Sitka Spruce is a large conifer, it can grow to a height of 100 metres or circa three hundred feet.   Its trunk can be 5 metres (16 feet) in diameter.  Its size is comparable to some of the Redwoods.   It is native to the west coast of North America.  Its name Sitka comes from an Alaskan community where it is widespread, though it can be found all along the west coast of Canada and the United States.   Loggimg has reduced much of the native spruce forest, particularly of the larger trees.   The spruce is a long lived tree, some estimated to have an age of 500 years or more.  Size in itself is not necessarily an indication of age as a tree can grow rapidly in the right conditions, adding up to a cubic metre of wood in a year.  The bark of the tree is ‘scaly’ and tends to flake off.  The deeper, inner bark has a reddish brown colour.  The leaves are needle like and stiff, somewhat flattened in cross section with a blue green colour.  The root system is relatively shallow, with long lateral roots, which means it can be susceptible to ‘wind throw’. Sitka ‘prefers’ soil high in calcium and magnesium (magnesium is essential for chlorophyll formation).  Its wind dispersed seeds readily colonise areas cleared by fire or exposed by land slip, acting as a pioneer species but in coastal areas it is a dominant, climax species. Because of its rapid growth rate and the nature of its wood, it is valued as a source of timber and used in paper production.  Specialist uses include the making of musical instruments (pianos, harps) because of its resonant nature.  It was introduced to the UK in the nineteenth century by David Douglas - the botanist after whom the Douglas Fir is named.   Sitka Spruce now accounts for some 25% of forest / plantation cover in the UK.  As with any monoculture, the biodiversity in plantations is limited and there is a move to change this.  Diversification helps make such forests more resilient to new pests and pathogens, and also climate change. Some 500+ species use Sitka trees as a space for living or for feeding, when viewed across the UK.   Most of these species are not specialists unique to Sitka and are found on a wide range of other trees.  Research is underway to use broad leaved trees to help diversify Sitka forests.   The introduction of such trees might improve litter decomposition and nutrient cycling.   A number of trees are possible candidates e,g. oak, birch, beech, spruce and pine.  They would help support existing species visiting Sitka and add others.  However,  individual trees of these tree species will not grow long-term in stands of Sitka. However, it might be possible to achieve the benefits of diversification by using small blocks of single species within specific management areas.  More research is needed to determine the optimal size and spatial arrangement of such blocks. [caption id="attachment_42460" align="aligncenter" width="675"] Sitka spruce[/caption] Further reading : https://academic.oup.com/forestry/advance-article-abstract/doi/10.1093/forestry/cpaf040/8203130?redirectedFrom=fulltext t