Evaluation of different revegetation measures on mudflow deposits in the Nature Park Sölktäler (Styria, Austria)

In mountain regions, the likelihood of mudflows might increase due to climate change. Although mudflows are common worldwide and devastate agricultural land, virtually nothing is known about the revegetation of mudflow deposits for agricultural purposes. To provide recommendations for rapid revegetation of mountain pastures, 52 permanent plots (4 m × 4 m) on 20 revegetated mudflow deposits in the Nature Park Sölktäler were established. We evaluated different revegetation measures (seed addition alone or combined with application of straw, lime or cattle manure) two years after sowing using commercial clover-grass seed mixtures. Furthermore, 27 permanent plots on 15 unsown mudflow deposits were surveyed. Sowing seeds can considerably accelerate revegetation on siliceous mudflow deposits. Festuca rubra, Agrostis capillaris, Lolium perenne, Trifolium repens and Lotus corniculatus are particularly suitable for rapid grassland reestablishment, whereas Poa pratensis is not recommendable. A pure straw application should be avoided because it delays the revegetation success. Lime addition is not recommended because it can lead to an undesirable legume dominance if clover-grass seed mixtures are used for revegetation. The most effective measure for large-scale revegetation seems to be seed addition without additives. To facilitate revegetation on coarse-grained deposits, large rocks should be crushed using a stone mill.