Portrait of Dr Joseph William Bull

Dr Joseph William Bull

Senior Lecturer in Conservation Science
Deputy Director of Recruitment and Admissions (Conservation)


Dr Joseph Bull is a quantitative conservation scientist with an academic background in Ecology and Physics. Following a stint as a private-sector environmental consultant focusing on Ecology and Climate Change, he undertook a PhD at Imperial College London (2010–2014). He came to DICE in 2017 following completion of a Marie Curie H2020 postdoctoral fellowship at the University of Copenhagen, Denmark, and remains a visiting researcher at the University of Oxford.
Joseph is primarily interested in natural resource management within dynamic socio-ecological systems, particularly in relation to economic development activities. His research currently focuses on biodiversity offsetting and the implementation of ‘no net loss’ policies, which he has explored all over the world (particularly in Central Asia, Australia, North America and Europe). He has also studied the management and conservation of wild populations, including saiga antelope in Uzbekistan and wolves in Scandinavia.
In 2012 Joseph co-founded an ecological consultancy (Wild Business Ltd), which he continues to direct. The consultancy puts conservation research into practice, particularly around the themes of ‘no net loss’ biodiversity and rewilding policies. 

Dr Joseph Bull is a member of the Durrell Institute of Conservation and Ecology

Research interests

  • Moving ecological targets and dynamic conservation interventions
  • Biodiversity offsets and their role in achieving ‘no net loss’ of biodiversity alongside development
  • Evaluating the effectiveness of conservation interventions under change scenarios, including development of useful baselines or counterfactuals (‘frames of reference’)
  • Business and corporate biodiversity strategy
  • Restoration and rewilding
  • Quantum biology and ecology


  • DI305: Biodiversity (module convenor)
  • DI522: Research Project (module convenor)
  • DI533: Professional Placements (module convenor)
  • DI537: Conservation Social Science: Methods and Research Design
  • DI876: Research Methods for Social Science (module convenor from September 2019)
  • DI1001: Multidisciplinary Perspectives on Conservation (module convenor)


Dr Bull is interested in supervising PhD students who bring either natural or social science research methods and expertise to any of his key research themes.  

Current postgraduate students 

  • Sophus zu Ermgassen, PhD: Are No Net Loss policies effective? Evaluating the outcomes of biodiversity offsetting and No Net Loss initiatives around the world 
  •  Zoe Lieb, MSc
  • Rachel Russell, MSc
  • Bethany Read, MSc
  • J. Lind Bejer, MSc: Conservation finance 
  • H. Hamilton, MRes: Corporate biodiversity benchmarking in the UK 


  • Victoria Griffiths, PhD, 2019: Social no net loss for hydropower development in Uganda.
  • Thomas White, MSc, 2018: Monitoring the effectiveness of biodiversity offsetting: implications for biodiversity mitigation approaches in the United States of America 
  • Alejandro Sanchez-Ortiz, MSc, 2018: Decision-making process for implementing biodiversity offsets
  • Maria Guerrero, MSc, 2017: Economic valuation of marine ecosystem services as means to foster conservation, “Tropical Pacific Seas Reserve” case study 
  • Daisy Blackhurst, MSc, 2012: Biodiversity offsetting: a qualitative exploration of applicability and thresholds 
  • Isabel Jones, MRes, 2012: Oil and gas development in Uzbekistan: vegetation responses to disturbance on the Ustyurt plateau 
  • Emma Marsden, MSc, 2011: Conservation of migratory species in the face of new threats and limited data availability, a case study of saiga antelope in Uzbekistan


Dr Bull is available to provide topical comment or in-depth discussion on topics related to biodiversity offsetting, no net loss and any other aspects of business interaction with biodiversity/private sector nature conservation interventions.

Selected, for Bull et al. (2018, Restoration Ecology)

The Times (13/06/2018) ‘Jurassic Park’ fences could bring grey wolves back to Scotland 

The Daily Mail (13/06/2018) Jurassic Park-style fences could mean packs of grey wolves can roam Scotland and reduce the country's vast deer population, scientists say
The Daily Telegraph (12/06/2018) Wolves could cut Scotland's deer numbers if they were in large reserves, says scientists 

For Keith & Bull (2016, Ecography)

Nautilus (10/29/2016) How climate change makes social learning among animals more important 

Selected, for Bull & Maron (2016, Proceedings of the Royal Society B: Biological Sciences)

The Atlantic (10/11/2016) Are humans creating more species than we’re killing?
The Washington Post (06/29/2016) Humans are driving the evolution of new species — and that could be just as bad as causing extinctions
IFL Science (06/29/2016) Humans are forcing new species to appear through unnatural selection
Wired (06/28/2016) Humanity is killing off thousands of species. But it’s creating them, too 

Following Bull et al. (2009, Wildlife Biology)

New Scientist (02/26/2014) Rewilding: bring in the big beasts to fix ecosystems



  • zu Ermgassen, S., Utamiputri, P., Bennun, L., Edwards, S. and Bull, J. (2019). The role of ‘No Net Loss’ policies in conserving biodiversity threatened by the global infrastructure boom. One Earth [Online]:303-304. Available at: http://dx.doi.org/10.1016/j.oneear.2019.10.019.
    Over US$60 trillion is predicted to be spent on new infrastructure globally by 2040. Is it possible to meet UN Sustainable Development Goal 9 (develop infrastructure networks) without sacrificing Goals 14 and 15 (ending biodiversity loss)? We explore the potential role of No Net Loss (NNL) policies in reconciling these SDGs. Assessing country-level overlaps between planned infrastructure expansion, infrastructure-threatened biodiversity, and national biodiversity compensation policies, around half of predicted infrastructure and infrastructure-threatened biodiversity falls within countries with some form of mandatory compensation policy. However, these policies currently have shortcomings, are unlikely to achieve NNL in biodiversity, and could risk doing more harm than good. We summarise policy transformations required for NNL policies to mitigate all infrastructure impacts on biodiversity. To achieve SDGs 9 alongside 14 and 15, capitalising on the global coverage of mandatory compensation policies and rapidly transforming them into robust NNL policies (emphasising impact avoidance) should be an urgent priority.
  • Bull, J., Milner-Gulland, E., Addison, P., Arlidge, W., Baker, J., Brooks, T., Burgass, M., Hinsley, A., Maron, M., Robinson, J., Sekhran, N., Sinclair, S., Stuart, S., zu Ermgassen, S. and Watson, J. (2019). Net positive outcomes for nature. Nature Ecology and Evolution [Online]. Available at: https://doi.org/10.1038/s41559-019-1022-z.
    Much research and policy effort is being expended on seeking ways to conserve living nature while enabling the economic and social development needed to increase global equity and end poverty. We propose that this will only be possible if the language of policy shifts away from setting conservation targets that focus on avoiding losses and towards developing processes that consider net outcomes for biodiversity.
  • Bull, J. and Milner-Gulland, E. (2019). Choosing prevention or cure when mitigating biodiversity loss: trade-offs under ‘no net loss’ policies. Journal of Applied Ecology [Online]. Available at: https://doi.org/10.1111/1365-2664.13524.
    1. Biodiversity cannot always be conserved. Economic development activities can result in biodiversity losses, but also increase human wellbeing, so trade-offs must sometimes be made between conservation and development. An alternative strategy to avoidance of impacts through the strict protection of biodiversity (‘prevention’) is to permit certain biodiversity losses and fully compensate for them through offsets elsewhere (‘cure’). 2. Here, we build a stochastic simulation model to explore trade-offs between biodiversity loss prevention and cure, in the context of development under ‘no net loss’ (NNL) biodiversity policies. Our model implements a Management Strategy Evaluation framework, monitoring outcomes using four different performance metrics: total biodiversity, net biodiversity, total economic activity, and development activity. 3. We find that a "cure" strategy can potentially perform just as well as a prevention strategy in terms of biodiversity objectives, whilst outperforming the latter from an economic perspective. However, this does not undermine the need for a mitigation hierarchy, and the best-performing strategy depends strongly upon both the degree of compliance with the NNL policy and upon underlying ecological parameters. 4. Perhaps counterintuitively, when evaluated as advised by the technical literature (i.e. against an appropriate counterfactual scenario), we find that net biodiversity outcomes are highest when natural ecosystem recovery rates are slow (so long as development rates are also slow). 5. Finally, using the illustrative example of US wetlands, we suggest that real-world NNL policies could already be driving landscape-scale avoidance of development impacts under a "prevention" approach. 6. Policy implications. No net loss (NNL) biodiversity policy is currently being developed or implemented by over 100 countries worldwide and incorporated into environmental safeguards by multinational lenders. The socio-ecological model presented here can be used to advise decision makers about the best structure for nascent NNL policy on the basis of region-specific ecosystem recovery rates, development activity, legal compliance and monitoring uncertainty. Further, the model presents a means for estimating the degree to which biodiversity impacts are avoided by developers under NNL – an important monitoring consideration given that ensuring high levels of avoidance is crucial to robust NNL policy, but which has to date evaded assessment through purely empirical means.
  • Jones, I. and Bull, J. (2019). Major dams and the challenge of achieving “No Net Loss” of biodiversity in the tropics. Sustainable Development [Online]. Available at: https://doi.org/10.1002/sd.1997.
    Dam construction is booming across tropical regions critical for global biodiversity and ecosystem service provision. The principle of “No Net Loss” (NNL)—under which biodiversity impacts of development projects are quantified and fully mitigated—is being increasingly applied to large infrastructure development worldwide, including dams. We discuss the impacts of major tropical dams and associated implementation of NNL policies and outline three major challenges in achieving NNL: (1) overcoming practicalities implementing NNL in highly connected river systems over large spatio‐temporal scales; (2) the stakes are high if NNL fails because tropical regions are hyper‐diverse, rich in species endemism, and difficult to restore; and (3) inclusion of ecosystem services in NNL design is necessary due to the importance of tropical biodiversity for ecosystem service provision at multiple spatial scales. Overcoming these challenges is crucial when hundreds of dams are planned and under construction across the tropics, many potentially subject to NNL policies.
  • zu Ermgassen, S., Baker, J., Griffiths, R., Strange, N., Struebig, M. and Bull, J. (2019). The ecological outcomes of biodiversity offsets under “no net loss” policies: A global review. Conservation Letters [Online]. Available at: https://doi.org/10.1111/conl.12664.
    No net loss (NNL) biodiversity policies mandating the application of a mitigation hierarchy (avoid, minimize, remediate, offset) to the ecological impacts of built infrastructure are proliferating globally. However, little is known about their effectiveness at achieving NNL outcomes. We reviewed the English-language peer-reviewed literature (capturing 15,715 articles), and identified 32 reports that observed ecological outcomes from NNL policies, including >300,000 ha of biodiversity offsets. Approximately one-third of NNL policies and individual biodiversity offsets reported achieving NNL, primarily in wetlands, although most studies used widely criticized area-based outcome measures. The most commonly cited reason for success was applying high offset multipliers (large offset area relative to the impacted area). We identified large gaps between the global implementation of offsets and the evidence for their effectiveness: despite two-thirds of the world’s biodiversity offsets being applied in forested ecosystems, we found none of four studies demonstrated successful NNL outcomes for forested habitats or species.We also found no evidence for NNL achievement using avoided loss offsets (impacts offset by protecting existing habitat elsewhere). Additionally, we summarized regional variability in compliance rates with NNL policies. As global infrastructural expansion accelerates, we must urgently improve the evidence-base around efforts to mitigate development impacts on biodiversity.
  • Griffiths, V., Sheremet, O., Hanley, N., Baker, J., Bull, J. and Milner-Gulland, E. (2019). Local people’s preferences for biodiversity offsets to achieve ‘no net loss’ for economic developments. Biological Conservation [Online] 236:162-170. Available at: https://doi.org/10.1016/j.biocon.2019.05.049.
    Understanding people's preferences for biodiversity offsetting activities can help to design offsets that achieve ‘no net loss’ (NNL) of biodiversity while incorporating the use and cultural values associated with this biodiversity. We use a stated preference choice experiment to solicit preferences for different proposed biodiversity offsets, linked to two hydropower developments in Uganda, with the aim of improving social outcomes of the offsets. We surveyed 1215 respondents from six villages located along the river impacted by the hydropower projects. Overall, people preferred offsets and compensatory activities that benefit the entire village rather than just a few individuals. People opposed the removal of non-native trees from their Central Forest Reserve and some responded negatively towards free access to spiritual sites. Respondents' choices were influenced by gender, age, education level, length of time lived in the village, level of poverty, and whether they believed that the hydropower development had affected their wellbeing. Preferences also varied significantly between villages. Our findings provide insight into locally preferred options for biodiversity NNL offsets. They also demonstrate the use of choice experiments to inform decisions about biodiversity offsets, as part of ensuring that NNL strategies do not make local people worse off.
  • Bull, J. and Strange, N. (2018). The global extent of biodiversity offset implementation under no net loss policies. Nature Sustainability [Online] 1:790-798. Available at: https://dx.doi.org/10.1038/s41893-018-0176-z.
    ‘No net loss’ (NNL) biodiversity policies, which seek to neutralize ongoing biodiversity losses caused by economic development activities, are applicable worldwide. Yet there has been no global assessment concerning practical measures actually implemented under NNL policies. Here, we systematically map the global implementation of biodiversity offsets (‘offsets’) – a crucial yet controversial NNL practice. We find, firstly, that offsets occupy an area up to two orders of magnitude larger than previously suggested: 12,983 offset projects extending over ?153,679?_(-64,223)^(+25,013) km2 across 37 countries. Secondly, offsets are far from homogeneous in implementation, and emerging economies (particularly in South America) are more dominant in terms of global offsetting area than expected. Thirdly, most offset projects are very small, and the overwhelming majority (99.7%) arise through regulatory requirements rather than prominent project finance safeguards. Our database provides a sampling frame via which future studies could evaluate the efficacy of NNL policies.
  • Griffiths, V., Bull, J., Baker, J. and Milner-Gulland, E. (2018). No Net Loss for people and biodiversity. Conservation Biology [Online]. Available at: https://doi.org/10.1111/cobi.13184.
  • Addison, P. and Bull, J. (2018). Using conservation science to advance corporate biodiversity accountability. Conservation Biology.
    Biodiversity declines threaten the sustainability of global economies and societies. Acknowledging this, businesses are beginning to make commitments to account for and mitigate their influence on biodiversity, and report this in sustainability reports. The top 100 of the 2016 Fortune 500 Global companies' (the Fortune 100) sustainability reports were assessed to gauge the current state of corporate biodiversity accountability. Many companies acknowledged biodiversity, but corporate biodiversity accountability is in its infancy. Almost half (49) of the Fortune 100 mentioned biodiversity in reports, and 31 made clear biodiversity commitments, of which only 5 could be considered specific, measureable and time?bound. A variety of biodiversity?related activities were disclosed (e.g., managing impacts, restoring biodiversity, and investing in biodiversity), but only 9 companies provided quantitative indicators to verify the magnitude of their activities (e.g., area of habitat restored). No companies reported quantitative biodiversity outcomes, making it difficult to determine whether business actions were of sufficient magnitude to address impacts, and are achieving positive outcomes for nature. Conservation science can help advance approaches to corporate biodiversity accountability through developing science?based biodiversity commitments, meaningful indicators, and more targeted activities to address business impacts. With the “biodiversity policy super?year” of 2020 rapidly approaching, now is the time for conservation scientists to engage with and support businesses to play a critical role in setting the new agenda for a sustainable future for the planet, with biodiversity at its heart.
  • Addison, P. and Bull, J. (2018). Conservation accord: Corporate incentives. Science [Online] 360:1195-1196. Available at: http://dx.doi.org/10.1126/science.aau0788.
  • Bull, J., Ejrnæs, R., Macdonald, D., Svenning, J. and Sandom, C. (2018). Fences can support restoration in human-dominated ecosystems when rewilding with large predators. Restoration Ecology [Online]. Available at: https://doi.org/10.1111/rec.12830.
    The use of fences in conservation can be controversial, as artificial barriers constrain natural behavior and ecological dynamics. However, in the case of large predators inhabiting protected areas within a hostile human?dominated landscape, predators may remain at low densities if they face high mortality upon leaving the reserve. In turn, this may compromise the potential for density?dependent effects such as top?down regulation of prey species abundance. We simulate the hypothetical reintroduction of gray wolves (Canis lupus) to reserves in their former range (Scottish Highlands), with the objectives of identifying parameters that allow a viable wolf population and the potential for direct top?down forcing of red deer (Cervus elaphus) densities. We examine the extent to which the number of dispersing wolves leaving the protected area influences whether these objectives are achieved. Our simulations confirm that source?sink population dynamics can result in a self?perpetuating wolf population, but one that never achieves densities needed for strong top?down forcing. When wolf density is weakly controlled by intraspecific competition, strong top?down forcing occurs when 20% of dispersing wolves or less leave the population. When 20–35% of dispersing wolves leave, the strength of top?down forcing is highly variable. The wolf population remained viable when 35–60% of dispersing wolves left, but then did not exert strong top?down forcing. Wolves were vulnerable to extinction at greater than 60% disperser loss. Despite their negative connotations, fences (including semi?permeable ones) could increase the potential for interspecific density?dependent processes in some cases, thereby facilitating trophic rewilding.
  • Arlidge, W., Bull, J., Addison, P., Burgass, M., Gianuca, D., Gorham, T., Jacob, C., Shumway, N., Sinclair, S., Watson, J., Wilcox, C. and Milner-Gulland, E. (2018). A Global Mitigation Hierarchy for Nature Conservation. BioScience [Online] 68:336-347. Available at: https://doi.org/10.1093/biosci/biy029.
    Efforts to conserve biodiversity comprise a patchwork of international goals, national-level plans, and local interventions that, overall, are
    failing. We discuss the potential utility of applying the mitigation hierarchy, widely used during economic development activities, to all negative
    human impacts on biodiversity. Evaluating all biodiversity losses and gains through the mitigation hierarchy could help prioritize consideration
    of conservation goals and drive the empirical evaluation of conservation investments through the explicit consideration of counterfactual
    trends and ecosystem dynamics across scales. We explore the challenges in using this framework to achieve global conservation goals, including
    operationalization and monitoring and compliance, and we discuss solutions and research priorities. The mitigation hierarchy’s conceptual
    power and ability to clarify thinking could provide the step change needed to integrate the multiple elements of conservation goals and
    interventions in order to achieve successful biodiversity outcomes.
  • Milner-Gulland, E., Garcia, S., Arlidge, W., Bull, J., Charles, A., Dagorn, L., Fordham, S., Graff Zivin, J., Hall, M., Shrader, J., Vestergaard, N., Wilcox, C. and Squires, D. (2018). Translating the terrestrial mitigation hierarchy to marine megafauna bycatch. Fish and Fisheries [Online]. Available at: https://doi.org/10.1111/faf.12273.
    In terrestrial and coastal systems, the mitigation hierarchy is widely and
    increasingly used to guide actions to ensure that no net loss of biodiversity
    ensues from development. We develop a conceptual model which applies
    this approach to the mitigation of marine megafauna bycatch in fisheries,
    going from defining an overarching goal with an associated quantitative
    target, through avoidance, minimisation, remediation to offsetting. We
    demonstrate the framework's utility as a tool for structuring thinking and
    exposing uncertainties. We draw comparisons between debates ongoing in
    terrestrial situations and in bycatch mitigation, to show how insights from
    each could inform the other; these are the hierarchical nature of
    mitigation, out-of-kind offsets, research as an offset, incentivising
    implementation of mitigation measures, societal limits and uncertainty. We
    explore how economic incentives could be used throughout the hierarchy to improve the achievement of bycatch goals. We conclude by highlighting the
    importance of clear agreed goals, of thinking beyond single species and
    individual jurisdictions to account for complex interactions and policy
    leakage, of taking uncertainty explicitly into account, and of thinking
    creatively about approaches to bycatch mitigation in order to improve
    outcomes for conservation and fishers. We suggest that the framework set
    out here could be helpful in supporting efforts to improve by catch
    mitigation efforts, and highlight the need for a full empirical application to
    substantiate this.
  • Maron, M., Brownlie, S. and Bull, J. (2018). The many meanings of No Net Loss in environmental policy. Nature Sustainability [Online] 1:19-27. Available at: http://dx.doi.org/10.1038/s41893-017-0007-7.
    ‘No net loss’ is a buzz phrase in environmental policy. Applied to a multitude of environmental targets such as biodiversity, wetlands and land productive capacity, no net loss (NNL) and related goals have been adopted by multiple countries and organizations, but these goals often lack clear reference scenarios: no net loss compared to what? Here, we examine policies with NNL and related goals, and identify three main forms of reference scenario. We categorize NNL policies as relating either to overarching policy goals, or to responses to specific impacts. We explore how to resolve conflicts between overarching and impact-specific NNL policies, and improve transparency about what NNL-type policies are actually designed to achieve.
  • Addison, P., Bull, J. and Milner-Gulland, E. (2018). Using conservation science to advance corporate biodiversity accountability. Conservation Biology [Online] 33:307-318. Available at: https://doi.org/10.1111/cobi.13190.
    Biodiversity declines threaten the sustainability of global economies and societies. Acknowledging this, businesses are beginning to make commitments to account for and mitigate their influence on biodiversity, and report this in sustainability reports. The top 100 of the 2016 Fortune 500 Global companies' (the Fortune 100) sustainability reports were assessed to gauge the current state of corporate biodiversity accountability. Many companies acknowledged biodiversity, but corporate biodiversity accountability is in its infancy. Almost half (49) of the Fortune 100 mentioned biodiversity in reports, and 31 made clear biodiversity commitments, of which only 5 could be considered specific, measureable and time?bound. A variety of biodiversity?related activities were disclosed (e.g., managing impacts, restoring biodiversity, and investing in biodiversity), but only 9 companies provided quantitative indicators to verify the magnitude of their activities (e.g., area of habitat restored). No companies reported quantitative biodiversity outcomes, making it difficult to determine whether business actions were of sufficient magnitude to address impacts, and are achieving positive outcomes for nature. Conservation science can help advance approaches to corporate biodiversity accountability through developing science?based biodiversity commitments, meaningful indicators, and more targeted activities to address business impacts. With the “biodiversity policy super?year” of 2020 rapidly approaching, now is the time for conservation scientists to engage with and support businesses to play a critical role in setting the new agenda for a sustainable future for the planet, with biodiversity at its heart.
  • Bull, J., Brauneder, K., Darbi, M., Van Teeffelen, A., Quétier, F., Brooks, S., Dunnett, S. and Strange, N. (2017). Data transparency regarding the implementation of European ‘no net loss’ biodiversity policies. Biological Conservation [Online] 218:64-72. Available at: https://doi.org/10.1016/j.biocon.2017.12.002.
    ‘No net loss’ (NNL) conservation policies seek to address development impacts on biodiversity. There have been no peer-reviewed multinational assessments concerning the actual implementation of NNL policies to date. Such assessments would facilitate more informed debates on the validity of NNL for conservation, but assessing implementation requires data. Here, we explore data transparency concerning NNL implementation, with four European countries providing a case study.

    Biodiversity offsets (offsets) are the most tangible outcome of NNL policy. Using an expert network to locate all offset datasets available within the public domain, we collated information on offset projects implemented in France, Germany, the Netherlands and Sweden. Implementation data for offsets were found to be non-transparent, but the degree of transparency varies widely by country. We discuss barriers preventing data transparency — including a perceived lack of necessity, lack of common protocols for collecting data, and a lack of resources to do so. For the data we collected we find that most offsets in Europe: are not within protected areas; involve active restoration; and, compensate for infrastructure development. The area occupied by European offsets is at least of the order ~ 102 km2.

    Transparent national NNL databases are essential for meeting good practice NNL principles, but are not currently available in Europe. We discuss what such databases might require to support evaluation of NNL policy effectiveness by researchers, the conservation community and policymakers.
  • Bull, J., Abatayo, A. and Strange, N. (2017). Counterintuitive Proposals for Trans-boundary Ecological Compensation Under ‘No Net Loss’ Biodiversity Policy. Ecological Economics [Online] 142:185-193. Available at: http://dx.doi.org/10.1016/j.ecolecon.2017.06.010.
    ‘No net loss’ (NNL) policies involve quantifying biodiversity impacts associated with economic development, and implementing commensurate conservation gains to balance losses. Local stakeholders are often affected by NNL biodiversity trades. But to what extent are NNL principles intuitive to stakeholders when they are not experts? We surveyed 691 students with limited or no knowledge of NNL policy across three countries, eliciting perceptions of what constitutes sufficient ecological compensation for forest habitat losses from infrastructure development.
    NNL policies assume that biodiversity compensation should be: close to development impacts; greater than losses; smaller, given a background trend of biodiversity decline; and, smaller when gains have co-benefits for biodiversity. However, survey participant proposals violated all four principles. Participants proposed substantial forest compensation abroad, did not always require commensurate compensation within their own country, and required more forest creation if background trends were for habitat decline or if forest creation had fauna co-benefits.
    Our findings suggest that, under certain circumstances, international biodiversity trades could deserve consideration. The findings also support proposals to incorporate social considerations into compensation ratios for NNL. Wherever the rationale underlying NNL is discovered to be counterintuitive insofar as relevant stakeholders are concerned, careful communication of policy intentions is required.
  • Bull, J., Lloyd, S. and Strange, N. (2017). Implementation Gap between the Theory and Practice of Biodiversity Offset Multipliers. Conservation Letters [Online] 10:656-669. Available at: http://dx.doi.org/10.1111/conl.12335.
    Emerging policies worldwide require biodiversity gains as compensation for losses associated with economic development, seeking to achieve “no net loss” (NNL). Multipliers – factors by which gains are larger than associated losses – can be crucial for true NNL. Here, we review the theoretical literature on multipliers. Then, we collate data on multipliers implemented in practice, representing the most complete such assessment to date. Finally, we explore remaining design gaps relating to social, ethical, and governance considerations. Multiplier values should theoretically be tens or hundreds when considering, for example, ecological uncertainties. We propose even larger multipliers required to satisfy previously ignored considerations – including prospect theory, taboo trades, and power relationships. Conversely, our data analyses show that multipliers are smaller in practice, regularly <10.0, and have not changed significantly in magnitude over time. We recommend that NNL policymakers provide explicit multiplier guidelines, require larger multipliers where appropriate, and ensure transparent reporting of multipliers used. Further research is necessary to determine reasons for the implementation gap we have identified. At the same time, there is a need to explore when and where the social, ethical, and governance requirements for NNL reviewed here can be met through approaches other than multipliers.
  • Keith, S. and Bull, J. (2016). Animal culture impacts species’ capacity to realise climate-driven range shifts. Ecography [Online] 40:296-304. Available at: http://dx.doi.org/10.1111/ecog.02481.
    Ecological predictions of how species will shift their geographical distributions under climate change generally consider individuals as machines that respond optimally to changing environmental conditions. However, animals frequently make active behavioural decisions based on imperfect information about their external environment, potentially mediated by information transmitted through social learning (i.e. culture). Vertical transmission of culture (between generations) might encourage conservative behaviour, constraining the ability of a species to respond, whilst horizontal transmission (within generations) can encourage innovation and so facilitate dynamic responses to a changing environment. We believe that the time is right to unite recent advances in ecological modelling and behavioural understanding to explicitly incorporate the influence of animal culture into future predictions of species distributions.
  • Real, R., Barbosa, A. and Bull, J. (2016). Species Distributions, Quantum Theory, and the Enhancement of Biodiversity Measures. Systematic Biology [Online] 66:453-462. Available at: http://dx.doi.org/10.1093/sysbio/syw072.
    Species distributions are typically represented by records of their observed occurrence at a given spatial and temporal scale. Such records are inevitably incomplete and contingent on the spatial–temporal circumstances under which the observations were made. Moreover, organisms may respond differently to similar environmental conditions at different places or moments, so their distribution is, in principle, not completely predictable. We argue that this uncertainty exists, and warrants considering species distributions as analogous to coherent quantum objects, whose distributions are better described by a wavefunction rather than by a set of locations. We use this to extend the existing concept of “dark diversity”, which incorporates into biodiversity metrics those species that could, but which have not yet been observed to, inhabit a region—thereby developing the idea of “potential biodiversity”. We show how conceptualizing species’ distributions in this way could help overcome important weaknesses in current biodiversity metrics, both in theory and by using a worked case study of mammal distributions in Spain over the last decade. We propose that considerable theoretical advances could eventually be gained through interdisciplinary collaboration between biogeographers and quantum physicists.
  • Bull, J., Gordon, A., Watson, J., Maron, M. and Carvalho, S. (2016). Seeking convergence on the key concepts in ‘no net loss’ policy. Journal of Applied Ecology [Online] 53:1686-1693. Available at: http://dx.doi.org/10.1111/1365-2664.12726.
    1. Biodiversity conservation policies incorporating a no net loss (NNL) principle are being implemented in many countries. However, there are linguistic and conceptual inconsistencies in the use of terms underlying these NNL policies.
    2. We identify inconsistencies that emerge in the usage of eight key terms and phrases associated with NNL policies: biodiversity, frames of reference (i.e. baselines, counterfactuals), no net loss, mitigation hierarchy, biodiversity offset, in-kind/out-of-kind, direct/indirect and multipliers.
    3. For each term, we make recommendations to support conceptual convergence, reduce ambiguity and improve clarity in communication and policy documentation. However, we also warn of the challenges in achieving convergence, especially given the linguistic inconsistencies in several of these key concepts among countries in which NNL policies are employed.
    4. Policy implications. The recommendations made in this article, on improving clarity and supporting convergence on key no net loss (NNL) concepts, should help eliminate ambiguity in policy documentation. This is crucial if policymakers are to design robust policies that are (i) transparent, (ii) translatable into practice in a consistent manner and (iii) sufficiently understood and supported by stakeholders to be effective in practice.
  • Bull, J. and Maron, M. (2016). How humans drive speciation as well as extinction. Proceedings of the Royal Society B: Biological Sciences [Online] 283:20160600. Available at: http://dx.doi.org/10.1098/rspb.2016.0600.
    A central topic for conservation science is evaluating how human activities influence global species diversity. Humanity exacerbates extinction rates. But by what mechanisms does humanity drive the emergence of new species? We review human-mediated speciation, compare speciation and known extinctions, and discuss the challenges of using net species diversity as a conservation objective. Humans drive rapid evolution through relocation, domestication, hunting and novel ecosystem creation—and emerging technologies could eventually provide additional mechanisms. The number of species relocated, domesticated and hunted during the Holocene is of comparable magnitude to the number of observed extinctions. While instances of human-mediated speciation are known, the overall effect these mechanisms have upon speciation rates has not yet been quantified. We also explore the importance of anthropogenic influence upon divergence in microorganisms. Even if human activities resulted in no net loss of species diversity by balancing speciation and extinction rates, this would probably be deemed unacceptable. We discuss why, based upon ‘no net loss’ conservation literature—considering phylogenetic diversity and other metrics, risk aversion, taboo trade-offs and spatial heterogeneity. We conclude that evaluating speciation alongside extinction could result in more nuanced understanding of biosphere trends, clarifying what it is we actually value about biodiversity.
  • Maron, M., Ives, C., Kujala, H., Bull, J., Maseyk, F., Bekessy, S., Gordon, A., Watson, J., Lentini, P., Gibbons, P., Possingham, H., Hobbs, R., Keith, D., Wintle, B. and Evans, M. (2016). Taming a Wicked Problem: Resolving Controversies in Biodiversity Offsetting. BioScience [Online] 66:489-498. Available at: http://dx.doi.org/10.1093/biosci/biw038.
    The rising popularity of biodiversity offsetting as a tool for balancing biodiversity losses from development with equivalent gains elsewhere has sparked debate on many fronts. The fundamental questions are the following: Is offsetting good, bad, or at least better than the status quo for biodiversity conservation outcomes, and what do we need to know to decide? We present a concise synthesis of the most contentious issues related to biodiversity offsetting, categorized as ethical, social, technical, or governance challenges. In each case, we discuss avenues for reducing disagreement over these issues and identify those that are likely to remain unresolved. We argue that there are many risks associated with the unscrutinized expansion of offset policy. Nevertheless, governments are increasingly adopting offset policies, so working rapidly to clarify and—where possible—to resolve these issues is essential.
  • Bull, J., Jobstvogt, N., Böhnke-Henrichs, A., Mascarenhas, A., Sitas, N., Baulcomb, C., Lambini, C., Rawlins, M., Baral, H., Zähringer, J., Carter-Silk, E., Balzan, M., Kenter, J., Häyhä, T., Petz, K. and Koss, R. (2015). Strengths, Weaknesses, Opportunities and Threats: A SWOT analysis of the ecosystem services framework. Ecosystem Services [Online] 17:99-111. Available at: http://dx.doi.org/10.1016/j.ecoser.2015.11.012.
    The ecosystem services concept (ES) is becoming a cornerstone of contemporary sustainability thought. Challenges with this concept and its applications are well documented, but have not yet been systematically assessed alongside strengths and external factors that influence uptake. Such an assessment could form the basis for improving ES thinking, further embedding it into environmental decisions and management.
    The Young Ecosystem Services Specialists (YESS) completed a Strengths–Weaknesses–Opportunities–Threats (SWOT) analysis of ES through YESS member surveys. Strengths include the approach being interdisciplinary, and a useful communication tool. Weaknesses include an incomplete scientific basis, frameworks being inconsistently applied, and accounting for nature's intrinsic value. Opportunities include alignment with existing policies and established methodologies, and increasing environmental awareness. Threats include resistance to change, and difficulty with interdisciplinary collaboration. Consideration of SWOT themes suggested five strategic areas for developing and implementing ES.
    The ES concept could improve decision-making related to natural resource use, and interpretation of the complexities of human-nature interactions. It is contradictory – valued as a simple means of communicating the importance of conservation, whilst also considered an oversimplification characterised by ambiguous language. Nonetheless, given sufficient funding and political will, the ES framework could facilitate interdisciplinary research, ensuring decision-making that supports sustainable development.
  • Bull, J., Hardy, M., Moilanen, A. and Gordon, A. (2015). Categories of flexibility in biodiversity offsetting, and their implications for conservation. Biological Conservation [Online] 192:522-532. Available at: http://dx.doi.org/10.1016/j.biocon.2015.08.003.
    Biodiversity offsets (‘offsets’) are an increasingly widespread conservation tool. Often, offset policies have a like-for-like requirement, whereby permitted biodiversity losses must be offset by gains in similar ecosystem components. It has been suggested that some flexibility might improve offset outcomes — such as out-of-kind offsets, which channel compensation towards priority species. But there has been little formal exploration of other types of flexibility, and the possible ecological consequences.
    Building upon an existing framework for analysing conservation interventions, we first categorise the types of flexibility relevant to offsetting. We then explore ecological outcomes under two types of flexibility in offsetting, using a model which tracks biodiversity value (via the surrogate of ‘habitat condition’ × area) over time for multiple vegetation communities. We simulate offset policies that are flexible in time (i.e., offsets implemented before or after development) and flexible in type (i.e., losses in one habitat compensated for by gains in another).
    Our categorisation of flexibility identifies categories previously not explicitly considered during offset policy development. The simulation model showed that offsets that were flexible in time resulted in biodiversity declines happening sooner or later than they would otherwise — important, as conservation priorities change with time. Incorporating flexibility in type resulted in significantly different outcomes in value for each vegetation community modelled, including some counter-intuitive results.
    We emphasize the importance of considering the full spectrum of flexibility in biodiversity offsets during policy development. As offset policies become increasingly prevalent, insufficient consideration of the consequences of flexibility could lead to undesirable biodiversity outcomes.
  • Bull, J., Singh, N., Suttle, K., Bykova, E. and Milner-Gulland, E. (2015). Creating a frame of reference for conservation interventions. Land Use Policy [Online] 49:273-286. Available at: http://dx.doi.org/10.1016/j.landusepol.2015.08.005.
    Understanding the context within which conservation interventions take place is critical to effective implementation. The context includes baseline status of conservation targets, and most likely counterfactual given recent trends in those targets i.e. what would have occurred in the absence of intervention. The baseline and counterfactual together provide a ‘frame of reference’ for judging conservation outcomes. It has recently been demonstrated that, since conservation interventions take place within dynamic systems, and involve either encouraging or discouraging changes in those systems, the reference frame against which interventions are evaluated fundamentally determines how much effort is required to achieve objectives, and whether they are deemed successful. In turn, this makes frames of reference crucial to planning and policy development. Counterfactuals are difficult to estimate, however, and subject to considerable uncertainty. They are consequently not widely specified in practice.
    We analyse the historical context, baseline and trends for Uzbekistan’s semi-arid Ustyurt plateau, as a case study development of a frame of reference for policymaking. Our framework incorporates physical, social, economic and institutional considerations. We conduct analyses of socio-ecological trends relevant to conservation targets in the region over the last 100 years – particularly the iconic, critically endangered saiga antelope Saiga tatarica – based upon primary data sets (e.g. vegetation surveys), secondary data sets obtained from collaborators (e.g. meteorological data), and satellite imagery.
    We demonstrate that an informative frame of reference can be developed even in the absence of exhaustive data on land use and landscape ecology. This is because the broader historical context, drivers of change, and interactions between these drivers are so influential upon the necessary design of conservation interventions. The approach taken here – of dividing trends and drivers of change into those that are physical, social, economic and institutional, and considering conservation targets in light of each in turn – provides a manageable structure for building a frame of reference. Additionally, it provides a means for making assumptions about the counterfactual explicit, leaving them open to critical evaluation.
    Finally, by developing alternative feasible counterfactuals, testable hypotheses can be outlined and used to improve future iterations of management plans—essentially, an adaptive management approach.
  • Bull, J. and Gordon, A. (2015). Schrödinger’s microbe: implications of coercing a living organism into a coherent quantum mechanical state. Biology & Philosophy [Online] 30:845-856. Available at: http://dx.doi.org/10.1007/s10539-015-9500-4.
    Consideration of the experimental activities carried out in one discipline, through the lens of another, can lead to novel insights. Here, we comment from a biological perspective upon experiments in quantum mechanics proposed by physicists that are likely to feasible in the near future. In these experiments, an entire living organism would be knowingly placed into a coherent quantum state for the first time, i.e. would be coerced into demonstrating quantum phenomena. The implications of the proposed experiment for a biologist depend to an extent upon the outcomes. If successful (i.e. quantum coherence is achieved and the organism survives after returning to a normal state), then the organism will have been temporarily in a state where it has an unmeasurable metabolism—not because a metabolic rate is undetectable, but because any attempt to measure it would automatically bring the organism out of the state. We argue that this would in essence represent a new category of cryptobiosis. Further, the organism would not necessarily retain all of the characteristics commonly attributed to living systems, unlike the currently known categories of cryptobiosis. If organisms can survive having previously been in a coherent state, then we must accept that living systems do not necessarily need to remain in a decoherent state at all times. This would be something new to biologists, even if it might seem trivial to physicists. It would have implications concerning the physical extremes organisms can tolerate, the search for extraterrestrial life, and our philosophical view of animation.
  • Maron, M., Bull, J., Evans, M. and Gordon, A. (2015). Locking in loss: Baselines of decline in Australian biodiversity offset policies. Biological Conservation [Online] 192:504-512. Available at: http://dx.doi.org/10.1016/j.biocon.2015.05.017.
    Biodiversity offset trades usually aim to achieve ‘no net loss’ of biodiversity. But the question remains: no net loss compared to what? Determining whether an offset can compensate for a given impact requires assumptions about the counterfactual scenario—that which would have happened without the offset—against which the gain at an offset site can be estimated. Where this counterfactual scenario, or ‘crediting baseline’, assumes a future trajectory of biodiversity decline, the intended net outcome of the offset trade is maintenance of that declining trajectory. If the rate of decline of the crediting baseline is implausibly steep, biodiversity offset trades can exacerbate biodiversity decline. We examined crediting baselines used in offset policies across Australia, and compared them with recent estimates of decline in woody vegetation extent. All jurisdictions permitted offset credit generated using averted loss—implying an assumption of background decline—but few were explicit about their crediting baseline. The credit calculation approaches implied assumed crediting baselines of up to 4.2% loss (of vegetation extent and/or condition) per annum; on average, the crediting baselines were >5 times steeper than recent rates of vegetation loss. For these crediting baselines to be plausible, declines in vegetation condition must be rapid, but this was not reflected in the approaches for which assumptions about decline in extent and condition could be separated. We conclude that crediting baselines in Australian offset schemes risk exacerbating biodiversity loss. The near-ubiquitous use of declining crediting baselines risks ‘locking in’ biodiversity decline across impact and offset sites, with implications for biodiversity conservation more broadly.
  • Gordon, A., Bull, J., Wilcox, C., Maron, M. and Banks-Leite, C. (2015). Perverse incentives risk undermining biodiversity offset policies. Journal of Applied Ecology [Online] 52:532-537. Available at: http://dx.doi.org/10.1111/1365-2664.12398.
    1. Offsetting is emerging as an important but controversial approach for managing environment– development conflicts. Biodiversity offsets are designed to compensate for damage to biodiversity from development by providing biodiversity gains elsewhere.
    2. Here, we suggest how biodiversity offset policies can generate behaviours that exacerbate biodiversity decline, and identify four perverse incentives that could arise even from soundly designed policies.
    3. These include incentives for (i) entrenching or exacerbating baseline biodiversity declines, (ii) winding back non-offset conservation actions, (iii) crowding out of conservation volunteerism and (iv) false public confidence in environmental outcomes due to marketing offset actions as gains.
    4. Synthesis and applications. Despite its goal of improving biodiversity outcomes, there is potential for best-practice offsetting to achieve the opposite result. Reducing this risk requires coupling offset crediting baselines to measured trajectories of biodiversity change and understanding the potential interaction between offsetting and other environmental policies.
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