Demographic variation and population viability in Gentianella campestris: effects of grassland management and environmental stochasticity

摘要: Summary 1  Transition matrix models were used to evaluate the effects of environmental stochasticity and four different methods grassland management on dynamics viability a population biennial Gentianella campestris (Gentianaceae) in species-rich grassland. Data collected between 1990 1995. 2  Continuous summer grazing, prevailing strategy Scandinavian grasslands, resulted high recruitment new plants, mainly because litter accumulation was prevented gaps created by trampling. Trampling repeated however, caused damage which reduced seed production. Lambda for average c. 0.77, stochastic model yielded an extinction probability total c. 0.08 within 50 years. 3  Mowing mid-July (used as conservation tool) increased production, but following re-growth vegetation establishment. risk similar continuous grazing. 4  Mowing October (another promoted low accumulation, output decreased plant growth impaired tall vegetation. 0.64, while very (c. 0.98 50 years). 5  Mid-July mowing followed autumn grazing (the historical regime) values both production establishment rosettes. 0.94 50 years below detection level. 6  Log-linear analysis showed that matrices differed significantly treatments years. The latter indicates stochasticity, here drought risk. may be slightly underestimated occurred one out five summers during study period, is compared with natural frequency. 7  We conclude traditional more favourable G. than prevail Scandinavia today. This serious problem, has replaced many remaining semi-natural grasslands throughout Europe.