Pacific northwest forest ecosystem in Scotland
The old growth forests of the Pacific northwest of America are home to many of the ‘exotic’ conifers that have been planted in Britain over the last two to three hundred years. Many of the species were introduced by foresters and planted in regimental rows in dense plantations, and have earned an unjust reputation among the public. The fault lies not with the trees but with how and where they were planted. The Sitka spruce (Picea sitchensis), Douglas-fir (Pseudotsuga menziesii), western red cedar (Thuja plicata) and western hemlock (Tsuga heterophylla) are all examples of beautiful coniferous trees native to areas such as Vancouver Island and the Olympic Peninsula.
As part of the research for my book, The New Sylva, I visited recently a remarkable place in Scotland where all these species are not only thriving but are forming a functioning forest ecosystem similar to that found in the Pacific northwest. Pucks Glen, owned and managed by the Forestry Commission, is located on a steep west-facing mountainside, and like its counterpart in America, is very wet. The conifers at Pucks Glen were planted in the 19th Century but have since been left mostly unmanaged. The forest is regenerating naturally and becoming an old-growth forest with the four main structures found in the Pacific northwest forests:
- There are large trees that store most of the biomass and form an upper canopy that towers above. Their needles and branches drop to provide nutrients to the forest floor. Their living structures host a multitude of life, from birds and mammals, to mosses, lichens and fungi. Even other trees and vascular plants grow among the crevices of their giant bark, or along horizontal branches.
- Large trees may die and remain standing, providing a rich source of nutrients and homes for other life forms.
- Trees eventually fall to the forest floor. On the steep-sided slopes, some even slip and remain living; often forming unique leaning trees in unusual locations. Dead trees rot to release nutrients and support a vast range of life especially invertebrates, fungi, mosses and lichens.
- The forest is multi-layered. The older trees do not form a continuous canopy and in the gaps of light between them, other trees will germinate and form small stands. Shade-tolerant species such as western hemlock will thrive in even the darkest places waiting for more light before shooting up to the upper canopy.
All these structures exist in Scotland at Pucks Glen, while another characteristic feature of these Pacific northwest forests can also be found: tree regeneration on nurse logs. The stems of large fallen trees become clad in a thick mat of mosses, and when tree seed falls on this, the seeds germinate and the resulting seedlings start to grow on top of the log. From the Pacific northwest we know that many of the seedlings will slough off, jettisoning some of the young trees with them. Eventually the host nurse log will rot away completely. Often the trees nursed on logs survive with amazing raised root systems; indicating where the nurse log once nurtured the tree when younger. Currently none of the logs at Pucks Glen are at this stage but some of the trees regenerating on nurse logs now reach 2m in height. Below are a few photos of the nurse logs at Pucks Glen.
Check out my tree photography blog at www.theTreePhotographer.com to see details about these and many more photographs of the trees and forest at Pucks Glen.