Management actions are required to improve the viability of the rare grassland herb Carlina biebersteinii

: Ramula S, Puhakainen L, Suhonen J, Vallius E

Publisher: WILEY-BLACKWELL

: 2008

Nordic Journal of Botany

NORDIC JOURNAL OF BOTANY

: NORD J BOT

: 26

: 1-2

: 83

: 90

: 8

: 0107-055X

DOI: https://doi.org/10.1111/j.1756-1051.2008.00159.x

Small population size of many rare or endangered plant species makes a quantitative assessment of population status challenging because of the lack of detailed demographic data on different life-history stages. However, an urgent assessment is often required to start possible management actions. We performed a count-based population viability analysis (PVA) using discontinuous time series to quantitatively assess the viability of a rare, monocarpic, grassland herb Carlina biebersteinii Bernh. ex Hornem. (synonyms: C. vulgaris L. ssp. longifolia, C. vulgaris L. ssp. stricta) and examined demographic and environmental factors contributing to its viability. Based on 12 abundance counts of eight C. biebersteinii populations in Finland, we found that seven out of the eight population sizes declined during the observation period, and that annual population growth rates were slightly synchronised among the populations. Synchrony in annual population growth rates declined with increasing geographic distances among the populations, while fluctuations in the number of flowering plants were unrelated to geographic distances among the populations. According to stochastic simulations, the risk of losing all flowering individuals during the next 20 years will be high for unmanaged populations. To prevent the populations from gradually declining, our results suggest that summer grazing or removal of woody vegetation is required to increase habitat openness and consequently, to improve fecundity and seedling recruitment.