A bit of slashing now and then: the lines are open for pollinators

by Athayde Tonhasca 

In 1926, the government body Central Electricity Board set out to create a nationwide electrical grid to bring cheap power for everyone. This was the biggest building project that Britain had ever seen, and soon steel pylons and transmission lines began popping up all over the landscape. Many people didn’t like what they saw. In 1929, Rudyard Kipling and John Maynard Keynes co-signed a letter to The Times protesting the construction of pylons, noting they were ‘the permanent disfigurement of a familiar feature of the English landscape.’ The pylon’s designer, architect Sir Reginald Blomfield, fired back: ‘Anyone who has seen these strange masts and lines striding across the country, ignoring all obstacles in their strenuous march, can realise without a great effort of imagination that [they] have an element of romance of their own. The wise man does not tilt at windmills – one may not like it, but the world moves on.’

You may side with Kipling and Keynes or Blomfield in this aesthetics vs utility debate, but transmission lines are here to stay, for a while at least. The British grid of high-voltage lines from power stations alone runs for ~25,000 km; adding to that several thousand kilometres of regional networks, power lines have become part of our landscape.

Transmission corridors, similar to roadsides and railway embankments, are routinely mowed, clear-cut or treated with herbicides to prevent the encroachment of trees and dense vegetation. These practices are viewed as necessary evils by the public and some conservationists; but, with the right touch, they create opportunities for bees and other pollinators.   

In ecology, ‘succession’ is the process by which a natural area changes after a disturbance or following the initial colonization of a new place. In terrestrial habitats, early succession refers to the period before they become enclosed by trees’ canopy. Weedy areas, grasslands, old fields or pastures, shrub thickets and young forests are all examples of early successional habitats. And so are transmission corridors, where maintenance crews prevent succession from reaching its equilibrium point or climax by cutting down the vegetation. 

Plant succession © OpenStax Biology, Wikipedia Creative Commons

It turns out that habitats in the early successional stages are excellent for bees. These areas offer a steady supply of nectar and pollen over much of the year, as opposed to forested areas where blooms peak in spring and are limited by the shaded canopy from midsummer on. The large majority of bee species nest in the ground; they need patches of bare soil of the right texture and moisture, and close to their food plants. Successional habitats are just the right place for this combination of features. So it’s not surprising that bee abundance and species richness decreases with increasing forest cover.

Lots of flowers, nesting/hibernation sites & sunshine: perfect for bees © Trevor Rickard, Wikipedia Creative Commons

In the northeastern United States, power companies have been maintaining power lines under Integrated Vegetation Management (IVM) since the 1950s with the objective of protecting the grid while providing habitat for threatened plants and animals. It sounds fancy, but essentially IVM comprises five-year cycles of selectively killing trees (mechanically or with herbicides), with no mowing or widespread spraying of herbicides. These simple techniques create a mosaic of meadow, herbaceous plants and shrubs, which have proved to be good for many reptiles, amphibians, birds, small mammals, and bees. A comprehensive survey along 140 km of a transmission line in New England revealed that the sunny, open corridors held nearly 10 times the number of bees and twice the number of bee species as compared to adjacent forested areas. Not only that, about half the known species for the region, including some rarities, were found in the survey. No comparable study exists in the UK, but we could expect similar effects. The ecological conditions are different – bracken control, for example, could be a greater challenge – but our bees would also benefit from vegetation management along power line corridors.   

A power line corridor, great habitat for bees © Humphrey Bolton, Wikipedia Creative Commons

Nobody likes the sight of a transmission line. But those ugly and gloomy steel towers and cables can be turned into pollinator and wildlife havens. All it takes is goodwill and some imaginative work. The lights will stay on, and there will more bees around.