Management of nature-based goods and services provisioning from the urban common: a pan-European perspective

The role of the urban common (i.e. shared space and resources) in sustainable provisioning of goods and services to city dwellers is discussed in this paper. Focusing on tree-based green infrastructure, the study scope includes three categories of provisioning (woody biomass, food/fibre, and non-timber forest products, i.e. NTFPs), alongside three categories of supporting services (fresh water replenishment, soil nutrient restoration, building preservation). As a first step, prospects of utilizing the urban common as facilitator of nature-based solution to the earmarked provisioning services are evaluated through dedicated literature survey and expert elicitation on perceived impact of environmental change triggers and management interventions (planning and/or governance). This is followed by a structured review of the state of affairs in four European cities (London, Amsterdam, Sofia, Ljubljana), representing different macro-geographical regions with distinct socio-economic drivers in managing these provisioning services. The pan-European expert elicitation exercise noted active management of the urban common as positively impacting on the performance of the majority of provisioning services, while environmental change impacts were found to be overriding and adversely influencing the provisioning of material resources (mainly NTFPs and woody biomass). The four-city case study highlighted some regional peculiarities in connecting the city dwellers to the urban common and identified the need to overcome socio-cultural barriers for enhancing pan-European best practice sharing in the management of goods and services provisioning. This is deemed essential to pave way for an emerging perspective on sustainable utilization of the urban common as an enabler for nature-based solution, making it fit for purpose in meeting the astronomical demands of future urban living.

     

Canopy precipitation interception in urban forests in relation to stand structure

Urban forests provide important ecosystem services. In terms of hydrological benefits, forest ecosystems in urban environments represent qualitative and quantitative filter for rainwater. We quantified the canopy interception in relation to urban forest stand structure and rainfall intensity in an urban transect of the mixed (upland) forest in the city centre, towards a riparian pine forest and a floodplain hardwood forest in the City of Ljubljana, Slovenia. Bulk precipitation in open areas and throughfall were measured with fixed rainfall collectors in each forest. Stemflow was estimated from a review of relevant literature. We found that canopy interception in selected urban forests was mainly affected by tree species composition and other stand structure variables, such as canopy cover and tree dimensions. Average annual canopy interception was highest in the mixed forest (18.0% of bulk precipitation), while the riparian pine forest had the lowest level (3.9% of bulk precipitation) and the floodplain hardwood forest had the intermediate level for interception (7.1% of bulk precipitation). The mixed forest exhibited the stand structure factors that contributed to the highest canopy interception among the studied forests: high assemblage of dominant coniferous trees, denser canopy cover and the highest growing stock. Furthermore, rainfall intensity has proven to be an important factor for the seasonal partitioning (comparing the leafed and leafless period) of canopy interception. A better understanding of precipitation interception processes in urban forests is needed to assist urban forest managing and planning, aiming at maximizing canopy interception for the mitigation of stormwater runoff and flooding in urbanized watershed.