The urban heat island effect (UHI) is among the major challenges of urban climate, which is continuously intensifying its impact on urban life and functioning. Against the backdrop of increasingly prolonged heatwaves observed in recent years, practical questions about adaptation measures in cities are growing—questions that traditional meteorological monitoring can hardly answer adequately. On the other hand, UHI has long been the focus of research interest, but due to the technological complexity of providing accurate spatially referenced data at high spatial resolution and the requirement to survey at strictly defined parts of the day, information provision is becoming a major challenge. This is one of the main reasons why UHI research results are less often used directly in urban spatial planning. However, advances in geospatial technologies, including unmanned aerial systems (UASs), are providing more and more reliable tools that can be applied to achieve better and higher-quality information resources that adequately characterize the UHI phenomenon. This paper presents a developed and tested methodology for the rapid and efficient assessment and mapping of the effects of surface urban heat island (SUHI). It is entirely based on the integrated use of data from unmanned aerial systems (UAS)-based remote sensing methods, including thermal photogrammetry and GIS-based analysis methods. The study follows the understanding that correct SUHI research depends on a proper understanding of the urban geosystem, its spatial and structural heterogeneity, and its functional systems, which in turn can only be achieved by supporting the research process with accurate and reliable information resources. In this regard, the possibilities offered by the proposed methodological scheme for efficient geospatial registration of SUHI variations at the microscale, including the calculation of intra-urban SUHI intensity, are discussed in detail. The methodology builds on classical approaches for using local climate zoning (LCZ), adding capabilities for precise delineation of individual zone types and for geostatistical characterization of the urban surface heat island (SUHI). Finally, the proposed scheme is based on state-of-the-art technological tools that provide flexible and automated capabilities to investigate the phenomenon at microscales, including by enabling flexible observation of its dynamics in terms of heat wave manifestation and evolution. Results are presented from a series of sequential tests conducted on the largest residential area in Bulgaria’s capital city, Sofia, in terms of area and population, over a relatively long period from 2021 to 2024.

Natural heritage (NH) includes natural features that can be described as outstanding universal value at a national level. It refers to the importance of ecosystems, biodiversity, and geodiversity for their existence value, and the ecosystems can be considered as the spatial units for its mapping and assessment. The ecosystem services (ES) concept provides an appropriate basis in the form of assessment and mapping methods that enable linking the state of ecosystems with human well-being. Thus, it can be used as a platform to find solutions to the problems related to the conflicts between conservation and the use of the NH. In this paper, we aim to present the process of developing a methodological framework for mapping and assessment of ecosystem services provided by the natural heritage in Bulgaria for recreation and tourism. The conceptual framework of the ecosystem-based assessment of NH in Bulgaria is based on the assumption that the generation of NH for the needs of tourism can be presented as the linkages between the natural systems and tourism in the form of ES potential, flow, and demand. The results demonstrate that the NH can be presented as a spatial phenomenon conceptualized by the flows of benefits from ecosystems to people which contribute to human well-being. The mapping and assessment procedures are fully developed for application at a national level, while for the regional and local level, few pilot studies mark some basic foundations for further development.

Natural habitats and their biodiversity are usually associated with protected areas, incompatible with direct anthropogenic influence. Is there a biodiversity in urban environment, what is the role of peri-urban areas to the provision of species richness and is their potential being properly utilized? These are current issues that deserve the attention of decision-makers because the human's need of natural environment in cities is expressed more intensely than in any previous period in history. Green and blue infrastructure elements, being part of the larger system of urban ecosystems, provide an essential and proven benefits to the city dwellers, like health improvement, opportunities for nature-based daily outdoor recreation, strengthening sense of place etc. The main objective of this research is to assess this part of the landscape elements in urban and peri-urban environment, which are most supportive to the maintenance of habitats and their biodiversity. Selected Functional urban area with center city of Burgas is choosen for a case study. The urban ecosystems are assessed in GIS environment with unified indicator (based on City Biodiversity Index approach) according to 5 criteria: hemeroby index, share of protected areas, fragmentation index, presence of water and species richness. The assessment is performed on two spatial levels: within Functional urban area by Urban Atlas spatial units and within urban core – by grid cells (local climate zones). The final higher scores identify areas that provide the greatest extent the maintenance of habitats and their biodiversity. The results could support the urban planning and help to optimize the link between the natural elements within the Functional urban areas, providing ecological, economic and social benefits to the regions through the enhancement of the urban ecosystem’s functions and their services.

The study considers forest therapy as a tool for diversification of forest management. An up-to-date integrated approach for assessing and mapping potential of forest areas which could provide conditions for forest therapy services is developed and tested. It is based on combining data from the traditional forest inventory in Bulgaria and other open databases with methods for integrated assessment and mapping of ecosystem services: 7 criteria groups and 22 indicators are proposed, rated on a 5-point scale. Overlay analysis is applied to generate a composite assessment for each forest unit. Using spatial statistics tools, territorial hot spots with potential for forest therapy are identified. The methodology was successfully tested in a pilot case-study region, Smolyan Municipality, but it is applicable at broader scale, regardless of the type and ownership of forests. This approach could be transferred to other countries as well after adapting to their geographical, geoecological and socio-cultural specifics and database available. It is a cost-effective and informative tool to support forest owners and managers to diversify forest welfare services focusing on insufficiently used forest recreation potential.

Natural heritage includes natural features or natural areas of outstanding universal value. At a national level, this value refers to the importance of ecosystems which can be considered as the spatial units representing the natural heritage of the particular area in terms of their values to people. Nature-based outdoor recreation represents an important service that interests millions of people and contributes to connecting them to nature, but it may also cause negative impacts in the form of pollution, erosion and habitats loss. We apply the ESTIMAP recreation model which provides a framework for a spatially-explicit assessment of local outdoor recreation and use it to identify and assess the natural heritage as a source of recreation services at a national level in Bulgaria. At the first stage of the study, we identify the natural heritage and the data sources to represent it in a spatially-explicit way. Then, we apply the module for recreation potential to assess the potential of the natural heritage to provide a recreation ecosystem service. At the third stage, the accessibility of the natural heritage is assessed in order to specify how the potential identified at the previous step can be really used. Finally, the recreation potential and accessibility are integrated into the recreation opportunity spectrum in order to develop the maps representing the ecosystem service supply provided by the natural heritage. The results are presented in form of a recreation potential map that reveals the capacity of natural heritage to provide the recreation potential, map of the accessibility of the natural heritage and map of the recreation opportunity spectrum representing the combination between the first two maps. The maps will be used for the development of an innovative geospatial platform designed to facilitate the access of the Bulgarian natural heritage to the European common knowledge and innovation markets. The results on the accessibility and recreation opportunity spectrum contribute to the development of the model in areas which were not covered by previous applications at the EU scale.

The paper focuses on the role of the Natural Heritage in Forest Areas (NHFA) as a resource that can generate economic, social and environmental benefits for society through the provision of a wide range of cultural ecosystem services. In the assessment of the role of NHFA, the approach for assessment and mapping of ES in a given territorial scope was applied in a pilot region of Velingrad Municipality, focusing on the capacity of the forest ecosystems to provide cultural ecosystem benefits and services to the people. The study confirms that the identification of NHFA could be a powerful driver for regional development by creating significant positive effects such as improving sustainable cultural tourism in forests, diversifying forestry and supporting sustainable development and management of forest areas. The integration of the cultural services of NHFA into forest-related legislation can encourage job creation in different sectors and for different levels of employment, education and cultural training. Evaluation and mapping of ecosystem services is an appropriate tool to support the development of a concept and methods for assessing and mapping the general knowledge framework for NHFA policy in Bulgaria by applying an interdisciplinary approach.