Study

Recruitment and survival of dominant emergents and mud-flat annuals in response to artificial drawdowns at Delta Marsh, Lake Manitoba, Manitoba, Canada

  • Published source details Welling C.H., Pederson R.L. & Van der Valk A.G. (1988) Temporal patterns in recruitment from the seed bank during drawdowns in a prairie wetland. Journal of Applied Ecology, 25, 999-1007

Actions

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 study in 1981–1984 of 10 adjacent brackish marshes in Manitoba, Canada (Welling et al. 1988) reported that seedlings germinated during two summers of drawdown following prolonged deep flooding, with most seedlings of dominant perennials germinating in the first summer. The study reported seedling numbers for seven herbaceous emergent species. For four perennial, grass-like species that dominated the marshes before intervention, 120–49,000 seedlings/100 m2 germinated in the first summer of drawdown (vs 160–3,400 seedlings/100 m2 in the second). For three annual forbs, 2,300–31,000 seedlings/100 m2 germinated in the first summer of drawdown (vs 85,000–200,000 seedlings/100 m2 in the second). 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. Seedlings were counted monthly in summer 1983 and 1984 in up to twenty 1-m2 quadrats/marsh. Quadrats were placed in the zone around the historical shoreline where emergent vegetation had been killed during flooding. This study was based on the same experimental set-up as (1).

    (Summarised by: Nigel Taylor)

Output references
What Works 2021 cover

What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read the latest volume: Volume 18

Go to the CE Journal

Discover more on our blog

Our blog contains the latest news and updates from the Conservation Evidence team, the Conservation Evidence Journal, and our global partners in evidence-based conservation.


Who uses Conservation Evidence?

Meet some of the evidence champions

Endangered Landscape Programme Red List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Bern wood Supporting Conservation Leaders National Biodiversity Network Sustainability Dashboard Frog Life The international journey of Conservation - Oryx British trust for ornithology Cool Farm Alliance UNEP AWFA Butterfly Conservation People trust for endangered species Vincet Wildlife Trust