London Wildlife Trust’s support for the AELTC Wimbledon Park Project biodiversity improvements
To assist those who may wish to understand more about London Wildlife Trust’s support for the biodiversity aspects of the AELTC Wimbledon Park project we are pleased to outline below a summary of our approach and conclusions.
Summary
In April 2021 London Wildlife Trust was invited to review proposals by the All England Lawn Tennis Club (AELTC) to reconfigure Wimbledon Golf Course, which lies adjacent to the AELTC Wimbledon facilities and Wimbledon Park. The initial introduction came from a Trust member who also lives nearby. We were asked to provide our view of the proposals insofar as they might align with London Wildlife Trust’s aims and objectives.
We have subsequently reviewed and commented on the suite of documents so far submitted as part of the planning application, including the ecological surveys carried out by the AELTC consultancy team which are publicly available in the planning application. We have visited the site on a number of occasions and had meetings with some of those who question the biodiversity elements of the plans to understand their views.
For over a year, we have worked closely with AELTC’s appointed ecologists and design consultants, Land Use Consultants (LUC), who are leading on the site’s ecological assessment and on the design of the landscape proposals, to help establish an accurate assessment of the current condition of habitats on site and the potential condition of habitats created and enhanced through these proposals.
Many enhancements are detailed within the current plans; desilting and reducing pollution into the lake, the creation of management plans for each veteran tree, planting of species-rich hedgerows, daylighting two currently culverted watercourses, and the creation of a publicly accessible nature-rich greenspace. We believe collectively these will bring about net gains for biodiversity and people's free access to nature.
We acknowledge that some observers are questioning the assessment of biodiversity net gain planned within the scheme. However, we confirm we have scrutinised the calculations made by LUC and concur with their calculations of the biodiversity net gain implementing the plans will bring.
In doing this work our approach has been conservative in assessments of potential ecological improvements. For example, revised calculations using the most recent Defra Biodiversity Net Gain (BNG) metric 3.1 have been based on a generous assessment of the site’s existing habitat values and the most conservative expectations of what could be delivered through these proposals; nevertheless, they indicate a significant net gain for biodiversity from the scheme.
We fully acknowledge proposed changes to the site involve matters other than the site’s existing wildlife and potential biodiversity net gain, which local people are understandably concerned to understand and comment on as part of the planning process. However from the perspective of ecology; utilising the BNG metric to help shape the AELTC scheme and designing in higher quality habitats and biodiversity features mean the plans should deliver real and measurable gains for nature.
Crucial to assessing whether a biodiversity net gain can be achieved is the assessment of the quality of habitats currently existing on site. Our assessments, rationale and analysis of that important ‘base line’, and an overview of some other important aspects of our analysis are outlined in the points below, which also reflect some important changes made over the past year to the assessments by the AELTC consultancy team at the Trust’s request.
Extent of ‘Wood-pasture and Parkland’
Much of the golf course area in the western part of the site has been described as ‘wood-pasture and parkland.’ It was adopted as part of the earlier Defra BNG Metric 2.0 calculations to recognise the ecological value of veteran trees and the historic landscape context of the site. However, we view some commentators’ descriptions of the quality and extent of the area assigned to this habitat as invalid – it would vastly overvalue the majority of amenity grassland and scattered tree habitat present. LWT agree with the AELTC consultancy team as to the current quality and extent of this habitat.
The habitats present represent highly improved amenity grasslands with scattered trees, lacking almost all of the typical features and characteristics associated with ‘wood pasture and parkland’. For example, the habitat present lacks the following key criteria for this habitat type:
- Grazing or browsing livestock, and the associated dung and resulting vegetative management grazing and browsing provides.
- Native scrub.
- Unimproved or semi-improved grasslands and associated fungi.
- Fallen deadwood (and very few examples of standing deadwood).
- Long standing wood pasture management practices, such as pollarding.
In contrast, the grasslands have been subjected to long standing application of fertilisers, remodelled to provide favourable golf course contours, have been mown intensively since establishment of the golf course in 1898 and are lacking in structural or species diversity.
The 41 veteran trees present will be retained and protected (and now have individual management plans), with extensive areas of wood pasture and parkland habitat restored in the long term.
There is strong ecological justification for removing the classification of ‘wood pasture and parkland’ altogether given the absence of features which characterise this land use and habitat type. Therefore, we agree with LUC who consider the extent of wood pasture and parkland recognised in the metric calculations to overestimate the site’s baseline value and to be suitably precautionary.
Nevertheless, there is the opportunity to further progress the detail and delivery of provision and restoration of this habitat type within the site.
Acid grassland
The scheme proposes to create extensive areas of acid grassland in the ‘Southern Parkland’. The feasibility of this ambition has been discussed by the Trust, LUC and AELTC as the objective stemmed from detailed soil surveys completed at the Site which specifically identified the potential for this habitat to be created. The Baseline Soil Survey report (Tim O’Hare Associates, 2020) states that the top soil is “Acid to slightly acid pH range (pH 5.0– 6.8)” and goes on to state: “This pH range is excellent for new planting and habitats as it is within the ‘optimum range’ that most plants either prefer or at least tolerate, so will not be a major constraint. Only plant species that specifically require alkaline, lime-rich (calcareous) soils would not be suited to these soils. The low phosphorus levels, in conjunction with high organic matter and nitrogen, are ideal for promoting biodiverse, species-rich habitats. These soil conditions are very rare in the Greater London area and offer a good opportunity for acid grassland habitat creation”.
Despite the high degree of certainty that acid grassland will be successfully created, in reality there is likely to be a natural gradation in grassland type, with some areas more consistent with acid grasslands and other areas being more neutral in character. The Trust believes this natural mosaic is to be welcomed and would be reflective of the natural variation and heterogeneity displayed in any natural semi-improved grasslands. Indeed, it would be expected to be of greater ecological value than, and therefore preferable to, a more homogenous sward.
Future management of the site will need to respond to monitoring results and therefore establishment and management of habitats in perpetuity will seek to focus on those priority habitat types and species assemblages which naturally favour the specific variations in soil conditions across the site.
Wet woodland
We acknowledge there are possible impacts to willow and alder habitats along the western edge of the lake. However currently this habitat represents a linear edge to the lake, essentially a fringe of willow and alder scrub which is not representative of ‘Wet Woodland’ as defined by a Priority Habitat status. Whilst there is an ambition for creation of Wet Woodland as part of scheme design, the extent of this habitat is limited by requirements to manage terrestrial, open water and reedbed habitat, and the potential to significantly increase this habitat type within the site is limited.
Lake - Surface water area
Wimbledon Park lake should benefit from increased size and the creation and management of priority habitats including the daylighting of the connected brooks, provision of extensive reedbed and aquatic vegetation and the installation of bespoke habitat features including bat roosts, sand martin banks, kingfisher banks and tern nesting rafts. In addition, current negative influences including nutrient inputs, excessive silt build up and currently high levels of disturbance from lighting and water sport activities will be remedied through appropriate habitat design and management. This should provide significant ecological benefits which exceed any current or prospective management of the site.
Conclusions
We understand there may be other interpretations of the current status of the habitats being promoted and discussed by some other commentators. We cannot comment as we have not been able to view any ecological data which may exist in support of these interpretations.
However, we have reviewed all ecological assessments we are aware of. As above it is difficult to scrutinise some of these assessments further without the data on which they are based being openly shared.
We will continue to scrutinise the AELTC’s plans, any new ecological survey data that may emerge, and any changes proposed as a result.
However, in light of our analysis of all data available to us to date, even taking a generous assessment of the site’s existing ecological value and a conservative assessment of what is planned in the future, the Trust’s view is the project will benefit wildlife and people’s access to significantly more natural, ecologically richer greenspace compared to the current base line situation. As such, the biodiversity plans and enhancements contained within the scheme have our support.