Toward a issue of box elder invasion into the forests around Moscow

Abstract

Anthropogenic and natural disturbances, such as damage to spruce forests by the eight-dentated bark beetle, favor the invasion of Acer negundo into the strongly fragmented forests close to Moscow. A crown closure of more than 0.5 as well as dense rowan understory or A. platanoides young growth, prevents the penetration of A. negundo into forest communities. Being less shade tolerant but more fertile and fast growing than A. platanoides, A. negundo gradually invades only slightly disturbed woodlands. Its ability to form multilayered stands faster than other wood species hampers the regeneration of local species. The progressing affection of A. negundo leaves by Phyllosticta negundinis fungus and noninfectious leaf toxicosis observed in Moscow may decrease its invasive potential.