Wildlife Trust Derbyshire Wildlife Trust
East Mill, Bridge Foot, Belper, Derbyshire, DE56 1XH
Tel: 01773 881188 Fax: 01773 821826
E-mail: enquiries@derbyshirewt.co.uk

Allestree Park Lake

Allestree Park Lake



Derbyshire Wildlife Trust
East Mill
Bridgefoot
Belper
Derbyshire
DE56 1XH
A report for the Wild About Ponds Project
Prepared by Trevor Taylor
Local Wildlife Sites Officer (Planning)
Derbyshire Wildlife Trust

August 2011

Protecting Wildlife for the future

Regisered charity no. 222212
DWT is a company registered in England and Wales
with the Company Number 715675

Allestree Park Lake

Background

Derbyshire Wildlife Trust was commissioned to survey the lake located within Allestree Park LNR as part of the Wild About Ponds Project in order to provide management recommendations based upon the findings of the survey. It would also enable a comparison of survey results against data obtained as part of the 2004/5 Derby City Pond Survey.

Map 1 shows the location of the lake which is present in the south eastern part of the site. The lake is fed by streams running from the woodland in the north and land drainage from the golf course and is essentially divided into two water bodies by a weir. The western water body (Allestree West) covers an area of approximately 11,000m2 and, as such, falls within the definition of a pond enabling a PSYM survey to be carried out. The eastern water body (Allestree East) with an area of over 34,000m2 falls outside of the definition of a pond and so a PSYM survey was not carried out. The site is a designated Local Wildlife Site DE011 and is registered on the Derby City Wildlife Alert Map.

The site is owned by Derby City Council and managed by the City Council Parks Department. At present one Ranger is allocated to the Park and the Friends of Allestree Park are actively involved in the sites’ management, in association with the Ranger and the Parks Department. The British Trust for Conservation Volunteers (BTCV), Derbyshire Conservation Volunteers and Groundwork have also been involved in carrying out various works on the site.

The public have largely enjoyed free unrestricted access to the Park since Derby City Council took on the responsibility for managing the site in 1947. The Park is very popular with local people, many of whom walk or walk their dogs on the Park daily.

The lower lake (Allestree East) is well used by anglers and several fishing platforms have been constructed on the northern bank.

The upper water body (Allestree West) is regarded as a conservation area with no fishing allowed. However, much public attention is focussed around the picnic bench and interpretation panel where the lake margins have become barren and eroded as a result of dogs entering the water and people congregating to feed the waterfowl. During 2010, as part of the Wild About Ponds Project, a platform was constructed in this area in attempt to minimse future erosion of the bank together with work to improve the structure of the bank. This work was carried out by BTCV and Groundwork in combination with members of the Friends of Alestree Park. Unfortunately, the platform was destroyed by fire a few months after its installation but was subsequently reinstated only to be subject to further outbreaks of vandalism during August 2011.

The lake is shown on Ordnance Survey First Edition maps dated 1882 and, as such, would appear to be of some local historic interest.

Allestree Park Lake

Survey objectives

The aim of the survey was to gather ecological information of the upper waterbody (Allestree West) using the PSYM methodology in order to determine the current overall ecological quality of the pond. An assessment of the ecological value of the lower lake (Allestree East) was also undertaken.

Methodology

The survey followed the standard survey methodology known as PSYM developed by Pond Action (now Pond Conservation) and the Environment Agency. PSYM, the Predictive System for Multimetrics, (pronounced sim) was developed to provide a standard method for assessing the biological qualities of still waters in England and Wales.

The method uses a number of aquatic plant and invertebrate measures (known as metrics) which are combined together and fed into a computer model, along with basic environmental and location data, to obtain a single value which represents the waterbody’s overall quality status.

The recommended time of year for carrying out PSYM pond surveys is during June, July and August. The pond was surveyed during August 2010.

The following information was gathered for the pond:

Calculating the pond metrics

The data collected from the surveys are used to calculate three plant metrics and three invertebrate metrics.

1. Number of submerged and emergent plant species

This is simply the number of submerged plant species plus the number of emergent plant species. The calculation does not include the number of floating-leaved species present. This is because the pond data suggest that the number of floating-leaved plants occurring at a site does not decline significantly with increasing degradation. The metric is therefore improved by omitting this plant group.

2. Trophic Ranking Score (TRS)

TRS is a measure of the average trophic rank for the pond. This is calculated by assigning each plant species with a trophic score based on its affinity to waters of a particular nutrient status. The trophic scores vary between 2.5 (dystrophic, i.e. very nutrient poor conditions) and eutrophic, i.e. nutrient rich conditions).
Unfortunately, not all plants have trophic scores. This situation has arisen because the current TRS values for standing waters (Palmer et al., 1992) are based only on analysis of lake data, and many plant species which are common in ponds occurred at too low a frequency in lakes to give them a score. Also, some plant species exhibit little nutrient preference.

The TRS value for a site is calculated as follows:

  1. The trophic scores from each plant species present at the site are summed together.
  2. The summed score is divided by the total number of plant species which have a trophic ranking score to give the TRS.
3. Uncommon Species Index

Uncommon species are those which have a rarity score of 2 or more. The number of these species is simply summed to give the number of uncommon species.

Uncommon species refers to species which can be best described as "local", "nationally scarce" or "Red Data Book". The rarity status values for Scarce and Red Data Book species are based on existing definitions derived from the Red data Books and other authorities. The definition of "local" has been used to define species which are not uniformly common and widespread in Britain: with plants this refers specifically to species recorded from between 100 and 700 10 x 10 km squares in England, Wales and Scotland.

4. Average Score per Taxon (ASPT)

The ASPT is calculated by summing the BMWP scores for all taxa present at the site and dividing by the total number of BMWP taxa present.

BMWP (Biological Monitoring Working Party) scores are assigned to taxa depending on their known tolerance to organic pollution, a higher score indicating lower tolerance. The scores were defined by Maitland in 1977.

5. Number of dragonfly and alderfly families.

This metric is the sum of the number of dragonfly (Odonata) and alderfly (Megaloptera) families.

6. Number of beetle families

This metric is the sum of the number of beetle (Coleoptera) families present at the site. The metric has a relationship with bank quality as well as water quality.

Results

The pond was surveyed using the PSYM methodology enabling an assessment of its biological quality to be made together with a comparison with other ponds in the area.

The PSYM scores are placed in four categories which reflect the ecological quality of the pond:

0-25% is very poor, 26-50% is poor, 51-75% is fair, and 76-100% is good

Allestree West

Site and sample details

Grid reference: SK 34880 40240

Site Name: Allestree West

Location: Allestree Park LNR

Owner/site access details: Derby City Council

Survey Date: 8th August 2010Surveyors: Trevor Taylor (Derbyshire Wildlife Trust)
Pat Sear

Environmental Data

Altitude: (m)67m aslpH:7.77
Shade: % pond overhung:15%% emergent plant cover5%
Inflow (absent = 0, present = 1):1Pond area (m2)10,916m2
% of pond margin grazed:0

Pond base: categories into one of three groups; 1=0%-32%, 2=33%-66%, 3=67%-100%

Clay/silt:2Sand, gravel, cobbles:3Bed rock:1
Peat1Other1

Emergent plants Rarity Score Trophic Ranking Score
 
Acorus calamus, Sweet Flag 1 -
Angelica sylvestris, Angelica 1 -
Deschampsia caespitosa, Tufted Hair-grass 1 -
Epilobium hirsutum, Great Willowherb 1 -
Galium palustre, Marsh Bedstraw 1 -
Impatiens glandulifera, Indian Balsam 1 -
Iris pseudoacorus, Yellow Iris 1 -
Juncus effusus, Soft Rush 1 -
Lycopus europaeus, Gipsywort 1 -
Mentha aquatica, Water Mint 1 7.3
Mimulus guttatus, Monkeyflower 1 -
Ranunculus flammula, Lesser Spearwort1-
Scrophularia auriculata, Water Figwort1-
Scutellaria galericulata, Skullcap1-
Solanum dulcamara,Bittersweet110
Sparganium erectum, Branched Bur-reed1 8.5
Veronica beccabunga, Brooklime1 10

Number of emergent and submerged species - 17
Number of uncommon species (with a rarity score of 2 or more) - 0

Trophic Ranking Score - 8.95


Macroinvertebrates
Group 1 taxa (BMWP:10)
Leptoceridae - Caddis fly (Cased) - Mystacides longicornis)

Group 4 taxa (BMWP:6)
Gammaridae - Crustacean (Shrimp)

Group 5 taxa (BMWP:5)
Planariidae - Flatworm
Gerridae - Water bug (water skater)

Group 6 taxa (BMWP:4)
Baetidae - Mayfly
Piscicolidae - Leech
Group 7 taxa (BMWP:3)
Planorbidae - Ramshorn Snail
Sphaeridae - Pea Mussel
Asellidae - Crustacean (water slater)

Group 8 taxa (BMWP:2)
Chironomidae - Fly (Non biting midge)

Total No. Of taxa10
Total BMWP Score45
ASPT4.5
No. OM taxa0
No. Coleopt taxa0

Index of Biotic Integrity (PSYM Score %) = 39. As such the pond would be considered to be in poor ecological condition.

The 2004/5 Derby City Pond Survey recorded a PSYM score of 28% for the site which shows that whilst the pond remains in the poor ecological condition category the pond has improved slightly in quality over the past seven years.

A conductivity test to measure the total quantity of chemicals dissolved in the water returned a reading of 330μS/cm2. This figure indicates that the pond is reasonably clean with no significant pollution or contamination issues. Where conductivity is 500-1000 + μS/cm this is usually a sign of some kind of pollution and a perfectly clean water pond would have a figure of 100μS/cm or less.

Survey Results

The site is largely surrounded by bankside trees and shrubs with Alder, Crack Willow and Sycamore particularly prominent along with occasional Yew, Hawthorn, Grey Willow. Elder, Holly and Silver Birch. The extent of overhanging branches is such that there are very few areas suitable to support emergent marginal aquatic vegetation. The areas of marginal vegetation are essentially confined to alongside the weir together with small patches at the south-east tip and towards the north-west corner under areas of

more open canopy. Whilst there is reasonable range of wetland plant species present they generally occur in limited quantity with the possible exception of Yellow Iris and Branched Bur-reed which are locally frequent along the top of the weir. A small amount of Indian Balsam occurs in the vicinity of the weir and along the south-east margin.

Indian Balsam

Left: Indian Balsam

No submerged or floating leaved wetland species were recorded and it is likely that the limited occurrence of wetland plants has a significant bearing on the paucity of freshwater invertebrates associated with the site.

The dense overhanging branches of Grey Willow along the northern bank provide excellent cover for waterfowl with a population of at least 20 Mandarin Ducks recorded during the survey visits. Good numbers of Mallard, Canada Geese, Coot and Moorhen were also noted along with a number of Greylag and domestic geese.

Manderin Ducks

Right: Manderin Ducks

Work to re-instate the eroded nature of the bank in the vicinity of the picnic bench was carried out by BTCV in 2010 by the use of wooden revetments and the installation of a wooden platform. Despite outbreaks of vandalism these features have generally addressed the issues and provide a safer environment for people wishing to access the bank to observe and feed the waterfowl.

The site provides breeding opportunities for Common Toad, a UK BAP priority species, with tadpoles recorded during the survey.

Recomendations

It is likely that the only solution to increase the overall ecological value of the site would be to increase the extent of wetland plant species, which would in turn attract a greater diversity of aquatic macroinvertebrates. However, it is acknowledged that, considering the extent of bankside tree cover and the presence of waterfowl, there are very little opportunities to achieve this outcome. One area where attention could be focussed is in the north-west corner of the site where a small quantity of emergent vegetation has become established. This emergent vegetation could be encouraged and extended by the clearance of adjacent bankside vegetation to allow the vegetation to colonise further areas

of the bank. The overhanging branches of willow and sycamore, which currently extend out into the water, could be cut back to expose area of bank suitable for colonisation by emergent vegetation. The branches should be cut back by coppicing the trees to ground level during the winter months to avoid impact on breeding birds. The dense willow growth on the opposite northern bank provides adequate shelter and nesting opportunities for waterfowl. Contractors need to be mindful of the presence of rabbit holes under the trees but these should not be adversely affected as the intention is to coppice the branches and stems and not to actually remove the trees. The resulting dead wood should be used to create habitat piles but they should be placed out of sight, possibly in amongst the nearby yew trees, to avoid any vandalism and fire threat. It will also be necessary to check for the presence of any tree preservation orders that maybe in place that may affect the proposed pruning work.

Any stems of Indian Balsam should be removed by pulling prior to the setting of seed during June, July and August. Material should be left in heaps to compost at a suitably identified location. Indian Balsam is now included in the 2010 variation of Schedule 9 of the Wildlife and Countryside Act which makes it an offence to cause the plant to grow.

Annual PSYM surveys should be undertaken during the period June to August to monitor the ecological condition of the site with the results forwarded to Derby City Pond Wardens Association and the Derbyshire Wildlife Trust.

Allestree East

The lower lake covers an area of 34,343m2 and, as such, far exceeds the definition of a pond. Therefore a PSYM survey of this eastern section could not be undertaken.

Like the upper pond, the site is surrounded by mature alder and willow trees with occasional hawthorn, holly and elder. It is well used by anglers with a number of platforms installed on the northern bank together with cleared "swims" on the southern bank. The combination of heavy shade from the trees together with disturbance from dogs, anglers and wave action has resulted in large areas of bare ground and erosion of the banks.


Allestree East

In an attempt to control the level of erosion and impact on the banks several areas have been selected for the incorporation of willow revetments.

Willow revetment

This work was carried out by Groundwork and BTCV during 2010 and 2011. One of the areas behind the revetment was planted with emergent vegetation including Reed Sweet­grass, Gipsywort and Great Willow­herb, which has started to establish. The revetments in other locations have been installed simply to halt the further erosion of the bank and, due to limited resources, have been left unplanted with a view to natural colonisation. It was noted during a survey visit in September 2011 that even though the willow has started to grow it has had no serious restrictions on use of the bank by anglers.

Anglers

Access to an area of the southern bank has been limited by the erection of fencing and the felling of a mature tree which has been left in situ. This will help to create an area of non-intervention to encourage the estab­lishment of emergent marginal vegetation.

The pond is known to contain a number of large carp together with other species including roach, perch, bream and tench which along with the waterfowl population, including a flock of Canada and Greylag geese, would have a potential significant impact upon the aquatic invertebrate population.

When compared with survey visits to the site in 2004 and 2005 there appears to be an increase in the extent of emergent aquatic vegetation present around the lake which is particularly noticeable on the northern bank in the eastern half of the lake where a band of Branched-Bur-reed, Yellow Iris, Sweet Flag and Lesser Pond-sedge is augmented with Water Forget-me-not, Great Willowherb, Water Figwort, Skullcap, Angelica and Water Mint.

The Derbyshire Red Data Book plant Various-leaved Water-starwort, Callitriche platycarpa, was confirmed growing on mud in the margins of the northern bank and a small, but increasing, population of Nodding Bur-marigold, Bidens cernua, occurs in the vicinity of the overflow structure.

A few small plants of Common Reed, Phragmites australis, have become established in the shallow margins at the extreme eastern tip of the lake. This area is very silted and stagnant and collects items of rubbish and debris giving this area of the lake a very degraded appearance. The establishment of a reedbed (Phragmities) in this area of the lake should be encouraged. As well as adding to the diversity of the site, once established, the leading edge will form a barrier, making the collection of debris and litter easier.

Like the upper pond, any stems of Indian Balsam should be removed by pulling prior to the setting of seed during June, July and August with the pulled material left in heaps to compost at a suitably identified location.

A selection of bank areas behind the willow revetments could be planted up by means of the local translocation of emergent wetland plants.



Allestree Park Lake


Allestree Park Map