Introduction: Among the most dangerous pollutants is PM2.5, which can directly pass through human lungs and move into the blood system. The use of nature-based solutions, such as increased vegetation cover in an urban landscape, is one of the possible solutions for reducing PM2.5 concentration. Our study objective was to understand the importance of green spaces in pollution reduction.

Green infrastructure and in particular green roofs are crucial to meet the challenge of sustainable urbanisation fostered by the current European Research and Innovation agenda. Several documents were issued in the last decades in Europe for regulating the design, construction and up-keep of roof greening. In particular, the actual German guidelines have been widely adopted as a reference basis for green roof design and regulation worldwide, because of its exhaustiveness and proven building- and landscaping tradition.

Urban parks play a key role in the provision of ecosystem services, actively participating in improving the quality of life and welfare of local residents. This paper reports on the application of an index designed to quantify the allergenicity of urban parks in a number of Spanish cities. The index, which records biological and biometric parameters for the tree species growing there, classifies parks in terms of the risk they pose for allergy sufferers, graded as null, low, moderate or high.

Urban forests represent key elements of green infrastructure and provide essential ecosystem services in both the ecological and social spheres. Therefore, forestation planning plays a decisive role in the sustainable development strategies of metropolitan areas and addresses the challenge of maintaining biodiversity while improving human health and well-being. The aim of this work is to present a methodological approach that can be used to identify priorities in urban forest planning and can provide comprehensive responses to ecological and social needs in any metropolitan context.

In many European cities, urban gardens are seen as increasingly important components of urban green space networks. We adopt an ecosystem services framework to assess contributions of urban gardens to the quality of of their users. First, we identify and characterize ecosystem services provided by urban gardens. Secondly, we assess the demographic and socioeconomic profile of its beneficiaries and the relative importance they attribute to different ecosystem services.

Increasing climate change impacts are a major threat to sustainable urban development, and challenge current governance structures, including actors' responsibilities for dealing with climate variability and extremes. The need for distributed risk governance and citizen engagement is increasingly recognised; however, few empirical studies systematically assess interactions between citizens and municipalities in climate risk management and adaptation.

Nature has provided humankind with food, fuel, and shelter throughout evolutionary history. However, in contemporary cities, many natural landscapes have become degraded and replaced with impermeable hard surfaces (e.g., roads, paving, car parks and buildings). The reversal of this trend is dynamic, complex and still in its infancy. There are many facets of urban greening initiatives involving multiple benefits, sensitivities and limitations.

Recently published green infrastructure, nature-based solutions, and ecosystem disservices (ED) literature have focused primarily on the supply of urban regulating and cultural ecosystem services (ES). Other literature on urban and peri-urban agriculture has mostly studied the role of localized, intensive agricultural practices in providing food to inhabitants.

Climate change impacts increase pressure on challenges to sustainability and the developmental needs of cities. Conventional, "hard" adaptation measures are often associated with high costs, inflexibility and conflicting interests related to the dense urban fabric, and ecosystem-based adaptation (EbA) has emerged as a potentially cost-efficient, comprehensive, and multifunctional approach. This paper reviews and systematises research on urban EbA. We propose an analytical framework that draws on theory from ecosystem services, climate change adaptation and sustainability science.

The Mediterranean region is facing many challenges, some of which can be addressed by nature-based solutions such as urban forests and green space. However, at best, urban forest research from Mediterranean countries has been only briefly addressed in review papers up to date. This Scopus-based review paper provides first insights into the development of urban forest research in the Mediterranean in the 20-year period from 1996 to 2015.