Seed Science Research

Research Papers

The germination niches of grassland species targeted for restoration: effects of seed pre-treatments

Markus Wagnera1 c1, Richard F. Pywella1, Tatjana Knoppa1 p1, James M. Bullocka1 and Matthew S. Hearda1

a1 NERC Centre for Ecology & Hydrology Wallingford, Benson Lane, Crowmarsh Gifford, OX10 8BB, UK

Abstract

Restoration of semi-natural grassland communities involves a combination of (1) sward disturbance to create a temporal window for establishment, and (2) target species introduction, the latter usually by seed sowing. With great regularity, particular species establish only poorly. More reliable establishment could improve outcome of restoration projects and increase cost-effectiveness. We investigated the abiotic germination niche of ten poorly establishing calcareous grassland species by simultaneously exploring the effects of moisture and light availability and temperature fluctuation on percentage germination and speed of germination. We also investigated the effects of three different pre-treatments used to enhance seed germination – cold-stratification, osmotic priming and priming in combination with gibberellic acid (GA3) – and how these affected abiotic germination niches. Species varied markedly in width of abiotic germination niche, ranging from Carex flacca with very strict abiotic requirements, to several species reliably germinating across the whole range of abiotic conditions. Our results suggest pronounced differences between species in gap requirements for establishment. Germination was improved in most species by at least one pre-treatment. Evidence for positive effects of adding GA3 to seed priming solutions was limited. In several species, pre-treated seeds germinated under a wider range of abiotic conditions than untreated seeds. Improved knowledge of species-specific germination niches and the effects of seed pre-treatments may help to improve species establishment by sowing, and to identify species for which sowing at a later stage of restoration or introduction as small plants may represent a more viable strategy.

(Received July 14 2010)

(Accepted December 06 2010)

(Online publication February 01 2011)

Keywords

  • abiotic germination niche;
  • calcareous grassland species;
  • cold-stratification;
  • osmotic seed priming;
  • seed sowing;
  • temperature fluctuation

Correspondence:

c1 Correspondence Email: mwagner@ceh.ac.uk

p1 Present address: Animal Ecology, University of Potsdam, Maulbeerallee 1, 14 469 Potsdam, Germany.

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