The Ecology of Hazel (Corylus avellana L.) in Glen Affric
Although hazel is widely distributed in Britain, it has not been studied much at all, and its role within the Caledonian Forest ecosystem is little-known. Over the years, we've discovered various hazel stands in Glen Affric and have initiated a programme to protect and extend them - for example, in the spring of 1996, volunteers planted out the first hazel seedlings, grown from nuts we collected in the glen, on the north shore of Loch Beinn a'Mheadhoin, just west of the last mature hazel trees.
In 1999, Jessica Colebrook, an honours degree student at Edinburgh University's Institute of Ecology and Resource Management, carried out a research project on hazel in Glen Affric last summer. She studied thirteen different hazel stands, which are mostly concentrated in the eastern end of the glen and are all on south facing slopes at lower elevations, growing mainly on, or at the base of, rocky slopes. Many of the sites are relatively inaccessible, and therefore may represent 'refuges' from excessive grazing when hazel was more widely distributed in the past. Eleven out of the thirteen stands show evidence of current grazing, and this is limiting the possibilities for regeneration in some cases. The average height of the trees was just under 5 metres, with some trees up to 10 metres tall, and the average number of stems per tree was thirteen, which illustrates hazel's ability to naturally coppice itself. Fruiting of the trees varied considerably, with half of the stands having no nuts visible at all, although the reasons for this, and its effect on the regeneration of the stands, are unclear.
Jessica's thesis ended with a number of recommendations, and we have subsequently been seeking to implement some of these, in consultation with Forest Enterprise, who own most of the land in Glen Affric where the hazel stands are situated.
Here is Jessica's summary of her work, from her thesis document:
Summary
This study addresses the ecology of hazel in Glen Affric. The main aim was, via careful measurement of tree and site factors, to enable prediction of where hazel was most likely to occur and thus ascertain where restoration efforts are best aimed. To this end it was necessary to locate and map existing hazel stands, determine whether site conditions affected hazel characteristics and deduce whether the stands were regenerating and extending their range. Vegetation surveys were undertaken and very simple methods of measuring tree characteristics and site factors employed, requiring little more than quadrats and measuring tapes.
Thirteen hazel stands were located and were found to be variable in area, density and structure. All were growing at low altitude on south-facing, uneven slopes with relatively high soil pH. Site conditions were found to influence several tree factors, namely seedling dispersal distance, tree height and nut production. A need to determine the cause of limited natural regeneration at the smaller stands was recognised.
Recommendations following this study include protecting the regeneration present at the larger plots from grazing, sowing seed around the smaller stands using the seedling dispersal distances as a guide and planting only when vital. Whole stand creation should be attempted on those sites similar to where hazel exists presently and preference given to the eastern end of the glen where the species is more common and perhaps more appropriate.
Hazel - related pages
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