How Controlled Burning Creates a "Pharmacy" for Wild Bees

Rob Beeson
3 days ago
4 min read

To the casual observer, heather moorland helps create a colourful, vibrant landscape. But to a bumblebee, that heather is something much more important than a pretty view. It is a critical lifeline, a vital foraging resource, and - according to groundbreaking research - a life-saving pharmacy.

The Secret in the Nectar

For years, we have known that heather is a vital source of energy for pollinators, helping them fatten up before the long winter. However, scientists from Royal Holloway and Kew Gardens have discovered something remarkable hidden within the nectar of common heather (Calluna vulgaris). They found a natural substance called "callunene." Think of callunene as a powerful, natural medicine that the plant produces to protect itself, which incidentally benefits the bees.

Bumblebees are often plagued by a debilitating intestinal parasite called Crithidia bombi, which spreads rapidly through colonies. This parasite causes severe physiological distress for bees, making them lethargic, unable to forage effectively, and significantly more likely to die.

The research showed that callunene attacks this parasite directly, breaking down its defenses. It effectively "detoxes" the bee, preventing the infection from taking hold and allowing the bee to recover its strength. In simple terms, a healthy heather moor isn't just a feeding ground; it is a dedicated hospital for our wild pollinators.

Why Fire Matters

This is where the role of the gamekeeper becomes vital in maintaining the health of the hive. Heather doesn't stay in prime condition forever; it has a natural lifecycle that eventually leads to decline. As heather plants get old, they become "degenerate" - woody, leggy, grey, and far less productive. Old heather produces fewer flowers, meaning there is significantly less of that medicinal nectar available for the bees.

To keep the "pharmacy" open and fully stocked, we need fresh, young plants that are full of vitality. This is why we use controlled burning, also known as muirburn, as a precision management tool. By burning small, specific patches of old heather, we initiate a regenerative cycle on the plant's lifecycle.

The cool, quick fire clears away the dead wood, and the resulting ash acts as a natural fertilizer for the soil. Soon after, fresh green shoots emerge from the ground, rich in nutrients. These young plants are vigorous and produce the abundant, nectar-rich flowers that bees desperately need to fight off disease.

The Magic of the "Mosaic"

Critics often misunderstand controlled burning, imagining that gamekeepers set the whole hill on fire at once, but the reality of modern keepering is exactly the opposite. Keepers aim for a "mosaic" - a complex patchwork quilt made up of different ages of heather. We burn small strips here and there, leaving other areas untouched for many years.

This creates the perfect structural balance for biodiversity, known as the "edge effect." The old, tall heather provides essential shelter from the wind and safe nesting sites for birds and insects, while the young, newly burnt patches provide the "superfood" medicine and warm basking spots.

A bee on a managed moor doesn't have to fly miles to find what it needs; it has shelter and food right next to each other. This structure supports not just bees, but also reptiles like adders that need open ground to warm up and deep cover to hide.

Why "Doing Nothing" Is a Disaster

Some people argue we should just leave the moors alone or use mechanical lawnmowers instead of fire, but the science tells us clearly why these alternatives fail to support the same level of biodiversity. If we simply abandon the moors ("rewilding" by neglect), the heather grows old, woody, and eventually collapses under its own weight. The medicinal flowers become scarce, and scrub or trees eventually take over, destroying the open habitat entirely.

Mowing is often suggested as a cleaner alternative, but it has a major ecological flaw. It leaves behind a thick mat of cuttings, known as "brash," which sits on the surface like a heavy blanket. This layer of rotting vegetation can smother the ground, altering the soil chemistry and stopping delicate mosses and new heather seeds from growing.

Burning, by contrast, leaves a clean, fertile seedbed that encourages rapid, healthy regeneration. It also creates the micro-topography - small bumps and hollows - that insects need, whereas mowing creates a uniform "bowling green" effect.

A Healthy Landscape

We are proud of the rich biodiversity our moors support. Every time a gamekeeper lights a controlled fire, they are not just managing the land for red grouse; they are renewing a complex ecosystem and fighting the decline of our most precious pollinators. They are ensuring that next summer, the hills will be alive with the buzz of healthy, disease-free bees.

It is active management, driven by evidence and centuries of practical knowledge. So, the next time you see smoke rising from the moors on a crisp day, remember what it means. It means the pharmacy is restocking its shelves for another year.

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