Seeds harvested during mowing from semi-natural grasslands as an ad hoc but effective solution for grassland restoration

Abstract

Species-rich grasslands formed by local ecotypes of native species provide numerous ecosystem services both in rural areas as well as urban grasslands. Nonetheless, their area is still too small, making grasslands one of the most frequently restored habitats. Successful restoration requires high-quality seed material, which is expensive and often not easy to acquire. In this study, we tested the potential of seeds accidentally collected during the mowing of a semi-natural grassland for grassland restoration. We tested seed purity, species composition, and germination capability in both laboratory and field conditions. Ninety percent of the collected material consisted of pure seeds of numerous species. Their germination capability was relatively low but still sufficient for successful grassland restoration under a typical seed density/mass per unit area seeding ratio. The germination capacity was the highest in the first two weeks after sowing and increased with overwintering seed storage. The results suggested that the seeds could be successfully used for species-rich grassland restoration. In terms of advantages, the seed mixture had a low cost and contained native species seeds representing local ecotypes. In terms of disadvantages, there was a relatively low amount of seed material and an inability to plan the time of seed harvesting. Thus, the use of the accidentally collected seeds can be considered an effective but rather ad hoc solution.

How to successfully improve the biodiversity of city grasslands?

“…Only Bunias orientalis was introduced accidently with FH on a single plot in first year, and it disappeared in the second year of the experiment. In light of the high prices for species-rich high-quality seed mixtures [ 26 ], the FM and MO seem to be reasonable alternatives for UG restoration, but an experienced botanist should choose the site and time of seed or fresh hay collection [ 27 ]. To our knowledge, FM and MO are rarely used in UG restoration and establishment, (but see [ [16] , [57] ]) however, they seem to constitute a promising approach.…”

“…A detailed description of FH and MO collection is presented in Ref. [ 27 ]. Table S2 presents the species composition of seed mixtures and the site from which the fresh hay was taken.…”

“…In practice, UG are restored or established using different seed mixtures of varying cost and quality, leading to a range of possible outcomes. High-quality species-rich seed mixtures of local ecotypes are very expensive, and in some regions, such as Poland, they are only available in small amounts [ 26 , 27 ]. Alternative methods of seed introduction (e.g., fresh hay application, seeds harvested by brush) are still in the initial stages of assessment for UG restoration [ [27] , [28] , [29] ].…”

“…High-quality species-rich seed mixtures of local ecotypes are very expensive, and in some regions, such as Poland, they are only available in small amounts [ 26 , 27 ]. Alternative methods of seed introduction (e.g., fresh hay application, seeds harvested by brush) are still in the initial stages of assessment for UG restoration [ [27] , [28] , [29] ]. Compared with the two above-mentioned methods of seed acquisition, mixtures of seeds collected from seed plantations carry the risk of unwanted introduction of undesired species, such as invasive species or weeds [ 28 ].…”