New nature by sowing? The current state of species introduction in grassland restoration, and the road ahead

Use slot/strip seeding

A review in 1996–2009 of three studies of semi-natural grassland restoration in the UK (Hedberg et al. 2010) found that strip seeding resulted in failed introductions of grassland species in the majority of cases. Two of three studies of strip seeding to restore semi-natural grasslands reported failed reintroductions, while one study did not report enough information to allow the success of the introduction to be determined. The review used keyword searches to identify studies where semi-natural grassland restoration was carried out. All studies of strip seeding used machinery to drill seeds into the soil.

(Summarised by: Philip Martin)

Plant grassland plants

A review in 1996–2009 of four studies of semi-natural grassland restoration in the UK and Australia (Hedberg & Kotowski 2010) found that planting grassland plants had mixed effects on planted species abundance. One of four studies of planting to restore semi-natural grasslands reported successful introductions of planted species, while one study reported limited success, one reported a failed reintroduction, and one did not report enough information to allow the success of introductions to be determined. The review used keyword searches to identify studies where semi-natural grassland restoration was carried out. All studies on planting used plug plants grown in a nursery.

(Summarised by: Philip Martin)

Restore or create traditional water meadows

A 2010 review of studies of scientific knowledge about how to re-establish plant communities in grasslands by reintroduction (Hedberg & Kotowski 2010) found that hay transfer has been shown to be an effective method in wet meadows. The review found 38 studies, 28 of which provided enough information to evaluate the outcome, 21 of these from European countries, six on wet meadows or fens. Studies were graded as: successful, of limited success, failed introductions, or without the necessary information to evaluate the outcome. All four studies on hay spreading in wet meadows or fens were successful (Patzelt et al. 2001, Hölzel & Otte 2003, Rasran et al. 2007, Klimkowska et al. 2010). Plug planting had limited success in one UK study (Tallowin & Smith 2001). Only one study looked at the effects of direct seeding on wet meadows and found the technique was not successful (Tallowin & Smith 2001).

Additional reference:

Rasran L., Vogt K. & Jensen K. (2007) Effects of topsoil removal, seed transfer with plant material and moderate grazing on restoration of riparian fen grasslands. Applied Vegetation Science, 10, 451-460.

Sow native grass and forbs

A review in 1996–2009 of 17 studies of semi-natural grassland restoration in Europe, North America, and Africa (Hedberg & Kotowski 2010) found that sowing grass and forb seeds had mixed effects on the introduction of sown species. Eight of 17 studies that carried out seeding to restore semi-natural grasslands reported successful introductions of sown species, while four studies reported limited success, one reported a failed reintroduction, and four studies did not report enough information to allow the success of introductions to be determined. The review used keyword searches to identify studies where semi-natural grassland restoration was carried out. All studies collected seeds from wild or cultivated plants, and often sowed them as multi-species mixes.

(Summarised by: Philip Martin)

Restore/create species-rich, semi-natural grassland

A 2010 review of studies of scientific knowledge about how to re-establish plant communities in grasslands by reintroduction (Hedberg & Kotowski 2010) found that direct seeding and hay transfer have been shown to be effective methods. The review found 38 studies, 28 of which provided enough information to evaluate the outcome, 21 of these from European countries (of which some also looked at the effects on wet meadows). Studies were graded as: successful, of limited success, failed introductions, or without the necessary information to evaluate the outcome. Direct seeding had success or limited success in 10 European studies. Hay spreading had success or limited success in seven European studies (four of which on wet meadows) and was not shown to fail ((Smith et al. 2000), Patzelt et al. 2001, Hölzel & Otte 2003, (Kiehl & Pfadenhauer 2007), Rasran et al. 2007, Schmiede et al. 2009, Klimkowska et al. 2010). Plug planting had success/limited success in two European studies (one on wet grassland) ((Fenner & Spellerberg 1988), Tallowin & Smith 2001). Strip seeding did not reintroduce species in two studies (both recorded in (Pywell et al. 2007)).

Additional references:

Patzelt A., Wild U. & Pfadenhauer J. (2001) Restoration of wet meadows by topsoil removal: vegetation development and germination biology of fen species. Restoration Ecology, 9, 127–136.

Tallowin J.R.B. & Smith R.E.N. (2001) Restoration of a Cirsio-Molinietum fen meadow on an agriculturally improved pasture. Restoration Ecology, 9, 167-178.

Hölzel N. & Otte A. (2003) Restoration of a species-rich flood meadow by topsoil removal and diaspora transfer with plant material. Applied Vegetation Science, 6, 131-140.

Rasran L., Vogt K. & Jensen K. (2007) Effects of topsoil removal, seed transfer with plant material and moderate grazing on restoration of riparian fen grasslands. Applied Vegetation Science, 10, 451–460.

Schmiede R., Donath T.W. & Otte A. (2009) Seed bank development after the restoration of alluvial grassland via transfer of seed-containing plant material. Biological Conservation, 142, 404-413.

Klimkowska A., Kotowski W., van Diggelen R., Grootjans A. P., Dzierża P., & Brzezińska K. (2010) Vegetation re-development after fen meadow restoration by topsoil removal and hay transfer. Restoration Ecology, 18, 924-933.