Utvärdering av näringsstatus inför återskapande av kalkkärr vid Hagebyhöga, Östergötland

Calcareous fens constitute a specific habitat which is uncommon in Europe and protected by the EU habitat directive due to its importance to several threatened species. Hagebyhöga in Östergötland is a calcareous fen habitat included in the Natura 2000 Networking Programme. Adjacent to the existing fen, a degraded fen area is situated. The area has been used for agriculture for several years but is now going to be restored to its former state by the county administrative board of Östergötland. When working with restoration of degraded fen areas it is important to aquire knowledge about the chemical soil conditions. Plant growth limited by phosphorus and low fertility are characteristic conditions for calcareous fens, whilst arable land usually is highly fertile and limited by nitrogen. The purpose of this study is to bring forth useful knowledge for restoring the degraded calcareous fen of Hagebyhöga. Phytometric assessments have been conducted on samples from the ground that is going to be restored, to investigate which element limits growth, and whether the fertility is comparable to that in the fen allready present. The results will be used when deciding whether the top soil layer needs to be removed, and if that is the case, how much of the soil needs to be removed to recreate the fen environment. The samples were collected from two areas (A and B) with different moisture content in the arable ground and three depths from each area (0-10 cm, 10-30 cm and 30-40 cm). As reference, a sample from the top soil layer of the existing fen was used. The results from the phytometric assessment reveals all samples from area A and the sample from area B, 30-40 cm to have plant growth limited by phosphorus. The results also reveals the fertility in all samples except for area A, 30-40 cm to be significantly higher than the fertility of the existing fen. Both conditions, low fertility and plant growth limited by phosphorus, are present in the sample from area A, 30-40 cm.