Wildflowers and Air Pollution
We all know we have a problem with air pollution, yet probably not many people consider the effect of pollution on wildflowers and the insects that depend on them.
Across the UK, the variety of wildflower species in many habitats is declining in areas with increased nitrogen deposition, which leads to acidification and accumulation of extra nutrients and a decrease in soil PH. Plants and fungi that have adapted to low-nutrient levels suffer in such conditions. A staggering 63% of all nitrogen-sensitive habitats across the UK have a higher nitrogen deposition than they can cope with. Examples of nitrogen-sensitive species include Harebell, Fary Flax and Birdsfoot Trefoil. On the flipside, more robust species such as Nettles, Hemlock and Cleavers thrive in high-nitrogen soils. This results in an abundance of such plants, often shading out or competing with other wildflowers, eg, the Marsh Fritillary butterfly relies upon its nitrogen-sensitive host plant Devil’s Bit Scabious as a food source – if that declines, so does the Marsh Fritillary. In NW Europe, a decline in grassland fungi has also been linked to high nitrogen deposition.
Ammonia emissions from farming practices are another problem. 64% of the UK has ammonia levels exceeding the critical level for lichens and bryophytes, eg, the already endangered Eyelash Treebeard lichen.
Air Pollution Disturbs Insect Pollinators from Finding Flowers
Research by the Universities of Reading and Birmingham, and the UK Centre for Ecology and Hydrology, found that there were up to 70% fewer insects and up to 90% fewer flower visits; and pollination reduction of 31% in test Black Mustard plants on deliberately-polluted research plots (with exhaust fumes), as opposed to unpolluted plots. This was even with using pollution levels LESS than that considered safe.
Insects often rely on smell to navigate. Pollution (particularly nitrogen oxide) causes these natural aromas to quickly vanish, making any scent that is left unrecognisable to insects. For example, researchers have found that Buff-tailed Bumblebees find it hard to locate their host plants above certain levels of ozone.
“Air pollution results in it being more difficult for pollinators such as honeybees to recognise, locate and memorise the location of their floral resources, which impacts foraging efficiency and consequently pollination. Particulate pollution can also be an issue for pollinators as the fine hairs on their bodies that become electrically charged to attract pollen can also attract other fine particulates, including dust and heavy metals. Studies have also shown increases in dead larvae and workers in colonies bumblebee colonies where the bees have been visiting plants enriched with excess nitrogen. There is also physical damage from consuming abrasive particles”. {https://naturalengland.blog.gov.uk/2022/07/21/bees-needs-why-air-pollution-matters-to-pollinators/}
If insects can’t detect flowers for nectar/pollen for themselves or young, then they have to travel further, using more energy resources.
Air Pollution and Plant Metabolism
Air pollution also changes plant metabolism and, thereby, alters the aroma flowers emit. Ozone can also affect the timing of a plant’s flowering period, affecting plant reproduction.
The Problem with the Effects of Air Pollution on Pollinators and Flowers
The problem is pretty obvious – air pollution not only affects insect and wildflower populations, this also has a knock-on effect on ecosystems and humans. Pollinators are vital for human food production – a decrease in pollinators will ultimately affect crop pollination and food supply for humans. It will also change the face of the countryside with wildflowers becoming even more endangered in their natural habitats.
How You Can Help Ease the Effects on Pollinators of Air Pollution
The easiest solution is to keep growing wildflowers! Make your garden a haven for wildflowers and the insects that rely on them. You can also reduce your own air-polluting emissions by, for example, using public transport more than your car, or cycling more places. Also buy locally-produced foods to reduce travel miles and eat according to what is seasonally-available, thereby avoiding air miles from eating non-UK foods, or foods that need high energy to produce them out of season.
Other sources of above info:
Plantlife “We Need to Talk About Nitrogen” and BBC Newsround.
