Replanting lost woodlands cuts the risk of extreme flooding

Pioneering research will for the first time monitor how the creation of England’s biggest new native woodland could help stave off the worst effects of climate change, such as flooding.

Over the next 20 years or more, a team of scientists will be monitoring the site at Snaizeholme, North Yorkshire and braving its harsh weather conditions.

It’s one of the wettest places in Yorkshire with 200cm of rainfall a year.

The monitoring by a research team from the University of Leeds and University of York will measure rainfall, soil properties and streamflow to track changes over time.

This will help the scientists understand how the flood mitigation benefits of the woodlands develop as the trees grow.

They are using specialist equipment such as soil moisture and temperature sensors, weather stations and state-of-the-art “lightning detectors” to measure extreme weather events.

Four scientists are standing near an instrument that captures weather data, which has been installed on open moorland.

Above: Some of the team involved in the study (left to right: Robyn Wrigley, John Crawford, Professor Dominick Spracklen and Francesca Darvill)

The results of this research have the potential to help communities adapt to the impacts of climate change by increasing the understanding of how trees can reduce flooding risk, capture and store carbon and provide vital habitat for nature recovery across UK uplands.

Professor Dominick Spracklen, from the School of Earth and Environment at Leeds and one of the lead scientists in the project, said: “Restoring habitats across a whole valley has the potential to deliver big benefits for people, nature and climate.

“We have used a computer model to calculate that restoring the valley would reduce downstream flooding during a 1-in-50-year storm event by nearly 10%.

“To check that our predictions are correct, we are now installing special equipment to monitor soil and vegetation properties, rainfall and river flow. This will allow us to understand how the flood reduction benefits of the project grow as the native woodlands mature.”

Another key focus will be investigating how establishing new trees alters the properties of soil.

Francesca Darvill, a doctoral researcher at Leeds who is involved in the project, said: “We still know relatively little about how soil carbon changes after tree planting.

“Most previous studies lack information about how much soil carbon was present before trees were planted, making it difficult to know how soil carbon has changed.

“At Snaizeholme, we are making detailed measurements of the variability of soil properties across the site before the trees are planted. In years to come this will allow us to better understand how the trees have altered the soils.

“Crucially, it will provide better information on how much carbon new woodland soils help to lock up.”

Unique and complex conservation work

Many centuries ago, the glacial valley at Snaizeholme would have been blessed with swathes of woodland stretching across the landscape but now the 561-hectare site is almost devoid of trees.

It’s a stark situation repeated across the Yorkshire Dales National Park, where total tree cover is less than 5% and ancient woodlands only make up 1% of that cover.

It's a unique and complex piece of conservation work due to the range of habitats and species, the topography and elevation.

Tree planting will exist alongside huge restoration projects, including 113 hectares (279 acres) of blanket bog or deep peat, approximately 100 hectares (247 acres) of limestone pavement and over 77.4 hectares (191 acres) of open valley bottom following Snaizeholme Beck.

Two of the researchers are measuring a small but fast flowing stream. They are standing either side of the stream.

Above: Left to right: Professor Dominick Spracklen and Robyn Wrigley monitoring water flow in one of the streams

The Woodland Trust is overseeing planting on the site and work started earlier this year. The Trust is planning to plant almost 291 hectares (719 acres) with native tree saplings.

The careful approach to planting will see different densities of trees planted across the site to create groves, glades and open woodlands that gently transition into and connect with the other habitats, all delivered without the use of plastic tree guards or herbicides.

It will create one of the largest contiguous new native woodlands in England.

Dr John Crawford, Conservation Evidence Officer for the Woodland Trust, said: “We know mature woodlands deliver a range of important benefits: they provide a home for nature, lock away carbon to fight climate change and slow the flow of water, helping to reduce downstream flooding.

“Less is known about new woodlands. Working together with world-leading researchers will allow us to take detailed measurements of how biodiversity and ecosystem functions change as the trees grow and the woodlands mature.

“The research has the power to be a game changer when it comes to how such a new site can combat the extreme effects of climate change.”

Phase one of woodland creation at Snaizeholme has been funded by the White Rose Forest through its Trees for Climate funding programme.

Trees for Climate, part of Defra’s Nature for Climate fund, provides grants for woodland creation within all Community Forest areas in England. Researchers at the University of Leeds are supported by the Peter Sowerby Foundation. The project at Snaizeholme is supported by Woodland Trust’s partners Aviva, B&Q, Screwfix, Bettys & Taylors of Harrogate.