Heartwood Forest - How England’s largest new forest is a leader in fighting climate change

A whitethroat takes to the air, it's numbers and that of many other bird species are bucking nationa

A whitethroat takes to the air, it's numbers and that of many other bird species are bucking national trends (c) Paul Rumble/Getty Images/iStockphoto - Credit: Getty Images/iStockphoto

England’s largest new native forest near Harpenden is an example of how the UK can tackle both wildlife loss and global warming.

Balloon ride over Heartwood Forest (c) Graham Custance/Alamy Stock Photo

Balloon ride over Heartwood Forest (c) Graham Custance/Alamy Stock Photo - Credit: Alamy Stock Photo

A lot has happened over the past 10 years at Heartwood Forest. Between 2009 and 2019, 600,000 trees were planted on former arable land to the east of Harpenden by thousands of local community members and many Woodland Trust volunteers – a monumental achievement. And the effort has certainly been worth it. Before our eyes, the land is transforming into what we had hoped – a wildlife-rich environment, beneficial for both our native species and ourselves. We are fortunate and proud to have this space in Hertfordshire, particularly at a time when it is more important than ever to have as many carbon-capturing trees as possible. According to the Woodland Trust, just 13 per cent of the UK is currently covered in woodland. The conservation charity aims to nearly treble this, to at least 37 per cent, in order to reach the UK’s carbon net zero target by 2050. At 858-acres, Heartwood Forest is directly contributing towards a better future for our planet, and at the same time providing a location to enhance physical and mental health in Hertfordshire.

An eclectic mix of habitat has been created at the site which is owned by the Woodland Trust and managed by volunteers with passion and dedication. It includes an orchard, where we have planted old Hertfordshire varieties of pears, apples, plums and quince; an arboretum that hosts all 60 native tree species; the wildflower meadows which buzz with insect life in spring and summer; the Disney woodland with its carved wooden animals; a wetland and more. These habitats are in addition to the original precious pockets of ancient bluebell woodland and old hedgerows.

Of the trees planted in the winter of 2011–12, the birch trees have grown the tallest. Behind them come the cherry and white willow, followed by the goat willow and field maple. Taking longer to establish themselves are the roses and wayfarer trees.

Each tree planted provides something for wildlife, with many trees supporting a whole ecosystem of their own. As just one example, the cherry trees feed bees in spring with nectar and pollen from their stunning blossoms, and then feed the birds in summer with their fruit.

Gateway to the Magical Wood at Heartwood Forest (c) Jason Ballard/Alamy Stock Photo

Gateway to the Magical Wood at Heartwood Forest (c) Jason Ballard/Alamy Stock Photo - Credit: Alamy Stock Photo

As we have such a range of habitat at Heartwood, the site supports a wide variety of wildlife. We have been monitoring species numbers since 2009 and now have 10 years’ worth of data showing a huge increase in biodiversity at Heartwood. This kind of data is potentially unique, and could prove to be invaluable for other conservation projects, as well as being useful to the management of the site in the future.

We have a vast array of birdlife, which has increased year-on-year. The most prevalent birds last year included starlings, skylarks, yellowhammers, wrens, goldfinches and linnets. Our latest data shows that warblers have particularly benefitted from the work, with the numbers of whitethroat more than tripling due to the thickets that have been created. We are also privileged to see more stunning raptors such as red kites and kestrels than before. Overall, bird numbers increased by 44 per cent between 2009 and 2019. As Heartwood remains a safe haven with essential resources for wildlife, we hope that these bird numbers will continue to go up, despite bird populations declining globally.

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Butterfly numbers are also on the rise. According to Andrew Steele, a Woodland Trust volunteer of the year from St Albans who has been monitoring butterflies throughout the project, sightings have gone from around 1,200 individuals in 2010 to more than 4,600 in 2019. Species include the small skipper, large white, common blue and gatekeeper. The browns did particularly well last year, with nearly six times the amount of meadow browns compared to 2010. Overall, butterfly numbers increased by a whopping 300 per cent between 2010 and 2019.

More than 20 mammal species live in or visit the area, including deer, badgers, foxes and weasels. We also have five species of bat. We hope to boost the amphibian numbers by further developing the wetland area, and we were very excited when a common lizard was spotted last October. As for me, one of my most surprising wildlife sightings was a pair of weasels playing in the corner of one of the ancient woodlands.

Weasels have been spotted playing on the woodland edges (c) Schaef1/Getty Images/iStockphoto

Weasels have been spotted playing on the woodland edges (c) Schaef1/Getty Images/iStockphoto - Credit: Getty Images/iStockphoto

It is heartening to see that nature is flourishing with a little help from us. It shows what a difference we can make. Yet although we can say the last 10 years have been a success, we are not about to rest on our laurels. Following the completion of the major planting project, we are now considering the way forward. There is still much that can be done to nurture and enhance Heartwood.

In 2018, a group of volunteers visited Knepp estate in West Sussex, to see what we could learn about the rewilding project there. We were impressed with the way in which cattle and pigs are allowed to roam, grazing the land and helping to spread seeds across vast areas. The pigs, by exposing bare soil with their rootling, have encouraged sallow to spread, which has directly led to Knepp becoming home to one of the UK’s largest breeding populations of purple emperor butterfly. Giving nature the chance to do its thing has brought rare and vulnerable species to the site, and this is food for thought for us.

We will of course think carefully before moving forward with any of our ideas. One thing we are hoping to do is to begin coppicing some trees. As well as lengthening their life, this ancient practice would make Heartwood more sustainable – the timber and associated products could be sold to pay for more conservation. A healthy wood is a mix of ages after all, so this seems like a sensible option. We will also continue to leave dead wood for the specialist invertebrates and to put nutrients back into the soil. Protecting the future of our ancient woodlands will always remain at the forefront of our minds, as well as maintaining our recently-planted trees.

We will carry on laying hedges too. As Brian Legg, Heartwood volunteer and author of a book on Heartwood’s arboretum, explains: ‘Hedges are of huge environmental value, producing cover and food for a wide variety of wild animals, birds and insects. By providing a link between woodland and other landscape features, hedgerows act as corridors for animals to use.’

Young woodland in what was an arable field, taken in 2018 (c) Judith Parry

Young woodland in what was an arable field, taken in 2018 (c) Judith Parry - Credit: Judith Parry

With a massive decrease in the UK’s wildlife being caused by habitat loss, hedges play an important role in providing a place for animals to shelter, forage and find mates.

Conscious of fast-moving climate change, we will keep an eye on which species are at risk and which will thrive, and act accordingly. In terms of trees, several of our native species are already vulnerable to pests and diseases, and may further struggle as a result of changes in temperature and weather. We will continue to monitor our trees and wildlife, to learn what we can and hopefully build a resilient landscape. Our aim is to further promote Heartwood’s biodiversity and secure its position as a sanctuary for both wildlife and nature-loving walkers.

As the Chinese proverb says, the best time to plant a tree is 20 years ago and the second best time is now. As someone who helped plant trees at a nearby site more than 20 years ago, I can promise that Heartwood will look very different in 20 years’ time. The trees that we spent 10 years planting will grow tall and collectively they will turn into treasured woodlands. And if we go on protecting and maintaining the site, it will be filled with all sorts of wonderful wildlife. I’m looking forward to it.

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