I always look forward to the three-week Sustainability Festival and participate in it every year. Now in its fourth year, over 150 events took place across St Albans, Harpenden and nearby villages earlier this month. This year I invited a friend along to join me on the Capturing Carbon Walk: Discover Heartwood’s Climate Benefit’ as I thought we might enjoy a leisurely stroll into Heartwood forest.

A small group of us set off through the forest following two Woodland Trust volunteers. It is one of those damp and misty evenings, so there is no chance of a sunset. The speaker introduces himself, he must be some sort of professor and in his retirement volunteers for the Woodland Trust. We learn that since 1972 when it was founded, the trust has planted more than 40 million trees and continues to maintain, expand and protect its woodland.

We’re told that we’ll be making four stops. We follow him until he decides on a tree then hooks a scrolled chart onto one of the branches; he pulls it down and explains that the talk will be about the benefits of planting woodland.

My friend has a PhD in some sciency subject and is totally focused on what he’s saying. I, on the other hand, am just happy to be here amid these meadows and wide-open landscapes. I have to concentrate as science was never my strong suit and he explains how by planting more trees we can remove carbon dioxide that has been released into the atmosphere. The chart depicts the correlation between C02 emissions and the Earth’s fluctuating temperatures.

We walk on through the meadows and then with pointer in hand, he continues to speak about the way in which new woodland helps to cut out C02 emissions. I’m surprised to learn that mature woodland and very old trees don’t give out as much oxygen as newly planted ones and are not as absorbent of carbon dioxide. He elaborates and shows us how new woodland creation in the right places helps contribute to flood risk management and diffuses pollution.

Birdsong in the background distracts me and I look up and marvel at the labyrinth of trees that surround us. I take a deep breath. We turn a corner and walk across the vast open fields, chatting as we go. The speaker finds another perfect branch on which to hitch his roll down chart and we learn more about the consequences of farmland making up about 65 per cent of the UK.

Back in 1875, a longitudinal study was carried out by Rothamsted Research wherein a piece of land was left to grow wild compared to the farmland beside it. They discovered what would happen when land is left to its own devices. Over time, oak, sycamore, ash and hawthorn grew; another finding showed that farmland actually emits more carbon dioxide than oxygen given the cycle of deforestation and use of fertilizers in cultivating crops and livestock. We’re shown the benefits of promoting sustainable farming and agroforestry (used in medieval times) when rich native woodland was often situated next to or merged with farmland, thereby maximising biodiversity.

I must admit that some of the talk went a little bit over my head but I’m eager to learn more about environmental issues from the experts. I enjoy listening to exactly how forests reduce the amount of greenhouse gases in the atmosphere by absorbing carbon dioxide (CO2), using the carbon (C) to produce sugars for tree growth and releasing the oxygen (O2) back into the air. As trees grow, how they store carbon in their leaves, twigs and trunk, and in the soil around them.

Despite the cool damp weather, the air is crystal clear and fresh and we take in the wide-open landscape. I have enjoyed the fellowship of the group, walking, chatting and listening to people’s questions.

I imagine what it would be like to become part of a walking club in my later years. It has been such an educational evening and so much better than lazing in front of the TV.

Living in Hertfordshire, and no longer strictly a city dweller, I am growing to love walking in woodland. I’m beginning to appreciate unaltered landscapes more and am less attracted to the formality of clipped hedges and orderly ranks of rosebushes. In the words of Thoreau, “what would become of us if we walked only in a garden or a mall?”

Tonight has reminded us how we’re consuming resources and polluting the planet at a level that the Earth cannot sustain. Festivals like this remind us that we can no longer take our home on this planet for granted, how we all need to adapt to our changing climate, and making an effort to improve, restore and protect our ancient woodland and realising that if we go too far, some things will simply be irreplaceable.

  • Marisa Laycock moved from south west London to St Albans in 2000. She enjoys sharing her experiences of living in the city