
==== Front
Philos Trans R Soc Lond B Biol Sci
Philos Trans R Soc Lond B Biol Sci
RSTB
royptb
Philosophical Transactions of the Royal Society B: Biological Sciences
0962-8436
1471-2970
The Royal Society

10.1098/rstb.2023.0015
rstb20230015
10016069207Articles
Review Articles
An assessment of the state of conservation planning in Europe
An assessment of the state of conservation planning in Europe
http://orcid.org/0000-0002-7569-1390
Jung Martin Conceptualization Data curation Formal analysis Investigation Methodology Project administration Resources Software Validation Visualization Writing – original draft Writing – review & editing jung@iiasa.ac.at
1 †
http://orcid.org/0000-0003-0710-3187
Alagador Diogo Data curation Validation Writing – original draft 2
http://orcid.org/0000-0002-1377-1539
Chapman Melissa Data curation Formal analysis Writing – original draft 1 3
http://orcid.org/0000-0003-3205-5033
Hermoso Virgilio Data curation Investigation Writing – original draft 4
http://orcid.org/0000-0001-9772-3202
Kujala Heini Writing – original draft 5
http://orcid.org/0000-0002-6671-9144
O'Connor Louise Writing – original draft 1 6
http://orcid.org/0000-0001-9374-5551
Schinegger Rafaela Writing – original draft 7
http://orcid.org/0000-0002-6977-7104
Verburg Peter H. Writing – original draft 8 9
http://orcid.org/0000-0001-6823-2826
Visconti Piero Conceptualization Funding acquisition Supervision Writing – original draft 1
1 Biodiversity, Ecology and Conservation Research Group, International Institute for Applied Systems Analysis (IIASA), Schlosspark 1, Laxenburg, 2361, Austria
2 Biodiversity Chair, MED: Mediterranean Institute for Agriculture, Environment and Development, 7006-554, University of Evora, Portugal
3 Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA 94720, USA
4 Department of Plant Biology and Ecology, University of Sevilla, 41012, Seville, Spain
5 Finnish Museum of Natural History, 00100 Helsinki, Finland
6 Laboratoire d'Ecologie Alpine, Université Grenoble Alpes, Université Savoie Mont Blanc, CNRS, LECA, Grenoble, F-38000 Grenoble, France
7 University of Natural Resources and Life Sciences Vienna, 1180 Vienna, Austria
8 VU University Amsterdam, 1081 HV Amsterdam, The Netherlands
9 Swiss Federal Institute WSL, CH-8903 Birmensdorf, Switzerland
One contribution of 16 to a theme issue ‘Ecological novelty and planetary stewardship: biodiversity dynamics in a transforming biosphere’.

† Present address: Biodiversity, Ecology and Conservation Research Group, International Institute for Applied Systems Analysis (IIASA), Schlosspark 1, Laxenburg, 2361 Austria.

Electronic supplementary material is available online at https://doi.org/10.6084/m9.figshare.c.7093258.

27 5 2024 May 27, 2024
8 4 2024 April 8, 2024
8 4 2024 April 8, 2024
379 1902 Theme issue ‘Ecological novelty and planetary stewardship: biodiversity dynamics in a transforming biosphere’ compiled and edited by Jens-Christian Svenning, Melodie A. McGeoch, Signe Normand, Alejandro Ordonez and Felix Riede 202300153 7 2023 July 3, 2023
11 11 2023 November 11, 2023
© 2024 The Authors.
2024
https://creativecommons.org/licenses/by/4.0/ Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited.

Expanding and managing current habitat and species protection measures is at the heart of the European biodiversity strategy. A structured approach is needed to gain insights into such issues is systematic conservation planning, which uses techniques from decision theory to identify places and actions that contribute most effectively to policy objectives given a set of constraints. Yet culturally and historically determined European landscapes make the implementation of any conservation plans challenging, requiring an analysis of synergies and trade-offs before implementation. In this work, we review the scientific literature for evidence of previous conservation planning approaches, highlighting recent advances and success stories. We find that the conceptual characteristics of European conservation planning studies likely reduced their potential in contributing to better-informed decisions. We outline pathways towards improving the uptake of decision theory and multi-criteria conservation planning at various scales, particularly highlighting the need for (a) open data and intuitive tools, (b) the integration of biodiversity-focused conservation planning with multiple objectives, (c) accounting of dynamic ecological processes and functions, and (d) better facilitation of entry-points and co-design practices of conservation planning scenarios with stakeholders. By adopting and improving these practices, European conservation planning might become more actionable and adaptable towards implementable policy outcomes.

This article is part of the theme issue ‘Ecological novelty and planetary stewardship: biodiversity dynamics in a transforming biosphere’.

biodiversity conservation
, spatial optimization
, prioritization
, ‘30 × 30’
, decision theory
, stakeholder
HORIZON EUROPE European Innovation Council http://dx.doi.org/10.13039/100018703 101060429 cover-dateMay 27, 2024
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pmc1. Introduction

There is an urgent need to halt the decline of biodiversity in the EU, and the ecosystem services it supports. Despite important past efforts to preserve biodiversity, such as the Birds and Habitats Directives or Water Framework Directive, there has been insufficient progress towards halting biodiversity decline [1–4]. For this reason, the European Union (EU) has committed to an ambitious biodiversity recovery plan supported by the Biodiversity Strategy for 2030, the Green Deal [5] and backed by the Global Biodiversity Framework [6]. These policy advances aim to set biodiversity in a recovery path and move towards sustainable development, focusing on the restoration of degraded habitats, protecting undisturbed lands, extending the network of protected areas and improving the effectiveness of management, governance and funding in this coming decade. Where and how these ambitioned goals are to be achieved, however, depends on the strategic allocation of conservation measures under limited and uncertain budgets [7] and an overall strong competition for land resources by multiple sectors. Given these challenges there is thus a need for robust decision-making into where and what to achieve with conservation and restoration actions in space and time.

European land- and seascapes have been shaped by a long history of intense anthropic use [8]. Many European landscapes can be classified as cultural landscapes that originate from distinct historical management processes, landscape structures and the constant evolution of human values [9,10]. Undisturbed natural areas are scarce [11,12] and most European land- and seascapes are firmly embedded in production systems that provide agricultural and fishery products, timber and other recreational functions [13]. At the same time, the historical management legacies of these unique cultural landscapes have, over time, shaped biodiversity and created unique habitats that are dependent on low-intensity management [14]. Managing such land- and seascapes in a way that is compatible with historic low-intensity practices and cultural practices could help to conserve those biodiversity aspects, which are often also in greatest need of conservation efforts [4]. This also highlights the necessity that European conservation measures consider context-specific aspects of cultural and management practices to maximize synergies and trade-offs between human use and biodiversity [14].

Europe has a long history of planning directives and policies with regard to nature conservation. The Natura 2000 network of internationally designated protected areas has been a tremendous success story, constituting the largest coordinated network of areas for managing biodiversity in the world. It covers 18.5% of land area in the EU and 9% of the sea [15] and it is complemented by nationally designated areas (national park, regional reserves and other national designations) covering an additional 7.9% of land, as of April 2023 (see the official EEA dashboard at https://www.eea.europa.eu/data-and-maps/dashboards/natura-2000-barometer).

In the marine realm, in addition to national and international designations following the EU Nature Directives and other national and international commitments (e.g. Convention on Biological Diversity protected area targets) a strong support for marine spatial planning has come from the EU marine strategy framework directive [16] which made marine spatial planning compulsory for all its member states [17]. Furthermore, the EU Water Framework Directive [18] and related River Basin Management Planning constitute a novel baseline for catchment-based planning and integrative water resources management across Europe.

The EU policy biodiversity strategy targets include a commitment to expand nature conservation through the means of area-based conservation targets (e.g. share of 30% protected areas of land and sea, of which one-third are under strict protection). While area-based percentage area targets have been criticized [19] for directing efforts towards the means (protection) rather than the ends (conserving habitats, species and ecological processes), a strategic implementation of these targets through the means of spatial planning can help ensure their meaningful contribution towards the overarching objectives of the Strategy (i.e. biodiversity conservation).

Planning for nature conservation can be conducted at various scales, each with its own purpose and way of contributing to decision-making processes and achieving overarching policy objectives. European- or regional-scale efforts are most effective at highlighting areas of broad conservation importance or identifying cross-border and transboundary collaboration opportunities [20,21]. National level planning, in contrast, is more suited to take into account country-specific datasets or accounting processes that might not be available or comparable at broader scales [22]. Ultimately, the implementation of any place-based conservation measures is usually done in local contexts, and under consultation and negotiation with relevant local and regional stakeholders and planning authorities. Although various planning approaches are widely applied globally, no comprehensive overview on their methodological and spatial application nor specific purpose exists for a European context.

Spatial planning can be achieved through the means of systematic conservation planning (SCP), which is a decision-theoretical framework that can help bridge the gap between politically driven area targets and the stated ambition of conserving biodiversity by identifying a set of areas requiring conservation management that satisfy a series of conservation objectives (e.g. for species, ecosystems or ecological processes). It leverages tools from decision theory to identify optimal management strategies in the face of uncertainty and multiple, often competing, objectives [23,24]. SCP approaches may not be exclusively applied for the identification of new protected areas, for which they have played a key role in recent decades [25]. They also can support the identification of optimal management actions [26], enable representation and rank priorities in terms of their importance or value for conservation management [27,28] and evaluate different scenarios given synergies and trade-offs of multiple objectives [27,29–31]. SCP approaches further allow the flexible integration of quantitative and qualitative evidence, including perspectives and visions of stakeholders [32–34]. Although SCP approaches are highly promising to guide strategic implementation and decision-making, it is unclear to what extent they have been applied across European landscapes and seascapes.

SCP can be conducted in a range of different ways and with a wide variety of analytical frameworks [35–37]. Frameworks and planning tools get more complex as they try to integrate more ecological complexity, socio-economic constraints and processes to inform the implementation of policies. For example, current rates of changes in climate and land use fundamentally affect the efficiency and role of protected areas, and new advances in SCP have enabled the better accounting of dynamics such as species distribution shifts in future protected area designations [38–40]. Other methodological developments have enabled a better integration of uncertainties [41], costs [42], connectivity [43,44], responses to management scenarios [45] and multi-objective optimizations [27,31,46,47], all of which add more nuance and realism to the resulting plan, potentially contributing to successful adoption of results. Ultimately, any implementation is dependent on the involvement of stakeholders and efforts have been taken to incorporate their visions, feedback and concerns at various stages of SCP exercises [33,35]. It is however not yet clear to what extent these advances have proliferated into SCP or other planning approaches.

In the recent past, a few studies systematically reviewed and mapped SCP studies and similar approaches globally [48–51]. However, to our knowledge, no such assessment has been conducted specifically for the European context. Given the timeliness of EU policies and the strong legacy of SCP application across Europe, we specifically review the scientific literature to assess where and how SCP and related conservation planning approaches have been applied in a European context. We explore the properties and indicators of complexity applied in the available literature and evaluate the uptake of these studies in subsequent scientific and policy documents. By also drawing on previous reviews at a global scale, we discuss prospects, directions and gaps in conservation planning applications in Europe and highlight opportunities for more integration across objectives, models and realms, emphasizing the critical role that SCP in particular will play in reaching European conservation policy targets across scales.

2. Methods

We conducted a structured review of existing scientific literature, covering references that applied SCP and other related approaches in a European context (including the UK, Norway and all Balkan states in the process of joining the European Union). We purposefully excluded global studies and set our focus on articles from the European geographical context, but recognize that a rich source of the literature that has applied such approaches on other continents also exists [50]. We primarily focused on literature with a conservation or restoration planning aim, including biodiversity conservation issues and gap analyses. Although the focus of the review was on SCP approaches (see search term in electronic supplementary materials), other approaches for identifying where to act or what to do were also captured. We did not specifically consider literature focusing on other fields (e.g. landscape- or urban planning), but explicitly record if and how land-use aspects have been considered in the analysed literature (table 1). To identify relevant literature, we used the Scopus search engine. We recognize that other search engines might yield slightly different results, but do not know of any systematic bias that would affect the broad scale patterns observed in this analysis. We also acknowledge other review guidelines that might increase repeatability in the future (http://prisma-statement.org/). The query was run on the 23rd of September 2022 and resulted in an initial 1459 articles for screening. A full list of the terms passed to the search engine can be found in the electronic supplementary material. Table 1. Depiction of variables, types, and the rationale behind the collection in the review.

variable name	unit/values	rationale	
extent	local | national | regional | Europe	Qualitative depiction of the extent of planning from small to larger scale.	
region	country name	The name of the European country in which the study was conducted. Enter multiple names or ‘Europe’ if study was conducted across multiple regions. Broad regions if the countries are not explicitly stated (Mediterranean)	
locality	free text	Any further information with regards to the region discussed in free text.	
realm	terrestrial | freshwater | marine |cross-realm	Realm of the planning exercise.	
ecosystem specificity	type	Covers whether specific to certain ‘ecosystems’ such as prioritization within coastal regions or forests. Single text description.	
period	contemporary | future | both	Temporal period considered in the planning scenario. With 'contemporary', we refer to any dataset collected prior to the conducted analysis. Future or dynamic planning approaches usually include or consider variables or constraints beyond the 2030 period. Analysis would consider both the contemporary state and future conditions (e.g. future climatic refugia).	
purpose of planning	type (single categorical term).	Broad categorization of the goal of the planning exercise, being for instance identification of priority areas for management implementation (e.g. placement of protected areas, usage zones, restoration), specific actions (e.g. eradication of invasive species), or representation (e.g. coverage of features) or identification of synergistic effects (e.g. minimization of costs across objectives).	
policy relevance	name of relevant policies or ‘none’; in the case of a specific  concrete case-study, enter ‘case study’	Whether the work is explicitly trying to address objectives of a policy as opposed to being curiosity- or methodologically-driven (e.g. demonstration of a new method using a particular EU case study).	
algorithm approach	method	Listing the tool or approach used for planning, i.e. Marxan	
biodiversity type	species | ecosystems | Nature Contributions to People (NCP) | other	What types of biodiversity data were considered in the work and at what level was it included.	
multiple objectives or management and land-use constraints	none|multi-objective |constraints| costs| other	Indication of whether the planning exercise has addressed multiple objectives (besides biodiversity) or accounted for or incorporated constraints related to anthropogenic production, constraints and/or land-use practices.	
connectivity	boundary | structural | functional | none	Was connectivity in any way considered in the planning. Available options include boundary connectivity (avoid clumping), structural connectivity through habitat features and functional connectivity through species dispersal and trait features.	
costs	yes/no	Were costs related to opportunity or land purchases considered?	
stakeholder involvement	yes/no	Were proposed planning inputs or outcomes communicated, informed or co-designed together with relevant stakeholders?	
number of features	number	How many features were considered in the process.	

We screened the title and abstract of each of the resulting articles for suitability for inclusion in the review, and removed all studies that were broadly irrelevant, i.e. unlikely to have applied any planning approaches in a biodiversity-relevant context, or were conducted at an irrelevant extent (globally, or outside of European Member states/the European continent). This yielded a total of 356 studies across terrestrial, freshwater and marine realms, which we then assessed in more detail by extracting a set of key variables and criteria relevant for this review (table 1). Finally, we also complemented these studies with other sources of scientific literature about conservation planning beknown to the authors. This was done in order to specifically include studies that were not indexed by Scopus, making use of a ‘snowballing’ system, where any added known study was screened for their cited references and assessed for further literature not yet considered.

All found European studies were then assessed for their fulfilment of different criteria of planning complexity (table 1). These criteria are whether a study accounted for connectivity, considered current/future conditions and competing land-uses, and had indicated policy relevance or involved stakeholders. For each identified study in our final dataset, we extracted information on the ‘uptake’ in the scientific and policy literature. As a generic proxy for 'uptake’, we make use of the number of citations in scientific and policy documents, realizing that this number can only give a conservative estimate of the true relevance of a work. We used the ‘rscopus’ package to extract this information for each article with a Digital Object Identifier [52] and here mainly relied on the PlumX citation metrics, which provide insights into by whom (social media, scientific, policy documents) and when articles are cited. See the Data accessibility section for access to the full list of studies considered. We furthermore provide an online interactive website to navigate through the outputs of the analysis (https://martin-jung.github.io/Review_EuropeanConservationPlanning).

Finally, we used the parameters extracted from the literature (table 1) and interrogated the data in terms of who cited them using a series of Bayesian regression models. In the case of citations, we used zero-inflated Poisson distributed Bayesian regression models to estimate the conditional effect of certain parameters on the relative rate of citations. We used a zero-inflated link function to account for the articles that have never been cited and furthermore included a temporal random intercept to account for year-to-year differences, given that older studies are more likely to have accumulated citations over time. Bernoulli distributed regressions were used for all other analyses, where the aim was to test for differences in the mean. Analyses were conducted using the ‘brms’ package [53,54].

3. Review findings

In total, we found 266 suitable studies covering 40 individual countries, or broader regional and European extents across the period from 1996 to 2023 (figure 1b). European studies using SCP and related approaches were mostly conducted on land (67% of all studies), followed by marine studies (20%). The most represented countries are Spain (10.7% of all studies), the UK (10%), Portugal (9.1%) and Finland (9.1%, figure 1a). Studies predominantly covered local scales (54%), with the fewest number of studies being conducted at the European scale (11.3%, figure 1b). Most studies aimed to either identify priority areas (40.3%) or investigate representation gaps and sufficiency (30%) of existing protection measures. The most applied methodological approaches were using heuristics (see also electronic supplementary material, table S1), with most of the studies using standalone software such as Marxan (31% of all studies), followed by Zonation (20%) or ranking and scoring approaches (19.7%). The remaining studies used exact algorithms such as Integer programming (19.4%); with other approaches such as multi-criteria analyses or machine learning accounting for the remaining 29.9%. Most planning studies considered multiple ecosystem types in terms of priorities for conservation areas or actions (62%). Close to half of all studies (46%) used features that only considered species in their work, ranging from 1 to over 4447 species (electronic supplementary material, figure S1), although an increasing number of studies also considered ecosystem services (10%, electronic supplementary material, figure S1) or multiple feature types together (24%). Figure 1. Spatial and temporal patterns of conservation planning studies in Europe. Shown are the spatial distribution (a), the temporal trend of studies separated by spatial extent (b), and the number of studies by realm (c).

Interestingly, not even one of the assessed studies of European extent fulfilled all criteria for an adequate accounting of the complexities of spatial planning (table 1 and figure 2). An overwhelming proportion of studies (87%) considered only contemporary data on biodiversity, land use, climate and other factors. Similarly, most studies focused on entire landscapes (62%) instead of making specific assessments, for example, forest conservation priorities (8.3%). Only 37% of all studies accounted somehow for connectivity in the prioritization, with the most common approach being neighbourhood constraints, which penalized the selection of isolated areas for conservation. Even fewer studies considered future states of their features (12.9%), i.e. using future distributions of species or habitats, or anticipated costs. Figure 2. Overview of the properties of the studies identified in the review. Shown are factors related to connectivity, whether a study accounted for land use, and if the study aimed at a particular policy objective and whether stakeholders have been involved in any capacity in the conceptualization of the study. The bottom axes separate between levels of these factors related to the study aim. The sizes of the points indicate the numbers of studies, while the colours show the proportions of all studies for the study aim (bottom axes).

Remarkably, very few studies (11.1%) involved stakeholders in the conceptualization or execution of their study, although 68% of all studies aimed to be relevant for or to influence one or more policies. Notably, not a single conservation planning study at European scale considered the views of stakeholders (electronic supplementary material, figure S2). Conservation priorities often compete with alternative land- or water uses. Yet only 54.5% of all studies somehow accounted for these constraints, most commonly in the form of opportunity costs.

Citations of scientific and policy documents can serve as a coarse proxy of their uptake by the respective communities. On average, any given planning study was cited about 27 times (median: 17, range: 0–162) in scientific documents, 1.4 times (median: 0, range: 0–21) in policy documents and 22 times in other outreach channels such as social media, blog posts or news articles (range: 0–434). While on average, a study is cited about 2.9 times for every year after it has been published, it can take an average up to 4.4 years before a study is first cited in any policy document. We also find that that the probability that a scientific study is cited by policy documents decreases every year as increasing numbers of scientific studies are published (β = −0.05, d.f. = 261, p = 0.03). We found no correlation between the number of social media mentions and the number of citations in scientific (r = −0.06, d.f. = 261, p = 0.34) or policy documents (r = 0.02, d.f. = 261, p = 0.79). We did however find that articles that are cited more frequently by scientific documents also tended to be cited more often in policy documents (r = 0.45, d.f. = 261, p < 0.001).

The number of citations by scientific and policy documents differed according to the properties of the respective studies (figure 3). We found that studies at European extent were more often cited than comparable studies at local extent by both policy documents (λEurope = 1.7) and scientific (λEurope = 26) documents published in the same year (figure 3). While studies that accounted for aspects of connectivity (λ = 31) or land use (λ = 26) were on average cited more frequently by scientific documents than comparable studies, the best determinant of higher citation rates by policy documents was the involvement of stakeholders in the study (λ = 2.24, figure 3). Studies that considered the views of stakeholders usually had case study-specific policy objectives and were of smaller extent (figure 3). Whether or not studies have made reference to none or some of the policy contexts resulted in small differences in scientific citations (figure 3, λnone = 28, λsingle = 32). However, studies that referred to a single policy context were more often cited in policy documents (λ = 2.8), although there was little difference in the uptake by scientific documents with regards to whether a study had or had not referred to any policy contexts (figure 3). Overall, these results highlight that the magnitude of uptake of SCP and related approaches differs among scientific and policy audiences with regard to study scale and complexity. Figure 3. The results of a Bayesian regression model assessing the difference in the number of citations in policy or scientific literature, or the probability of stakeholder involvement, differ depending on certain properties of the reviewed studies.

4. Discussion

Expansion of areas under effective conservation management is a key aspect in European biodiversity policies. However, given the limited financial resources, trade-offs between preservation of biodiversity and other competing human objectives, there is a need to prioritize efforts. In this work, we reviewed the scientific literature on SCP and related approaches in Europe to understand where and how planning for places and actions has been applied across scales and realms. Clear patterns of predominant practices emerged, and crucially we found that not a single study accounted for all aspects of planning complexity that might be preferable in a well-designated spatial plan of conservation priorities (table 1). Very few studies (13%) accounted for future conditions in some form, which is a large oversight given that climate change is expected to shift the distribution of most European species and habitats [38,55] and conservation management is expected to contrast projected land-use change, where it would have the highest negative impacts on biodiversity [56]. Nevertheless, we show that many SCP studies, specifically those referring to specific policy contexts, are cited in policy documents, highlighting the relevance of prioritization studies as scientific evidence and decision support. Unfortunately, in Europe, which SCP studies have resulted in the designation of new spatially targeted conservation areas or improved management and restoration actions is not known or officially documented.

Implementing the EU Biodiversity strategy for 2030 requires engaging diverse stakeholders, including the general public, about how biodiversity management should be conducted within and outside protected areas [57]. We find that—regardless of the method of consultation, scale or purpose of planning—stakeholder inputs are rarely considered in European planning studies (figure 2). This result aligns with the findings of global reviews of integrated land-sea planning studies, which found that most did not involve or consult stakeholders in any form [58]. Further, our results suggest that studies considering the views of stakeholders were on average more often cited by policy documents than scientific literature (figure 3d), which could hint at a disconnect between the relevance of conservation prioritization studies for scientific outlets and policy making. Although the benefits and necessities in addressing and integrating drivers of biodiversity decline across scales and extents are well identified [59,60], is also notable that not a single study at European scales engaged with stakeholders and only a few at national or regional scales, which might further enforce the perception that conservation planning can be seen as a ‘top–down’ approach or ‘black-box’ driven by science.

Terrestrial studies by far dominated the scientific literature, whereas freshwater and cross-realm planning approaches, e.g. those that consider terrestrial as well as freshwater and/or marine systems [21,35,37], have rarely been conducted (figure 1). This constitutes a problematic issue, as there is increasing evidence that drivers behind biodiversity pressures are interlinked across realms [59]. We thus amplify previous calls to step up implementations and proof-of-concept case studies of cross-realm European planning to adequately design and implement catchment plans that can contribute to jointly halting the decline of freshwater and terrestrial biodiversity [1].

Overall, 55.4% of investigated studies consider some type of socio-economic cost or constraint in their planning (figure 2). And additionally, studies that incorporated multiple objectives criteria received on average 10% more scientific citations than those studies that did not, and they make up less than half of all studies that incorporated non-biological factors into their planning exercises. This aligns with previous reviews of conservation planning studies that highlighted a general focus on biological rather than socio-economic patterns and processes [48]. In a European context that can be an issue as the heterogeneity and governance of different land systems necessitate planning concepts that ideally fulfil multiple functions for nature, economy and society [14,61]. Integrated planning has been highlighted as key to address the multiple drivers of biodiversity decline and to maximize synergies across policy goals and realms [1,5,6,62,63]. Clearly, there is a need to further mainstream the consideration of multiple objectives in SCP, especially in working landscapes and for including nature's contributions to people.

(a) Perspective on recent advances

Our review has shown that a wide range of approaches and tools have been applied in European planning studies and among them SCP remains the best-suited approach to prioritize and evaluate potential conservation outcomes and explicitly address conflicts and trade-offs.

(i) Novel tools and ease of access

SCP software continues to be developed and expanded in terms of complexity [25]. Recent developments include spatially optimal zoning [43,64], next-generation ranking algorithms for spatial prioritization [65], integer programming for planning for places and actions [66–68], restoration of specific landscapes patterns [69] or the use of reinforcement learning for identifying conservation priorities [70] or management actions [71]. Recent studies have proposed new objective functions that allow the achievement of multiple targets linearly [27,68] or by identifying more compact solutions with core areas to benefit species sensitive to edge effects [72]. Each of these approaches comes with their own promises, benefits and caveats (see electronic supplementary material, table S1) and there is no tool that is universally regarded as the most appropriate by all end-users.

Nevertheless, simple scoring methods remain pervasive in planning processes across scales (figure 2), often driven by the demand of stakeholders for transparent and understandable processes. This is worrying, given that these have been known to be imprecise and potentially misleading in identifying priorities for places or actions [73]. Most likely, there remains a lack of easily useable tools particularly for non-academics or those unfamiliar with developing analytical code, as well as a lack of capacity building to strengthen the skillset with existing tools. The move towards cloud-based prioritization software such as the Marxan Planning Platform (MaPP, https://marxansolutions.org/marxanmapp/) will hopefully also contribute towards reducing entry barriers for analysts with less technical training.

(ii) Towards integrated spatial planning

We highlight several methodological developments in SCP, for which we see a promise in their application in the context of spatial planning at the European extent (table 2). The integration of conservation actions within human-dominated landscapes makes conservation challenging, as any actions to restrict use and access will directly affect the users of these landscapes or displace other types of land use [86]. An answer could be integrated planning solutions, that balance competing demands between preservation of biodiversity, provision of ecosystem services and economic or cultural demands towards land and seascapes [31,62,87,88]. Such applications of SCP hold great promise in identifying priorities that integrate across policy sectors (horizontal) and scales (vertical). For example, in the context of the European Biodiversity Strategy it is necessary to ensure that management for conservation is effective, especially considering limited resources, and that it ideally maximizes benefits across varying policy objectives such as biodiversity and climate mitigation and adaptation goals [55,89]. Table 2. Recent conceptual and methodological innovations and developments in SCP, with exemplary studies for their application.

innovation	concept	key reference examples	
planning for actions	Implicit consideration of what to do in a given context, for example by identifying optimal priorities to allocate or improve management actions for threat abatement.	targeted priorities for actions [26,67,74]	
dynamic conservation planning	Explicit accounting of multiple temporal timesteps to identify priorities for spatial management zones or their actions.	ensuring resilience to future change [38,75]	
scheduling of management actions in the light of changing pressures [71,76]	
formulations of robust biological informed targets	Current practices of setting feature targets in prioritizations are often naïve or abstract. New advances are being made in improving the formulation of targets to improve their biological realism	Targets informed by RedList criteria [27,77], Favourable reference values [78], indicators of landscape metrics [69]	
integrated and joint planning across sectors	Integration of features and targets from different sectors into a single prioritization, thus allowing the balancing of synergies and trade-offs with biodiversity and other demands, for example, through weights.	Integrated planning for both biodiversity and land use targets [31,47,79–81]	
Joint planning balancing multiple objectives [27,82]	
Consideration of NCPs in SCP [27,36,83]	
co-design with stakeholders	Involve those actors affected or benefiting by the implementation of the conservation priorities in the design and execution of the analytical process	Guidelines and examples for increased effectiveness [33], co-design of planning with stakeholders [79,84]	
connectivity	Directly incorporate connectivity in the design of current or future reserve networks.	Incorporating ecological connectivity in SCP [43,44,85]	

However, the data or required information are not always available for developing a spatial plan, and with greater complexity this increases the risk of incorrectly prioritizing areas or actions due to poor data or modelling assumptions [90]. For example, it has been found that planning solutions are particularly sensitive to aggregated constraints, e.g. those acting at the level of a single planning unit or over the whole area of interest [91]. The complex dynamics and socio-cultural factors (i.e. sense of place and ownership, land tenure) governing European working landscapes highlight the importance of considering non-biological factors in spatial plans. Yet, the critical decision of which socio-economic data are ‘good enough’ to include highlights issues of data harmonization and provenance. Overall, there seems an urgent need to better align social, economic and ecological objectives in spatial planning.

Similarly, most conservation planning approaches try to reduce planning complexity by using static ‘proxy’ variables for threats to biodiversity or level of intactness, such as aggregated ‘human-footprint’ indices. This lack of differentiation of separate pressures to biodiversity, and accounting for their specific impacts, impede the identification of appropriate management actions to abate these threats, and also come with the invalid assumptions that pressures have additive impacts [92]. Future integrated planning studies should attempt to better account for such idiosyncrasies by proposing ways to manage different types of land- and seascapes, ideally through linkages with domain-specific data and knowledge.

(iii) Dynamics and process-based planning

To ensure that SCP is fit for purpose to tackle the complexity of conservation problems, more conceptual work on expanding and testing common problem formulations for the selection of areas is needed. Current SCP approaches do not yet comprehensively evaluate the impact of future changes or account for dynamics of natural and socio-economic systems (figure 2; electronic supplementary material, table S1). Here a better incorporation of connectivity within the problem formulation could help to identify solutions that are more robust to future changes [43,44,85]. For example, the identification of adaptive dispersal corridors can help species populations to persist in the light of climate change and for future range expansion [38,93]. Further, novel approaches such as reinforcement learning bring some promises, for example, for spatial planning over highly dynamic problems or policy horizons [71]. At the same time, this also comes with the cost of interpretability because resulting planning solutions cannot be easily explained by analysts (typical ‘black box’) and the influence of data or model uncertainties cannot be comprehended. Clearly, there is a need to better understand uncertainties in parameter choices and how they influence resulting solutions and communicate them, especially towards stakeholders and less-trained analysts.

(iv) Adequacy of scale-specific planning

There is also an increasing realization that SCP needs to integrate across scales [60]. For example, while many management problems for protected areas might only effectively be addressed at local scale (figure 1), influencing pressures such as climate change or governance regulations and constraints to national biodiversity strategies occur beyond the local scale [94]. There is a need to identify practical ways forward regarding how bottom–up and top–down objectives can be integrated in spatial planning. Plausible scenarios for evaluating trade-offs, as well as a well-designed theory of change underpinning any proposed place or action-based implementation, will likely help to improve acceptance and policy impact of SCP. Supporting the implementation of SCP along all implementation steps in commonly used frameworks [37] would likely support a more effective implementation.

Moving forward, we also recommend that evidence and results from SCP studies should be more readily accessible across different scales and realms, and some such efforts have been spearheaded elsewhere in Gabon or globally [17,50,95]. One idea could be to build a European-wide reference database highlighting different SCP frameworks, case-studies and tools, by also providing the evidence behind these works (e.g. data, maps and indicators used for evaluation) in a transparent and digestible way. Similar databases already exist in the context of the European Marine Spatial Planning directive (Directive 2014/89/EU, https://maritime-spatial-planning.ec.europa.eu/msp-practice/database), but not for either terrestrial or freshwater systems. A European hub of SCP frameworks and evidence could help to improve cohesiveness and consciousness for conservation issues, particularly for cross-border or cross-realm challenges, and may contribute to a widespread adoption of SCP.

5. Conclusion

Our review on the current state of SCP in European contexts highlights the varying levels of complexity—or lack thereof—in how conservation decisions are determined. In a mission-driven discipline like conservation, scholarly work should strive to be useful and close to implementation. Policy relevance can be achieved through addressing many of the complexity factors outlined above, such as the following: (a) by incorporating stakeholder visions and preferences in SCP. The fact that stakeholders are rarely consulted in scientifically oriented SCP studies might hint at one of the symptoms explaining why protected areas are often of low efficiency, particularly if conflicting objectives and initial ‘buy-in’ by stakeholders are ignored; (b) by more comprehensively integrating multiple objectives and the socio-economic aspects that matter. Spatial plans for conservation in European multi-functional landscapes cannot be realized without considering the trade-offs with such management actions; (c) by considering robust policy contexts and targets for the biodiversity attributes that matter, rather than ‘proxy’ variables with little prospect of implementation or actionable advice; (d) by expanding and developing the set of openly available data and tools and providing decision makers with capacity-building opportunities and training to expand the use of SCP as standard.

SCP can contribute more than just maps. It can estimate the sufficiency of management plans, identify synergies and trade-offs or evaluate different planning scenarios in terms of their benefits. Addressing current and future conservation challenges can only happen through widespread adoption of best practices and use of evidence, with scientists and practitioners jointly contributing to this process in a concerted way. We thus urge European scientists to thus make further efforts to increase the relevance of their planning work.

Acknowledgments

This manuscript has been inspired by discussions in the ‘Planning where and how to best conserve and restore biodiversity’ symposium at the ECCB 2022, Prague and the BIOCHANGE symposium held at the University of Aarhus, Denmark. The authors would like to thank Kristian Metcalfe and one anonymous reviewer for suggestions that improved the manuscript.

Data accessibility

The datasets supporting this article have been uploaded as part of the electronic supplementary material and also from the Zenodo repository: doi:10.5281/zenodo.8104715 [96]. The analysis code used to create the figures and statistics are accessible from the GitHub repository: https://github.com/Martin-Jung/Review_EuropeanConservationPlanning [97].

The data are provided in electronic supplementary material [98].

Declaration of AI use

We have not used AI-assisted technologies in creating this article.

Authors' contributions

M.J.: conceptualization, data curation, formal analysis, investigation, methodology, project administration, resources, software, validation, visualization, writing—original draft, writing—review and editing; D.A.: data curation, validation, writing—original draft; M.C.: data curation, formal analysis, writing—original draft; V.H.: data curation, investigation, writing—original draft; H.K.: writing—original draft; L.O.: writing—original draft; R.S.: writing—original draft; P.H.V.: writing—original draft; P.V.: conceptualization, funding acquisition, supervision, writing—original draft.

All authors gave final approval for publication and agreed to be held accountable for the work performed therein.

Conflict of interest declaration

We have no competing interests.

Funding

M.C. would like to acknowledge financial support from the International Institute for Applied Systems Analysis, Laxenburg (Austria) and the National Member Organizations that support the institute in taking part in the Young Scientists Summer Program. M.J., L.O., R.S., H.K. and P.V. would like to acknowledge funding under the Horizon Europe project ‘NaturaConnect’. NaturaConnect receives funding under the European Union's Horizon Europe research and innovation programme under grant agreement number 101060429. M.J. and P.V. furthermore acknowledge funding from the 2021–2022 BiodivERsA call for research proposals under the BiodivProtect program (funding organization: FWF Austrian Science Fund, Grant DOI 10.55776/I6396). DA received support from the Portuguese Science Foundation (FCT) project UIDB/05183/2020.
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References

1. Van Rees CB et al. 2020 Safeguarding freshwater life beyond 2020: Recommendations for the new global biodiversity framework from the European experience. Conserv. Lett. 14 , 1-17. (10.1111/conl.12771)
2. Eichenberg D et al. 2021 Widespread decline in Central European plant diversity across six decades. Glob. Change Biol. 27 , 1097-1110. (10.1111/gcb.15447)
3. Burns F, Eaton MA, Burfield IJ, Klvaňová A, Šilarová E, Staneva A, Gregory RD. 2021 Abundance decline in the avifauna of the European Union reveals cross-continental similarities in biodiversity change. Ecol. Evol. 11 , 16 647-16 660. (10.1002/ece3.8282)
4. Rigal S et al. 2023 Farmland practices are driving bird population decline across Europe. Proc. Natl Acad. Sci. USA 120 , e2216573120. (10.1073/pnas.2216573120)37186854
5. European Commission, Directorate-General for Environment 2021 EEU biodiversity strategy for 2030 – Bringing nature back into our lives. Luxembourg: Publications Office of the European Union. (10.2779/677548)
6. Convention of Biological Diversity (CBD). 2022 Kunming–Montreal Global biodiversity framework. See https://www.cbd.int/doc/c/f98d/390c/d25842dd39bd8dc3d7d2ae14/cop-15-17-en.pdf.
7. Hermoso V et al. 2022 The EU Biodiversity Strategy for 2030: opportunities and challenges on the path towards biodiversity recovery. Environ. Sci. Policy 127 , 263-271. (10.1016/j.envsci.2021.10.028)
8. Visconti P et al. 2018 Status, trends and future dynamics of biodiversity and ecosystems underpinning nature's contributions to people. In The IPBES regional assessment report on biodiversity and ecosystem services for Europe and Central Asia (eds M Rounsevell, M Fischer, A Torre-Marin Rando, A Mader), pp. 187-384. Bonn, Germany: IPBES.
9. Jepsen MR et al. 2015 Transitions in European land-management regimes between 1800 and 2010. Land Use Policy 49 , 53-64. (10.1016/j.landusepol.2015.07.003)
10. Tieskens KF, Schulp CJE, Levers C, Lieskovský J, Kuemmerle T, Plieninger T, Verburg PH. 2017 Characterizing European cultural landscapes: Accounting for structure, management intensity and value of agricultural and forest landscapes. Land Use Policy 62 , 29-39. (10.1016/j.landusepol.2016.12.001)
11. Sabatini FM et al. 2020 Protection gaps and restoration opportunities for primary forests in Europe. Divers. Distrib. 26 , 1646-1662. (10.1111/ddi.13158)
12. Dou Y, Cosentino F, Malek Z, Maiorano L, Thuiller W, Verburg PH. 2021 A new European land systems representation accounting for landscape characteristics. Landscape Ecol. 36 , 2215-2234. (10.1007/s10980-021-01227-5)
13. Debonne N, Bürgi M, Diogo V, Helfenstein J, Herzog F, Levers C, Mohr F, Swart R, Verburg P. 2022 The geography of megatrends affecting European agriculture. Glob. Environ. Change 75 , 102551. (10.1016/j.gloenvcha.2022.102551)
14. Felix L, Houet T, Verburg PH. 2022 Mapping biodiversity and ecosystem service trade-offs and synergies of agricultural change trajectories in Europe. Environ. Sci. Policy 136 , 387-399. (10.1016/j.envsci.2022.07.004)
15. Evans D. 2012 Building the European Union's Natura 2000 network. NC 1 , 11-26. (10.3897/natureconservation.1.1808)
16. European Commission. 2014 89/EU of the European Parliament and of the Council of 23 July 2014 establishing a framework for maritime spatial planning. Off. J. Eur. Union 257 , L257. (See https://eur-lex.europa.eu/legalcontent/EN/TXT/?uri=CELEX:32014L0089.)
17. Ehler CN. 2021 Two decades of progress in Marine Spatial Planning. Marine Policy 132 , 104134. (10.1016/j.marpol.2020.104134)
18. European Commission. 2000 Water Framework Directive (WFD) 2000/60/EC: Directive 2000/60/EC of the European Parliament and of the Council of 23 October 2000 establishing a framework for Community action in the field of water policy. (See https://www.eea.europa.eu/policy-documents/water-framework-directive-wfd-2000; https://eur-lex.europa.eu/legalcontent/EN/TXT/?uri=CELEX%3A32000L0060&qid=1709665116307.)
19. Visconti P, Butchart SHM, Brooks TM, Langhammer PF, Marnewick D, Vergara S, Yanosky A, Watson JEM. 2019 Protected area targets post-2020. Science 364 , eaav6886. (10.1126/science.aav6886)
20. Kark S, Tulloch A, Gordon A, Mazor T, Bunnefeld N, Levin N. 2015 Cross-boundary collaboration: key to the conservation puzzle. Curr. Opin. Environ. Sustainab. 12 , 12-24. (10.1016/j.cosust.2014.08.005)
21. Domisch S et al. 2019 Social equity shapes zone-selection: balancing aquatic biodiversity conservation and ecosystem services delivery in the transboundary Danube River Basin. Sci. Total Environ. 656 , 797-807. (10.1016/j.scitotenv.2018.11.348)30530149
22. Cardona Santos EM et al. 2023 Mainstreaming revisited: experiences from eight countries on the role of National Biodiversity Strategies in practice. Earth Syst. Govern. 16 , 100177. (10.1016/j.esg.2023.100177)
23. Margules CR, Pressey RL. 2000 Systematic conservation planning. Nature 405 , 243-253. (10.1038/35012251)10821285
24. Hemming V et al. 2022 An introduction to decision science for conservation. Conserv. Biol. 36 , 1-49. (10.1111/cobi.13868)
25. Maxwell SL et al. 2020 Area-based conservation in the twenty-first century. Nature 586 , 217-227. (10.1038/s41586-020-2773-z)33028996
26. Hermoso V, Salgado-Rojas J, Lanzas M, Álvarez-Miranda E. 2022 Spatial prioritisation of management for biodiversity conservation across the EU. Biol. Conserv. 272 , 109638. (10.1016/j.biocon.2022.109638)
27. Jung M et al. 2021 Areas of global importance for conserving terrestrial biodiversity, carbon and water. Nat. Ecol. Evol. 5 , 1499-1509. (10.1038/s41559-021-01528-7)34429536
28. Jetz W, Mcgowan J, Rinnan DS, Possingham HP, Visconti P, O'donnell B, Londoño-Murcia MC. 2022 Include biodiversity representation indicators in area-based conservation targets. Nat. Ecol. Evol. 6 , 123-126. (10.1038/s41559-021-01620-y)34887542
29. Goldstein JH, Caldarone G, Duarte TK, Ennaanay D, Hannahs N, Mendoza G, Polasky S, Wolny S, Daily GC. 2012 Integrating ecosystem-service tradeoffs into land-use decisions. Proc. Natl Acad. Sci. USA 109 , 7565-7570. (10.1073/pnas.1201040109)22529388
30. Seliger C, Scheikl S, Schmutz S, Schinegger R, Fleck S, Neubarth J, Walder C, Muhar S. 2016 Hy:Con: a strategic tool for balancing hydropower development and conservation needs. River Res. Applic. 32 , 1438-1449. (10.1002/rra.2985)
31. Fastré C, Van Zeist W-J, Watson JEM, Visconti P. 2021 Integrated spatial planning for biodiversity conservation and food production. One Earth 4 , 1635-1644. (10.1016/j.oneear.2021.10.014)
32. Adams VM, Mills M, Jupiter SD, Pressey RL. 2011 Improving social acceptability of marine protected area networks: a method for estimating opportunity costs to multiple gear types in both fished and currently unfished areas. Biol. Conserv. 144 , 350-361. (10.1016/j.biocon.2010.09.012)
33. Langhans SD, Gessner J, Hermoso V, Wolter C. 2016 Coupling systematic planning and expert judgement enhances the efficiency of river restoration. Sci. Total Environ. 560–561 , 266-273. (10.1016/j.scitotenv.2016.03.232)
34. Iwamura T, Le Polain De Waroux Y, Mascia MB. 2018 Considering people in systematic conservation planning: insights from land system science. Front. Ecol. Environ. 16 , 388-396. (10.1002/fee.1824)
35. Álvarez-Romero JG et al. 2015 Integrated cross-realm planning: a decision-makers' perspective. Biol. Conserv. 191 , 799-808. (10.1016/j.biocon.2015.07.003)
36. Villarreal-Rosas J, Sonter LJ, Runting RK, López-Cubillos S, Dade MC, Possingham HP, Rhodes JR. 2020 Advancing systematic conservation planning for ecosystem services. Trends Ecol. Evol. 35 , 1129-1139. (10.1016/j.tree.2020.08.016)32977982
37. Tulloch VJD et al. 2021 Minimizing cross-realm threats from land-use change: a national-scale conservation framework connecting land, freshwater and marine systems. Biol. Conserv. 254 , 108954. (10.1016/j.biocon.2021.108954)
38. Alagador D, Cerdeira JO, Araújo MB. 2016 Climate change, species range shifts and dispersal corridors: an evaluation of spatial conservation models. Methods Ecol. Evol. 7 , 853-866. (10.1111/2041-210X.12524)
39. Lanzas M, Hermoso V, Morán-Ordoñez A, Regos A, Bota G, Brotons L. 2021 The value of unprotected land for future conservation efforts under dynamic conditions. Biol. Conserv. 261 , 109232. (10.1016/j.biocon.2021.109232)
40. Verniest F, Galewski T, Julliard R, Guelmami A, Le Viol I. 2022 Coupling future climate and land-use projections reveals where to strengthen the protection of Mediterranean Key Biodiversity Areas. Conserv. Sci. Prac. 4 , e12807. (10.1111/csp2.12807)
41. Eaton MJ, Yurek S, Haider Z, Martin J, Johnson FA, Udell BJ, Charkhgard H, Kwon C. 2019 Spatial conservation planning under uncertainty: adapting to climate change risks using modern portfolio theory. Ecol. Appl. 29 , e01962. (10.1002/eap.1962)31243844
42. Smallhorn-West PF, Pressey RL. 2022 Why does conservation minimize opportunity costs? Conserv. Sci. Prac. 4 , e12808. (10.1111/csp2.12808)
43. Daigle RM, Metaxas A, Balbar AC, McGowan J, Treml EA, Kuempel CD, Possingham HP, Beger M. 2020 Operationalizing ecological connectivity in spatial conservation planning with Marxan Connect. Methods Ecol. Evol. 11 , 570-579. (10.1111/2041-210X.13349)
44. Beger M, Metaxas A, Balbar AC, McGowan JA, Daigle R, Kuempel CD, Treml EA, Possingham HP. 2022 Demystifying ecological connectivity for actionable spatial conservation planning. Trends Ecol. Evol. 37 , S0169534722002221. (10.1016/j.tree.2022.09.002)
45. Metcalfe K, Vaz S, Engelhard GH, Villanueva MC, Smith RJ, Mackinson S. 2015 Evaluating conservation and fisheries management strategies by linking spatial prioritization software and ecosystem and fisheries modelling tools. J. Appl. Ecol. 52 , 665-674. (10.1111/1365-2664.12404)
46. Wesemeyer M, Kamp J, Schmitz T, Müller D, Lakes T. 2023 Multi-objective spatial optimization to balance trade-offs between farmland bird diversity and potential agricultural net returns. Agric. Ecosyst. Environ. 345 , 108316. (10.1016/j.agee.2022.108316)
47. Hermoso V, Bota G, Brotons L, Morán-Ordóñez A. 2023 Addressing the challenge of photovoltaic growth: integrating multiple objectives towards sustainable green energy development. Land Use Policy 128 , 106592. (10.1016/j.landusepol.2023.106592)
48. Mair L, Mill AC, Robertson PA, Rushton SP, Shirley MDF, Rodriguez JP, McGowan PJK. 2018 The contribution of scientific research to conservation planning. Biol. Conserv. 223 , 82-96. (10.1016/j.biocon.2018.04.037)
49. McIntosh EJ, Chapman S, Kearney SG, Williams B, Althor G, Thorn JPR, Pressey RL, McKinnon MC, Grenyer R. 2018 Absence of evidence for the conservation outcomes of systematic conservation planning around the globe: a systematic map. Environ. Evid. 7 , 22. (10.1186/s13750-018-0134-2)
50. Álvarez-Romero JG et al. 2018 Research advances and gaps in marine planning: towards a global database in systematic conservation planning. Biol. Conserv. 227 , 369-382. (10.1016/j.biocon.2018.06.027)
51. Chalastani VI, Tsoukala VK, Coccossis H, Duarte CM. 2021 A bibliometric assessment of progress in marine spatial planning. Marine Policy 127 , 104329. (10.1016/j.marpol.2020.104329)
52. Muschelli J. 2019 rscopus: Scopus Database ‘API’ Interface. See https://CRAN.R-project.org/package=rscopus.
53. Bürkner P-C. 2017 brms: An R package for Bayesian multilevel models using Stan. J. Stat. Softw. 80 , 1-28. (10.18637/jss.v080.i01)
54. Bürkner P-C. 2018 Advanced Bayesian multilevel modeling with the R Package brms. The R J. 10 , 395. (10.32614/RJ-2018-017)
55. Arneth A, Leadley P, Claudet J, Coll M, Rondinini C, Rounsevell MDA, Shin Y, Alexander P, Fuchs R. 2023 Making protected areas effective for biodiversity, climate and food. Glob. Change Biol. 29 , 16664. (10.1111/gcb.16664)
56. Pressey RL, Visconti P, Mckinnon MC, Gurney GG, Barnes MD, Glew L, Maron M. 2021 The mismeasure of conservation. Trends Ecol. Evol. 36 , 808-821. (10.1016/j.tree.2021.06.008)34303527
57. Hermoso V, Morán-Ordóñez A, Lanzas M, Brotons L. 2020 Designing a network of green infrastructure for the EU. Landsc. Urban Plann. 196 , 103732. (10.1016/j.landurbplan.2019.103732)
58. Reuter KE, Juhn D, Grantham HS. 2016 Integrated land-sea management: recommendations for planning, implementation and management. Environ. Conserv. 43 , 181-198. (10.1017/S0376892916000023)
59. Giakoumi S et al. 2019 Conserving European biodiversity across realms. Conserv. Lett. 12 , e12586. (10.1111/conl.12586)
60. Chaplin-Kramer R et al. 2021 Conservation needs to integrate knowledge across scales. Nat. Ecol. Evol. 6 , 118-119. (10.1038/s41559-021-01605-x)
61. Neyret M et al. 2023 Landscape management strategies for multifunctionality and social equity. Nat. Sustain. 6 , 391-403. (10.1038/s41893-022-01045-w)
62. Barbosa A et al. 2019 Cost-effective restoration and conservation planning in Green and Blue Infrastructure designs. A case study on the Intercontinental Biosphere Reserve of the Mediterranean: Andalusia (Spain) – Morocco. Sci. Total Environ. 652 , 1463-1473. (10.1016/j.scitotenv.2018.10.416)30586831
63. Carvalho L et al. 2019 Protecting and restoring Europe's waters: an analysis of the future development needs of the Water Framework Directive. Sci. Total Environ. 658 , 1228-1238. (10.1016/j.scitotenv.2018.12.255)30677985
64. Watts ME, Ball IR, Stewart RS, Klein CJ, Wilson K, Steinback C, Lourival R, Kircher L, Possingham HP. 2009 Marxan with Zones: software for optimal conservation based land- and sea-use zoning. Environ. Model. Softw. 24 , 1513-1521. (10.1016/j.envsoft.2009.06.005)
65. Moilanen A, Lehtinen P, Kohonen I, Jalkanen J, Virtanen EA, Kujala H. 2022 Novel methods for spatial prioritization with applications in conservation, land use planning and ecological impact avoidance. Methods Ecol. Evol. 13 , 1062-1072. (10.1111/2041-210X.13819)
66. Hanson JO, Schuster R, Morrell N, Strimas-Mackey M, Edwards BPM, Watts ME, Arcese P, Bennett J, Possingham HP 2023 prioritizr: Systematic Conservation Prioritization in R. R package v. 8.0.3. (See https://CRAN.R-project.org/package=prioritizr.)
67. Salgado-Rojas J, Álvarez-Miranda E, Hermoso V, Garcia-Gonzalo J, Weintraub A. 2020 A mixed integer programming approach for multi-action planning for threat management. Ecol. Modell. 418 , 108901. (10.1016/j.ecolmodel.2019.108901)
68. Alagador D, Cerdeira JO. 2020 Revisiting the minimum set cover, the maximal coverage problems and a maximum benefit area selection problem to make climate-change-concerned conservation plans effective. Methods Ecol. Evol. 11 , 1325-1337. (10.1111/2041-210X.13455)
69. Justeau-Allaire D, Hanson JO, Lannuzel G, Vismara P, Lorca X, Birnbaum P. 2023 restoptr : an R package for ecological restoration planning. Restor. Ecol. 31 , e13910. (10.1111/rec.13910)
70. Silvestro D, Goria S, Sterner T, Antonelli A. 2022 Improving biodiversity protection through artificial intelligence. Nat. Sustainab. 5 , 415-424. (10.1038/s41893-022-00851-6)
71. Lapeyrolerie M, Chapman MS, Norman KEA, Boettiger C. 2022 Deep reinforcement learning for conservation decisions. Methods Ecol. Evol. 13 , 2649-2662. (10.1111/2041-210X.13954)
72. Weerasena L, Shier D, Tonkyn D, Mcfeaters M, Collins C. 2023 A sequential approach to reserve design with compactness and contiguity considerations. Ecol. Modell. 478 , 110281. (10.1016/j.ecolmodel.2023.110281)
73. Ribeiro BR, Brum FT, Pressey RL, Loyola R. 2017 Scoring methods do not provide reliable conservation priorities for marine biodiversity protection. Biol. Conserv. 210 , 349-350. (10.1016/j.biocon.2017.02.038)
74. Canessa S et al. 2023 Designing an optimal large-scale reintroduction plan for a critically endangered species. J. Appl. Ecol. 60 , 1365-2664. (10.1111/1365-2664.14345)
75. Kujala H, Moilanen A, Araújo MB, Cabeza M. 2013 Conservation planning with uncertain climate change projections. PLoS ONE 8 , e53315. (10.1371/journal.pone.0053315)23405068
76. Gerling C, Drechsler M, Keuler K, Leins JA, Radtke K, Schulz B, Sturm A, Wätzold F. 2022 Climate–ecological–economic modelling for the cost-effective spatiotemporal allocation of conservation measures in cultural landscapes facing climate change. Q. Open 2 , qoac004. (10.1093/qopen/qoac004)
77. Fastre C, Mogg S, Jung M, Visconti P. 2019 Targeted expansion of Protected Areas to maximise the persistence of terrestrial mammals. bioRxiv 3124 , 1-19. (10.1101/608992)
78. Bijlsma R et al . 2019 Defining and applying the concept of favourable reference values for species habitats under the EU birds and habitats directives: examples of setting favourable reference values. Wageningen, The Netherlands: Wageningen Environmental Research. (10.18174/468534)
79. Adams VM, Pressey RL, Álvarez-Romero JG. 2016 Using optimal land-use scenarios to assess trade-offs between conservation, development, and social values. PLoS ONE 11 , e0158350. (10.1371/journal.pone.0158350)27362347
80. Law EA et al. 2021 Fading opportunities for mitigating agriculture–environment trade-offs in a south American deforestation hotspot. Biol. Conserv. 262 , 109310. (10.1016/j.biocon.2021.109310)
81. Abarca H, Morán-Ordoñez A, Villero D, Guinart D, Brotons L, Hermoso V. 2022 Spatial prioritisation of management zones in protected areas for the integration of multiple objectives. Biodivers. Conserv. 31 , 1197-1215. (10.1007/s10531-022-02383-z)
82. Strassburg BBN et al. 2020 Global priority areas for ecosystem restoration. Nature 586 , 724-729. (10.1038/s41586-020-2784-9)33057198
83. O'Connor LMJ, Pollock LJ, Renaud J, Verhagen W, Verburg PH, Lavorel S, Maiorano L, Thuiller W. 2021 Balancing conservation priorities for nature and for people in Europe. Science 372 , 856-860. (10.1126/science.abc4896)34016780
84. Horta ECB et al. 2022 Co-design of a marine protected area zoning and the lessons learned from it. Front. Mar. Sci. 9 , 969234. (10.3389/fmars.2022.969234)
85. Hanson JO, Fuller RA, Rhodes JR. 2019 Conventional methods for enhancing connectivity in conservation planning do not always maintain gene flow. J. Appl. Ecol. 56 , 913-922. (10.1111/1365-2664.13315)
86. Staccione A, Brown C, Arneth A, Rounsevell M, Hrast Essenfelder A, Seo B, Mysiak J. 2023 Exploring the effects of protected area networks on the European land system. J. Environ. Manage. 337 , 117741. (10.1016/j.jenvman.2023.117741)36966632
87. Katsanevakis S et al. 2020 Twelve recommendations for advancing marine conservation in European and contiguous seas. Front. Mar. Sci. 7 , 565968. (10.3389/fmars.2020.565968)
88. Chapman M, Jung M, Leclère D, Boettiger C, Augustynczik AL, Gusti M, Ringwald L, Visconti P. 2023 Meeting European conservation and restoration targets under future land-use demands. (https://osf.io/preprints/osf/ynqfx)
89. Pörtner H-O et al. 2023 Overcoming the coupled climate and biodiversity crises and their societal impacts. Science 380 , eabl4881. (10.1126/science.abl4881)37079687
90. Muscatello A, Elith J, Kujala H. 2021 How decisions about fitting species distribution models affect conservation outcomes. Conserv. Biol. 35 , 1309-1320. (10.1111/cobi.13669)33236808
91. Kujala H, Lahoz-Monfort JJ, Elith J, Moilanen A. 2018 Not all data are equal: influence of data type and amount in spatial conservation prioritisation. Methods Ecol. Evol. 9 , 2249-2261. (10.1111/2041-210X.13084)
92. Côté IM, Darling ES, Brown CJ. 2016 Interactions among ecosystem stressors and their importance in conservation. Proc. R. Soc. B 283 , 20152592. (10.1098/rspb.2015.2592)
93. Alagador D, Cerdeira JO. 2019 Introducing spatio-temporal conservation units: models for flexible optimization of species persistence under climate change. In Handbook of climate change and biodiversity (eds W Leal Filho, J Barbir, R Preziosi), pp. 243-258. Cham, Switzerland: Springer International Publishing.
94. Santini L, Antão LH, Jung M, Benítez-López A, Rapacciuolo G, Di Marco M, Jones FAM, Haghkerdar JM, González-Suárez M. 2021 The interface between macroecology and conservation: existing links and untapped opportunities. Front. Biogeogr. 13 . (10.21425/F5FBG53025)
95. Metcalfe K et al. 2022 Fulfilling global marine commitments; lessons learned from Gabon. Conserv. Lett. 15 , e12872. (10.1111/conl.12872)
96. Jung M, Diogo A, Chapman M, Virgilio H, Kujala H, O'Connor L, Schinegger R, Verburg P, Piero V. 2023 Reviewed literature on the state of conservation planning in Europe [Data set]. In Philosophical Transactions B (1.0). Zenodo. (10.5281/zenodo.8104715)
97. Jung M, Diogo A, Chapman M, Virgilio H, Kujala H, O'Connor L, Schinegger R, Verburg P, Piero V. 2024 An assessment of the state of conservation planning in Europe. GitHub repository. (https://github.com/Martin-Jung/Review_EuropeanConservationPlanning)
98. Jung M, Alagador D, Chapman M, Hermoso V, Kujala H, O'Connor L, Schinegger R, Verburg PH, Visconti P. 2024 An assessment of the state of conservation planning in Europe. Figshare. (10.6084/m9.figshare.c.7093258)
