Weeds head for the hills as climate warms

Weeds head for the hills as climate warms

As temperatures rise, plants head up mountainsides, with weeds spreading to higher altitudes twice as fast as native plants, according to an international team of researchers.

While it was known that this occurred in native plants, this is the first study to look at non-native weeds. A warming climate makes more land available to these plants, threatening vulnerable alpine ecosystems, but their colonisation is helped along by alpine tourism, as weed seeds hitch rides up the mountain along roads.

The study looked at the European Alps, but a local researcher who was involved said that the situation might be even more dire in New Zealand due to the higher numbers of invasive weeds.

The research shows that as temperatures have risen, plants have spread up mountainsides, with weeds being the fastest movers.

“We know native plants are moving up mountains as climate warms, but until now no one had looked at how non-native weeds might respond,” says Professor Philip Hulme of the Bio-Protection Research Centre, Lincoln University.

The international team of researchers discovered that weeds quickly outpaced other plants. It seems that roads are one of the culprits, with traffic helping to transport their seeds further.

These findings should raise concerns for New Zealand’s unique alpine environments explains Professor Hulme.

“I suspect the situation is possibly more dire in New Zealand given that our lowland regions are far more invaded by non-native weeds than similar regions in Europe and our montane (mountain ecosystems) regions are coming under increasing pressure from tourism, skiing developments and other infrastructure such as roads.”

The research used more than 130,000 records of 1334 plant species collected over 20 years in a single region of the European Alps.

“The challenge for New Zealand is that we are no longer collecting the systematic, long-term data on how our flora is changing in these environments,” says Professor Hulme, “such data are essential if we want to keep our glorious mountain landscapes free of weeds such as gorse, broom and wilding pines.”

The authors of the study point out that such rapid spread into vulnerable habitats is a further threat to species already stressed by higher temperatures.“We must take action soon otherwise our native alpine plant communities are likely to suffer dramatic changes with ongoing warming and increasing human activity in mountain regions,” concludes Professor Hulme.

The research was published in the journal Nature Climate Change.

Source: Lincoln University

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