Explaining the reasons behind the spread of bracken

I HAVE been associated with the moors since my teenage years nearly 60 years ago and, as a biologist, I have been stunned by the encroachment of bracken over this period (Yorkshire Post, August 9).

With the arrival of the Glorious Twelfth, the start of the grouse shooting season, many readers might be wondering about the bracken problem and why it is such an issue.

Traditionally, sheep have had the run of the moors and they graze on grass as well as heather. On the lower slopes cows used to be herded by boys and old men with sticks, moving them on from one patch of grass to another. In the early summer, May to July, emerging bracken shoots, “croziers”, were trampled by the cattle’s feet and perished. Some denser beds of bracken were maintained and cut for bedding for the cattle stalls back at the farm. In these ways bracken was kept under control.

In earlier times bracken was harvested and used in the making of glass and soap and for packing slates for transport. It has also been used as thatch but it was not as durable in this use as reeds, rye straw or – sometimes in the Dales – heather.

Eaten in quantity, bracken is poisonous and carcinogenic. It seems that young animals are educated by their parents to avoid it. Rarely, a sheep may forget this training and feed on bracken fronds. They may even shows sign of addiction. A sheep with cancer of the mouth caused by eating bracken is a most pitiful sight.

The fact that bracken is shunned as food by animals gives it a special advantage. If only rabbits would eat bracken, it just wouldn’t be a problem.

Bracken as a problem is a reflection of rising wages and the decline in the numbers of farm workers throughout the 20th century. The many lives lost in the First World War caused a sudden reduction in the labour force. This was compounded with the continuing rise of manufacturing, then the Second World War, the increasing power of trade unions and a gradual re-assessment of working conditions.

The basic cow-herding jobs in the Dales quickly disappeared and bracken started to spread on the moorsides. It invaded the better areas of soil which support grass, so the sheep moved increasingly on to the heather which is where they compete directly with the grouse, who feed almost exclusively on heather shoots.

Thus there exists a debate between grouse moor managers and neighbouring sheep farmers as to how many sheep should be allowed on the moors. The continuing encroachment of bracken enlivens this debate. It is also argued that the warming of our climate, with longer frost-free periods, encourages the spread of bracken.