Far north native forests leading the way in protection of rivers and burns
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New riverside native woodlands in Caithness and Sutherland are leading the way in new forestry practices that protect watercourses and enhance biodiversity.
Forests in the far north have been planted with species such as alder and downy birch, aspen, and rowan alongside rivers and burns.
The process of reintroducing these “riparian” woodlands helps to tackle rising water temperatures, restore habitats and reinstate healthy river systems that support some of Scotland's most celebrated species including otter, osprey and Atlantic salmon.
Foresters at Forestry and Land Scotland are now planting hundreds of hectares of new riverside woodlands across the country, with a focus on the north of Scotland.
Speaking about the importance of riparian woodlands, Neil McInnes, beat forester for Caithness and Sutherland, who led most of the riparian woodland restoration in the far north, said: "Shade is an obvious antidote to rising water temperatures and a lifeline for young fish, but river, or ‘riparian,’ woodland, does so much more.
“The submerged roots of trees like alder and willow protect fish from the sun and provide hidey-holes during high-flow events.
“Tree roots and deadwood in river channels helps to stabilise riverbanks, reducing erosion and encouraging deep pools and riffles, favoured by fish such as salmon and trout, to re-form.
“Retaining more water for longer in wet woodland, spongy peatlands, and boggy glades, slows and filters run-off, and reduces the extremes of flooding and drought.
“Overhanging trees also increase insect numbers which, in turn, means more food for hungry fish, other aquatic species, and birds.”
Former forestry practices allowed the planting of non-native conifers right to the edge of watercourses, increasing acidity in some cases and causing other problems like over-shading.
As the conifer forests of the mid 20th century are being felled, riparian zones are being replanted with mostly native species. FLS says it is also planting new woodlands on riverbanks in glens that – over centuries – have been denuded of trees largely because of deer grazing pressures.
The new woodlands can very quickly establish and bring benefits to animals, insects and fish that rely on a rich, riverside ecosystem of shrubs and bushes, tall trees, tiny trees, and even dead and dying trees, festooned in lichens, liverworts and mosses.
Foresters are finding that in those areas where new riverbank woodlands have already been planted, the benefits are being seen within five to seven years – and increasing every season.
Foresters argue that these restored riverside woodlands can provide an undisturbed framework around which forest production can continue, without the historical negative impacts on the aquatic environment.
FLS’s planning team and beat foresters are now identifying all areas that should be designated as riparian zones. Then, depending on the relevant land management plan, the area will be designed and planted with specific stocking levels and set amounts of open space.
Mr McInnes said: “We’ve already carried out riparian planting on several hundred hectares of ground – particularly at Borgie, Dalchork and Rumster forests – but this is just the start of this task.
"With rising water temperatures increasingly affecting Scotland’s rivers, and even Highland rivers reaching temperatures that can kill fish, there is no time to lose.
“Despite their reputation for beauty and drama, too many of the glens through which our rivers run remain bare and treeless, reflecting the centuries of ecological decline that we've come to accept as normal.
“Restoring riparian woodlands on the land that we are responsible for as soon as possible – to provide shade to watercourses and restore dynamic ecosystems – is an absolute priority for us.”
Alongside new riparian planting, FLS are also restructuring old plantation forests when they are harvested for timber, with a more complex mix of trees, shrubs and understorey plants stretching out over the watersheds into the wider catchment.
Active deer management to reduce grazing pressures is also helping to support natural regeneration, FLS says.
As the agency revises its land management plans it is identifying the most appropriate extent of riparian protection, adding to the national effort to protect Scotland's water environment, enhancing climate resilience, and boosting biodiversity in river systems.
In the northern Highlands, it plans to restore almost 5000 hectares of riparian woodland over the next few years, which FLS says will give every watercourse the breathing space it needs by establishing permanent buffers of native woodland and scrub up to 100 metres wide.