Influence of cutting and fertilising management on the botanical composition of Ljubljana marsh grasslands

Abstract

The effects of grassland management on herbage botanical characteristics were investigated in two 4-year field trials, in split-plot design with 4 replications. The trials were established in the Arrhenatherion (T1) and Molinion (T2) alliances in the Ljubljana marsh in 1999. Treatment factors were cutting regime, i) 2 cuts – with standard and delayed first cut, ii) 3 cuts and iii) 4 cuts per year as the main plots, and fertiliser regime, i) zero fertiliser – control, ii) PK and iii) NPK with 2 N rates as sub-plots. After four years, the appearance of both swards was significantly altered, by the application of fertiliser and to a lesser extent, by the cutting regime. However, the intensification of forage production did not decrease the number of species. In T1 the proportion of grasses increased with cutting number to the detriment of herbs and generally rare legumes. The proportion of grasses was also increased by NPK treatments compared to the control and PK treatment in T1. Applying fertiliser considerably reduced the proportion of Equisetum palustre in T1 (max. 25%, min. 1%). This effect was most pronounced within 3 and 4 cut regime. In terms of botanical groups in T2, the delayed 2 cut regime differed significantly from all other cutting regimes. The proportion of herbs within this cut regime increased and was more pronounced under the fertiliser inputs. Applying PK increased proportion of legumes in T2, however not above 6%. In both trials fertilising was the dominant factor that determined plant species composition. It promoted competitors at the expense of stress-tolerant species in T1, while initially a highly abundant stress-tolerant Molinia caerulea in T2 was replaced by species with C-S-R strategy.