Recruitment from the seed bank and the development of zonation of emergent vegetation during a drawdown in a prairie wetland

  • Published source details Welling C.H., Pederson R.L. & van d.V.A.G. (1988) Recruitment from the seed bank and the development of zonation of emergent vegetation during a drawdown in a prairie wetland. Journal of Ecology, 76, 483.


This study is summarised as evidence for the following.

Action Category

Actively manage water level: brackish/salt marshes

Action Link
Marsh and Swamp Conservation
  1. Actively manage water level: brackish/salt marshes

    A replicated, before-and-after, site comparison study in 1981–1984 of 12 adjacent brackish marshes in Manitoba, Canada (Welling et al. 1988) reported that during the first 2–3 months of drawdown following prolonged deep flooding, seedlings of dominant plants germinated. For four of five species, most seedlings grew around the elevation where adult plants had been dominant before flooding (see original paper for data). The exception was common reed Phragmites australis. Adult plants persisted at the higher elevations where common reed dominated, and these adult plants likely inhibited seedling growth. Most (81%) quadrats in the 10 experimental marshes contained seedlings of >1 species, whereas most (64%) quadrats in two nearby mature marshes contained adult plants of only one species. Methods: The water level in 10 slightly brackish (2–3 ppt) diked marshes on the shores of Lake Manitoba was actively managed: deep flooding for two years (water level raised 1 m above normal, killing most emergent vegetation) followed by drawdown in spring 1983 or 1984 (water level dropped to 20 cm below normal). This mimicked historical water level fluctuations in Lake Manitoba. Over the first summer of drawdown, seedlings were counted monthly in twenty 1-m2 quadrats/marsh. Pre-intervention vegetation was mapped from aerial photographs taken in August 1980. Plant species were also recorded in two adjacent, unmanipulated marshes in August 1983 (thirty 1-m2 quadrats/marsh). This study was based on the same experimental set-up as (2).

    (Summarised by: Nigel Taylor)

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