Background restoration

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Edmund Black
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2 Background Once the harvest of peat from a bog has been completed, restoration is an important step in its management. The goal of restoration is to re-establish an ecosystem with the same ecological functions as the original bog, that is to say a wetland dominated by typical bog plants and accumulating peat. In the absence of restoration efforts, harvested sites remain denuded or become colonized by forest or agricultural plants. Without appropriate intervention, bog plants become re-established slowlier or not at all.

4 This guide describes the six steps of bog restoration: 1 - Planning p Preparing the land p Collecting plant materials p Spreading the Sphagnum moss p Spreading the straw p Blocking drainage p. 22 Fertilization p. 23 Monitoring p. 24 Budget p. 26 3

5 1 Planning Restoration of peat bogs involves a considerable investment of human and monetary resources. In order to obtain the expected results in the field and stay within the budget, the restoration project must be planned at the earliest possible stages of production on the site; that is, the restoration plan should be established as soon as exploitation of the bog begins. Purchasing straw The price of straw varies greatly from year to year and from region to region. It is thus a good idea to stock up on straw when prices are low, and plan for transporting the straw in advance, if necessary. It may also be advantageous to order straw from a nearby farmer a year in advance. If straw is stockpiled in advance, it must be kept dry to avoid spoilage. 4

6 Restoration work Restoration operations involve a lot of movement of machinery in the post-harvest areas to be restored and in the natural areas used as donor sites. It is thus crucial that the machinery be able to move easily without sinking into the surface. When the ground is too soft, the costs of the restoration project skyrocket (see Budget section, p ). Collecting plant materials and spreading the Sphagnum mosses and straw can be done when the ground is still frozen in early spring. The restoration activities should be included in the plans for the company s normal operations in order to manage the availability of machinery and manpower. It is best to restore large areas to reduce the cost per hectare and facilitate rewetting of the restored site. It is preferable to carry out restoration work shortly after harvesting operations have ceased, in order to slow the decomposition and oxidation of the remaining peat. However, it is also preferable to restore large areas that can be efficiently rewetted rather than small areas for which rewetting may be incomplete. Hence the importance of planning the sequence of opening and closing the fields and integrating these processes into the plans for the company s operations. 5

7 The chances of successful restoration of the site will be increased by certain conditions: Acidic residual peat (ph 5.1 or less) with a low to medium level of decomposition (H5 or less on the von Post scale). Large enough to be efficiently rewetted or isolated from areas still being harvested with respect to drainage. Source of good quality plant material readily available in sufficient quantities. Not adjacent to fields still being harvested, because dust from harvesting impairs regrowth of Sphagnum mosses ph Scale Conducive to restoration Not conducive to restoration Strongly acidic Acidic Neutral Basic Strongly basic 6

8 Von Post Scale H1 H2 H3 H4 H5 H6 H7 H8 H9 H10 Blond peat Brown peat Peat humus Marshy woody peat Reed and sedge peat Mud Mineral subsoil H1: Undecomposed: structure of plants unaltered; yields clear, slightly brown or yellowish water when squeezed. H2: Almost undecomposed: structure of plants distinct; yields clear, slightly brown or yellowish water when squeezed. H3: Very slightly decomposed: structure of plants distinct; yields slightly turbid, yellow-brown water when squeezed; no peat extruded between fingers; residue not soggy. H4: Slightly decomposed: structure of plants distinct; yields very turbid water when squeezed; no peat extruded between fingers; residue rather soggy. H5: Moderately well decomposed: structure of plants still evident but becoming difficult to identify; yields turbid brown water when squeezed; some peat extruded between fingers; residue very soggy. H6: Well decomposed: structure of plants indistinct but more evident than in the residue; about one third of peat sample extruded between fingers. H7: Strongly decomposed: structure of plants indistinct but some still identifiable; about half of peat sample extruded between fingers. H8: Very strongly decomposed: plant structure very indistinct; about two-thirds of peat sample extruded between fingers; residue almost entirely composed of tough root fibres and wood. H9: Almost completely decomposed: hardly any identifiable plant structures; almost all the peat sample extruded between fingers. H10: Completely decomposed: no identifiable plant structures; all the peat sample extruded between fingers. 7

9 2 Preparing the land Re-profiling fields Site preparation begins with using a levelling auger (leveller) to modify the surface profile of the harvested peat fields, which typically have a convex, domed shape. This step is essential for three reasons: The convex shape promotes rapid drainage of peat fields to facilitate harvest. For restoration to be successful, the fields must be flattened so that the water will be evenly distributed. Sphagnum mosses need a lot of water and low mineral content to grow well. Exposing the mineral subsoil should thus be avoided. Flattening the fields also helps create an even layer of residual peat, spreading it toward the edges of the fields, where there is usually less remaining peat. 8

Good contact between fresh residual peat and the introduced Sphagnum mosses is

10 The levelling auger can also freshen the surface and reduce the amount of surface crust. Good contact between fresh residual peat and the introduced Sphagnum mosses is essential, because the new plants obtain water through capillary action. Branches Branch leaves The water rises in the branches through capillary action Crust formation 9

11 Berms and drainage If the land is not flat, it may be advantageous to create berms or dikes during site preparation, and to fill the secondary drainage ditches with peat. On sloping sites, creating berms or dikes perpendicular to the slope helps spread water over the site and reduces the extent of areas that are either too flooded or too dry. 10

The drainage ditches can be filled using an auger and a grader. This step is even more important if the ditches have become colonized by herbaceous plants.

12 The drainage ditches can be filled using an auger and a grader. This step is even more important if the ditches have become colonized by herbaceous plants. Filling the ditches helps eliminate the undesirable plants, which might otherwise compete with the regrowth of Sphagnum mosses and other bog plants. Undesirable plants If the restoration site has been retired from production for some time, undesirable plants may have become established in the fields and drainage ditches. These plants should be eliminated either with the levelling auger or by repeated passes with a harrow, followed by the levelling auger. 11

13 Pools Pools can contribute to the biodiversity of the restored bog. Although there are no set rules on what form such pools should take, here are a few useful tips: A rectangle approximately 6 to 8 metres wide, 12 to 15 metres long, and 1 to 2 metres deep is the easiest to create using machinery and is large enough to provide habitat for many wildlife species. The pool should be deep enough (1 2 m) to hold water during dry summer months, but it is important that any excavation not reach the mineral subsoil. To provide varied habitat, one bank of the pool should be gently sloping and the other should be steep. Finally, it is a good idea to include partially submerged materials (e.g., tree trunks with branches) in pools to encourage colonization with diverse species. 6 to 8 m 12 to 15 m 1 to 2 m If the secondary drainage ditches do not reach the mineral subsoil, they can be left as is or widened, turning them into elongated pools. 12

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15 3 Collecting plant materials Choosing the donor site If you plan on opening a new peat bog, make plans to use the surface vegetation as donor material to restore retired sites. The donor site must have plants that are appropriate for bog restoration, namely abundant Sphagnum and Polytrichum mosses (see Practical Identification Guide, pages 18 and 22). The choice of a suitable donor site is a critical factor for the success of the restoration project. The donor site must be accessible, sparsely wooded and as close as possible to the restoration site to reduce transportation costs. To estimate the required size of the donor site, use a 1:10 ratio as a rule of thumb. That is, it is estimated that fresh surface vegetation collected from 1 m 2 is sufficient to spread over 10 m 2 of the restoration site. 14

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17 Harvesting of plant material Once the donor site is selected, it is measured and marked out with stakes and ribbons. The surface vegetation is then shredded to a depth of no more than 10 cm using a rotovator. Only the top 10 cm is used for several reasons: The fragments of Sphagnum mosses in the top 10 cm have the best regenerative potential, whereas it is best to avoid the deeper, decomposing fragments. This limits the impact on the collection site, allowing it to recover more quickly. The hummock-forming Sphagnum mosses (i.e., Sphagnum fuscum and S. rubellum) are the most suitable for restoration. Once the material is shredded, it is picked up with a mechanical shovel or front loader to be transported close to the restoration site. If the material cannot be spread the same day, it must be piled up to keep it from drying out. 16

18 Sphagnum fuscum SPHAGNUM rubellum Gilles Ayotte Gilles Ayotte 17

19 4 Spreading the Sphagnum mosses The plant material is usually spread using a manure spreader (rear- or side-discharge). It is critical that the right amount of Sphagnum moss fragments be spread, covering the ground with a continuous thin layer, 1 to 2 cm thick, without clumps. The fragments of fresh vegetation should be in close contact with the remaining layer of peat to ensure that the Sphagnum moss does not dry out. As much as possible, avoid creating ruts on soft ground and do not drive over the freshly spread plant material. 18

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21 5 Spreading the straw The freshly spread fragments of vegetation would be exposed to harsh conditions unless protected with mulch. Oat straw is often used because its long stems provide adequate protection and good results. The straw should form a layer of air above the ground to keep the Sphagnum mosses cool and moist while allowing enough light to penetrate to encourage plant growth. If too thick, the layer of straw can smother the plant fragments and interfere with establishment of the new vegetation, so using the right amount is important. For each hectare of the restoration site to be covered, the recommended amount is 3,000 kg of straw, the equivalent of 20 large round bales (5 feet in diameter). 20

Driving machinery over the newly spread plant fragments is not recommended, so the straw should be spread after

22 The straw should be spread at the same time as the Sphagnum moss fragments, preferably using a side-discharge bale processor. Driving machinery over the newly spread plant fragments is not recommended, so the straw should be spread after every two or three passes of the manure spreader, depending on how far the bale processor blows the straw. Driving over mulched surfaces causes less damage than driving over the exposed Sphagnum moss fragments. 21

6 Blocking drainage Adequate water is essential to successful restoration, so blocking drainage ditches is crucial and should be done properly.

23 6 Blocking drainage Adequate water is essential to successful restoration, so blocking drainage ditches is crucial and should be done properly. Take the following precautions to ensure that the blocking dams are watertight: Use moist, well-decomposed peat (i.e., peat harvested from a fairly deep level). Remove all vegetation on both sides of the ditches. The blocking dam must: be compacted with heavy equipment, be 2 to 3 metres wide, be higher than the surrounding ground surface. 22

24 It is best to wait until the very end of the restoration work before blocking the drainage ditches, even if doing so results in driving on a small planted area, because once the ditches are blocked the groundwater level can rise quickly, which would interfere with completion of the rest of the work. Fertilization In some cases, fertilization can increase the chances of the restoration succeeding. When a site has undergone frost heaving of the peat layer, an application of 15 kg per hectare of granular rock phosphate during the summer following the restoration work is recommended. This can be done using an all-terrain vehicle equipped with a fertilizer spreader. Rock phosphate stimulates the rapid growth of Polytrichum mosses, which help stabilize the ground surface. 23

25 Monitoring Restoration is not always completely successful on the first try, so the restored site should be monitored for a few years (1 to 5 years) after completion of the initial work. In the first year, hydrological wells can be installed to monitor the level of the water table. Ideally, it should be less than 20 cm below the surface. If the water table is too low, the restoration will be compromised. To correct the situation, the blockage of the drainage ditches should be checked and modified where needed. Stopper with attached cord PVC pipe, perforated over its entire length Fastener Nylon stocking Height of the water table Water level gauge 24

In the second or third year, the Sphagnum and Polytrichum mosses that are becoming established on the site can be seen. The presence of bog species should be monitored by setting up quadrats.

26 In the second or third year, the Sphagnum and Polytrichum mosses that are becoming established on the site can be seen. The presence of bog species should be monitored by setting up quadrats. Early in the restoration, the main species of interest are Sphagnum mosses, so quadrats measuring 25 X 25 cm are adequate. The plant species present in each quadrat are inventoried and the total area covered by any vegetation is estimated. The area covered by species grouped by vegetation strata (Sphagnum spp., liverworts and brown mosses, heaths, grasses, trees and shrubs) is also estimated. A plant inventory should be made once a year, at the end of the growing season. The progress of the restoration should also be documented with photographs. Regrowth of vegetation after one year. 25

27 Budget The budget data presented in the following tables was compiled from two sources. The Projects data are derived from restoration work carried out as part of the projects coordinated by the Peat Moss and Agri-Environmental Cluster, whereas the Industry Average data are taken from a report commissioned by Environment Canada*. * Golder Associates, March Évaluation des coûts de la restauration des tourbières au Canada. Time devoted to each operation (in hours): Operation Industry Projects Average Preparing the land Collecting plant material Spreading the Sphagnum Spreading the straw Blocking drainage 1.5 Total hours per hectare

28 Cost of restoration operations: Operation Industry Projects Average Preparing the land $635 $306 Collecting $1,079 $863 plant material Spreading $902 $489 the Sphagnum Spreading the straw $422 $465 Blocking drainage $138 Other expenses $894 $1,362 Total cost per hectare $4,070 $3,485 Key points for restoration cost reduction: Plan the work (purchasing straw, collecting plant material, preparing the site when the ground is frozen, etc.). Plan for restoration well in advance, so that large areas can be restored at the same time. Equipment operator training and supervisor experience (information regarding goals and objectives). Conservation and monitoring of a well-located collection site. Use of appropriate machinery. As weather conditions can affect the restoration activities, allow some leeway in the work schedule so that each operation can be carried out at the right time. 27

29 Acknowledgements This document was prepared as part of the implementation of the action plan of the Peat Moss and Agri-Environmental Cluster of the ACCORD program and its financial partners, Canada Economic Development for Quebec Regions and the Ministère des Finances et de l Économie du Québec. We are grateful to the photographers who contributed images, especially Gilles Ayotte, and to the editors and reviewers of the text, Stéphanie Boudreau, Geneviève Potvin and Rémy Pouliot. Author: Marlies Hähni, project manager, geographer, M.Sc. Environmental Science. Partners Canada Economic Development for Quebec Region s 28

30 Peatland Restoration - Operations Manual 2013

The Nature of Soil Soil Conservation Sustainable Ag.

Chapter 6 & 7 The Nature of Soil Soil Conservation Sustainable Ag. Climate Soil Forming Factors Parent material Organisms Topography Time Value of Soil Soil is under appreciated Condition of soil affects