Restoration Techniques: Site Preparation Overview

Restoration Techniques: Site Preparation

• Site preparation depends on previous land use and functions
• It involves recontouring, structure forming, or grading prior to vegetation application
• Careful soil handling is required for successful ecosystem development
• Site preparation lays the foundation for successful ecosystem development

Landscape and Surface Expression

• Defining visible features of a land area is a crucial goal
• Goals include recreating pre-disturbance landforms, matching local drainage, and preparing for planned land use
• Reclamation criteria assess the site holistically from various vantage points, comparing it to adjacent land
• Drainage operability and contour are considered aspects of successful landscape development

Landscape and Surface Expression (Continued)

• Reclamation criteria involve qualitative evaluations (e.g., forested and grassland)
• Drainage patterns and capacity are assessed
• Erosion signs (wind or water) are evaluated
• Slope stability issues like movement, subsidence, and tension cracks are noted
• Bare areas should match surrounding communities
• Contours and intended land uses are compatible
• Industrial debris is not present

Landscape and Surface Expression (Continued 2)

• Landform features influence plant establishment
• Crucial features include slope, aspect, shape, stability, and soil texture
• Natural site restoration focuses on small-scale modifications
• Uniform areas are preferred, and traditional reclamation leads to simplified contours and filling of features

Landscape and Surface Expression (Continued 3)

• Natural sites have varied soils, leading to greater plant species diversity
• Graphs display topsoil depth vs. grass and forb percentages and cover rates.

Modification of Surface Features

• Landform reconstruction shows heterogeneity of materials and mesotopography
• This relates to oil sands mining rehabilitation in Alberta, Canada

Landscape and Surface Expression (Continued 4)

• Increasing surface structure enhances wildlife habitat
• Important features include escape terrain, nesting sites, burrowing sites, and cover from climatic extremes

Landscape and Surface Expression (Continued 5)

• Site stability is a concern, especially with compaction
• Issues may include compaction from roads, access points, and storage areas
• Compaction depths vary based on grassland or forest soil types, affecting freeze-thaw cycles and root zone depth
• Alleviating compaction requires addressing potential problems, like impenetrable layers and nutrient and water movement restrictions

Alleviating Compaction- Shallow

• Microsite focus enhances native plant germination
• Techniques include chisel plows, curved shanks, disk plows, and field cultivators, affecting soil depth (5-10cm)
• The shallower methods aim to hold topsoil for germination

Alleviating Compaction- Deep

• Deep methods use winged subsoilers, rippers, and excavators to improve soil structure
• Commonly used in frozen or dry but not saturated boreal sites with high organic content

Modification of Surface Features (Continued)

• Surface roughness modification increases site diversity and manipulates topsoil, overburden, and debris
• Resulting benefits include increased habitat diversity and reduced runoff
• Methods include adding above-grade features and below-grade features
• Above-ground features reduce wind and water flow, improve nutrient and organic matter retention, and support plant growth
• Examples include free dumping overburden, track packing, and mounded pits and adds

Modification of Surface Features (Continued 2)

• Below-ground additions like depressions accumulate water, nutrients, and organics
• Utilizing natural disturbance features is an option
• Inversions in mounds, either above or below grade can be part of creating "rough and loose" textures and topography

Modification of Surface Features (Continued 3)

• Excavation techniques create above and below-grade features, like mounds and pits
• Techniques like mounding are frequently observed on peatland and forested sites

Topsoil Replacement

• Ideal topsoil is the growing medium and living soil
• Salvage of original topsoil is preferable
• Matching topsoil thickness to site requirements is essential, especially for original and off-site comparison
• Moisture content should be less than 75% field capacity

Topsoil Characteristics

• Crucial considerations in topsoil replacement include salvage depth, salvage time, stockpiling duration, placement depth, amendments, and placement shapes

Placement -islands

• Maximizing surface area promotes native species egress
• Initial two years focus on grass and forb seed dispersal
• Vegetative expansion is slow

Topsoil Concerns

• Placement considerations influence deed bank quality, soil characteristics, salvage depth, stockpile characteristics, placement depth, and placement location

Topsoil Replacement (Continued)

• Peatland soil restoration prioritizes hydrologic connectivity
• Challenges arise due to external material and compaction in peatland environments
• Peatlands often require incorporating air and pore space
• This can be done using techniques such as partial pad inversion or complete pad inversion

Method 1: Removal and Re-Exposure

• This involves removing the complete clay pad, geotextile, and promoting hydrological functionality using a fluffing technique to restore volume
• Stopping the procedure in areas with insufficient peat and using alternative techniques for varying locations for optimal results is essential

Complete Peat Inversion

• The invert method overturns the clay pad and underlying layers in a process that resets and isolates the clay/mineral surface from the peat
• Removal of the underlying peat is a crucial step, allowing further action

Method 3: Partial Pad Removal + Inversion (aka Mineral Initiation)

• This method involves partial and complete clay pad removal in one portion, then reconfiguring layers of existing material
• This process entails moving native materials and geotextile, then placing the remaining layers on top
• The outcome ensures both hydrology function and biodiversity

Stability Issues

• Ensuring landscape stability involves managing erosion and sedimentation
• Methods like increasing surface heterogeneity through mounds and shelves, along with cover crops or bioengineering techniques, are beneficial

Bank Stability and Waterbodies

• Understanding waterbody use and risk factors is crucial to stability concerns
• Flow rate changes and land use modifications are important factors
• Solutions often involve filtration systems, vegetation, structure, and effective mitigation measures

Bioengineering

• Bioengineering techniques for slope stabilization include riprap (various sizes of stones placed, which limits erosion) and other approaches
• This can involve staking riprap to halt erosion
• Sometimes, bank extensions may be needed to halt erosion and sedimentation
• Deterring use, either for wildlife, or human access, reduces disturbance to the landscape

Examples of Slope Stabilization with Bioengineering

• Gabion cages, rock-shaped fences with rocks inside are used for vegetation growth
• These are examples of slope stabilization with bioengineering techniques

Examples of Slope Stabilization (Continued)

• Alternative design treatments for slope toes may use logs, riprap, rootwads, or geobags

Site Preparation Timing

• Site preparation needs to be carefully timed to have success as early efforts may be repeated if too early
• Site preparation is often dependent on scale, access, challenges, and overwinter considerations
• The timing of the preparation must consider the vegetation planting schedule, freeze-thaw cycles, and any lingering compaction issues

Summary

• Effective site preparation is vital for a thriving ecosystem
• Key aspects include stability, topsoil addition and vegetation selection that ensures a healthy growing environment
• Consideration of water retention is also crucial.