Rewetting of a cutover peatland: Hydrologic assessment

Abstract

Exploitation of peatlands results in the degradation of hydrophysical conditions suitable for the re-establishment of peat-forming vegetation, notably Sphagnum mosses. Regeneration of peat-forming mosses necessitates a high and stable water table. The objective of this study was to evaluate the performance of open water reservoirs constructed to improve the hydrologic conditions required for growth of Sphagnum.A section of abandoned peatland, where former drainage ditches have been blocked, was treated by excavating reservoir ditches at 3-, 5-, and 8-m intervals to increase the local water storage. The colonization of Sphagnum fuscum and S. angustifolium diaspores scattered on the experimental baulks between the reservoir ditches was measured. Results indicate that water storage increased at the experimental site. The water table was higher and more stable, with an average maximum depth of 0.46 m at the rewetted site compared to 0.55 m at the control site. The volumetric moisture content of the surface peat was improved by rewetting, showing an average of 62% compared to 55% at the control site. Negative soil water tension at the -0.1 m depth was ameliorated at the experimental sites and nearly eliminated where 5-m experimental ditch-reservoir spacing was employed. Sphagnum establishment was successful on all experimental baulks, showing a higher percentage cover where soil moisture was more readily available.

Moisture dynamics and hydrophysical properties of a transplanted acrotelm on a cutover peatland

“…While current management techniques aim to rewet the cutover surface by blocking drainage ditches (Eggelsmann, 1988) to restore the water balance to more natural peatland conditions, it does not necessarily prevent a deep and variable water table (Price, 1996) or high soil-water tension at the surface (Price, 1997) from occurring. Additional restoration techniques such as seepage reservoirs (LaRose et al, 1997;Price 1998), artificial topography , companion species (Ferland and Rochefort, 1997), and straw mulch application (Quinty and Rochefort, 1996;Price, 1997), can all aid in reducing surface soil-water tension, increasing VMC and improve the likelihood of Sphagnum reestablishment on the peat surface (Price et al, 2003). However, these techniques are both costly and labour intensive to conduct where peatlands can be abandoned for many years before restoration is even considered.…”

The Impact of Peatland Restoration on the Site Hydrology of an Abandoned Block-Cut Bog

“…Natural recolonization of abandoned sites may take decades or may not occur at all (Price et al 2003), necessitating the implementation of proper site management techniques to reduce the impact of peat harvesting. Water management approaches, such as site rewetting by blocking drainage ditches, can accelerate the restoration of cutover sites by improving the hydrological conditions within the peat substrate (LaRose et al 1997;Price et al 2003;Shantz and Price 2006b); however, the response of the hydraulic parameters of the substrate (e.g., K sat ) following water table reestablishment is poorly understood (Holden 2005). Furthermore, altered water dynamics and distribution within a bog following rewetting has direct implications for the components of the water balance, inevitably changing the distribution and magnitude of water losses from the site.…”

Field experiment ofSphagnum reintroduction on a dry abandoned peatland in eastern Canada

“…Natural revegetation of Sphagnum, the dominant peatforming vegetation in bogs, has rarely been observed in rewetted bogs (Poschlod 1992) due to persistantly harsh hydrologic and microclimatic conditions (Price 1996). Early attempts at peatland restoration have focused on restoring the wet conditions typical of undisturbed peatlands by damming the drainage ditches, building embankments, and creating water reservoirs (Nick 1984, Eggelsmann 1988, Schouwenaars 1988, Meade 1992, Roderfeld 1993, Wheeler and Shaw 1995, LaRose et al 1997. Until recently, peatland restoration has relied mostly on active water management practices but little on plant reintroduction (Wheeler and Shaw 1995).…”