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

Education Pond

Alvaston



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

November 2010

Protecting Wildlife for the future

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

Education Pond, Alvaston

Background

Derbyshire Wildlife Trust was commissioned to survey the pond as part of the Wild About Ponds Project and provide management recommendations based upon the findings of the survey.

Map 1 shows the location of the pond which was formed within an area of public open space as part of the construction of the A6 Alvaston by-pass in 2002. However, the creation of the pond was not part of the official mitigation scheme required for the loss of ponds supporting great crested newts but is believed to have been created to provide additional biodiversity enhancement and educational benefits, particularly for the nearby St. John Fisher Primary School. A dipping platform has been incorporated on the northern bank of the pond. The site is still under the ownership of the Highways Agency but will eventually transfer to Derby City Council Parks Department.

The pond was formed using a geotextile liner and is located within an area of largely unmanaged grassland, scrub and immature broadleaved plantation which is accessed by a number of crushed stone paths. A metre wide strip alongside the paths is cleared of vegetation on a regular basis and the area is fairly well-used by members of the public, particularly for dog-walking.

The site is registered on the Derby City Wildlife Alert Map and it has to be recognised that since the preparation of the map the A6 Alvaston by-pass has been constructed to the north of the pond.

The pond was surveyed as part of the 2004/5 Derby City Pond Survey and was also the subject of monitoring survey work for great crested newt in association with the construction of the A6 Alvaston by-pass. The results of the survey identified the presence of breeding Common Frog and Smooth Newt but no great crested newts were found.

It is believed that between 2004 and 2010 damage to the pond liner was caused as a result of work carried out to alleviate a sewage contamination incident. The damage has seriously reduced the pond’s water holding capacity which in turn has favoured the vigorous spread of Typha which in 2010 was noted to have largely dominated the pond resulting in the presence of very little open water. The extensive stand and vigorous spread of Typha also contributes to the accelerated drying out of the pond which is normally totally dry by early summer.

A work party comprised of BTCV, Groundwork and members of the local community created some areas of open water by clearing Typha and removing a number of willow saplings in August 2010. BTCV also removed a number of planted tree saplings from the

banks of the pond during autumn 2010 in an attempt to remove the potential risk of future shading of the pond. The tree saplings were re-planted elsewhere on the site.

Survey objectives

The aim of the survey was to gather ecological information using the PSYM methodology in order to determine the overall ecological quality of the pond and inform management recommendations to enhance the biodiversity value.

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 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

Site and sample details

Grid reference: SK 38893 33781

Site Name: Education Pond

Location: South of A6 Alvaston By-pass, Alvaston

Owner/site access details: Highways Agency - access available

Survey Date: 25th June 2010Surveyors: Trevor Taylor (Derbyshire Wildlife Trust)

Environmental Data

Altitude: (m)41m aslpH:7.22
Shade: % pond overhung:0% % emergent plant cover95%
Inflow (absent = 0, present = 1):0Pond area (m2)831m2
% of pond margin grazed:0

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

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

Emergent plants Rarity Score Trophic Ranking Score
 
Alopecurus geniculatus, Marsh Foxtail1-
Caltha palustris, Marsh Marigold17
Deschampsia caespitosa, Tufted Hair-grass1-
Epilobium hirsutum, Great Willowherb1-
Glyceria fluitans, Floating Sweet-grass 1 -
Juncus articulatus, Jointed Rush 1 -
Juncus conglomeratus, Conglomerate Rush1-
Juncus effusus, Soft rush1-
Juncus inflexus, Hard Rush1-
Phragmites australis, Common Reed17.3
Solanum dulcamara, Bittersweet110
Ranunculus sceleratus, Celery-leaved Buttercup110
Typha latifolia, Bulrush18.5
 
Floating-leaved plants
 
Lemna minuta, Least Duckweed1-
 
Submerged plants
Callitriche platycarpa, Various-leaved Water Starwort2-
Ranunculus aquatilis, Common Water Crowfoot210

Number of emergent and submerged species – 15
Number of uncommon species (with a rarity score of 2 or more) – 2

Trophic Ranking Score – 8.80

Macroinvertebrates

Group 5 taxa (BMWP:5)
Nepidae - Water bug (Water scorpion)
Corixidae – Water bug (Lesser Water Boatman)
Dytiscidae – Water beetle (Diving)

Group 7 taxa (BMWP:3)
Spheridae – Pea Mussel

Group 9 taxa (BMWP:1)
Oligochaetae - True worm

Total No. Of taxa5
Total BMWP Score19
ASPT3.8
No. OM taxa0
No. Coleopt taxa1

Index of Biotic Integrity (PSYM Score %) = 50. As such the pond would be considered to be in poor ecological condition.

Survey Results

The most noticeable feature of the pond is the domination of Bulrush, Typha latifolia, which has spread considerably in recent years and now covers the majority of the pond area. The perimeter is fringed with clumps of Soft Rush, Hard Rush and Conglomerate Rush with occasional stands of Great Willowherb. A small quantity of Common Reed is present at the eastern tip of the pond. while a single clump of Marsh Marigold occurs in the centre of the pond in front of the dipping platform.

Various-leaved Water Starwort occurs in the margins of the northern and southern banks together with small quantities of Common Water-crowfoot and Jointed Rush. Isolated plants of Celery-leaved Buttercup are also present. A survey visit in July 2011 identified that following the clearance of Typha in August 2010 the cleared areas have become rapidly colonised by Floating Sweet-grass, Glyceria fluitans, and the small quantity of Common Water-crowfoot is now restricted to a small area of open mud at the western end of the pond.

The 2004/5 Derby City Pond Survey recorded a PSYM score of 56% for the pond which shows that the pond has degraded slightly. This is likely to be as a result of the loss of open water due to the considerable increase in the extent of Typha which can be observed from the photographs below. The loss of open water and the dominance of Typha would appear to have made the pond less suitable for dragonflies and damselflies, which had been recorded as breeding in the pond in 2005, and there is currently little opportunity for Common Water Crowfoot.

Alvaston

May 2005

Alvaston

August 2010

Amphibians

Frog spawn and Smooth Newt were recorded in the pond by ESL during monitoring surveys carried out in 2004 and 2005

A torchlight survey carried out on 19th April 2010 found 9 male and 3 female smooth newts along with large numbers of Common Frog tadpoles. It was noted during a visit on May 14th 2010 that the good numbers of Common Frog tadpoles had attracted a number of predating Carrion Crows.

Management Recommendations

The main ecological concern with regard to the site is the domination of the pond with Bulrush which has resulted in the presence of very little open water and the accelerated drying out of the pond during the late spring/summer period. This obviously significantly reduces the success rate of breeding amphibians and, in addition, the lack of open water and the long dry periods reduces the pond’s suitability for aquatic invertebrates, including damselflies and dragonflies, which is reflected in the reduced PSYM score since 2005.

Unfortunately the damaged pond liner and resulting poor water holding capacity combined with the vigorous spread of Typha means that the pond is unlikely to fulfil its maximum potential as an educational resource for pond dipping activities.

Whilst the removal of Typha is a management objective, it must be recognised that this is a very labour intensive operation with little benefit due to the damage that has occurred to the liner in the past meaning that the pond has little capacity to hold a significant quantity of water even if large quantities of Typha are removed. It is also recognised that any areas which are cleared of Typha are rapidly colonised by Glyceria.

The removal of Typha is still recommended to try and maintain some open areas and the digging out of Glyceria should also be undertaken together with the removal of any willow saplings. It is likely that the removal of Typha and Glyceria will need to be carried out on an annual basis.

Both of these tasks should be carried out during the autumn period, ideally between the months of September to November in order to minimise impacts upon nesting birds and breeding amphibians. All material left on the pond margin for at least 24 hours to allow any invertebrates to recolonise the pond. The material should then be removed to a previously identified area of the site and stored as compost heaps to provide additional habitat.

Annual PSYM and amphibian surveys should be undertaken to monitor the success of the Typha and Glyceria removal against the baseline information.

Serious consideration should be given to the formation of a new pond in the area of grassland to the west of the existing pond. The pond would require a liner due to changes in hydrology that appear to have occurred as a result of the construction of the by-pass. It is likely that a new pond would provide a better facility for pond dipping and for breeding amphibians than the existing pond which eventually may have to be sacrificed and left to succession as swamp habitat due to the labour intensive nature of management which would be required to control the Typha and Glyceria. It may have to be accepted that even with Typha and Glyceria removal the pond may still not hold water for a sufficient period of time due to the damaged liner.

In August 2010, two hollows were identified to the west of the existing pond which were considered to be potential new pond sites. However, on a visit to the site in July 2011 it was noted that a large single mammal hole had recently been excavated in this area. Whilst it was unclear whether the hole was being used by badger or fox, its presence has made the site unsuitable for any pond creation. There is an alternative pond creation site in area of open rough grassland further to the west but this will require some degree of excavation prior to the installation of a liner.

Common Water-Crowfoot

Common Water-Crowfoot - May 2005

Map of Alvaston