Individual study: Rehabilitation of acidified fens by buffered surface water addition and sod removal in Ilperveld, Noord Holland, the Netherlands
Bootsma M. C., van den Broek T., Barendregt A. & Beltman T. (2002) Rehabilitation of acidified floating fens by addition of buffered surface water. Restoration Ecology, 10, 112-121
This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.
Drain/replace acidic water
A controlled, before-and-after study in 1991–1996 in a degraded floating fen in the Netherlands (Bootsma et al. 2002) reported that draining acidic surface water (and replacing it with less acidic water) increased plant species richness and Sphagnum moss cover, but had no effect on sedge or common reed abundance. These results were not tested for statistical significance. Before intervention, plots contained approximately 16 species. After five years, drained plots contained 22–43 plant species, compared to 14–16 species in undrained plots. Drained plots had 41–100% Sphagnum cover, compared to 21–40% in undrained plots. Drain and undrained plots had similar cover of sedge Carex nigra (0–20%) and abundance of common reed Phragmites australis (in 81–100% of quadrats). Effects of drainage on cottongrass Eriophorum angustifolium abundance were more complicated and depended on whether moss was also removed (see original paper). In January 1992, ditches were built to drain surface water from one plot in an acidified, nutrient-enriched fen. An inflow of less acidic water was also created. Water was not manipulated in a neighbouring plot. Within each plot, surface moss was cleared from three subplots but not three others. Between 1991 and 1996, vegetation was estimated in quadrats covering 6–8 m2 of each subplot.
(Summarised by Nigel Taylor)
Physically remove problematic plants
A replicated, controlled, before-and-after study in 1991–1996 in a degraded floating fen in the Netherlands (Bootsma et al. 2002) reported that moss removal consistently reduced cover of black sedge Carex nigra and common cottongrass Eriophorum angustifolium, but that the effect on plant species richness and Sphagnum moss cover depended on whether plots had been drained. These results were not tested for statistical significance. After five years, black sedge and common cottongrass were less abundant in plots cleared of moss (sedge: absent; cottongrass: in 21–60% of quadrats) than uncleared plots (sedge: in 11–20% of quadrats; cottongrass: in 61–100% of quadrats). In a drained area, moss removal increased the number of plant species/plot (removal: 32–43; non-removal: 22–36) and Sphagnum cover (removal: 61–100%; non-removal: 41–60%). However, in an undrained area, moss removal reduced the number of species/plot (removal: 14; non-removal: 16) and had no effect on Sphagnum cover (removal: 21–40%; non-removal: 21–40%). Before intervention, plots contained 16 species and had 21–40% Sphagnum cover. In January 1992, the thick moss carpet was cleared from six plots in an acidified, nutrient-enriched fen. Six adjacent plots were not cleared. Half of the plots were in an area drained of acidic surface water and half in an undrained area. Between 1991 and 1996, cover of every plant species was estimated in quadrats covering 6–8 m2 of each plot.