Bracken is a familiar problem for field archaeologists, as anyone who has undertaken field survey can testify. After mid-June each year, a large part of our rural archaeological heritage disappears under a blanket of waving green fronds, only to re-emerge in the late autumn, even then remaining cloaked in dry brown stems until mid-winter. The frustration of crisscrossing a steep hillside in vain search of a favourite site, thigh-deep or eye-deep in bracken and plagued by insects, is sufficient to burn the bracken fern into any archaeologist’s consciousness.
The cloaking effect of bracken was what primarily concerned archaeologists until recently. It concealed unrecorded sites from recognition and study, requiring much field survey to take place in the early months of the year, when poorer weather lowered productivity and motivation. More seriously, it concealed recorded sites from forestry workers or construction engineers, leading to inadvertent destruction. We had the impression that bracken was spreading more widely, and were aware that the agricultural community was developing techniques to control it, because of its toxic effects on livestock. But in the main, bracken was something archaeologists lived with.
Public consciousness has focused on bracken more recently, when research began to suggest it might have carcinogenic properties. Concern rose for the health of those who suffered regular exposure to bracken, especially when its spores were active. This news reached the archaeological community, but did little more than raise mild concern – although any excuse to avoid bracken was always welcome.
About the same time, field archaeologists working on a number of sites in the Highlands, who were collaborating increasingly with soil scientists, noted that bracken appeared to be associated with soils that had lost their structure. This observation caused little surprise, for we had long recognised the surface link between bracken and former human cultivation or habitation sites – indeed it was quite useful in the field, and many of us had followed the maxim of ‘start at the bracken patches and work out’. If bracken indicated de-structured soils, this was useful knowledge, because such soils would have poorer or absent stratigraphy, and would therefore be less informative about early farming or other activities. Logic dictated that sites, or areas of sites, that were free of bracken should be excavated in preference to those with bracken. But how were we to establish whether or not bracken was mobile: were present-day bracken-free areas truly unaffected, or were they simply passing through a bracken-free phase in a cycle of repeated colonisation and retreat?
As work continued, the possibility emerged that bracken, rather than simply colonising disturbed soils, might actual-ly be the principal agent of this destructuring. For the first time we saw bracken as an active cause of damage to sites, rather than as a passive problem. If it is truly the case that bracken destructures soils, then we were watching the archaeological value of sites being destroyed before our eyes. From being an inevitable nuisance, bracken had moved to being a positive threat, and potentially one on the same scale as rabbit burrowing or coastal erosion.
With this perception of threat came a need for systematic study. Excavators were tasked to keep records of bracken and the extent of its effects on stratigraphy. Major excavations, for example at Lairg, found themselves turning into de facto bracken research projects. Sister disciplines were approached for relevant research. We needed to understand the problem and to prove the causal links, so that we could argue for control measures, either funded directly from archaeology budgets or through agri-environment schemes or forestry estate management. And we needed to identify control measures that were effective while avoiding incidental damage to the archaeology. We needed to know whether it was more cost-effective to concentrate on con-trolling and eradicating bracken on sites where it was present, or preventing it spreading to unaffected sites.
Many research avenues are still open but the time has arrived to provide an interim statement on many of the key matters. This Note draws together what archaeologists who are not intimately familiar with ‘the bracken question’ need to know to understand the plant, its interaction with archaeology, and the measures available for its control. It also seeks to provide an understanding of the archaeological issues for those already familiar with bracken matters through work in, for example, agriculture and forestry.
Bracken is a shared problem for all who manage Scotland’s rural land, for production, pleasure and conservation. The way forward must be to build understanding of the scope of the problem from our different perspectives and to exchange information about possible solutions. This Note represents an interim contribution to that process. It does not contain the answers, if indeed there are full answers, but it is an important marker on the way. I com-mend it to all land managers who care about their heritage, and to all archaeologists who care about what is happening within the sites and landscapes we study.