Nature on our doorsteps: Leaving the leaves

Rosaleen Dwyer is the County Heritage Officer at South Dublin County Council – every week she gives us an insight into nature on our doorsteps and the beautiful biodiversity of its plants and wildlife.

WHILE many people enjoy the autumn colours and the crunch of fallen leaves underfoot, others see fallen leaves as something to be quickly cleared up and disposed of in bins or plastic bags.

There are good safety reasons for doing this, as wet leaves can be slippery on paths and driveways.

There are many other good reasons, however, why at least some leaves should be left on the ground wherever possible.

Fallen leaves offer so many benefits to insects, birds, and soil health that it is worth considering where space could be left so that wildlife, and us, can benefit. In recent years, campaigns to support pollinating insects in summertime have been very successful.

There is now a greater awareness of not using chemicals in the garden and knowing the best nectar and pollen-rich flowers to grow. When summertime ends, however, the next critical stage of the insect lifecycle is only beginning.

This is where leaf litter plays a vital role. Insects pass the winter either as adults, larvae or caterpillars, or as a developing chrysalis or pupa.

Many of these need places like leaf litter in which to hide over winter.

Continually clearing away autumn leaves can therefore significantly reduce the numbers of adult insects for next year.

Worms and other invertebrates pull leaves back under the soil. Organic matter and its vital nutrients are naturally recycled in this way, making them available for next year’s growth.

Layers of fallen leaves help insulate the soil in frosty conditions and can even supress weed growth in mild winter weather. Birds like Blackbirds and Robins will also poke through winter leaf litter to feed on hibernating insects.

So, while it may be necessary to keep paths clear of wet leaves, consider leaving some leaves around the base of trees, along the bottom of a hedgerow or a wall, along the edge of the lawn, or in a loose pile at the back of the garden, or even use them as a mulch on the vegetable patch or flower bed.

Next year’s insects need this year’s fallen leaves.