Walking under trees on a hot day, alongside a babbling river with sunlight dappling patterns on the path, is a lovely way to spend a summer’s afternoon. Often we don’t think about the direct impact trees have on our watercourses; planting trees is often used in large land-based habitat restoration projects, to boost biodiversity and fight climate change by capturing carbon dioxide.

In fact, trees are our river’s best friend and our best defence against multiple environmental issues. These carbon-capturing wonders are vital in restoring river ecosystems needing better ecological health, as well as providing all the benefits to wildlife and local communities.

How do trees help our rivers?

Flooding: Milder and wetter winters accelerated by climate change in recent years have shown us that severe storms and flooding events are becoming more frequent across the UK. 

A tree’s deep rooting systems create pathways into soil, improving infiltration, collecting and filtering run-off from surrounding fields. This improves water quality as well as helping alleviate flooding. The slower that heavy rainfall hits a running channel, the better in terms of alleviating flooding downstream.

As Chris explains, “Sedimentation is a primary issue in contributing to flooding from rivers, gradually accumulating on the riverbed which means there is less space available for additional water. This is often caused by riverbanks eroding during rain events, heavy livestock poaching, and runoff from adjacent arable fields. Extensive tree root networks on planted riverbanks and field perimeters bind these loose soils to the tree, meaning that the risk of sediment runoff is significantly reduced and as trees grow, so do their root systems!"

“The reduced flooding risk from planting trees also has significant benefits for our local communities by reducing the likelihood of local businesses, housing and infrastructure being damaged or destroyed by floodwaters. Improved public safety is another benefit; by stabilising riverbanks that have public pathways for safe usage, and reducing road closures in local catchment areas, so that rural communities and farms are less likely to be cut off due to rivers flooding.”

What other benefits does planting trees on riverbanks have?

As well as attracting an incredible range of wildlife, from kingfishers and finches to  caterpillars and moths, and creating a much more species-diverse riverbank, the shade and nutrients provided by trees are also hugely beneficial for a wide range of different wild creatures. 

As Suzie explains, “Leaf litter which falls into rivers is an essential resource for food webs, with microbes and macroinvertebrates depending on this resource. The breakdown of leaf litter by microbes and invertebrates releases essential nutrients into the water, which are then used by other organisms, contributing to the overall health and productivity of the river.

“The shading effect of trees is also needed for our aquatic wildlife, which is accustomed to cooler waters. Riverflies and other freshwater invertebrates are an essential source of food for fish and birds such as dippers, and they all require cool, clean water to thrive. As we have more hot-weather events, we must cool our streams and rivers to help wildlife there thrive.”

Tree planting in our river restoration projects

BEACH Esk – Chris Watt

Tree-planting and incorporating woodland into river restoration has been an integral part of the Better Estuaries & Coastal Habitats (BEACH Esk) project located in the Lower Esk Catchment near Whitby. 

Since 2022, we have planted 5500 trees; from wet-loving species such as alder, alder-buckthorn, downy birch and willow along river corridors, to a mix of birch-oak woodland with an understory of hazel and holly on drier, steeper slopes. On the edges of new areas of woodland, we have also planted scrubby species such as crab apple, field maple and hawthorn to add structure and variety, and to maximise biodiversity.

We have also utilised the woody material created through coppicing and pollarding to create leaky dams and add woody debris into watercourses. This mimics natural processes as trees would typically collapse and lodge themselves into rivers, slowing water flow, reducing velocity, suspending sediments and providing refuge for spawning fish species such as lamprey, sea trout and salmon. 

Chris says, “It has been great working with a variety of landowners, volunteers, and local interest groups across this special corner of the Esk Catchment. It is incredibly rewarding to see our efforts beginning to connect at scale, improve water-quality and restore nature.”

Upper Aire Project – Suzie Knight

The Upper Aire Project is a 12-year partnership project run in collaboration with the Environment Agency, Wild Trout Trust, Yorkshire Dales National Park, and Yorkshire Wildlife and Farming Partnership, which encompasses the river Aire from its source by Malham Tarn to the Middle Aire at Keighley, crossing almost the whole of Yorkshire. 

We have been planting trees along becks and rivers in the catchment since 2011, as well as reconnecting hedgerows to create more space for wildlife to roam. In fact, to date we have planted, managed and restored 280ha of woodland across the catchment with much more to come. Many of these woodlands are now maturing and we’re out with our fabulous volunteers removing and recycling the tree guards which protected them from the abundance of deer in the area.  

Suzie says, “Tree planting is very popular with volunteers, but sometimes maintaining these schemes until they become functioning woodland is difficult. The consistent support from local volunteers like Malhamdale Environmental Group means long term management of new planting, ensuring these become woodlands for future generations to enjoy.”