干旱区生态环境知识资源中心

We investigated vegetation structure and microenvironments on bare volcanic soil covered by scoria above the forest limit on Mt. Fuji, central Japan, to evaluate the effects of patches of a pioneer dwarf shrub (Salix reinii) on the establishment of early successional tree seedlings (Larix kaempferi). We analyzed species distribution patterns and the associations among them, and compared the performance (growth and survivorship) of Larix seedlings and the local environment (temperature, solar radiation, soil surface stability, soil moisture, and nitrogen) inside and outside Salix patches. Larix displayed significantly clumped distribution, and the clumping was apparently associated with the preferential occurrence of Larix in Salix patches. Salix patches moderated severe microenvironmental factors, such as drought, high temperature, and movement of the soil surface. Salix patches promoted increased height and decreased root:shoot ratio, but not higher rate of biomass accumulation in Larix seedlings. Survival rate of L. kaenipferi inside Saliv patches was higher than that outside patches at the younger stage, but it was lower at the older stage after L. kaempferi emerged from the Saliv crown. The results indicate S. reinii enhances seedling establishment and survival of young L. kaempferi, but may compete with it at later stages. The overall net effect of Salix patches on L. kaenipferi is positive, and therefore S. reinii appears to accelerate succession from scoria bare land to pioneer woodland.