival in the UK, this species is native to Africa, but has been frequently brought in with food imports. Reportedly widespread in southern Europe, it has been recorded annually in southern Britain since 2003.

Southern Green Shieldbug (Nezara viridula) - possibly a 4th instar nymph - was found on Urtica dioica. This is a one-handed, significantly-enlarged mobile phone camera picture taken in poor light, hence the slight lack of sharpness

In an alleyway between Friday Rd and Alford Rd. were several small Sun Spurge and also escaped Strawberry.

This demolition site on Fraser Rd has been vacant for a couple of years, but used to have a lot more vegetation. It looks like it has been part 'sanitised' by bulldozer simply for the sake of applying a warped notion of tidiness to everything and anything. Can't it be left to the wildlife until proper work begins?

Seed heads of Wild Carrot seen through chain link fence and green plastic mesh present an ethereal, slightly artistic picture of the site margin


Another bit of 'greenspace' destined for the chop - once the economy 'improves', one suspects - is the former Erith Tramways Depot site by Walnut Tree Rd. It ought to be possible to leave a goodly belt of trees round the perimeter, and I hope that's what will happen .......

White Melilot, recorded here last year, was still present on the Tramways Depot site, and Narrow-leaved Ragwort has also found its way to this patch of ground.

I was rather taken aback to see a Red Admiral flutter overhead on the adjoining Cricketers' Close at 17.18, in what were not sunny conditions.

On the railway cutting sides just south of Erith Station and the Bexley Road overbridge a Greater Celandine was noted, also an Asparagus plant. There were a number of Ash trees, and a circa ten feet tall Turkey Oak (Quercus cerris) carrying acorns.

Not having run my botanical eye over Queens Rd. before, this Jasmine (probably officinale ) growing out from under several trees (left foreground) and over the railway fence just past the Avenue Rd. footbridge, was most surprising. Given the location it seemed unlikely that it had been planted, but I have never seen it as a garden escape before.

Further down the line there was quite a lot of Elm.

There was Spotted Medick on Thanet Rd, lots of Buck's-horn Plantain at Boundary Street and a Greater Celandine behind the derelict 'Style and Winch' public house on Northend Rd. Black Horehound was by a housing estate here.

It was by now rather gloomy, but I was cheered by coming across a fourth site in the Borough for the uncommmon plant Dittander - on a mound at the south-east corner of a grassy area by flats on Northend Rd, next to a garage/petrol station. This neatly fills in a gap between my other three locations which are Thames Road Wetland, part way up Thames Rd towards the junction with Northend Rd and then the south east corner of the Erith Quarry site.

A Senecio cinerea above a retaining wall at the top of the hill on Colyers Lane appeared to be outside the garden boundary, and had the look of an 'escape', though it might conceivably have been planted. There was also a lone Narrow-leaved Ragwort here.

2/7/10: New White-letter Hairstreak colony in Bexley

The LNHS Horsenden Hill meeting, which was the first time I'd seen White-letter Hairstreaks, was a useful event for getting my 'eye in' and was absolutely instrumental in enabling me to find the species along Moat Lane on Crayford Marshes today. I was also spurred on by Tristan Bantock having said he also thought there was a good chance of it being there when we were making our way along the lane towards Slade Green aftera bug-hunt earlier in June.

Moat Lane, Crayford Marshes, on a sunny evening back on the 23rd April 2010. The substantial English Elm 'hedge' where the White-letter Hairstreaks were found is on the left (south) side, here catching the evening sun from the west.

The lane has longish stretches of English Elm 'monoculture' to about 18-20' tall along the south side, and a few rather smaller ones on the north side. Horses are pastured on the rough grazing adjacent to the hedge. I saw between 7 and 9 likely different individuals, two of which I got side-on good binocular views of and so can be absolutely certain of the ID. They appeared to only be using the (south side) Elm some way along the lane at present (around TQ 530 767), and not that near the Slade Green station end or opposite the moat of Howbury Grange.

The weather was hot and sunny, with some blustery breezes and the odd dark cloud blotting out the sun for short periods. The observations were made between 11.40 a.m. to around 13.30.

The White-letter Hairstreak is a UK and London Borough of Bexley Council BAP priority species, and the Council's website says the only place it occurs in the Borough is in a wood at Foot's Cray Meadows.

Other species seen along the lane today were:

Probable Holly Blue
Common Blue
Large Skipper
Small Skipper
Small White
Meadow Brown
Comma

and a couple of female Broad-bodied Chasers and Darter species.

There were 4 Swallows (probably fledglings) sitting on the barbed wire fence of the field around the moat, and a few Swifts overhead.

Coming hard on the heels of the W-LHS find, a little further along the lane towards the River Darent were 2 or 3 clumps of Crown Vetch, my second find of it in the Borough - the other also having been on the Marshes, in that case away to the west near Crossness.

Out by the river were a Small Heath, 2 Common Blues, a Kestrel and Tufted Vetch.