Ian Brand

Wharfedale Naturalists Society

EACH morning, as I open the bedroom curtains, I am greeted by the sight of a beautiful old Ash tree. Standing 32 metres (105 feet) tall, it is indeed a gentle old giant. Sadly, it now has the early signs of ash dieback.

Casting my eyes around the surrounding countryside, most of the other trees are Sycamore (Acer psuedoplatanus) (see photo). Ash, Oak, Beech and Lime all have their admirers. Not so it would seem with Sycamore. It is the arboreal ‘bad guy’!

The case for the prosecution is well made:

It is not part of our native flora, although there is debate about exactly when it was introduced. Having arrived, sycamore has spread rapidly, and is now the most widespread tree in the UK. Finally, it would also appear not to be good for biodiversity, supporting only 15 species of herbivorous insects, compared to the oak’s 300.

Like most headline news, this doesn’t tell the whole story. I agree, it is not a native species, but look at any British flora, and we find up to 50% of the species have been introduced and are now naturalised in the countryside.

Sycamores produce a large number of flowers in spring, providing both nectar and pollen for bees and other foraging insects. Then in winter, the seeds are food for small rodents and fun for young children playing ‘helicopters’.

Aphids are particularly abundant on sycamore, with an estimated 2.25 million on a mature tree in late summer, a wonderful source of food for birds, ladybirds, and hoverflies.

Park your car under a sycamore in summer and it will be annoyingly covered in a sticky substance called honeydew. Aphids feed on the tree sap, which is their only source of food. It is essentially just a sugar solution, with just 1-2% protein. The insect must therefore ingest large amounts of sap to get enough protein, so what comes out is very similar to what went in – minus a few amino acids. Honeydew - is really just aphid pooh! Ants can often be found ‘milking’ the aphids, and bees and wasps will often turn to honeydew in late summer when there is a shortage of flowering plants for nectar.

Sycamores, like plane trees, also have a flaky bark, under which it is home for many invertebrates.

We do need to remove sycamores from our ancient semi-natural woodlands, but elsewhere I suggest we need to be more tolerant and appreciative of their positive impact.