French oak tree (wine barrel staves in their natural environment) - image from iStockphoto, shown in ScienceDaily article quoted below.

From France we learn that some trees, growing in areas that are nutrient-poor, may encourage the development of specific soil microbes to turn inorganic chemicals from the soil into nutrients that the tree's roots are able to absorb.

Acidic forest soils can be nutrient-poor and this can impose a limit on the development of trees (such as beech and oak).  There are bacteria that are effective at breaking down the inorganic chemicals in such soils.  This process is known as "mineral weathering".  Both bacteria and fungi have been shown to have a role mineral weathering, including in the breaking down of minerals (rocks) left behind by receding glaciers, releasing nutrients useful for plants.

Trees that have better access to nutrients will out-compete other trees.  There is a natural advantage for trees which can attract the bacteria needed to undertake this mineral weathering.  The researchers compared the bacterial populations in soil samples taken from around the roots of beech, oak and Norway spruce trees and compared them with the background levels of such bacteria in forest soils further from the trees.  Levels of mineral-weathering bacteria around the beech and oak trees were higher, whilst those around the spruce trees showed no difference.  

"Our results suggest that certain tree species have developed indirect strategies for mineral weathering in nutrient-poor soils, which lie in the selection of bacterial communities with efficient mineral weathering potentials," says Stéphane Uroz, one of the scientific team.

Yet another of the amazing interactions between plants and the micro-organisms in the soil.

More details are at:  http://www.sciencedaily.com/releases/2010/07/100729172332.htm