Pines Commonly Graft to Nearby Neighbours

Densely growing lodgepole pines readily form root grafts with nearby pines at any early age.

Well over 90 percent of grafts established within 20 years of trees sprouting in the fire-initiated stands that were studied in western Alberta.

The lodgepole pines examined averaged 2.6 root grafts each, with as many as 14. By 30 years of age, 73 percent of the pines had linked with roots of adjacent trees.

Grafts begin between small roots, under 50 mm diameter. These root connections typically become functional by the time trees are 20 years old, whereby the xylem and phloem tissues of the two trees join. Once this happens, water, nutrients and hormones can transfer between the grafted trees.

Most grafts occur within 20 cm of a tree stem, and between pines less than half a metre apart. Denser tree stocking produces a higher frequency of root grafts. No grafts were found connecting trees located over 110 cm apart, an equivalent stand stocking of 8,500 stems per hectare.