“Though many pioneer tree species are intolerant of shade and so cause little problem in southern beech forests, Douglas fir Pseudotsuga menziesii has considerable shade tolerance and its wildings invade canopy gaps in indigenous forest, while sycamore Acer pseudoplatanus is the most shade-tolerant tree in the country, is multileadered, coppices, and is very difficult to remove as European foresters know only too well. Fortunately, herbivores find it highly palatable and it is not commonly planted.” Alien Species Book:Ecology of Woodlands and Forests: Description, Dynamics and Diversity Source: Ecology of Woodlands and Forests: Description, Dynamics and Diversity