报告题目：Urban trees: what do we know about the services they provide?
报告人：Heikki Setälä 教授
The influence of plant type (grass/lawn, evergreen trees, deciduous trees) on soils and their ecosystem services (ESS) was studied in 41 parks of varying ages in two cities in Finland. Soils were sampled for physical-chemical-biological properties and heavy metals close to each plant type up to a 50 cm depth. Air quality was monitored in near-road environments in tree-covered and open areas. We hypothesize that 1) plant types, especially conifers, modify the soils differently resulting in divergent ESS between plant types, and (2) that air is cleaner under tree canopies compared to open areas.
Urban vegetation, particularly evergreen trees, had a clear effect on soil quality: they lowered soil water content and pH and increased soil organic matter, carbon and nitrogen sequestration compared to lawns. Also metal and nutrient pools and their mobility in the park soils was influenced by plant traits. We showed that, despite the ability of trees to reduce concentrations of road dust, urban trees seem ineffective (PM2.5), and even increase the levels of traffic-derived gaseous pollutants (NO2, VOCs, PAHs). These studies suggest that urban trees can be important in the provision of ESS, but that managing urban greenspace for better ESS provision requires specific knowledge on, e.g. plant types and the spatial structure of greenspaces within