RESTORATION EVIDENCE

Individual study: Vegetation recovery after multiple-site experimental fen restorations

Published source details

Hedberg P., Kotowski W., Saetre P., Mälson K., Rydin H. & Sundberg S. (2012) Vegetation recovery after multiple-site experimental fen restorations. Biological Conservation, 147, 60-67


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Cut/remove/thin forest plantations Peatland Conservation

A replicated, paired, controlled, before-and-after study in 2002–2010 in three tree-colonized rich fens in Sweden (Hedberg et al. 2012) found that following tree removal, there were increases in plant species richness and bryophyte, grass and sedge cover, but not cover of fen-characteristic plants. In cleared plots, plant species richness increased from 9 plant species/0.25 m2 before tree removal to 11 species/0.25 m2 eight years after, although it peaked at 12 species/0.25 m2 after three years. Cover increased of Sphagnum mosses (from 10% before tree removal to 15% eight years after), wetland-characteristic bryophytes (from 27 to 37%), grasses (from 2 to 4%) and sedges (from 1 to 3%). There was no significant change in cover of fen-characteristic mosses or vascular plants (data not reported). In plots that remained forested, there was no change in species richness or vegetation cover. In winter 2002/2003, in each of three forested fens, trees were removed from one 50 x 300 m plot whilst an adjacent plot was left forested. Half of each plot remained drained whilst half was rewetted. Between 2002 (before intervention) and 2010, cover of every plant species was estimated at 40 points/plot, in 0.25 m2 quadrats. This study was based on the same experimental set-up as (2) and (4).

(Summarised by Nigel Taylor)

Cut/remove/thin forest plantations and rewet peat Peatland Conservation

A replicated, paired, controlled, before-and-after study in 2002–2010 in three drained, tree-colonized, rich fens in Sweden (Hedberg et al. 2012) reported that following tree removal and rewetting, there were increases in plant species richness, bryophyte cover and sedge cover. These results are not based on tests of statistical significance. There were 9 plant species/0.25 m2 before intervention but 13 species/0.25 m2 eight years after. Cover of wetland-characteristic bryophytes was 33% before and 46% after, Sphagnum mosses 23% before and 33% after, sedges 1% before and 5% after. Similar changes in cover occurred in plots that were rewetted (without tree removal) or had trees removed (without rewetting). In control plots that remained both drained and forested, there was no change in the number of plant species or vegetation cover. In winter 2002/2003, four restoration treatments were applied in each drained and tree-colonized fen, in adjacent 50 x 150 m plots: cutting and removal of all trees, rewetting (by ditch blocking; water table raised by 12–25 cm), tree removal and rewetting, or none. Between 2002 (before intervention) and 2010, cover of every plant species was estimated at 20 points/plot, in 0.25 m2 quadrats. This study was based on the same experimental set-up as (4) and (8).

(Summarised by Nigel Taylor)

Rewet peatland (raise water table) Peatland Conservation

A replicated, paired, controlled, before-and-after study in 2002–2010 in three degraded rich fens in Sweden (Hedberg et al. 2012) found that following rewetting bryophyte and sedge cover increased, but there was no change in species richness, fen-characteristic plant cover or grass cover. Cover of wetland-characteristic bryophytes increased from 33% before rewetting to 46% eight years after. Sphagnum moss cover increased from 10 to 18%. Sedge cover increased from 1 to 3%. There was no significant change in cover of fen-characteristic plants or grasses (data not reported) or plant species richness (from 8 to 10 species/0.25 m2). In plots that remained drained, none of the metrics changed significantly over the eight years. In winter 2002/2003, one 100 x 150 m plot in each drained fen was rewetted by blocking a drainage ditch (water table raised by 12–25 cm). An adjacent plot in each fen remained drained. Trees were also removed from half of each plot. Between 2002 (before intervention) and 2010, cover of every plant species was estimated at 40 points/plot, in 0.25 m2 quadrats. This study was based on the same experimental set-up as (13) and (23).

(Summarised by Nigel Taylor)