Why are there large gaps in the British distribution of Common Elder?

Back in mid-April, Karin and I spent a long weekend in the New Forest, exploring the walking trails around the village of Brockenhurst and watching the bird life of the coastal wetlands near Lymington. After a few days something odd struck me: the hedgerows and woodland edges in the area contained almost no Common Elder (Sambucus nigra). Why is that odd? Well, in the article I wrote about Common Elder in 2022 for British Wildlife, I described the plant as ‘so commonplace that we hardly give it a second glance’. Common Elder is such a ubiquitous species that, as Sherlock Holmes observed in The Adventure of Silver Blaze, its absence in a landscape struck me as a ‘curious incident’.

At first I thought that I was so preoccupied with the New Forest’s birds and other wildlife and just not spotting elder, which early in the season, before it flowers, tends to merge into the general greenery of the countryside. Because elder is everywhere, right? In fact this map from the Biological Flora of the British Isles account of the species showing the occurrence of the species in 10km squares suggests just that:

Similarly, if you look at the distribution map of Sambucus nigra from the NBN Atlas, it also appears that it’s everywhere, a big blob of elderlyness across the whole country:

That’s not surprising, I can imagine you’re thinking, after all its berries are eaten by a range of birds and mammals, that disperse its seeds far and wide. It’s just the kind of species that you would expect to be widespread across the country. Which of course it is – it’s a very common species. But once you focus more closely on specific parts of Britain you see that there are some striking gaps in where elder is commonly found. Indeed one of these elder lacunae is in and around the New Forest:

So my impression was correct – the New Forest really is an elder cold spot, along with most of the Isle of Wight. Zoom back out and we see that this lacuna is part of a wider band of elder absence that extends across the southeast of England. There’s also gaps further west, in Somerset and in Devon.

It’s not just in southern England that these elder lacunae occur – look at its absence from much of Lincolnshire, for instance:

What’s going on here? Why do these gaps in the distribution of this common species occur? Part of the answer is that, being so common, Common Elder tends not to be recorded because naturalists often focus on rare and unusual species, neglecting the commoners. This form of bias is often encountered when dealing with biodiversity databases – we found it in our study of trends in diversity and abundance of Neotropical pollinators, for instance. I’m certain that this is a factor in the NBN Atlas account of Common Elder, because if we look at a part of Britain with which I am very familiar, centered on the town of Northampton, I know for a fact that elder is extremely abundant even if the map suggests otherwise:

But lack of records cannot be the only answer to these gaps: Common Elder really is not very common in the New Forest – I’ve (not) seen it with my own eyes! So what else could be going on? It doesn’t seem to relate to underlying geology or soil type, and indeed Common Elder is tolerant of a wide range of edaphic conditions: the Biological Flora account shows that it occurs on sandy, chalky and loamy soils, ranging from pH 4.2 to pH 8.7. So I wonder if the answer has a more cultural basis? Has Common Elder been actively removed from some areas in the past, perhaps because of its supernatural associations (something that I discussed in my article) or, more prosaically, because it’s believed by farmers to be toxic to stock, or just not a very good hedging plant?

As always, I’d love to hear your thoughts on this, please comment below or send me a message via my Contact page.