Ants feel at home in this ‘foreign’ forest

"The northern hairy wood ant is a keystone species in forests because it supports a wide range of birds and invertebrates," says Duncan Procter. (Credit: Richard Bartz/Flickr)

A species of ant is thriving in new habitats created by thousands of acres of coniferous forest planted in a UK national park.

The success of the northern hairy wood ant (Formica lugubris) in colonizing mostly non-native coniferous species in the North York Moors National Park backs up recent suggestions that non-native plantations can benefit forest-dependent species, researchers say.

Northern hairy wood ant
Northern hairy wood ant on a rabbit carcass. (Credit: Duncan Procter)
nest mound
Nest mound in the forest. (Credit: Sam Ellis)

Forest cover in Britain has more than doubled over the last century and a half. Forests now cover 13 percent of British land area compared with five percent in 1900.

But most of the expansion is due to new non-native coniferous species that have been grown for commercial forestry. Large areas of the current plantations are in areas where there were no forests until 60 or so years ago.

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For a new study, published in Forest Ecology and Management, researchers mapped more than 5,500 ant nests that were mostly on the edges of coniferous plantations in the North York Moors.

“The northern hairy wood ant is a keystone species in forests because it supports a wide range of birds and invertebrates,” says Duncan Procter, a PhD student in the biology department at the University of York.

“Some of the latter are only found in the wood ants’ nests which, as they are large mounds of organic matter, play an important role in the decomposition cycle of the forest.”

Suitable habitat

The findings show that there has been a remarkable expansion of the population of the northern hairy wood ant into new plantations that were close to established woodlands.

Colonization of these new conifer habitats has, however, been slow—current wood ant populations have only extended up to a maximum of 800 meters from where forest was in the past.

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Nevertheless, geographical population expansions into newly formed forest suggest the recently planted non-native conifer plantations are a suitable habitat.

“Our work reveals that Formica lugubris has not yet spread through all available suitable habitat due to its very poor dispersal ability, displaying a severe lag behind the availability of new habitat,” Procter says.

“We believe, therefore, that we should re-assess the idea that a coniferous monoculture is bad for diversity. Forest managers should not assume that unoccupied habitat is unsuitable if species have not yet had a chance to disperse to it nor should they expect to see immediate colonization of plantations.

“Future forest creation should be targeted close to existing woodland to facilitate colonization by these forest specialists. Just because you don’t see a species in a particular location at the moment doesn’t mean it’s not a good habitat for it.”

“It’s great that here we have a conservation story that has a really positive message,” says coauthor Elva Robinson, a research fellow in the biology department. “Clearly, there are still challenges to address but this research illustrates nature’s remarkable ability to adapt to environmental change.”

Source: University of York