Urban green infrastructure plays a crucial role in sustainable city development by offering a multitude of benefits, including improved environmental quality, increased social well-being, and enhanced economic prosperity. Evaluation and monitoring of regulatory implementation stand as essential components in the advancement of urban green infrastructure (GI) as they indicate the efficacy of regulatory acts and enable the assessment of their implementation success and adaptability to identified needs. This study identifies barriers and drivers based on the views of 352 professionals surveyed between 2018 and 2023 in Serbia. The primary data collection method employed questionnaire surveys. This study identified a range of barriers within existing legal frameworks, foremost of which include the lack of coordination and coherence between relevant ministries and governmental agencies, insufficient financial and human resources, the lack of transparency in the regulation development process, the need for strengthening technical capacities, and the absence of an adequate urban GI strategy. This research serves as a foundation for conceptualising GI regulatory elements that enhance urban GI development. Addressing these barriers necessitates efforts to improve coordination and collaboration among stakeholders, increase public participation, and enhance transparency in the regulatory process.

Summary: This study aims to analyze the impact of climatic variables on the fruiting of blackthorn (Prunus spinosa L.), a species which serves as both a food source and a habitat, offering birds shelter and providing other species with refuge from predators. Accordingly, blackthorn fruiting was recorded through field research in the peri-urban green infrastructure of Belgrade over 18 consecutive years. Urban edges are often the sites of expanding artificial surfaces, habitat fragmentation, and complex land-use transitions, including agricultural intensification and abandonment, which collectively increase pressures on residual semi-natural ecosystems. The integration of floristic sampling, phenological observations, landscape measures, and climatic variables allowed for an exploration of landscapes where blackthorn is successfully incorporated into semi-natural ecosystem remnants within a peri-urban context. The results obtained indicate that the phenological patterns of blackthorn, in response to climate change, demonstrate both adaptability and vulnerability to extreme climatic events during the flowering phase. In 2024, flowering began 6 days earlier than the earliest recorded start date and 43 days earlier than the latest start recorded over the previous 17 years. Regarding the fruiting (phonological) pattern, the average fruit maturation period was 288 days, while in 2024 it occurred 61 days earlier. The statistical significance of earlier fruit maturation and reduced accumulated heat requirements for fruit ripening was confirmed, revealing that as temperatures rise, key phenological events occur earlier with reduced heat accumulation, indicating a dependency on climatic parameters. Understanding the mechanism of phenological patterns is crucial for promoting effective environmental management practices and biodiversity conservation. The study also contributes to the potential application of its findings in designing green spaces in other peri-urban regions, supporting the sustainable development of complex peripheral landscapes by integrating blackthorn into green infrastructure planning.

The aims of the research were to determine the variability of the phenological patterns of natural populations of Prunus spinosa L. in the ecotones of the southeastern part of the Balkan Peninsula and to create an informational database regarding the impact of air temperature and precipitation on the phenology of this species, based on research conducted during the period from 2007 to 2024. The obtained data were analysed using descriptive and multivariate statistical methods. The results showed that the onset of spring phenological phases has been significantly accelerated by the increase in air temperature, especially in 2024, when flowering started 31 days earlier, the flowering phase lasted 13 days longer, and fruit ripening occurred 65 days earlier compared to the 2007-2023 period. The content of phenols, flavonoids, anthocyanins, and antioxidant activity in fruits was determined in distilled water and 70% ethanol. The analysed extracts contained a high percentage of phenols and demonstrated significant antioxidant activity. The obtained results are the starting point for studying changes in the phenological patterns of blackthorn in response to climate change under the agro-ecological conditions of the southwestern suburb of Belgrade. The study confirmed the adaptability of blackthorn, except for the vulnerability of its flowering phenophase to late spring frosts, as observed in 2023. The resilience of the species to climatic challenges was further confirmed by its drought tolerance in 2024 and a significant correlation between fruit ripening and high air temperatures during the growing season over 18 consecutive years of research.

In recent decades, contemporary cities have been exposed to numerous impacts, primarily population growth and climate change, resulting in a condition where the overall quality of their living environment, as well as the quality of life of their inhabitants, increasingly takes on negative aspects. Green infrastructure, as a planning concept, has long been recognized as a measure for establishing a healthier living framework in urban landscapes while respecting the characteristics and potential services of natural and nature-based ecosystems. The search for establishing a regulatory framework for green infrastructure, applying a modern, multidisciplinary, and scalable approach, is a process unfolding worldwide. Based on the principles of international and national conventions and directives, as well as an analysis of all administrative and physical constituent elements of green infrastructure, the Green Infrastructure Strategy of the City of Belgrade was developed and adopted by the city governance. The strategy identifi ed key challenges in implementing the concept and defi ned specifi c objectives, outlining strategic guidelines for achieving urban ecosystem services. Through the implementation of measures and activities prescribed by the strategy, the process of forming a comprehensive regulatory and professional framework for the preservation and development of the city's green infrastructure has begun, contributing to the creation of a resilient Belgrade urban landscapes.

The study establishes a locally specific basis that may serve as an indicator for the selection of climate-adaptive taxa in urban landscape design through a comparative evaluation of the effects of thermal anomalies on the flowering phenodynamics of Forsythia × intermedia and Kerria japonica ‘Pleniflora’ in Belgrade (2007–2026). By integrating empirical phenological parameters into a long-term climatological retrospective, the study bridges a methodological gap and distinguishes anthropogenic influences from regional climatic fluctuations. Non-parametric analyses identified a stable long-term trend, while the absence of statistically significant macro-scale effects confirms the predominant role of natural climatic variability. Nevertheless, microclimatic modifications induce distinct, taxon-specific phenological responses. Non-linear regression models identified two divergent adaptive mechanisms during warmer years: a phenological compression model in F. × intermedia (shortening of the flowering cycle accompanied by an annual increase in growing degree days (GDDs) of 0.71%) and a non-linear expansion model in K. japonica ‘Pleniflora’ (extension of the flowering period by more than one month, with the end of flowering delayed by 8.4 days per decade). Circular statistical analyses confirmed a high degree of temporal synchronisation and genetically determined phenological rhythmicity in both taxa, while revealing asynchrony in the terminal phenophases that was independent of growing degree day (GDD) accumulation. The synchronous shift towards warmer thermal classes positions both taxa as bioindicators of microclimatic change, although K. japonica ‘Pleniflora’ exhibited greater adaptive capacity. These findings highlight the importance of applying non-linear models in phenological forecasting and a contextualised taxonomic and ecological basis for the planning, introduction, and management of green spaces, supporting the sustainability of shrub taxa within the analysed urban core.