CONSERVING BIODIVERSITY THAT MATTERS: PRACTITIONERS’ PERSPECTIVES ON BROWNFIELD DEVELOPMENT AND URBAN NATURE CONSERVATION.
Carolyn Harrison* and Gail Davies, Senior Lecturer and Lecturer, Environment and Society Research Unit, Department of Geography, University College London, 26 Bedford Way, London WC1H OAP. UK.. * Corresponding author:E-mail: c.harrison@geog.ucl.ac.uk (C. Harrison)
Introduction
January 2001 saw the launch of The London Biodiversity Action Plan (LBAP) sponsored by the London Biodiversity Partnership (2001).  It details plans to enhance the survival of rare and valued species associated with some fifteen London habitats such as woodland, heathland, railway linesides, private gardens, cemeteries and wastelands. Giving official recognition to the rich and varied wildlife that resides in the capital city, the LBAP is confirmation that nature conservation is no longer just a countryside concern - urban nature too requires conserving.  Signalling a shift in thinking that gives credence to the distinctive ecology of urban assemblages such as wasteland, as well as to ‘areas of encapsulated countryside’ such as woodlands and heathlands, the LBA also demonstrates a shift in expectations about who is responsible for conserving biodiversity in London.  All sectors whether private, public or voluntary are expected to play their part in conserving urban nature and the cross-sector London Biodiversity Partnership is evidence of this commitment. Significant too is its publication at a time when changes are taking place in the way London is governed. Most notable is the fact that under the terms of the GLA Act 1999, the Mayor of London is required to produce and support a Biodiversity Strategy as an integral part of his development policies. In this respect the Audit is intended to provide the basis on which that Strategy will be developed. Seemingly, the conservation of nature is to be placed on an equal footing with those economic and social concerns that have traditionally guided development in London.
But, at the same that the conservation of urban nature appears to have gained political saliency, development pressures in the capital are increasing. The rising demand for new homes and general acceptance by central government that 60% of these homes should be built on brownfield sites (DETR 2000a) including some sites of nature conservation importance, means that the conservation of urban nature will be contested terrain. So, although policies to protect urban nature have gained ground in the public sector, development threats and emerging housing policies designed to facilitate residential development within the urban area, especially on so called ‘brownfield sites’, are increasing. 
This changing policy context has added fuel to a debate about the goals of nature conservation and biodiversity plans (Adams, 1997) and to debates about the most appropriate and robust ways of valuing nature (Foster 1997). In urban areas debate has focussed on ways of valuing those  ‘wasteland habitats’ most commonly associated with brownfield sites  (Hunot 1999; Urban Wildlife Partnership1999, Box and Shirley 1999). Such sites through their obvious artificial origin and transient presence do not immediately qualify for consideration as sites of nature conservation importance. Likewise, their ambiguous aesthetic appeal and association with socially undesirable users, means that such areas do not appear to be of amenity or social value. Their dominant portrayal as ‘wasting assets’, notably by the Urban Task Force report (1999) and the Urban White Paper (DETR 2000b) serves to reinforce this negative appraisal. As a result ‘development’ is seen as a means of bringing such land into ‘beneficial’ use.   This dominant portrayal of brownfield sites as wasting assets discounts a more pluralistic understanding of brownfield sites as communal resources in which all sections of society have an interest or stake. From this more pluralistic perspective, brownfield sites represent examples of ‘near natural’ or ‘wild’ areas in the city and are part of the ‘unofficial countryside’ celebrated by Richard Mabey (1973) and the ‘urban commons’ of Oliver Gilbert (1991, 1993). Through this lens, habitats encountered on brownfield areas are as much a part of our natural and cultural heritage as many other valued artificial habitats in the UK.   
In taking forward the claim that some brownfield habitats are deserving of conservation, proponents have to address ever-present tensions between the scientific and political goals of nature conservation. In the context of an urban renaissance such tensions are brought centre stage in part because some developers are adopting new green credentials.  New ecologically sensitive developments offer ‘gains’ for wildlife where previously none were forthcoming. Seen as part of a process of ecological modernisation (Buttel 2000 ), these ecologically sensitive proposals are beginning to mobilise new knowledge networks whose members had previously worked separately and often in opposition to each other. Our objective in this paper is to reveal how different actors in the development process - natural historians, professional conservationists, planners, statutory consultees and ecological consultants – negotiate the new challenges provoked by this process of ecological modernisation.  
To date few studies have attempted to examine how professional ecologists and conservationists in different sectors and institutional settings address these tensions in their working practices. Some exceptions are Whatmore and Boucher’s (1993) study of planning agreements and nature conservation with its focus on the views of  planning officers; Cowell’s 1997 study of a mitigation process in a rural setting, and studies of the discourses of conservation, development and regeneration provided by Rydin  (1998) and Harrison and Burgess (1994) in the context of the east Thames corridor. However, few studies focus on the process of knowledge mobilisation and its relationship with the re-development process.  A focus on knowledge networks positions the re-development process less as a concrete ‘given’ and more as process of ‘becoming’ in which actors and their sense of agency are enmeshed and within which differing understandings of nature, technologies and practices of nature conservation are enlisted (Burgess et al 2000).  ((Gail does this need fleshing out – remembering our audience tho’)). The London case discussed here adds several dimensions to this actor-network perspective. First, the pressure to develop brownfield sites in London is very high.  Latest estimates from the DETR (1999) suggest that 24.000 homes are expected to be built each year in London. Failure to meet the allocated number of homes within the urban area will add fuel to the brownfield-greenfield debate and the competing spatial and environmental rationalities underpinning it (Murdoch 2000). Second, the high pressure for development means it is inevitable that some brownfield sites of nature conservation value will be threatened by development.  Hence, the requirement for a robust process of identifying and protecting local ‘brownfield’ sites of importance for nature conservation (SINCs) is an urgent one (Box and Shitley 1999).  In practice, the method for identifying local sites of importance for nature conservation developed by the former London Ecology Unit (LEU) is thought to be one of the most successful in Britain and has gained international recognition (Dawson, 2000).  Adopted by the majority of London boroughs, the LEU’s spatial hierarchy of metropolitan, borough and local sites of importance for nature conservation includes several brownfield sites. In practice, the political commitment of local authorities determines whether these policies are upheld.  But, such policies and the political commitment of many local authorities to them can be expected to serve as a brake on the development process of brownfield sites, if as proposed, the spatial hierarchy of SINCs becomes mandatory under the Greater London Authority’s spatial development strategy (GLA 2001).
Third, it remains to be seen whether the much heralded strategies being prepared by the new Greater London Authority - each of which is required to contribute to sustainable development – will give effective consideration to the nature conservation value of brownfield sites.  Strategies for Biodiversity, Transport and Spatial Development for example, will need to be integrated with the Economic Strategy prepared by the London Development Agency (2000) and boroughs will be expected to implement them.  The translation of strategic guidance for London into effective conservation policies for brownfield sites will depend on the nature of the relationship to be established between the GLA and the boroughs since it does not possess strong regulatory powers, nor is it a provider of services. The effectiveness of this relationship is likely to depend on both formal and informal partnerships - much as the London Biodiversity Partnership seeks to promote.  In other words, how the re-development process operates will be strongly influenced by local practices as well as by the relative importance given to economic, social and environmental concerns at the city-wide scale.
Taken together, these dimensions of the London case mean that the capital has been a forcing ground for debate about nature conservation and the development of brownfield sites. Two issues are central to the debate: how to assess the biodiversity value of spontaneous herbaceous, scrub and woodland communities associated with abandoned brownfield sites for nature conservation and how the re-development process is to accommodate concerns about biodiversity.   
The study: conserving biodiversity that matters   
The study we report on here seeks to contribute to the debate about the nature conservation value of wasteland sites in London in two ways. First, we provide an appraisal of key issues raised in interviews conducted with professional ecologists based in the public, private and voluntary sectors. These issues focus on the methods and processes that practitioners employ, and believe should be employed, to promote or accommodate conservation of nature and biodiversity in the re-development of brownfield sites.  Second, we focus on those practices adopted by different actors as they begin to negotiate their involvement with a processes of ecological modernisation through which developers and site owners are beginning to take a more pro-active approach to more ecologically sensitive development. The majority of respondents had been recruited through their involvement with two proposals to develop brownfield sites in London and both sites were assessed as having value for nature conservation. We tracked both sites through the application and decision stages of the development process in the period between October 1999 and June 2000. We consulted all papers in the public domain associated with each application, attended public meetings associated with each application and interviewed key members of the development team, officers and elected members in each local authority and members of the public who objected to the proposals. For the sake of simplification, we focus here on the interviews conducted with professional ecologists and conservationists.  By drawing on their experience with these active development proposals, respondents were able to provide detailed insights about their working practices and in particular explored what knowledge networks they drew on in the development process. Structured interviews of an hour and half in length were held with thirteen people. Respondents included four private sector consultants, two conservation officers employed in statutory agencies with responsibilities for the London area, three members of voluntary sector trusts based in London and two naturalists who also work as consultants. Three public sector officers with responsibilities for ecology and nature conservation were also interviewed. Two respondents were based in local authority planning departments and one in the environmental strategy team of the Greater London Authority and formerly part of the London Ecology Unit. 
The two case studies were chosen as types of brownfield development present in London. Site one is a small ( < 1ha), on former railway land and located in a middle London borough with a strong commitment to pursuing nature conservation policies. Site two is located in a central London borough. It is a large (>3.0ha) former industrial site on the Thames and is typical of many of the riverside developments in central London.  The local authority has a strong commitment to urban regeneration. The first site permits an analysis of issues surrounding the potential loss to development of part of a brownfield site already accorded protection through nature conservation policies identified a the Unitary Development Plan. Part of the development site is within a Local Nature Reserve and Site of Nature Conservation Importance and on a Green Walk and Green Corridor. The second, larger site has no official recognition in terms of nature conservation importance although, as revealed through studies undertaken during the development process, the site supports a number of rare species and is of potential nature conservation value. This former industrial site provides an opportunity to track the process through which an ecologically sympathetic design came to incorporate re-created wasteland habitats as part of the proposal. 
The paper is structured in the following way. First we examine the role of science in codifying the biological status of brownfield sites as  ‘wasteland habitats’ and in assessing their potential value for nature conservation. We move on to explore the rationales employed by actors when seeking to promote claims for a more pluralistic approach to nature conservation that positions nature conservation as both a scientific and social project. Finally we explore some of the strategies and tactics employed by different players as they seek to mobilise a range of knowledges in a process of ecological modernisation.  We discuss some of the issues raised by the study for the conservation and biodiversity value of brownfield sites. 
Brownfield sites as a wildlife resource: the scientific basis of site inventory and appraisal. 
All the respondents believed that the framing of  brownfield sites in national debates as land that was a wasting asset failed to recognise both the existing and potential value of brownfield sites as wildlife habitats. However, there was less agreement  about the form this characterisation process should take or, who should be involved in it.  Much of the debate concerned the role of science and scientific experts in the codification of these sites as wildlife habitats and their importance for nature conservation.
Science as a basis of site  inventory and appraisal: All respondents accepted that part of the site characterisation process need to be based within a scientific framework whilst rather less attention was given by ecological consultants to the need to identify the social and cultural character of sites. A focus on the scientific ecology of urban sites meant that consultants most frequently adopted English Nature’s  Phase 1 survey as the main approach to characterising  habitat types and key species present on the site. Even then respondents  recognised that some consultants undertake rather cursory one-off site descriptions that are neither sensitive to the exigencies of seasonal change, nor to the distinctive attributes of  sites that relate to their urban context. The dilemma for ecologists is whether to accept a quick, but standardised inventory as an adequate basis on which to form a judgement about the potential conservation value of the site, or whether to accept that the ecology of urban areas is different and requires a new approach. For example, the high biodiversity of many wasteland sites in particular suggests that to proceed with a full species inventory of all major plant and animal groups might be desirable.  Given the time constraints under which most ecological consultants operate this is not likely to be possible and the dearth of ecologists capable of undertaking accurate inventories, especially ecologists familiar with the urban area, militates against this approach. One consultant explained : ‘There’s a sort of ideal that you have to do everything and if you talk to some people in the Institute for Ecology and Environmental Management, they’ll tell you that on any site you’ve got to everything from invertebrates to mosses where in reality you don’t.  You target particular things related to protected species, the plant habitats and anything else which you come across, and you deal with them.’  Adopting an approach that is informed first by the needs of existing regulations and second by practical possibilities, this consultant argued for a pragmatic approach rather than one guided by high minded ideals that couldn’t be achieved.    
Notwithstanding the fact that there are only a handful of urban ecologists working in the UK, reliance on the adequacy of the Phase 1 approach to characterise urban wasteland sites is also to ignore where the science of urban ecology ’is at’.  Two aspects of  the state of scientific knowledge of urban sites were raised by respondents. The first relates to the need to keep abreast with scientific studies of the ecology of artificial habitats such as wasteland sites and the extent to which different players in the development process use and act on this knowledge.  The second, relates to the kind of knowledge which resides with local specialists and enthusiasts and the credence given to this knowledge in the planning process.  
Keeping up to date with the scientific basis of urban ecology : There was broad agreement amongst respondents that urban sites were ecologically different  from rural sites. Urban nature included native and non-native species and these unusual assemblages needed to be recognised and acknowledged in their own right.  At the time of the study, the absence of any national inventory of vegetation communities in urban areas such as that provided for other community types by the National Vegetation Classification (NVC) was seen as a disadvantage by several ecologists. Thought to be useful as a means of codifying and communicating to others what vegetation communities are present on a site, the NVC however is not a classification designed to assess the conservation value of a site.  It cannot be used to determine the representativness or rarity of a community nor is it a prescriptive classification capable of determining what range of species a site should be expected to support.  As one consultant remarked the sheer diversity of native and non-native species and the different social and economic histories of  urban sites would seem to suggest  that such a classification would prove impossible to achieve: ‘Things are so city specific …I can’t conceive how a classification would be done…I can’t conceive how they’ve managed to give them assemblages , and those assemblages certainly won’t carry any cultural overtones, I assume’. ( Quote: LC)  The absence of such a framework by others served to strengthen the fact that ‘the ecology of wasteland sites is like where nature conservation was back in the 1970s - pre NVC; pre Ratcliffe’ .
Whilst the absence of a framework for codifying the vegetation characteristics of urban sites seemed to confirm the weak scientific base of urban ecology, respondents were aware that research studies had shown that site characterisations which rely on vegetation such as NVC are a poor indicators of their associated fauna. One scientific study in particular had made an important contribution to  the scientific understanding of urban sites. Gibson’s study (1998) entitled ‘ Brownfield: red data: the values artificial habitats have for uncommon invertebrates.’ was commissioned by English Nature - the public agency with statutory responsibilities for nature conservation. It demonstrated the importance of artificial urban habitats as reservoirs for several nationally scarce invertebrate species that were otherwise understood to be members of rural habitats such as grasslands, heathland and coastal areas. This publication was referred to by several of the  ecologists  we interviewed. Whilst the focus of Gibson’s study is on rare invertebrates,  the burden of his argument is that existing Phase 1 surveys on which most site appraisals are made – including that of the London Ecology Unit  - are wholly inadequate for an assessment of artificial habitats such as wasteland. Pointing to the over dependence of the Phase 1 method on vegetation and its oversimplification of structural elements important to invertebrates, he identified several key components of inventory that need attention. These include an estimate of site age and succession rate; substrate material and pH, particle size, aspect and shelter as habitat  components as well as evidence of  clear limiting toxicity or pollution.   
Gibson’s study and the suggested additions it makes for improving approaches to the inventory of artificial habitats such as urban wastelands proved influential with  several ecologists we interviewed.  Respondents from the statutory agencies believed that this was the kind of routine inventory that should be conducted on all wasteland sites ‘rather than meaningless lists of species’ ,  and one private sector ecologists talked about the impact this study had had on his own thinking:  ‘The theory was there were quite a few species that may have always been there ( in urban habitats) and how they survived or adapted  to these habitats, whereas in the wider countryside the use of chemicals had led to them dying out.  So the idea suddenly came, ‘urban reservoir populations’, which put a whole new conservation side on brownfield ecology from my point of view’. Scientific evidence provided justification for conserving brownfield habitats in their own right and convinced this consultant to adopt this new approach to site characterisation in his own work.  However, as evidenced by other respondents this approach had not become routine practice.  
Coping with scientific uncertainties and the development process: Recognition of the authority that a scientific approach gives to working practices meant that several respondents emphasised the need to employ consultants who were familiar with urban ecology in particular.   The fact that there were few urban ecologists in the UK meant that few general principles could be made about the likely composition of urban communities, their relationship with the physical habitat  or their likely succession or developmental trends. Under these circumstances several respondents emphasised the importance of an ‘experiential and experimental approach’ to learning how urban habitats and species functioned. Talking about the Thames and its urban habitats, one respondent said: ‘You know a lot of work has been done on salt marsh on the coastline, and the transition of salt-marsh habitats, and nothing in an urban situation where you’ve got coastal screes, you’ve got encroachment, you’ve got high walls. So we literally learnt, myself, the biologists, the fishery officer just spent two or three days out on the river …, stopping off at every bit of foreshore and different habitats, and different hides, and looking at the invertebrates, and looking at where the fish fry were lying up, mapping plant species… So we did literally back of the beer mat science … to give us enough knowledge to sit down with the engineers and say: “OK, this is our best guess, but it’s the best experienced scientific guess.  We need these terraces at these heights. We want this size gravel – xyz – can you build it?”’.  
In a similar vein one naturalist regarded by many to be ‘the expert’ on a nationally rare species put the tension between science and locally acquired  knowledge  like this:  ‘…if you’re trained as an ecologist, you’re trained in this kind of scientific thinking…and half the things I’m talking about and everybody accepts, well,  I don’t know whether it’s going to work, I haven’t got any idea if it will work, it’s only subjective…actually a lot of ecology is subjective …’  The highly provisional nature of knowledge about urban ecology meant that assessing both the conservation status of species and habitats in urban areas and the likely success of mitigation measures itself is highly speculative. 
The poor state of scientific knowledge that resided in the statutory agencies was a concern to their members and to the ecological consultants who seek their advice and guidance.  As one ecological consultant put it ‘ if you look at an organisation such as English Nature…basically there isn’t a sort of depth of analysis of  nature conservation resources.’  As a result , the comments of statutory consultees who were asked regularly to comment on development applications   ‘were often made in wishy-washy  language which tends to sort of walk around the houses’ . For two of the private sector consultants this seemed at least to under-utilise the power the state had invested in them as statutory advisers. In turn, this level of ignorance engendered a sense of inadequacy as well as frustration for employees of the statutory agencies.  A sense that was heightened by a planning system that positioned statutory consultees as ‘experts’ and promoted an adversarial process that pitted one set of experts against another.  As one public sector respondent put it: ‘the planning system ‘did little to promote or secure the conservation of sites of nature conservation importance’ . Reflecting perhaps the more aggressive stance the EA could take through its statutory remit to promote nature conservation in its work, these same consultants believed the Agency to be the more effective of the two in providing critical and constructive ecological advice. In practice therefore, although the science base of urban ecology was weak, the culture of public sector agencies also seemed to influence whether their staff adopt a ‘bullish stance’ to insisting that development should address nature conservation issues seriously. 
The lack of authoritative comments from the statutory agencies meant that some private sector ecologists turned to local enthusiasts and natural historians as a source of expertise about urban sites.  One private sector ecologist described this relationship in the following way: ‘London is a big place, about a fifth of the British population, so there’s a lot of interested people there who work on wildlife, and quite frankly one would be extremely arrogant to think that one  could contribute to a process without tapping into that resource.  Funnily enough though a large number of consultants do exactly that and never tap into expertise, they never really take things to the spirit of where the science is, they don’t take it far enough at all, which may facilitate some development with very little extra work for the developer.  Treading a diplomatic line between using local wildlife experts as ‘hired hands’ to save the developer money, and wanting to give due recognition to the contribution local enthusiasts make to the scientific base of urban ecology, this consultant demonstrates some of the tensions facing scientific experts. Trained in a discipline that did not recognise the distinctiveness of urban areas as worthy of study in their own right, ecological consultants were often highly dependent on local naturalists and other local professional ecologists to assist them in their work.
Another consultant was less convinced of the need to work routinely with local experts and wildlife trusts.  In part this was because he felt it was up to the local authority to provide a clear framework within which ecological consultants could work.  Placing the onus firmly on the local authority, he supported the efforts of one local authority planner to provide ecological guidelines aimed at the planning profession. ‘It’s like a series of check lists, you know, this is what should be done before your investigation, this should be done when you’re considering giving planning permission, this is what should be done afterwards. It’s very clear and it brings what is really a very complex discipline together.’  The corollary of this approach is that with a clear set of guidelines about what ecological information is required of them by the planning authority, then consultants would be able to provide it without recourse to local wildlife groups or naturalists. From another perspective however, one public sector ecologist believed that the check-list approach ‘gives the impression that it’s a case of destroying the enemy by picking off the soldiers one by one; no bats; no badgers; that little patch there is of negligible value etc, and you will find that the whole site has a very low value rating.’   In his view, the ability of the check-list approach to offer the integrative and holistic appraisal the scientific discipline of ecology seemed to require, was itself a matter of dispute.  
This check list approach to best practice has been supported by other sectors too, for example the RSPB in association with WWF-UK and the Wildlife Trusts (Byron 2000). Aimed primarily at planners and consultants such an approach suggests a confidence in these professions to acquire, interpret and apply ecological knowledge to brownfield sites that other respondents felt misplaced. As one other consultant put it : ‘I think among planners there is a great gap, they don’t perceive wastelands as having wildlife value’.  Notwithstanding the fact that within the planning system there is general acceptance that ‘there is nature in urban areas that is of value’, acceptance of the proposition that brownfield and wasteland sites have wildlife value still demands a culture shift amongst local authority planners. Other respondents pointed to the fact that while planners were comfortable with the fact that ‘woodlands are valuable wildlife habitats’,  this same appraisal did not extend to wasteland habitats. Being charitable to planners one environmental consultant suggested ‘in fairness to planners, they’re blind, they’ve had no exposure to it.  They’re not trying to be obstructive, they simply do not know…There are a number of local authorities which have internal people who are ecologists, and quite a number of them have wildlife trusts attached to them, there’s quite a close link, and so long as planners have rubbed up against that, they perceive that there might be an interest, but where they haven’t had the opportunity to rub against that, they perceive that there is no interest, so it doesn’t even cross their minds that they might need to call someone in.’.   Adding support to this interpretation, one local authority ecologist admitted that it was not ‘routine practice for planners to inform me  when development applications on brownfield sites were being proposed or discussed’.   In other words it was up to the ecologist to take the initiative to seek out development proposals and in most cases this meant that advice could only be reactive and not pro-active. 
One of the naturalists pointed to a different problem.  Planners often ‘compartmentalised’ biodiversity and nature conservation: ‘convincing planners and councillors that biodiversity is integral to the urban infra-structure is the problem…they think we all want it to be a National Nature Reserve, but that’s not what I’m after!’  Promoting the conservation of  rare and declining species as ‘flagship’ species that required a more holisitic approach to re-development was one means of addressing this issue, but without an effective knowledge network that planners routinely mobilise to inform them of the conservation value of  key species associated with wasteland sites, it is difficult to assess how ‘professional’ local planners can be when it comes to advising their councillors about nature conservation. 
Wasteland habitats: transience, re-creatability and the science underpinning mitigation measures: Scientific studies of wasteland habitats point to their high species diversity but also to their transient properties. Left to themselves,  the open and herbaceous communities of recently abandoned wasteland sites  will be colonised by shrub and tree species such as buddleia and willow.  As one professional ecologist put it ‘every ecologist knows it’s that transition that makes them of value’.  In this respect like many other artificial habitats such as heathland and chalk grassland, wasteland habitats would require managing if their species complement is to be maintained. Deciding which ‘desired state’ is optimal for achieving and maintaining high biodiversity would need to be made based on further  detailed studies.  For these reasons several professional ecologists recognised the value of wasteland sites as ‘ecological laboratories’ through which the ‘status of wastelands ecologically would be raised.’   Studies would contribute new scientific knowledge about how communities are assembled and the role of competition, isolation and urban micro-climates in explaining levels of biodiversity. As potential laboratories wastelands have intrinsic value but their distinctive ecology also means that assessing their conservation value and the damage associated with development is often highly speculative.  
Concerns about how damage limitation and mitigation measures were to be assessed also  focused on the transient nature of wasteland habitats. and the need for management. Ecologically-informed advice to the developer would probably include a recommendation ‘that we scrape the site and make it safe and just leave it… smash up the concrete – because I can see how a developer wouldn’t want chunks of concrete 30, centimetres across – well, 2 centimetres, yes you can live with that, so that’s the kind of recommendation maybe we should be pushing harder for.’ Such an approach is contrary to conventional landscaping approaches that often involve scraping the surface of the site, removing this debris and importing new topsoil.  Likewise, management practices required to maintain the desired ‘ecological state’ are likely to involve scarifying the surface every five or six years and some hand pulling of shrubs and cutting back brambles.  Recognition that wasteland communities could be re-created as part of the landscaping process and would require provision for future management as part of damage limitation and mitigation measures was not routinely addressed either in the advice sought or offered by planners, or by the majority of professional ecologists. Mitigation  measures were addressed in the two case studies and in both cases were offered as deliverable ‘products’ that paid little attention to the uncertainities which surrounded their origins or implementation. 
The mitigation measures offered by the developers at the larger wasteland site were based on an experimental but ecologically informed approach to habitat re-creation. Of perhaps most significance however, was the fact that these mitigation measures were proposed for a former industrial wasteland site that had no recognised importance for biodiversity or nature conservation. To all intents and purposes the local authority regarded the site to be a ‘wasting asset’. However, the detailed ecological inventory undertaken by a team of local urban ecologists assembled by the developer’s consultant, revealed the site to have high biodiversity. Several rare and nationally declining invertebrate species were recorded on the site and the site was assessed as being capable of supporting breeding opportunities for a nationally rare bird – the black redstart.  Through a complex process of networking that involved the consultant in drawing on the experience of ecologists working in the public and voluntary sectors and local naturalists, a series of mitigation measures were assembled that secured cross-sector support.  Among several proposed mitigation measures, the development application included the use of crushed concrete derived from the original site to form re-created wasteland habitats that were to be sown with locally collected seeds.  Other proposals addressed measures such as nesting boxes for bats and birds, green roofing material impregnated with Sedum species to serve as a roof top habitat for insects and birds, and soft-engineering approaches to the creation of marginal riverside habitats. Highly innovative in design and as the consultant put it ‘claiming back space from the architects for ecology’ meant that the submitted proposal included many benefits to nature.  Letters of objection and council papers show that many of the environmental measures were welcomed by local residents and members of amenity societies even though they objected strongly to the scale and overall design of the development.  However, our interviews reveal that all the professional ecologists involved with the application regarded these measures as highly experimental and without any guarantee of success. In the words of the developer’s consultant: ‘habitat creation in urban areas can only be experimental – we don’t have a Vymura book of options to offer the client or the public’. Furthermore as the borough’s ecologist noted, without  securing a commitment to managing the future development in an ecologically informed way, many of the proposed benefits would be transient.
The mitigation measures offered by the developer at the small former railway land  site, addressed future this kind of concern through the provision of a commuted sum of money to fund a management programme for the Local Nature Reserve. The commuted sum was included in the Planning Agreement forged between the developer and the local authority.  The London Wildlife Trust (LWT) managed the site by agreement with the local authority as a site of importance for nature conservation. Protracted discussions with the local authority, the site owners, had eventually led to the site being declared a Local Nature Reserve at the same time that active discussions about developing part of the site for housing were taking place. The developers were bemused by the local authority’s position – seemingly the local authority wanted to conserve the site on the one hand but to develop part of it on the other. A senior local authority officer explained their position in these terms. The development was a ‘win:win’ proposal – ‘the developer gained space for more housing and nature benefited as well’ . Members of the local LWT group who managed the small wasteland site were opposed to the incursion of housing into the Local Nature Reserve but ‘were not prepared to go to wall about it’.  More important was to manage the remainder of the site to ensure high populations of species that frequented it. The commuted sum offered by the developer for managing the site seemed to compensate for a small incursion of housing onto the site especially in circumstances where raising funds for recurrent expenditure were difficult. This opinion differed from the view offered by other public sector professionals who had advised against this proposition on the grounds that to permit an incursion of housing onto a locally designated site of importance for conservation was to underestimate its value. It was this latter view which resonated with local residents.  The open meeting of the planning committee, at which permission was given, heard many objections from local residents. The burden of their opposition lay with the proper conduct of the council and their expectation that a policy designed to protect local sites of importance for nature conservation would be upheld precisely because these policies had been agreed on as part of a democratic process open to public scrutiny. By contrast, the planning agreement under which a commuted sum for the management of the remainder of the site as a Local Nature Reserve seemed like a ‘deal’ between the local authority and the developer over which local people had no say..  Here, not only is the scientific basis of nature conservation under challenge but also the democratic process through which local sites of conservation importance are taken forward into the Unitary Development Plan.  Valuing mitigation measures in terms of the benefits that might accrue in scientific terms was not commensurate with local people values. For local residents the conflict between conservation and development was as much a political project as a scientific one.   
Social and cultural rationales for promoting nature conservation
One of the characteristics of the urban wildlife movement has been its engagement with social as well as scientific concerns. In London the spatial hierarchy of sites of importance for nature conservation goals is a deliberate attempt to ensure that residents have access to high quality natural environments.  Their approach  recognises ‘areas deficient in access to wildlife sites’ when a SINC cannot be  reached within reasonable walking distance of the home.  English Nature as a statutory agency with responsibility for nature conservation has adopted similar guidance in its own policies for urban areas (Box and Barker 1999). Most private sector ecologists did not mention these aspects of assessing the nature conservation value of a development site preferring instead to be guided by national criteria that rely heavily on a scientific base (Ratcliffe 1977).  For members of the voluntary sector however, these social and cultural concern were fundamental to what urban nature conservation was about, even though this emphasis often led to tensions with both their members and other naturalists. 
In many respects local enthusiasts and volunteers provide legitimacy to the Trusts in their capacity of ‘speaking on behalf of the community’ in the planning process.  Members of the voluntary sector argued strongly that this is a role that none of the statutory agencies or the LEU could legitimately play because ‘they have little direct contact with local communities – staff in these organisations seldom work at weekends or in the evenings’. So whilst statutory agencies and local authority advisers such as LEU are keen to advance policies of ‘local sites for local people’,   voluntary sector groups see themselves as the only ones with a legitimate community  base on which to build these claims.  Acquiring this legitimacy brought frustrations too.  For example, investment in community outreach work had declined during the economic depression of the 1990s as Trusts sought to improve their financial footing. Without the professional expertise offered by these outreach officers, professional ecologists who are employed by Trusts because they are knowledgeable about the ecology of urban sites are often ill-equipped to play a wider capacity-building role in the local community.  This was especially true in the ethnically diverse communities of east London.  As one voluntary sector employee put it: ‘It’s just hard, but even with us trying to get ore volunteers involved, it’s picking up, but it’s a hard job, and we’re not getting enough people from – I was going to say the ethnic minority – but it’s like the ethnic majority in the area, they’re not involved in doing the work.’  Moreover, while the professed goal of urban nature conservation was to improve people’s quality of life through improving accessibility to wildlife sites, this socially inspired goal does not always find support with some ‘‘dyed in the wool’ and often long serving volunteers’.  The proposition that single interest groups like Wildlife Trusts should adopt a more active role in urban regeneration has been an ever-present one. In London it was one of the primary motivating goals of ‘the young turks’ (Smyth 1987) who founded the LWT in the 1970s.  But implementing this vision often proves one step too far for several conservative volunteers and some influential members of the wildlife trusts who believe that to seek wider social goals is ‘too political’. This despite that fact that funds are available to achieve this goal for example, in the Single Regeneration Budget and Millennium funds.  The establishment of environmental regeneration trusts such as Groundwork Trusts and the changing role of other voluntary sector groups such as the British Trust for Conservation Volunteers was cited by  voluntary sector respondents as evidence of the opportunities such an approach offers. From this perspective externally driven change and the reluctance of influential members of the voluntary sector to take advantage of these new funding opportunities had consequences for the role wildlife trusts could play in the planning process. As a result it seemed that the legitimate claims of the voluntary wildlife groups to represent local people and to contribute considerable local knowledge about the ecology of sites would be marginalised and discounted (Murdoch and Clark 1994).    
Our interviews suggest that some respondents believed urban nature conservation to be as much about social goals as about improving the future of wildlife, but the emphasis given to people was often difficult to promote in practice. That having been said some respondents defined urban ecologists in terms of their ability to work across the natural and social sciences. For example, one public sector respondent  said that urban ecologists recognised that ‘the biodiversity of wasteland sites was ‘fantastic’ and also recognised their  significance as cultural linkages with the past.’  She explained what it meant to be an urban ecologist involved with wastelands:  ‘ I like urban nature, I like to see how much nature has adapted to urban situations, but also how much diversity there is on these sites. That  you can actually bring people into these sites who are actually living in the city, how people’s life experiences are actually changed by that. So I think that we’ve got a very good network of some very, very good ecologists, and very committed people in London, so the sense of the knowledge that we’ve got about wasteland sites, I think is extremely good.’.  For this respondent, the scientific, social and cultural goals of urban nature conservation that can be expressed trough working with education projects concerned with wasteland sites seems to capture the essence of what being an urban ecologist means. 
Naturalists who often worked on their own did not necessarily see themselves as part of the conservation movement. Instead they emphasised that they were members of the community with a passion for place as well as being passionate about individual species. Trying to convince planners in particular of the importance of  ‘place’ in terms of its functional role as a habitat for wildlife was an uphill struggle. Talking about the sectoral approach taken by planners to amenity and nature conservation, one naturalist said: ’It’s like …”you’ve got 20 meters over there”… I say “No, no, no, we’re talking about this bird that lives in the whole area that’s 3 miles square and actually the whole area is a wildlife site!" Other respondents whilst prepared to promote the conservation of wasteland sites and access to them also recognise the ambivalent attitudes such wastelands provoke. Aesthetically unattractive during the winter and giving the appearance of being uncared for at all times of the year means that it is difficult to displace the dominant cultural aesthetic which has traditionally placed high value on the manicured and orderly landscape or a more tamed and pastoral  landscape.  One consultant ecologist commented that while in the countryside ‘people are more prepared to accept areas of rough grass in order to benefit wildlife and that this is perhaps one indication that these cultural tastes are changing.  The same is not quite so true in urban areas.’ Letting the wild into urban areas is always likely to be an assault on the countryside aesthetic that prevails – countering this often powerful opposition would needed thought and diplomacy especially as one public sector ecologist put it: ‘… now they’re seen as places for joy riders, drug takers, various other anti-social activities, certain dangerous places they go to, …it’s the last place that anyone would allow their kids to go, and it’s totally understandable.’. Raising the social profile of wasteland sites meant emphasising their positive values: ‘they are really colourful, they change through the seasons, the insect life is much more…well things happen in comparison with a green desert.’ 
The task of capturing the multiple social and cultural values wastelands are invested with is problematic for most urban ecologists - including those with a social science background (Rhode and Kendle, 1994). For the greater part this is because there is no nationally agreed methodology for revealing or evaluating the conservation importance of sites which fall outside a statutory framework – the so-called local sites or Sites of Importance for Nature Conservation or SINCs.  However in London the experience of the LEU is a material consideration. The criteria used by the LEU to compare different sites include sixteen criteria, several of which give expression to social and cultural reasons for assigning importance to a site. Criteria include for example, use for education, research and quiet enjoyment of nature, aesthetic appeal, and cultural and historic character.  These criteria have been developed and applied in a variety of urban contexts throughout London and have proved sufficiently robust in formal planning enquiries to prevent development on a number of SINCs.  However, any system of evaluation that is expert driven will be contested by other experts, particularly in situations where the scientific basis of site evaluation is highly provisional and where a full range of stakeholders have not been included in the evaluation process.  The expert approach also discounts consideration of common and familiar plants and animals and for many people it is this everyday nature that is enjoyed most (Harrison et al 1988).  It is for these reasons members of the voluntary sector assert that, without a base in the community or an effective means of consulting local people, it is difficult for statutory and other public sector groups to claim that they represent what is valued by a local community.
More fundamentally perhaps is the call for such methods of site evaluation to better capture what is valued by local people well before development proposals are cast in stone. One approach to providing a more participative approach to site evaluation is  called Environmental Capital (CAG/LUC 1998). This approach has being supported by statutory agencies such as EA, EN and English Heritage. As rehearsed by one consultant familiar with  the approach: ‘Environmental Capital has the flexibility of dealing with two sides of the coin. In other words it has the flexibility to deal with a knowledge of the scientific value of these sites, you know , biodiversity and rarity, and deals with the cultural and locally important issues, like “We like it because it’s the only place that has birds that sing at us”. Putting it another way it’s a way of thinking that emphasises benefits.  ‘If you say to any anybody, be it professional or man in the street: ”Why is this site important to you?”, they tend to come back in benefits language . They’ll say “because of the bird song, because it’s a nice place to sit, and I go fishing every Saturday. It provides a framework that automatically accepts that this is the kind of information you’re going to get back which is what the Environmental Capital approach does, then it can be a helpful way of doing things’.  Although not  yet sufficiently refined in its detail  to be adopted widely in the planning process as a workable methodology, Environmental Capital  has been used by several local authorities. It is also being used  by some house builders, for example, in developing proposals for the extension of settlements in South East England. If used early on in the development process such an approach offers a transparent and inclusive  means of  capturing the range of values local people and other stakeholders  attach to brownfield sites. The methodology also offers itself as the comprehensive and integrated approach to ‘capacity studies’ required to achieve sustainable development. Rather than placing the focus on the physical capacity of brownfield sites, such an approach would deliberately include an assessment of the  values local people attribute to existing sites. This more locally-centred approach seemed especially important in the context of the London case for in the past, the ups and downs of the development cycle had ensured new wasteland sites were created regularly.  Now, the scale and intensity of development being experienced in London seemed to be unprecedented and likely to put  the survival of all wasteland sites at risk. 
Knowledge networks and the process of ecological modernization. 
Given that the goals of nature conservation are many and the values justifying them are often incommensurable, it is easy to see why, when confronted by this multiplicity of arguments, even those local authorities most committed to nature conservation will be persuaded by the ‘development imperative’.  Coupled with the adversarial nature of the development planning process, several respondents felt that if  nature conservation policies for  wasteland habitats are to gain political clout then  advocates need to share their knowledge and understanding in ways that  transcend traditional allegiances. Either that, or members of these communities needed to work with developers from the outset – an action that runs the risk of ’capture by association’ and alienation by their peers. One of the naturalists who had worked as a consultant with the voluntary sector and who had been approached by an ecologist working for a developer explained what these tensions involved. ‘I talked with him (the developer’s ecologist) and to be honest I said to him: “What you’re coming up with, struck me would be fine”.  His problems were with the developer.  To a certain extent one would have liked more, but it seemed to me politic at the time of the public display - when we all went down and looked at the plans, and may be it’s just my sort of intuitive understanding, he was almost looking for my support. So there’s a case in point, of like, where you know, when somebody is genuinely pushing an argument and actually may be pushing to the point where it’s actually getting near breaking point.  And because of my role as a non-government officer, I tried to make it very clear that it could have been much better, but this was actually the second most …scheme we had come across, because it hadn’t actually been decided…I don’t think that was like for cynical reasons.’  Finding himself in the role of  ‘salesman’ (sic) this respondent was conscious of his own role as a knowledge broker. His own ‘expertise’ was not acquired through formal scientific training but through the cumulative knowledge of the committed amateur but on this occasion it could give authority to the proposals offered by the ‘expert’  consultant.  Such ‘role reversal’ is seldom given credence in the public arena of formal planning inquiries for example, where science and scientific experts are usually pitted against each other and the knowledge of local naturalists is discounted or admitted as just one of many local views.
Viewed from the public sector there is also support for a more collaborative way of working through which developers and land owners seek guidance from professional ecologists.  ‘Most recently, in fact it was the initiative of the site developers, not the house builders, they had discussions with the Environment Agency as well…they are now sort of in a process of encouraging others to come on board including the GLA to sort of work together for the best ecological possible plans about development…. They’re quite keen to sort of get things as good as they can for nature conservation'.    The question of whether or not developers will take their own environmental responsibilities seriously remains to be seen.  There is some evidence that developers are prepared to commission more ecologically sensitive development proposals both because they learn from the ‘successes’ of their competitors, and are reminded of the costly delays posed by direct action that has prevented some brownfield sites in London from going forward. Gargoyle Wharf for example, in the London borough of Wandsworth has remained ‘un-developed’ for several years through a combination of direct action and sustained local opposition.  Working with developers early on in the development process is seen by many ecological consultants and some naturalists as a key concern that might see biodiversity considerations taken into account more effectively than is current practice. However, without a planning process that is more accessible and responsive to local people’s views, this approach may also be contested at the local level. 
Conclusions
This analysis of the tensions experienced by ecologists and conservation professionals engaged in the re-development process of brownfield sites raises several unresolved issues. First, scientific claims that wasteland habitats associated with brownfield sites are of intrinsic importance rest on the codification of these habitats as distinctive habitats characterised by suites of species and abiotic conditions that fulfil a range of scientific criteria.  Conventionally such criteria relate to high habitat and species diversity and to the geographical and biological status of species as ‘rare’ or ‘declining’.   In urban areas however, the poor scientific knowledge of wasteland sites, and in particular the absence of any systematic survey and evaluation of such habitats, means that these claims are difficult to substantiate.  Instead, most ecological knowledge about these sites resides with amateur naturalists and enthusiasts whose working practices often fail to conform to scientific methods of recording and evaluation. The question then arises about what credence can, or should be given to other kinds of knowledge in determining the conservation status of  brownfield sites - notably the value of wasteland habitats.  As shown here scientists do not have a monopoly of knowledge about wasteland habitats, how to manage them or how to re-create them. Urban nature in general and wasteland habitats in particular, might be better served if scientific conservation were to concede more ground to local knowledge and local specificity of place.   
Second, although the immense public appeal of nature conservation stems from  cultural associations of nature, the practice of nature conservation has been dominated by the rationality of science, (Adams, 1997) As a result rationales used at a national and regional scale prioritise scientific criteria to determine which key sites should be protected. In the London case however, the approach developed in the public sector by the London Ecology Unit seeks to ensure that the practice of nature conservation is both a scientific project and a social one through which equal access to high quality environments is promoted. Such an approach accurately reflects government advice, for example, PPG 9 Nature Conservation (DETR 1994) but at present the approach lacks the authority that would result were it to become mandatory.  Local authorities will continue to exercise discretion in their interpretation of policies designed to protect local sites of importance for nature conservation and decisions made at the local level to permit development may well impact on SINCs including some brownfield sites. Given that central government policy asks local authorities to examine the housing capacity of brownfield sites first and other land only second, this wider political climate gives added legitimacy to local decisions even when they appear to flout democratically agreed policies that contradict them. It seems likely too that the weight local authorities give to protecting nature conservation sites is likely to be increasingly influenced by the outcomes of negotiated Planning Agreements. Some authorities already take an aggressive stance on planning agreements for achieving benefits for nature conservation but others do not.  More importantly, such agreements are a product of an essentially ‘private’ process from which the public and other parties are excluded. In practice therefore any conservation ‘benefits’ are likely to rely much on the competence of professional planners to make judgements about nature conservation.  Our study suggests that this competence is highly variable and public confidence in the planning system to act in the public interest is low.   
Third, in seeking to advance or contest a more pluralistic approach to nature conservation, the numerous actors involved in the development process draw on a range of knowledges and rationales to support their respective case. For example, consultants retained by developers need to access local knowledges that reside in the organised and un-organised voluntary sector. Public sector authorities often work closely with the voluntary sector because the successful delivery of their nature conservation policies often depends on a close partnership with voluntary groups (Marshall and Smith 1999). In addition, local naturalists who work independently and often outside the organised nature conservation sector, are called upon by all parties - especially in cases concerned with particular sites or locally rare and vulnerable species. Whether their knowledge is mobilised and acted on in the planning process is likely to depend on the predisposition of particular naturalists and those who seek their advice. Importantly too, the planning process is a process dominated by an instrumental rationality that privileges scientific knowledge at the expense of other knowledge and arguments.  Therefore, unless developers and their consultants make an active decision early on in the development process to pursue an ecologically sympathetic approach, the adversarial process of public debate means that neither the scientific nor the social rationales underpinning nature conservation claims will fare well. 
The requirement to mobilise knowledge networks during the planning process is an important one not least because some developers are adopting ‘green credentials’. Seen as a process of ecological modernisation, this process involves private sector organisations seeking to adopt an environmentally responsible approach to development without challenging the structural or legislative basis of the status quo. Often regarded with suspicion by conservationists as a means of pursuing a quick and least costly route to gaining planning permission ‘greening’ often amounts to little more than ‘cosmetic landscaping’. However, some developers are seeking to address these concerns at the outset of the development process rather than as an outcome of it, and this pro-active approach poses new challenges to all the key players in the development process.   For the developer accessing and mobilising local knowledge and not just expert knowledge may become a requirement of  this pro-active approach and naturalists and professional ecologists who are familiar with local conditions find themselves being enlisted into this process.  On the evidence of our study, actors negotiate their roles in this process of ecological modernisation in different ways.  In some cases where the development threat to valued local brownfield sites is regarded as being so potent and powerful, direct action such as site occupation by local groups seems one justifiable response.   Other responses amongst professional actors include reliance on ‘good practice guidelines’ to inform the planning process that works in the ‘public interest’. Yet other actors adopt a more flexible and pragmatic approach that eschews  ‘best-practice guidelines’ in favour of more loosely formed ‘alliances’.  In all cases the mobilisation of knowledge networks plays an important part in how the re-development process unfolds.  At present these knowledge networks are fluid, unpredictable and unstable. In many respects the activities of the London Biodiversity Partnership are an attempt to formalise these networks. The Partnership may well provide a congenial atmosphere in which to exchange knowledge about conserving biodiversity but unless the private sector takes its responsibilities towards conservation seriously, the Partnership will always be prey to the whims of developers. For example, unlike landscape architects, ecologists are not regarded an integral part of a developers’ team and the ecological dimensions of site design and construction are often poor or missing. As a result, ecologists in the public and voluntary sectors often have to act as both consultant and scrutineer – something they are hard pressed to achieve without compromising their own independent position.  If the ecological aspects of proposed developments are to be improved, developers and the construction industry need to change their practices as well as their attitudes to biodiversity conservation.
10.300 approx
 words.
 Acknowledgement: The study forms part of ESRC Project Ref: R000238127.
‘Conserving biodiversity that matters.’  The authors would like to thank other members of the research team for comments on an earlier manuscript.

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