Created grassland diversity afrer 12years of mowing in Southern Sweden

Abstract

Understanding the relationship between soil fertility and species richness in grasslands is important for conservation of species rich grasslands particularly for habitat creation. In this study, species composition and species number was examined on a meadow constructed in 1997 on formerly agricultural soil in Scania, southern Sweden. The site consisted of a 1,600 m long and about 10m wide strip. On this, 3 different seed treatments were created; one grass mixture, one simple herbal-grass mixture, and one rich grass and herb mixture. The rich herb-grass mixture consisted of a mixture of 75% herbaceous species seeds and 25 % grass species seeds while the simple herb-grass mixture contained 25% herbaceous species seeds and 25% grass species seeds. For this study only the rich grass-herb and the grass mixture sites were used since the simple grass-herb mixture site had no significant difference in composition when compared to the rich grass-herb site. The species number was determined using 10m transects on each plot which had 6 replicates for each treatment. The same was done in 3 independent plots which were the reference sites of this study. The biomass and soil samples were collected and subsequently analysed for each plot. The soil chemistry including the extractable N (KCI), extractable P (Bray I) and soil pH (KCI) was determined. Total foliar Nand P levels (after digestion in sulphuric acid), were also determined from the leaves of the dominant species. The species diversity was also calculated. A significant negative relationship was observed between species richness and soil fertility especially with extractable soil phosphorous which had an influence on species richness (F3,1=6.462, p=O.018).There was also a moderate influence on biomass by the distance from the forest edge where the meadow was constructed adjacent a planted forest. It was concluded that soil P has an influence on species diversity. The interactions between available nitrogen and phosphorus and their influence on the vegetation play an important role in the control of the grassland plant diversity. Thus, for both conservation and restoration of species rich grasslands, it is necessary to maintain low levels of soil P and to carefully sow seed mixtures which are appropriate for the area to ensure establishment and succession. This study shows that species richness is related to soil P.