Dendrologist Zaiga Graudiņa believes that small shrubs will not harm a tree, but trees that grow quickly and reach a large size should certainly be cleared. One of the greatest pests is the birch. It is fast-growing and voracious, with an excellent ability to suppress its competitors. Furthermore, as it grows large, its drooping branches in winter tend to "whip" nearby trees, whose own branches are fragile in the frost.