What trees do in summer: sunlight, drought, and the wisdom of veteran trees

By the time June arrives, the woodland feels full of life. The canopy has closed in, casting dappled light across the ground. Birds are raising second broods, insects are everywhere, and if you pause for a moment, you can hear the steady hum of activity all around. It’s easy to imagine that the trees are simply standing still, quietly enjoying the sun, but in truth, this is one of the busiest times of year for them.

In summer, trees make the most of long daylight hours to photosynthesise. This is the process by which leaves capture sunlight and convert it into energy, powering everything from new growth to seed production. Photosynthesis also releases oxygen into the atmosphere and draws carbon dioxide out, making it one of the most important processes on Earth. In a healthy woodland, the sheer scale of this energy exchange is extraordinary, and June is when it’s at its peak.

But summer brings challenges, too. More sunlight usually means warmer temperatures and drier soil, especially if rain is in short supply. For young plants with shallow roots, or trees that have recently been planted, this can be a real struggle. But for older trees, especially the veterans that have been rooted in place for hundreds of years, summer is a season they know how to survive.

At Tortworth Forest Centre, many of our most characterful trees are veterans. These are trees that are not only old, but ecologically important. They are home to hundreds of other species and often shaped by the landscape, weather and people who have managed them over time. Their gnarled bark, hollow trunks and wide-spreading branches are outward signs of age, but also of resilience.

When faced with drought, veteran trees draw on deep, extensive root systems that younger trees haven’t yet developed. These roots can reach down into the soil to find hidden moisture even during dry spells. Their leaves may also be better adapted to conserve water: some trees reduce the surface area of their leaves, or develop thick, waxy coatings to slow evaporation. Others adjust the angle of their leaves to limit how much direct sunlight they absorb.

The experience of age has taught these trees how to weather change. And in doing so, they help the woodland around them survive too. Veteran trees create shade that cools the ground and slows water loss. They shelter young saplings, offer stable habitats for insects and fungi, and anchor the soil with their roots. Their presence brings continuity to a landscape that is always shifting.

As we head further into summer, spare a thought for the trees doing quiet work all around us. While we soak up the sunshine, they are hard at work, gathering energy, conserving water, and playing their part in keeping the woodland ecosystem alive. At Tortworth, their steady presence reminds us that with time, adaptability, and deep roots, we can weather more than we think.