Study

Managed water levels and the expansion of emergent vegetation along a lakeshore

  • Published source details Coops H., Vulink J.T. & van Nes E.H. (2004) Managed water levels and the expansion of emergent vegetation along a lakeshore. Limnologica, 34, 57-64.

Actions

This study is summarised as evidence for the following.

Action Category

Actively manage water level: freshwater marshes

Action Link
Marsh and Swamp Conservation

Exclude wild vertebrates: freshwater marshes

Action Link
Marsh and Swamp Conservation
  1. Actively manage water level: freshwater marshes

    A study in 1995–1998 on the shore of a freshwater lake in the Netherlands (Coops et al. 2004) reported that following a managed sequence of drawdowns and floods, a band of emergent wetland vegetation developed. Initially, the study area was a sandy shoreline with little or no vegetation (not quantified). After three years, a 50-m-wide band of tall emergent vegetation had developed around and just below the drawdown water line. This included sea club rush Bolboschoenus maritimus, common reed Phragmites australis, cattails Typha spp. and bulrushes Schoenoplectus spp. Total above-ground biomass of these species reached 520–630 g/m2 in the most densely vegetated areas (data reported graphically). Brackish marsh vegetation developed at slightly higher elevations (not quantified). Methods: In 1995, a watertight exclosure was established around a 3-ha area on the shoreline of Lake Volkerak-Zoommeer. The lake was created from an estuary in 1987 and the water level had been held stable since. The water level was lowered throughout 1995 and 1996 (exposing a 60-m-wide band of shoreline), then raised each winter and lowered each summer (exposing a 20- to 30-m-wide band of shoreline). Parts of the study area were fenced to exclude waterbirds, but parts were left open. Each summer between 1995 and 1998, vegetation was surveyed along transects spanning the drawdown zone (i.e. perpendicular to shoreline).

    (Summarised by: Nigel Taylor)

  2. Exclude wild vertebrates: freshwater marshes

    A replicated, controlled study in 1995–1998 on the shore of a freshwater lake in the Netherlands (Coops et al. 2004) reported that areas fenced to exclude waterbirds contained more emergent vegetation biomass, over three years, than plots left open to grazing. In three of three years, the total above-ground biomass of tall emergent vegetation was greater in fenced than open areas (data reported graphically). This was driven by herbivory in shallow water: the maximum biomass in deeper water was actually slightly lower in fenced plots than open plots (e.g. after three years, fenced: 520 g/m2; open: 630 g/m2). Methods: The study used a 3-ha area of the shoreline of Lake Volkerak-Zoommeer, where tall emergent vegetation was developing following experimental drawdowns and floods (beginning in spring 1995). Parts of the study area were fenced to exclude waterbirds (2-m-high fence with ropes above) and parts were left open. Each summer between 1995 and 1998, above-ground biomass was sampled in transects in the fenced and open areas. The study does not report further details of the experimental set-up or sampling methods.

    (Summarised by: Nigel Taylor)

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