Floristic composition of established vegetation and the soil seed bank in pasture communities under different traditional management regimes

The floristic composition of the established vegetation and the soil seed b ank in seven herbaceous communities under different traditional management regimes were compared in the Valdeon Valley (Picos de Europa, Spain), a val ley chosen for study because of its high diversity and non-dominance of any single species which have become increasingly rare in Western Europe as a result of changes in agriculture practices. Although the biological richnes s in this valley is well know, few studies have been made of the effects of different traditional management regimes on the floristic soil seed bank c omposition of these grasslands. The aim of this study was to examine the in fluence of traditional management regimes on the floristic composition of t he established vegetation and soil seed bank determining which species grou ps are most represented in each case to increase scientific information abo ut these communities that every day are more scarce in Western Europe becau se of intensive management (generally due to fertiliser application to incr ease production) and abandonment of the traditional methods of management w ith a profound modification of the agrarian structure. An indirect germinat ion method was used to study the seed bank. Soil samples were put into a ge rmination chamber. 119 species of the vegetation and 104 of the seed bank w ere identified, 54 species being common to both. Results were analysed usin g Correspondence Analysis (CA), samples and species on the above-ground flo ra being ordered in the first two axes in well-defined groups: limestone an d siliceous pastures, formerly-cultivated land and hay meadow, In the case of the below-ground seed bank, the manure used as fertiliser in some commun ities affected principally the concentration of therophytes in the soil and defined the different groups. Sampling time, management and differences be tween the persistence of seeds of different species in the soil seed bank w ere responsible for the large differences between the composition of the ve getation and seed bank, Ruderal species, species with persistent seeds and therophytes, which were better represented in the seed bank were responsibl e for the low correlation between seed bank and vegetation established. (C) 2000 Elsevier Science B.V. All rights reserved.