Population dynamics and spatial arrangement of Ranunculus glacialis L., an alpine perennial herb,in permanent plots

In 1986 sixteen permanent plots (625 cm² each) were established in scree slopes dominated by Ranunculus glacialis at Mt. Glungezer, Austria (2600 m elevation) in order to document the population dynamics of herbaceous perennials near the upper altitudinal limits of plant existence. The abundance and sizes of individual R. glacialis shoots, their leaf numbers and reproductive status were evaluated over a 6-year period. On South-facing slopes the population sizes of adult and juvenile shoots remained constant over the years, while seedling numbers fluctuated significantly. Overall density of all developmental stages of R. glacialis was significantly lower on North-facing slopes and year-to-year fluctuations were greater, than on thermally-favorable Southern slopes. The spatial pattern of adult shoots and seedlings was clumped, while juvenile shoots had a random or clumped distribution. Fertilization had no effects on population dynamics. Proposed greenhouse effects, e.g. increases in CO₂ and temperature, should result in population growth on North-facing slopes and may increase mortality on South-facing sites.