In the early 2000s, Beijing faced several challenges related to its uncoordinated functional urban layout, with ecological issues becoming increasingly apparent. Districts and counties leveraged their local geographic advantages to pursue development opportunities and achieved substantial economic growth (Zhou and Zhu, 2009). However, developmental homogenization, especially between mountainous and plain areas, limited the capital’s overall functionality. The planning and construction of functional zones and ecological conservation areas emerged as essential solutions (Xie and Wang, 2023). Subsequent plans, regulations, and policies guided BECA’s construction with a focus on balancing comprehensive development across the region, which integrated the production and distribution between mountainous and plain areas within the top-level design. As the National Main Functional Zone Planning advanced, city and district governments reached a consensus for promoting BECA to harmonize past conflicts between ecological protection and social development. Early studies primarily addressed the necessity and objectives of BECA’s construction.

Based on policy reforms and implementation, BECA’s development over the past two decades can be summarized as “two shifts and three phases” (Table 1). The Beijing Urban Master Plan (2004-2020) adopted the “Five Coordinations” as its guiding principle, which emphasized the need to balance development between the plains and mountainous areas under coordinated regional development. In 2012, the Beijing Major Function-Oriented Zoning Plan incorporated seven towns in Changping and 16 townships in Fangshan into the Ecological Conservation Development Zone as restricted development areas. This marked the transition from the differentiated transformation phase to the optimization phase, reflecting a shift toward ecological compensation and a shift toward broader regional coordination. In 2017, the new master plan renamed this zone as BECA, which signified the transition to the modern green development phase characterized by a comprehensive modernization shift.

(1) Phase I focused on foundational issues such as water source protection, ecological industry development, zoning, and industrial layout, and was driven by water conservation and ecological buffering objectives. During this phase, industry and academia collaborated through commissioned cross-sectoral studies.

(2) Phase II maintained continuity with previous research and placed greater emphasis on realizing the economic value of Lucid Waters and Lush Mountains. This involved research on inter-regional ecological compensation, central-to-local ecological protection transfer payments, and pathways for market-based mechanisms for ecological products. With the deepening of the Beijing-Tianjin-Hebei Coordinated Development strategy, some studies also began to explore integrated ecological protection between the northwestern mountainous region of Hebei and BECA.

(3) Phase III emphasized sufficient development and balanced development to align with meeting people’s aspirations for a better life. This phase integrated new themes such as rural livelihoods, rural revitalization, water conservation, carbon sequestration, and spatial productivity in conservation areas, which enriched the research framework. The advancement of “Five-in-One”^①

① “Five-in-One” is China’s integrated development strategy that coordinates progress in five key areas. It represents a holistic approach to national modernization, ensuring balanced growth across all critical sectors of society.

development further deepened research in these areas.

Research on BECA reflects a layered approach that addresses both meso- and macro-level issues at the administrative unit scale and micro-level issues within geographic units such as watersheds, scenic areas, and villages. Each spatial scale aligns with the corresponding research methods, where scale, hierarchy, and interactions reflect BECA’s ecosystem characteristics. In the “real-world issues-spatial scale-data methodology” framework, scale functions as a connective element. Thus, BECA’s spatial characteristics both reflect and shape the research questions and methods applied to this area.

Issues such as non-point source pollution control in the Miyun Reservoir watershed, biodiversity conservation in the Yanshan and Taihang mountains, and vegetation restoration on decommissioned mining areas fall within the natural sciences. These topics correspond to natural geographic units, with data sourced mainly from meteorological and hydrological monitoring stations, remote sensing imagery, and field sampling.

Conversely, topics like improving the farmers’ livelihoods, land use optimization, industrial transformation, and economic restructuring fall within the social sciences. These correspond to administrative units, with data collected from national statistical surveys, research institution sampling, questionnaires, and interviews.

BECA also includes five district-level administrative units such as Huairou, along with mountainous areas in Changping and Fangshan. This region connects with northwestern Hebei, jointly supporting water conservation and ecological functions for the capital’s plains development area. This spatial relationship requires expanding the research to include upstream regions and winter windward areas like Zhangjiakou and Chengde, which impact eco-cooperation and industrial collaboration between Beijing and Hebei. Consequently, the research must also address the administrative scale to examine inter-regional interactions, compensation, and cooperative mechanisms.

The Beijing Ecological Conservation Area is defined by its complex ecosystem and unique role as a functional zone within the capital, making it a focal point of multiple research fields. This multidimensional area encompasses various issues, including ecological product value realization, rural socio-economic development, watershed conservation, and industrial-ecological balance. These diverse topics have attracted researchers from fields such as ecology, geography, economics, management, and other disciplines, forming a comprehensive research community that addresses both theoretical and practical challenges.

Research on BECA reflects its distinctive geographic context and examines how rural development, modernization, cultural services, and ecological restoration intertwine. Studies have focused on the economic improvement of rural areas through infrastructure and new industry development while emphasizing the area’s role in the broader ecological civilization of Beijing. In addition, BECA’s potential for leisure tourism and its significance in providing regulatory and cultural services have been explored, along with crucial efforts in the ecological protection and restoration of natural landscapes. This integrated perspective underscores the complexity of issues facing BECA and the need for comprehensive, collaborative research approaches.

Ecological products, also referred to as ecological assets, provide both tangible resources and intangible services (Yang et al., 2021), and they primarily encompass material supply, regulating services, and cultural services (Ma et al., 2017). Recognizing and actualizing this value for improving people’s lives and advancing social development is a significant alternative to traditional industrial growth in the BECA.

Throughout history, humans have thrived in nature by extracting various benefits from the natural environment, which highlights the intrinsic value of ecological products (Daily, 2013; Peng and Yuchi, 2021). The discussion on how to convert ecological value into economic value is becoming increasingly intense, and four levels of practical problems have been gradually proposed around ecological products: value assessment, supply and demand relationships, value realization, and ecological compensation. These issues reflect the evolving discourse surrounding ecological products and their essential role in promoting sustainable development within BECA (Zheng, 2013) (Figure 2).

Value assessment serves both as a quantification of the worth of “Lucid Waters and Lush Mountains”, providing a direct reflection of the welfare benefits offered by ecological products (Kong et al., 2016), and as an evaluation of the overall performance of ecological protection policies (Li, 2019). Research has focused on different spatial variations, temporal fluctuations, and the value flow relationships between various ecological sub-systems within BECA through methods such as reconstructing ecological service value assessment models and energy value accounting analysis (Ma and Liu, 2014; Ma et al., 2017). The findings have indicated that as urbanization accelerates, the importance of forest and aquatic ecosystems increases, which is consistent with societal demands for the functions of BECA. Conversely, the significance of agricultural ecosystems declines, while leisure agriculture and tourism emerge as primary avenues for the transformation and development of BECA.

The supply-demand relationship determines the efficiency of transforming ecological advantages into economic advantages.. Clarifying the corresponding supply-demand relationships for various ecological products is fundamental to their market value realization (Dai et al., 2021). On the supply side, the emphasis is placed on enhancing product added value and supply capacity, defining property rights over ecological resources, and capitalizing these resources (Peng and Yuchi, 2021; Jin and Cao, 2024). On the demand side, human preferences exhibit significant variability influenced by factors such as cultural education and income levels, which leads to differing demands for ecological products (Ding et al., 2023). Research on supply and demand focuses on equilibrium solutions, specifically the optimal supply quantity of ecological products. Improving supply levels and stimulating effective market demand are two critical drivers for realizing the value of ecological products. Related studies within this theoretical context have validated the rationale for transitioning from a single-region model of “pollute first, clean up later” to a dual-region approach of seeking wealth and green development in synergy, providing theoretical support and guidance for the specialized division of labor between urban areas and ecological conservation zones (Sun et al., 2015).

The realization of ecological product value is the core mechanism for resolving the contradiction between development and protection (Gao et al., 2020). Nationwide, the realization and conversion of ecological product value constitute essential tasks for all ecological protection functional areas. In the context of addressing ecological issues in a megacity like Beijing, the realization of value within BECA is a practical pathway for transforming ecological advantages into economic benefits (Wang, 2023). Studies have typically categorized ecological products based on their supply and functional attributes (Lu, 2022), clarified the feasibility of value realization based on the nature of different ecological products and proposed both direct and indirect pathways for achieving value (Zhu and Guo, 2006; Liu, 2023). Ecological compensation represents a unique means of value realization that involves vertical transfer payments to ecological protectors or horizontal developmental substitutes (Li, 2011). After the establishment of BECA, local economic development and villager livelihoods were inevitably transformed, posing challenges for balanced regional development; thus, establishing an ecological compensation system has become necessary. Many studies have explored questions such as “how to compensate” and “how much to compensate” from a policy or institutional perspective (Hao et al., 2022; Lu, 2023), and proposed various methods like opportunity cost analysis, energy value methods, gross value product accounting, equivalence factor methods, simulated market pricing, and environmental restoration cost assessments (Li et al., 2019). Developing a reasonable compensation mechanism remains a focal point of research. While existing studies have ventured into exploratory designs concerning institutional completeness, financing channel enhancement, and performance evaluation adjustments, the policy recommendations presented so far are still somewhat abstract and require further refinement.

Rural areas within BECA have undergone significant transformations in their socio-economic structures and functional roles. Studies have examined these changes from multiple perspectives, including livelihood strategies, industrial development, and spatial reorganization (Yan, 2008). In the early stages, as the overall socioeconomic level of the capital improved, the income gap between urban areas in the plains and rural areas in the mountains widened (Feng, 2016). Thus, in the context of rural revitalization, BECA has introduced support policies distinct from those in urban regions (Liu, 2019). Increasing farmer income is the foremost issue in agricultural development (Xie et al., 2018), with related research focusing on the factors affecting farmer income, income enhancement strategies, and the relationship between household livelihoods and ecological services (Wang et al., 2021; Xie et al., 2022; Guo et al., 2023). Policy recommendations have been proposed in areas such as infrastructure development, environmental protection, human capital investment, and the exploration of local culture (Wu et al., 2024), and they have provided a theoretical foundation for creating a “diversified regional ecological cooperation community” that enhances both ecological environments and farmer well-being through green development practices.

The transformation of land use is a significant marker and spatial projection of the development transition process (Xu et al., 2023). The construction of ecological conservation areas, the transformation of economic development modes, and the implementation of rural revitalization strategies have collectively driven changes in the functions of mountain towns in Beijing, shifts in land use for regional industries, and the redefinition of functions within rural homesteads. Economic activities, agricultural production, and ecological services within BECA are interwoven across various towns, creating a balanced and collaborative relationship among their respective functions (Liu et al., 2021). However, challenges remain in land use, such as the unclear nature of land designated for emerging industries and the high land costs associated with green industries. Consequently, strategies have been proposed to enhance the alignment between industry and conservation area positioning, as well as to explore the establishment of flexible land use types for integrated industrial development (Yang et al., 2022).

The shift in the functions of rural homesteads can be viewed as the result of spatial production or reproduction in rural areas. External actors are driving the replacement of primary homestead entities and promoting functional upgrades. Under the interplay of local capital, external investment, and government regulation, spatial utilization is gradually adjusting alongside economic and industrial development, with capital playing a dominant role in the transformation of rural functions (Cai and Wang, 2022). Relevant studies primarily employ theoretical or interview-based research paradigms, while empirical studies based on mathematical modeling are relatively scarce.

The primary objectives for the construction of BECA have long included water conservation, forest preservation, and soil erosion control, which align with its designation as an “ecological barrier and important water source protection area”. Research related to these goals encompasses comprehensive issues and strategies for building ecological conservation areas, hydrological characteristics at various scales, and the impacts of ecological environments and responses to those impacts. With the introduction of the “dual carbon” goals, studies focusing on the carbon sequestration functions of BECA have also gained prominence (Li et al., 2020; Wang et al., 2023).

Currently, there are two main sources of freshwater for the capital: the “South-to-North Water Diversion” project, which draws water from the Danjiangkou Reservoir, and the natural rivers within Beijing, including the Miyun (Wang, 2011; Zhang et al., 2020) and Guanting (Liu and Li, 2010; Ou and Wang, 2015) Reservoir watersheds, which are crucial for ensuring the water resource supply. Investigating these areas is vital for maintaining the quality of aquatic systems and enhancing their ecological service capacities (Meng, 2022). Water conservation and protection represent a holistic challenge, as both water quality and quantity are influenced by regions extending into northwestern Hebei province and the Taihang Mountains (Wang and Wang, 2015; Niu et al., 2016). Therefore, broadening the research area is beneficial for addressing these ecological concerns at their root.

From a hydrological perspective, research on BECA has examined various natural geographical units such as reservoirs, river basins, and mountainous terrains, with a focus on the temporal and spatial differentiation of water quality and quantity and the factors affecting them. Studies indicate significant differences in the average water conservation amounts among the different functional areas in Beijing, with only the ecological conservation area showing positive values (Xu et al., 2019). Agricultural activities and diverse land use practices within BECA notably impact water quality (Zhang et al., 2019; Xia et al., 2024), while efforts like ecological replenishment positively contribute to ecological restoration and the recovery of water areas (Li et al., 2022; Ma et al., 2023).

Natural disasters and human activities pose significant threats to environmental quality within BECA, necessitating the construction of resilient urban infrastructure that enhances the capacity to withstand risks and recover from ecological disturbances. Therefore, evaluating the ecological risk response capabilities of BECA and proposing strategies to mitigate pollution damage and enhance self-restoration capabilities of the ecological environment are of paramount importance.

The construction of BECA has established a “green threshold” for the land use and industrial sectors, guiding the migration or transformation of high-energy-consuming and high-pollution industries. BECA faces the dual challenges of adjusting industrial development models and relinquishing certain growth opportunities. Important research topics have emerged around the need to combine ecological protection requirements with the competitive advantages of various districts to redefine dominant industries, adjust industrial structures, coordinate regional industrial development directions, optimize spatial layouts, and develop collaborative strategies for ecological protection and industrial growth.

Simply aggregating the dominant industries of individual regions does not guarantee a rational industrial spatial layout for BECA as a whole. Therefore, integrating the strengths and development opportunities across different areas is crucial for achieving optimal benefits. Analyzing the advantageous industries of each district serves as the premise and foundation for optimizing the overall spatial structure (Sun et al., 2016), and corridor analysis offers a unique perspective on the spatial structure of industries in mountainous areas (Mu et al., 2012). Land acts as the spatial carrier for economic activities, and the delineation of functional areas reflects the transformation of urban spatial structures. On one hand, land use patterns can reveal the conditions of natural resources and social development (Wang et al., 2013); while on the other hand, the nature of land use can influence the direction of industrial growth. For the development of emerging industries in BECA, it is necessary to incorporate flexible industrial land use into planning, which will promote the integration of industries through combined land use, thereby supporting the transformation of economic development models (Yang et al., 2022).

Since the establishment of BECA, addressing the historical contradiction between environmental protection and economic development has become a key issue, which has made the search for a suitable green development approach crucial. Related research has consistently evolved and remains a hot topic. Studies emphasize the integration of ecological environment construction with industrial development, while focusing on the implementation of development positioning and promoting agricultural and forestry economies (Zhong and Wang, 2013). Industries such as leisure tourism are being developed to enhance the added value of ecological products, thereby creating new engines for economic growth (Guo, 2018). With the continuous advancement of industrial transformation and upgrading, significant progress has been made in reconciling ecological conservation with economic growth. However, the need for further attention to regional endowment differences and the refinement of differentiated management measures remains (Zheng et al., 2024).

Building on this foundation, assessments of the green development level and the coordination between ecology and industry within BECA, and even the broader Beijing-Tianjin-Hebei ecological conservation area, are essential for recognizing developmental achievements while also addressing new challenges in the current phase (Sun et al., 2018). Some progress has been made in balancing protection and development. Some areas have become national ecological demonstration zones, and the functional positioning of the ecological conservation area has gradually become prominent. The market competitiveness of characteristic industries has gradually increased, and the sustainability of economic development has been enhanced. However, there is still room for optimization in the institutional design of green development, which also puts forward new requirements for existing research. Demonstrating the development path according to the new development situation and the policy-market environment is necessary (Mu, 2023).

The construction of BECA is closely aligned with national macro policies, including the scientific outlook on development, main functional area planning, and ecological civilization construction. This reflects a comprehensive policy design progressing from macro to micro levels and from concepts to implementation. BECA represents a meso-scale spatial arrangement between the main functional areas and the “three zones and three lines” delineation. The theoretical logic of its green development is guided by principles of ecological priority, regional coordination, and harmonious human-nature coexistence. It adopts systematic governance, government guidance, and multi-party participation to promote coordinated economic, social, and environmental development, with the aim of balancing the economic, social, and ecological benefits. The green development framework for BECA can be explained through four key relationships (Figure 3).

The interrelationship between green and development. “Green” and “development” are intertwined and interactive transformational directions, and the boundaries between them are incomplete. Their interaction often reveals practical contradictions. For example, “green” calls for transformations in production methods and industrial structures, while “development” requires the ecological environment to achieve economic value. The “green” approach emphasizes moving away from high-energy-consuming industries and reducing negative externalities. While this may initially conflict with development goals, environmentally friendly development is ultimately inevitable for sustainability.

The implementation of policies and economic structure adjustments still faces the criticism that “environmental protection requirements are excessively high and premature”. However, as the capital city and a global showcase, Beijing must coordinate its environmental protection and development mechanisms. Development must prioritize environmental and ecological health over short-term economic gains. In addition, ecological conservation should depend not only on investment but also on innovation within regional economic contexts to create and realize economic value (Zhang, 2009).

The “green” approach provides new directions and impetus for the economy, fostering green technologies and industries that generate new economic growth. The interplay and contradictions between green initiatives and development are unified within BECA’s construction practices.

The new era significance of green development. Harmonious human-nature coexistence is intrinsic to advancing China’s modernization. Urban development and production activities in Beijing’s mountainous areas continue to pose severe ecosystem threats (Zheng et al., 2020). Watershed governance and protection tasks remain daunting, and green development can help reverse ecological deterioration at its source. The Ecological Conservation Area contributes to carbon neutrality goals, promotes regional green development, and aligns with new era development requirements. It emphasizes respecting, aligning with, and protecting nature while optimizing rural industrial structures and consolidating poverty alleviation achievements. This also involves implementing functional area planning to serve key development zones while balancing urban safety with ecological diversity protection in mountainous regions.

BECA serves as a practical example of integrating Marxist ecological development perspectives with China’s actual economic and social conditions, and it reflects the trends and patterns of economic and social development in a historically new phase.

The functions of green development in the conservation area. The Ecological Conservation Area has multiple tasks of acting as an ecological barrier and protecting water resources, providing ecological products, and fostering ecological economic development. It supports new development patterns and promotes regional coordination (Zhu and Guo, 2006). In spatial management, environmental protection requires delineating boundaries based on arable land, permanent basic farmland, ecological protection red lines, and urban development boundaries (Yu et al., 2011). Such boundaries allow for protective and restorative governance strategies for the ecological spaces while enabling appropriate development in the production and living spaces.

Regarding economic growth, BECA aims to create high-quality leisure and sightseeing venues and supply material ecological products. This involves measuring and accounting for the value of ecological products, designing pathways and mechanisms for realizing that value, and exploring channels for the assetization and privatization of service resources (Wang, 2009). The long-term ecological protection efforts not only enhance the supply of ecological products within the conservation area but also improve the overall quality of economic growth in the capital, thereby driving innovation in development models. These efforts provide a pioneering example of transforming ecological assets—Lucid Waters and Lush Mountains—into economic benefits (Chen et al., 2021).

The macro goals for the conservation area. To deepen ecological protection and green development within the Ecological Conservation Area, we must promote the modernization of ecological civilization to achieve sustainable economic and social development. It is essential to recognize that enhancing ecological sharing, building an ecological, cultural, and high-quality recreational space system, and increasing the happiness and sense of gain for all people are intrinsic requirements of social development (Wang and Yang, 2023c). Improving the service quality of the Ecological Conservation Area to support high-level ecological civilization requires not only realizing the value of ecological products but also ensuring that modern green development has a universally beneficial impact.

Green development also implies achieving coordinated urban-rural development. This includes extending urban public facilities and services into the Ecological Conservation Area and promoting resource sharing and complementary advantages between urban and suburban areas, thereby establishing ecologically distinctive towns and new rural areas. Ultimately, this approach aims to create diverse development models for ecological conservation areas that reflect their unique characteristics.

Based on the analysis of existing research and the green development logic of BECA, several promising directions for future research can be identified.

(1) Methodological and technological outlook for research on BECA

The evolution from relying on individual data sources to utilizing multi-source data and the shift from adopting findings from abroad to innovating local methodologies have become key characteristics and trends in the research on BECA. New data methods and technological tools can provide novel solutions to traditional problems, while interdisciplinary collaboration and integration across various fields can enhance the innovation and reliability of research outcomes.

Specifically, in data utilization, combining socioeconomic statistical data with spatiotemporal data from remote sensing and other geographic information technologies, along with big data from the Internet of Things and primary data from field interviews, is essential. The application of machine learning algorithms from artificial intelligence, as well as rigorous modeling approaches from mathematics and economics, can deepen the research on BECA regarding forest cultivation, soil conservation, industrial transformation, ecological product value cultivation and conversion, and rural income growth.

In terms of methodological references, incorporating the latest research findings on ecological protection area construction from both domestic and international contexts is important, while also emphasizing innovations in local technical methodologies that are applicable to the capital’s ecological conservation area. The northwestern mountainous region of Beijing is a pioneering area for ecological conservation functions, but provinces and cities like Hebei, Suzhou, Kunming, and Nanjing have also made progress in this regard, providing opportunities for exchange and learning. Comparative studies on the construction of different ecological functional areas are necessary.

(2) Thematic and paradigmatic outlook for research on BECA

Similar to other urban spaces, the Beijing Ecological Conservation Area is a multifaceted regional unit characterized by the interweaving of production, living, and ecological dimensions. This complexity generates a diverse range of research questions, which in turn calls for an integrative approach to the research paradigms. This area has its unique characteristics that are primarily reflected in its prioritization of ecological protection, focus on green and modern industrial development, and emphasis on the living conditions of rural farmers.

In the research on BECA, the topics must address three practical issues.

Resolving the conflict between ecological protection and economic growth. This can be achieved by studying the realization of ecological product value and ecological compensation. The implementation plan released in December 2022 for promoting high-quality ecological protection and green development in ecological conservation areas outlines a directional arrangement for the next five years, but specific operational details still need further research to resolve these issues.

Promoting cross-regional coordination for water source conservation and ecological barrier functions. The spatial and topographical relationships between the Beijing mountainous areas and places like Zhangjiakou in Hebei dictate that these environmental issues must be addressed through intergovernmental cooperation. The coordinated development strategy for Beijing-Tianjin-Hebei provides the institutional framework necessary for this collaboration.

Creating a model for rural revitalization through specialized and diversified urban-rural industries. To control non-point source pollution, many energy-intensive enterprises have been closed or relocated. Strategies like converting rice cultivation to dry farming methods have been adopted to restore river and lake water levels. Future research should focus on how various regions can identify and develop specialized industries within the constraints of green development and how to organize and integrate these industries over a broader area to establish distinctive new rural business patterns.

(3) Perspectives and goals for research on BECA

Currently, the academic interest in BECA is rapidly increasing, and the theoretical frameworks and starting points for analyzing problems are undergoing significant transformations. Deconstructing the complexities of ecological conservation areas is an important method for enhancing the applicability of research conclusions. Different perspectives or starting points can offer diverse theoretical frameworks and methodological tools for investigating comprehensive issues. From a policy perspective, the construction of ecological conservation areas should align with national priorities, while understanding the characteristics and requirements of development in the new era. From an ecological perspective, future research should focus on biodiversity, ecosystem structure, and ecological service functions. From a sociological perspective, the population structure, social relations, and community development need to be considered. From an economic perspective, resource utilization, economic development models, and improving economic benefits should be emphasized.

The research objectives or focal points are crucial for efficiently advancing disciplinary development or solving practical problems. These would include: expanding pollution prevention measures and standardizing monitoring and survey protocols based on innovation-driven development strategies; narrowing the welfare gap between residents in the mountainous and plain areas of Beijing through urban-rural integration goals; and deepening economic innovation, optimizing environmental quality, and preserving local culture through rural revitalization initiatives.

From initial exploration to integrated multi-directional collaboration, the construction of BECA has gradually achieved significant milestones. Academic research on ecological protection, economic growth, and social harmony has made notable progress. Since two decades is a relatively short period for ecological environmental governance and adjustments in social production, various pressing issues in ecological conservation area construction remain. Future development will face increasingly complex and profound challenges, and the corresponding disciplinary research will rely on a richer and more robust academic foundation. Future construction efforts in BECA should draw extensively from pioneering domestic and international experiences and theories, creatively establish a new coordinated framework for ecological protection and green development in mega-cities, and use a human-nature coupling geographical perspective to understand the “human-land relationship” within the conservation area.