Pesky seeds hitch a ride with hikers


hiking boots

Credit: iStockphoto

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BRISBANE: Scratchy seeds are a bane to every bushwalker's feet, but it turns out those seeds may be more of a pain to national parks.

Ecologist Catherine Pickering and student Ann Mount, of Griffith University, Brisbane, have found that seeds of pesky plants are hitching a ride in hikers' socks - potentially spreading the weeds into new territory.

Walkers in Kosciuszko National Park had up to 1,000 seeds in their socks after just one day's hike, the researches found. Even worse, they could each collect about 1,300 seeds in just five minutes of roadside walking.

That's a real problem, because most bushwalkers trek along the roadside from the carpark to the start of the trail, collecting non-native weeds before they head into the park.

Non-native weeds can upset a park's delicate ecosystem by competing with native plants and altering water cycles and soil nutrients.

"They're also incredibly expensive," Pickering said. Weed control costs $500,000 a year in Kosciuszko National Park alone.

Well travelled

It's not just introduced pest plants that are benefiting from bushwalkers' wandering ways; the native herb Acaena also seems to be increasing its distribution by hitchhiking with walkers, the researchers said.

The researchers counted almost 25,000 seeds from 70 species stuck on the socks, shoelaces, trousers and legs of walkers in Kosciuszko National Park, one of Australia's largest conservation areas and a UNESCO Biosphere Reserve.

There are 212 plant species in the park, and at least 21 are found nowhere else.

Park managers have noticed higher proportions of weeds around tracks, lookouts and other visitor infrastructure over the years, said Dave Woods, the environmental liaison for the resorts section of Kosciusko National Park.

"The wonderful bit of information about Catherine and Ann's research is that there are some easy solutions to help reduce seeds being transported this way," he said. Woods hopes to use the research in his education and awareness programs for visitors to the Kosciuszko resorts.

Pickering's team is now running similar experiments in southeast Queensland's Lamington and Springbrook National Parks. So far, there are nine major weeds hitching rides in these experiments, with the bushwalker's curse, the cobbler's peg, the most well travelled.

Responsible hiking tips
  • Choose your gear wisely. The study found that sports socks collected more seed than hiking socks, and wearing trousers over socks and shoelaces cut down seed collection by 17 per cent.
  • Clean your shoes and other gear before you come to a national park.
  • Spend as little time as possible on weedy roadsides and refrain from picking the seeds off your socks at lunchtime.