Individual study: Impact of drainage and hydrological restoration on vegetation structure in boreal spruce swamp forests
Maanavilja L., Aapala K., Haapalehto T., Kotiaho J.S. & Tuittila E.-S. (2014) Impact of drainage and hydrological restoration on vegetation structure in boreal spruce swamp forests. Forest Ecology and Management, 330, 115-125
This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.
Rewet peatland (raise water table)
A replicated site comparison study in 2009 in 36 forested fens in Finland (Maanavilja et al. 2014) found that rewetting changed the plant community composition towards a more natural state, but had no effect on plant richness or diversity, tree volume or vegetation cover. After 1–14 years, the overall plant community composition in rewetted sites was intermediate between, but significantly different from, both drained and natural sites (data reported as a graphical analysis). In contrast, rewetting had no significant effect on plant species richness (rewetted: 31; drained: 30 species/site), plant diversity (reported as a diversity index), tree volume (rewetted: 235; drained: 335 m3/ha) and Sphagnum moss cover (rewetted: 25%: drained: 9%). Also similar between sites, but not statistically tested, were other moss cover (rewetted: 22%: drained: 25%), shrub cover (rewetted: 9%: drained: 8%) and herb cover (rewetted: 5%: drained: 2%). Compared to natural sites, rewetted sites had lower Sphagnum moss cover (natural: 46%) but greater cover of other mosses (natural: 3%) and greater plant diversity. Of the 36 forested fens studied, 18 had been rewetted in 1995–2008 by filling or blocking drainage ditches (water table raised to 15 cm below the peat surface). Nine fens remained drained (ditches open; water table 40 cm below surface). Nine fens had never been drained (water table 17 cm below surface). In 2009, vegetation cover and species were recorded in 72 circular (30 cm diameter) quadrats/site. Tree volume was measured in one 30 x 30 m plot/site. This study used the same sites as (32).
(Summarised by Nigel Taylor)