Trajectories of Plant Recovery in Block-Cut Peatlands 35 Years After Peat Extraction

Abstract

Abstract. The initial question of any ecological restoration project should be whether the degraded ecosystem may recover spontaneously in a reasonable time period or active intervention is needed. We examined the successional trajectories of vegetation within peatlands exploited by the traditional blockcut technique in Eastern Canada, with the final purpose of identifying sites which need human intervention to ensure the return of a typical Sphagnum-dominated bog community that accumulates C. Ordinations showed that the development of vegetation was different between three block-cut peatland regions. Peatlands of one of the regions were initially colonized by tall, dense ericaceous shrubs. There, communities tended to become increasingly dominated by trees and understories were closing over time, therefore not being on a trajectory toward the recovery of a Sphagnum-dominated system that accumulates peat in the future. Intervention is therefore recommended, for example by blocking still active drainage ditches. In the peatlands of the other two regions, Sphagnum had a high initial cover and remained dominant ten years later. However, species typically found in hummocks gained relative importance vs. those associated to hollows. More time is needed to decide whether these sites could be left unmanaged as they have remained after their abandonment 35 years ago.

Assessment of an integrated peat-harvesting and reclamation method: peatland-atmosphere carbon fluxes and vegetation recovery

“…The health of the surviving Sphagnum seems to have been facilitated by the wet conditions there, as well as perhaps the higher than average rainfall in both years. Flooding of basins or trenches in previously block-cut peatlands has been seen to invigorate Sphagnum growth on timescales similar to our study, including dry-niche, hummock-forming species such as S. fuscum (Rochefort et al 2002) and also over decadal timescales (Bönsel and Sonneck 2011;González et al 2013). The moss-transplant method often uses straw mulch to protect Sphagnum diaspores during early stages of regrowth by shading and improving near-surface moisture retention (Price et al 1998).…”

“…Price and Whitehead (2001) discovered Sphagnum recovery was greatest in shallow ditches and absent in raised baulks. Even after several decades, recovery of Sphagnum mosses are limited to shallow ditch areas, with adjacent raised baulks devoid of Sphagnum, leaving plant communities dissimilar to those that existed preharvest (Elling and Knighton 1984;Yli-Petäys et al 2007;Pouliot et al 2011Pouliot et al , 2012González et al 2013). In vacuum harvested peatlands, active restoration and reclamation techniques such as ditch blocking (Price et al 1998) and the moss-transplant method, where Sphagnum diaspores are re-introduced onto bare peat surfaces (Ferland and Rochefort 1997;Graf et al 2012;González and Rochefort 2014), can sometimes promote the re-establishment of plant communities and may help to restore pre-harvest peat-accumulation and carbon-sequestration functions (Waddington and Warner 2001;Tuittila et al 2004;Waddington et al 2010).…”

“…In vacuum harvested peatlands, active restoration and reclamation techniques such as ditch blocking (Price et al 1998) and the moss-transplant method, where Sphagnum diaspores are re-introduced onto bare peat surfaces (Ferland and Rochefort 1997;Graf et al 2012;González and Rochefort 2014), can sometimes promote the re-establishment of plant communities and may help to restore pre-harvest peat-accumulation and carbon-sequestration functions (Waddington and Warner 2001;Tuittila et al 2004;Waddington et al 2010). However, in many cases the ecohydrological damage caused by peat harvesting may be long lasting even in spite of restoration efforts (Waddington and McNeil 2002;Pouliot et al 2012;González et al 2013).…”

Resilience of peatland ecosystem services over millennial timescales: evidence from a degraded British bog

“…) or repeated harvesting in the same peatland (Cooper, McCann & Hamill ), can alter peat hydraulic properties sufficiently to surpass the ecosystem's threshold for resistance or resilience. The result can be runaway degradation, including loss of biodiversity and soil carbon (Waddington & McNeil ; González, Rochefort & Poulin ). Studies that document peatland ecosystem dynamics after harvesting shed some light on the resilience of peatland ecosystem services, although the study periods are typically no longer than 50–70 years (e.g.…”

Vegetation development of forestry reclaimed sand and sand‐gravel pits: is it on a way towards more natural species composition?

“…In contrast to the many studies which describe the process of vegetation development in spontaneously revegetated post‐mining sites (see e.g. Prach ; Wiegleb & Felinks ; González et al ), including sand and sand‐gravel pits (Borgegård ; Řehounková & Prach ), direct comparisons of vegetation development between spontaneously revegetated and forestry reclaimed sites are still rather limited (Hodačová & Prach ; Pietrzykowski ; Mudrák et al ; Woziwoda & Kopeć ; Šebelíková et al ). Moreover, there is a lack of studies describing vegetation development in forestry reclaimed sites (but see Holl ; Evans et al ).…”