Riparian Woodland Creation
During the winter and spring of 2020/21 we delivered a second project in Glen Banchor creating riparian woodland along a 4.5km stretch of the River Calder.
Re-wooding the River Calder – Spey Catchment Initiative BCF Project Reference : 501348.
This project is supported by the NatureScot Biodiversity Challenge Fund.
Objectives
• Increased water-logging of peaty soils to preserve and enhance carbon storage.
• Increased deposition of particulates and nutrients on flood plain to retain and store soil organic carbon.
• Expansion of wetland and wet grassland habitat.
• Storage of flood water on flood plain during medium to high flows, reducing intensity of peak flows and flood risk downstream.
• Increased retention of water in wetland areas and ground water, acting as a reservoir to recharge the burn and mitigate very low flows during drought conditions.
1. Project Summary
The aim of this project is to establish up to 15ha of riparian woodland along 3.5 km of the River Calder, an upland tributary of the Spey (SAC), by installing deer fencing to remove grazing pressure, planting with native tree species and encouraging natural regeneration.
The benefits will include new riparian woodland habitat, and improved in-river habitat and water quality for salmonid fish and other aquatic species. The woodland, a nature-based solution, will mitigate against the predicted impacts of climate change by helping to control water temperature by shading, providing natural flood management benefits and sequestering carbon.
Strategically located areas of riparian woodland will be created along both banks of the River Calder and a short distance up the Allt Fionndrigh tributary, re-wooding riparian areas which are currently largely bare of trees and shrubs. There is a seed source nearby from patches of birch-dominated woodland on the slope on the south side of the glen and some small existing woodland schemes set back from the river.
Habitat connectivity will be hugely improved by forming woodland links between isolated areas of existing woodland to create a woodland corridor along the river, and helping to link the upper glen with the more wooded gorge section in the lower glen. The riparian woodland will also complement the landscape scale woodland expansion across the wider glen and restructuring of existing conifer plantations which is currently being separately progressed by Glenbanchor Estate.
SCI delivered a linked project in August 2020 which involved installing around 30 Large Woody Structures (LWS, whole felled trees with root plates attached) along most of the reach of the Calder being re-wooded. The LWS are intended to improve in-channel habitat diversity and quality and have already resulted in deposition of new areas of spawning gravels where salmon redds have been recorded. Establishment of riparian woodland will ensure a sustainable supply of natural dead wood into the system in future. The complementary outcomes of the two projects together should achieve significant habitat and biodiversity improvements.
2. Project Delivery
2.1 Pre-construction
Project planning commenced in December 2019 and plans were developed through detailed discussion between the agents for landowners Pitmain and Glenbanchor Estates Ltd (north bank) and Cluny Estate (south bank), woodland agents Cawdor Forestry Ltd, and the Spey Catchment Initiative (SCI). Common objectives, the scope of the project and roles of each partner in management and delivery were agreed, and woodland plans were drawn up by Cawdor Forestry, complying with the UK Forestry Standard and all other relevant forestry policy and guidance. Scottish Forestry approval was granted. As the site is an SSSI, consent was obtained from NatureScot. Landscape, public access and archaeology advice were obtained. Surveys were carried out for peat depth, birds, protected species and archaeology. Public consultation was undertaken.
Detailed discussions were held with estate staff to ensure that requirements for sporting, deer control and farming activities were taken into account. This liaison was continued throughout the delivery phase.
Three separate fenced enclosures were planned, each straddling the Calder, with water gates installed at each end. This was chosen as the most efficient design in terms of maximising the area of woodland in relation to length of fence, and will allow trees to grow right up to the water line where ground conditions allow. The separate enclosures allow gaps for deer movement, essential for deer management by the estates and deer welfare. Once the woodland is sufficiently established, and depending on levels of future grazing pressure in the glen, the intention is to gradually remove the fencing.
2.2 Construction
Following competitive tendering, Highland contractors Taiga Upland Ltd were engaged to provide fencing and ground preparation. Works commenced in October 2021.
Three deer fenced enclosures were constructed to exclude deer, sheep, hares and rabbits from riparian zones totalling 37 ha (see map appended). The fences were marked to avoid bird strikes, rabbit-netted and fitted with extra stays to be resistant to harsh weather conditions. In some sections lengths of sound existing fence were upgraded, and redundant deer and stock fencing was removed. Pedestrian and vehicle access gates were installed. Water gates were constructed to a robust design with metal stantions on concrete bases supporting suspended sections of alkathane pipe at 5” spacing across the river. Where flooding is likely, swinging flood fencing sections were installed to the side of the water gates to reduce the risk of flood damage.
2.3 Planting
Ground preparation (inverted mounding) took place in early March 2021 in accordance with a carefully considered planting plan, taking account of soil conditions, wet/dry areas, etc. Species rich grassland was avoided and open areas were retained adjacent to shingle banks on the river to ensure open habitat for some rarer invertebrate species. Planting was designed to replicate natural woodland with a mosaic distribution of variable densities and clumps of single species in places.
Tree seedlings of native species and appropriate provenance were supplied by the Woodland Trust and were hand-planted in late March over a total area of 11ha. In addition to planting, 3-4 ha of natural regeneration of trees and shrubby vegetation is expected originating from existing nearby seed sources.
Main Contributors
Our Partners
Core running costs are currently funded by Scottish Natural Heritage, Cairngorms National Park Authority and Diageo, reflecting the public/private partnership support which is one of the key strengths of the Initiative.
