Global plastic pollution has become a major concern because of its effects on environmental and human health. A major fraction of environmental plastics is likely stored temporarily within terrestrial soils. However, even though forests represent the third most common type of land cover on Earth, almost nothing is known about plastics in forest soils. The atmospheric transport of micro- and nanoplastics provides ample opportunity for forest canopies to intercept plastic particles. These plastic particles, together with local plastic sources like litter and items used in forest management, eventually reach forest soils. In this paper we discuss the potential role of forest soils as a hub within global plastic cycles; transport processes from the atmosphere to the soil; and the integration of plastics into forest material cycles. Taken together, plastic in forests could have a major impact on sensitive ecosystems, economically important functions and global environmental plastic budgets. We also develop a roadmap for further investigation into plastics in forest soil systems.
