EFFECTS OF FOREST DYNAMICS ON THE LIFE HISTORY AND POPULATION DYNAMICS OF UNDERSTORY PLANTS

点击翻译按钮获取中文摘要

1. The environments of forest understory vary during regeneration processes of individual canopy trees. Temporal changes in understory environments directly affect the life-history and population dynamics of understory herbaceous plants. To understand the life-history strategy of herbaceous plants under the dynamic forest regeneration processes, we investigated the effects of forest regeneration on the life-history and population dynamics of an understory plant population.2. Six plots with various light conditions were chosen for demography of an understory plants, Pteridophyllum racemosum, in two types of forest regeneration; gap-regeneration and wave-regeneration, on Mt Shimagare, Kita-Yatsugatake, Nagano Prefecture in central Japan. All Pteridophyllum racemosum plants in the plots were marked and the overwintering bud of individual rosettes were determined at the end of growing season each year. Newly recruited individuals originating from vegetative propagation were also marked and … More measured.3. Based on the demographic data, we constructed stage-specific transient matrix models and analyzed the effects of changes in population growth rates and life history on the population dynamics of the species. Populations in a gap-regenerating forest showed higher population growth rate than those in a wave-regenerating forest. In the gap-regenerating forest, the population growth rate was low in shaded condition under a closed canopy, while in the wave-regenerating forest the population growth rate was low at the high-light site of standing dead of canopy trees. Sensitivity analyses of mega-matrix models revealed that survivorship of juveniles and flowering plants and recruitment of seedlings most contributed to the maintenance of populations in the gap-regenerating forestry. Life-table response experiment (LTRE) were applied to the mega-matrices corresponding to the populations in the two types forests. Differences in the long-term population growth rates in respective forests were mainly caused by the differences in the light conditions and in the interaction effects of light environments and regeneration patterns. These factors influenced the population dynamics through the survivorship of juveniles and transition probabilities from juveniles to flowering plants. Less