Effects of 16-Year Deer Exclusion on the Forbs and Tree Saplings in a Beech (Fagus crenata) Forest Degraded by Sika Deer in Eastern Japan

Long-term exclusion of deer may decrease some plant species through interspecific competition. I studied the effects of deer exclosures for 16 y on tall forbs and tree saplings inside and outside three exclosures of beech forest in the Tanzawa Mountains, eastern Japan. Understory cover ranged from 69% to 95%, and herb-layer height ranged from 1.1 to 1.4 m, inside and outside the exclosures. The density of 2–4 of 18 targeted tall forb species was significantly greater inside than outside the exclosures (Mann–Whitney U-test, P 1 m in height were observed outside the exclosures. The results suggested that deer exclusion for 16 y maintained growth of tall forbs and concurrently promoted establishment of tree saplings, and almost no suppression of forbs and tree saplings was induced by the dense understory.