Traits influence the role of trees on ecosystem services: phytostabilization of trace elements and carbon sequestration

Abstract

Functional traits of trees affect soil functions and ecosystem services in different ways. Here we studied a restored land affected by a mine-spill in SW Spain. We analysed morphological and chemical traits on leaves and roots of seven afforested tree species with contrasted leaf habit. We evaluated two ecosystem services: 1) the regulation of soil quality by immobilization of trace elements (phytostabilization), and 2) the mitigation of climate change by C sequestration. A main trend of trait variation was associated with higher SLA and SRL, and lower leaf C:N in deciduous species, while a secondary trend separated Populus alba with higher leaf Cd concentration. The retention of trace elements on the roots was higher for Fraxinus angustifolia and Celtis australis favouring the phytostabilization process, while the high transfer of Cd to leaves of Populus alba (above toxicity levels) favoured its mobilization, adding a risk for herbivores. In general, soil underneath all tree species accumulated more organic matter than in non-afforested sites, due to a higher litter input and a lower respiration rate. Ceratonia siliqua showed a higher C accumulation in the forest floor, a relatively low C:N, and a high soil C density; all favouring C sequestration.