September 18, 2008

DOC Battles Big Sycamore Weeds

By DYKES, Mervyn

These fast-growing monsters, capable of adapting to many different habitats, are among the most invasive of species. -------- ------------ One of the world's biggest "weeds" has the Department of Conservation (DOC) ready to do battle in the bush areas of Manawatu.

These are not typical back-garden weeds, but fast-growing monsters reaching heights of more than 25m and capable of broadcasting seeds over extensive areas.

They are numbered among the most invasive of species and DOC has urged trampers, hikers, rural landowners and even home gardeners to lookout for them.

So what are they? They're sycamores (Acer pseudoplatanus) whose winged seeds delight children everywhere.

"They have often been planted for the golden autumn colours which brighten up the bush, and also for timber," said DOC biodiversity programme manager Vivienne McGlynn.

The main concern from a conservation perspective was that the sycamore will readily establish along forest margins, quickly pushing into light gaps and working deeper into the bush.

It then squeezes out other species that are slower growing by preventing them establishing.

Sycamores are also capable of adapting to many different habitats, rapidly colonising open spaces and forming dense stands, she said.

The fluttering seeds can be blown considerable distances from the "parent" tree and even crop up in home gardens. In rural settings they often "escape" into wilder places and soon begin their advance.

"We don't think we have any in the Ruahine Forest Park yet," she said.

However, DOC staff from the Pohangina Field Centre have been working with a neighbouring landowner to stop sycamores encroaching toward the park.

Some came down in the recent storms and others had their tops broken and were likely to die, so, with the agreement of their neighbour, DOC removed the trees.

Mrs McGlynn said 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," Mr Brummit said.

At the same time he acknowledged that they were a 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 1-20m high."

DOC will continue to assist Mr Brummit to remove sycamores, especially as the prolific seed source has now been removed.

Mrs McGlynn said DOC would be happy to help other landowners to identify suspect stands of trees.

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