Influences of Leaf Tannin Content on 12-year Changes in Survival Rates and Height of Sprouting Trees Under Cattle Grazing Conditions

摘要

We investigated the differences in survival rates and height growth among 10 sprouting tree species under cattle grazing conditions in a clearcut area of a secondary forest, as well as the relationship between survival and growth and the species' leaf tannin contents. A clearcut area of a deciduous broad-leaved secondary forest was grazed by two breeding cattle from 1990 until 2001. The height and viability of marked sprouting trees in the area were monitored annually before the initial spring grazing period for 12 years. The tannin contents in leaves were measured from 1996 until 1998. The target tree species differed greatly in the patterns of survival and height growth and were classified into four categories based on these patterns. Similarly, tannin contents in leaves varied widely (1.3% to 11.6%) among the species. Survival rates of the target species in 2001 correlated significantly with the tannin contents in leaves. Our findings indicate that tannin content in leaves is an influential factor affecting the survival and growth of sprouting trees under cattle grazing conditions.