One of the biggest silver Birches(Betula pendula) in Britain, this tree had a circumference of 3.02m at breast height when we measured it in 1996. The tree was in good health and still growing.
There is also a fine specimen of pine(pinus) growing beside the birch.
Birch and pine trees share the same mycorhizal partners and it has been suggested that because the mycorhizal can connect to both trees at the same time it can equal out the nutrients for optimum growth periods and extend the trees protection from pathogen attack. There are many complementry reasons why birch and pine do well together, not just sharing nutrients via the living conduit of the mycorhizal.
In this instance pines and birch trees both share a liking for acidic soils, in the region of 4.0 to 6.5 ph, Birch trees have a fairly shallow root pattern which they developed over aeons as they followed the retreating ice caps growing their roots in the thin soils.
Pine trees on the other hand, developed deeper tap roots which it uses to anchor itself amongst the rocks of its more natural environment. So their roots compete at different levals for minerals and moisture. The mix of leaf litter also encourages more soil flora and fauna which leads to quicker breakdown by decomposing and the return of nutrients to the top soil.