28th July 2016
ATF Scotland in the Highlands
Adam Riedi, co-ordinator of Ancient Tree Forum Scotland, writes about the group’s visit in July to the Brahan Estate in the Scottish Highlands
The Brahan estate lies to the north of River Conon, around 25 miles north from Inverness.
Planting records show tree planting dating from the 17th century. At a time where east Highland society was still based upon the tribal loyalties of the clan system and the journey form Edinburgh was a serious undertaking, the estate of the Seaforths were beginning wide scale afforestation and the design of a planned landscape. Trees from the 1680’s can still be seen today, including the very fine Pinus sylvestris (Scots pine) growing on the banks of the Conon.
In my role of co-ordinator for the Ancient Tree Forum (ATF) in Scotland, it seemed an exciting destination for the first field trip of 2016. Brahan is perhaps best known for the Dell garden and it was here that myself and Gordon Gray-Stephens recently completed arboricultural and landscape management plans of the National Tree Collection of Scotland. The wider estate and other parts of the historic planned landscape was rumoured to have many exceptional trees and on further exploration this proved to be the case. Along with 19th and early 20th century planting of deciduous and coniferous trees of great botanical interest and varied provenance, vestiges of plantings from the 18th and 17th century remain. The owners of Brahan, the Matheson family, were very supportive of the proposed ATF visit and Andrew Matheson and his wife Judith gave many interesting insights into the history and past management of the tree collections.
As the event was, after all, a meeting of the Ancient tree forum, I felt a slightly uncomfortable obligation to try to focus more on visiting the trees that could be described as veteran or ancient. Perhaps I needed have worried as even the 19th century exotic conifers showed many of the adaptive strategy we associate with trees in the post-mature crown phase.
For example, following degrees of upper crown removal from high winds, many trees of the genus Abies, exhibited the formation of epicormic growth that is heliotrophic and reiterative in form. One mature example of Abies borisii-regis (King Boris fir) is reforming a new crown of apparent viability having been reduced to around 10 metres in height from an original height of close to 30 metres. This way of becoming bio-mechanically compact (through significant structural failure induced by exceptional wind loads) seems quite distinct from the more measured strategies one associates with the gradual retrenchment of the typical open grown deciduous tree. In fact, many of the large mature trees of the genus Abies that I commonly work with have a excurrent form and high crown base. Not at first thought, obvious candidates for adopting a successful strategy of “growing down” without a dose of mechanical trauma. These trees may of course behave quite differently in their native range. I am insufficiently well-travelled to say! Trees of the genera Picea. Pseudotsuga and Larix (amongst others) in the collection seem quite adept at lowering the crown base through the production of epicormic growth. Trees of the genera Taxus, Thuja and Tsuga are well known for their ability to form new trunks through the process of layering.
Although many of these conifers are not apparently ancient the nature and extent of their life cycle may not yet be clear in western Europe, especially this far north. There is an abundance of trees at Brahan that are early examples of planting for many introduced species.
Perhaps Brahan might be a good a place as any to come in the future to gauge the longevity and characteristics of exotic conifers growing in northern Europe
The Beech Circle, or roundel (pictured above), is thought to have been planted in the 18th century. As such this circular planting of common beech (Fagus sylvatica) are in the late mature/veteran phase of their life cycle. The structural condition of many of the trees has been altered by extensive root and trunk decay, compression fork failure and the collapse of phototropic limbs. The voids and features created appear to have significant habitat value.
It was only from more recent visits in summer that I quite appreciated the quality and frequency of epicormics growth, even in trees with poorly demarcated decay columns with associated xylem dysfunction
Trees with existing significant upper crown damage and removal from high winds show a strong tendency to create sustainable epicormic growth and this has occurred around the points of primary branch breakage, throughout the crown and even the lower trunk where one might expect the dormant buds to be stubborn or encased in the deposition of the more recent annual rings. This epicormic growth will hopefully form the basis of future crown management of the group.
We also visited a line of ancient common lime (Tilia x europaea) of similar size. These trees represent different phases in the process of crown retrenchment. The non-durable ripe wood has pronounced decay. The trees first couple of centuries of growth has been entirely removed by the action of wood decay fungi. In order to age further the trees are embracing the morphology of their youth in the formation of new embryonic growth.
After a pleasant walk through the parkland to view very large coppice limes, layering horse chestnuts and veteran beech and oak we arrived at the largest of several wych elm (Ulmus glabra). Whether the survival of this tree is as a function genetic characteristics or simply good luck, i could not say. What I can say is the TROBI has described the trees as the UK and Ireland champion for girth. It may be almost 300 years old according to estate records.
Thanks to Andrew and Judith Matheson for hosting ATF Scotland, to Gordon Gray-Stephens for his valued contributions and to all those who travelled near and far (mostly far!) to make our first field trip a real pleasure.