From a pollinator perspective, weeds are good
‘Weed’ is very much a loaded term. Plants are plants, but some of them we have defined as being against our economic, and sometimes aesthetic, interests.
In truth, one organism’s weed is another’s livelihood — and this has been profoundly underlined in a recent study from the University of Sussex, which showed that plants categorised as weeds are actually pretty fantastic for pollinators.
Hated v hyped
In a neatly-designed field experiment, researchers compared the visits made by pollinators to five ‘weed’ species, including dock, thistle and ragwort, to plants recommended for use in government-backed agri-environmental schemes.
In short, the much-maligned species won the argument quite spectacularly.
They attracted double the number of visits of the supposedly pollinator-friendly flowers, covering all the major insect groups. After an extensive analysis of previous research looking at similar phenomena, it was found that this was by no means an anomaly. Pollinators are definitively big fans of weeds, for want of a better term.
As for the ‘why’, the authors offered up a few highly-plausible ideas: plants dubbed weeds tend to be widely-distributed, have flowers that are easy to forage upon, and have comparatively high amounts of nectar available. It’s not rocket science; it’s ecology 101.
Leave it and they will come
So what do we do with this slightly uncomfortable truth? With millions been spent on killing weeds, and far more again being spent on subsidised programmes to encourage pollinators, there are some quite colossal logical black holes here. The bad are good and the good are not as good as the bad.
At this point, it’s worth noting that the study’s authors are not advocating nations choked in weeds. They acknowledge that allowing such species carte blanche can have extremely negative effects on plant diversity, disproportionally affecting smaller, less vigorous plants.
A degree of change is more than possible, though — but it will require a considerable re-think about how we perceive the greenery around us.
Then, there seems to be a strong case for policy tweaks, considering it seems that just leaving weeds where they are would provide more effective ecosystem services than planting wildflower meadows at field boundaries. Sometimes the best solution has been right there all the time, we’ve just become distracted by neat concepts that seem to make sense.
For farmers, a light-touch approach to weeding is likely to sound decidedly unnerving, but the authors point out a number of other plus-points about species considered weeds that will likely appeal to those making a living from growing our food. These include their ability to harbour predators and parasitoids that can naturally dispense with crop pests, as well as make soil improvements.
A testing time
We are living through a pollinator crisis. Numerous studies have shown wild pollinators in decline, and I’ve just written a story about how managed pollinators — also known as beekeeping — just can’t keep up with crop pollination demand.
A stable food supply rests on healthy populations of wild pollinators, supplemented by wise use of domesticated insects where necessary. Maintaining such beneficial systems requires lots of effort on lots of fronts, but making sure there’s lots of the plants insects like to visit is a pretty solid place to start.