When good trees go bad
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Date: 15 September 2008
Isn't any tree a good tree? "Not when it's a sycamore!" claims Biodiversity Programme Manger for the Department of Conservation (DOC), Vivienne McGlynn.
Sycamore (Acer pseudoplatanus) is one of the most invasive tree species in New Zealand. It is a fast growing, large deciduous tree growing up to 25m or more. "They have often been planted for the golden autumn colours which 'brighten' up the bush, and also for timber" says Mrs McGlynn, "however it is also considered a weed due to its highly invasive nature".
The main concern from a conservation perspective is that the sycamore will readily establish along forest margins, quickly occupying any light gaps further in the bush. It then squeezes out other species that are slower growing by preventing them establishing. It is also adaptable to many different habitats, rapidly colonising open spaces and forming dense stands.
Sycamore seed
The winged 'helicopter' seed of the sycamore enables seedlings to establish some distance from the adult, with a lush crop of young shade tolerant seedlings soon popping up and occupying the area. In the home garden this may pass unnoticed, but in the rural setting they escape into wilder places and soon begin their advance.
DOC staff from the Pohangina Field Centre have been watching sycamore trees on a neighbouring property seed each year and encroach toward the Ruahine Forest Park without being able to do anything about it. Some of these very large trees came down in the recent storms and others had their tops broken and were likely to die. So now, with agreement from the neighbour, DOC has removed the trees.
The landowner, John Brummit, was rather fond of the sycamores which were planted at the time the house was built about 100 years ago. "They were beautiful trees lining the drive on both sides, and I haven't been too keen in the past to fell them". At the same time he acknowledges that they are also a nasty pest weed that he would rather do without. "The seedlings pop up all over the place, even in the lawn" he said. "I've got them all over the farm now from 1-20 m high". DOC will continue to assist Mr Brummit to remove sycamores, especially as the prolific seed source has now been removed.