Friday 6 May 2011

Old veteran oak trees and unusual deadwood insects.

Veteran oak trees and unusual deadwood insects.


At Chatsworth, the old park has been made an SSSI (Site of Special Scientific Interest) on account of its very old trees or veteran trees' richness of insect and lichen (and fungi) life. So, why are these old trees, especially old oak and lime, so important?


The SSSI status is based on the richness of the insect life found on the old oak trees. Using an index of ecological continuity, the site is in the top 50 for the UK. In addition, lowland and southern sites like Chatsworth are even more important, as they are far richer in insect life, being located in generally warmer areas.


Many highly localised species benefit from the continuity that historic woodlands offer. South west facing trees for example, are the most attractive to insects as they are warm and more hospitable. Part of the forest at Chatsworth is called Greater Sherwood with sites loosely connected to the real Sherwood Forest itself. There are some spectacular looking insects, which Roger Key (of Natural England) has identified. These include;


Net-winged beetle – a scarlet and black beetle which is one of the Sherwood specialities.


Tanbark beetle - a large scarlet and metallic blue longhorn beetle, in thick oak bark.


Longhorn beetle – highly ornate, patterned, large longhorn beetle.


Cobweb beetle - this has very fuzzy larva which are covered in little tufty bristles, to keep spiders at bay.


The important ecological niches for all these deadwood beetles are almost all associated with old oak trees (and one is associated with old lime trees.) For instance, fungal heart decay in very old oak trees provides a variety of wood mould of various consistencies. This provides an ecological niche which is highly specialised and which allows a number of unusual insect species to thrive. The thick, loose bark of old oaks is another very important habitat for insect species.


So, not only are old oak trees beautiful but their role as insect host to unusual insect species is also vital. This is why we need to try to keep all our old oak trees safe and to preserve them for future generations to enjoy. Planting new tree species of oak and also hawthorn as a nectar source for saproxylic invertebrates (insects), adjacent to and near to existing veteran oak tree woods is important. This will give continuity to veteran oak tree habitats, for future generations to enjoy.