I’ve always had a soft spot for the weirder side of wildlife. As a child, I was obsessed with insects and founded my exclusive club, ‘The Weed Trust’, in an attempt to seek justice on behalf of this much-maligned group of plants. Although I was completely mortified at the time, the fact that my first and only primary school detention was given to me for stroking bumblebees is now a tale I tell with pride.
It’ll probably come as no surprise that in recent years I’ve made it my mission to champion and help protect many of our planet’s slightly more peculiar inhabitants – from orchids, bats, and frogs to seabirds and moths. So far, my conservation volunteering and science communication work have taken me everywhere from the picturesque estuaries of northern Norway, where I learned how AI is being used to safeguard the native Atlantic salmon, to the jungles of Panama, where I documented behind the scenes at a wildlife rescue centre (as well as being a surrogate mum to a bunch of orphaned, baby sloths!).
But now, I’m turning my attention back to the curious creatures that live right on my doorstep which, despite their tiny size and far-from-glamorous reputations, first sparked my interest in the natural world when I was exploring my small, suburban garden in east London as a child. As part of my latest (and somewhat more serious) undertaking, a MSc by Research at Royal Holloway University, I’ve teamed up with The Orchard Project to explore the role that London’s urban orchards play in protecting threatened species and fighting climate change.
Between now and the end of next spring, I’ll be surveying insects – specifically, bumblebees, solitary bees, butterflies and ground (or carabid) beetles – and analyzing the carbon contents of soil cores I’ll collect from urban orchards dotted in and around the city.
I’m particularly interested in how an orchard’s age might affect its insect communities and soil carbon stocks. While there’s loads of information about how old ‘veteran’ and traditionally managed orchards can provide important habitat for wildlife, we know far less about the ecological and environmental value of younger, less formally managed ones.
By surveying orchards that range in age from one to over a hundred years old, I’m hoping to show that younger orchards can provide their own, distinct benefits for nature and the climate as long as they’re designed and managed with wildlife in mind.
There are of course countless other factors that might influence the numbers and different kinds of insects that call an urban orchard home. They include the kinds of plants that are growing between the fruit trees; whether any wildlife-friendly features like log piles, wildflower beds, or ponds have been added; how often the grass gets mown; the orchard’s overall size and shape; and how connected it is to other patches of suitable habitat.
So as well as catching bees, beetles, and butterflies, I’m also gathering data on the plant communities growing within each of my study orchards. Later in the year I plan to use aerial mapping software to calculate what proportion of the surrounding land is covered by either buildings and concrete, or wildlife-friendly green space. This will help me figure out if there are any general patterns in the ways that insects respond not only to the orchard’s age, but also habitat patch size and connectedness.
Last month marked the start of my first insect collecting season and with a grand total of 60 orchards to survey between now and next May, I’ve certainly got my work cut out! Fortunately for me, bees and butterflies tend to lie low if the weather’s bad, so I’m mostly only out and about when it’s dry and the sun’s shining (which hasn’t been very often so far).
Sampling these two groups of insects involves spending about an hour wandering around a given orchard at a slow, steady pace, catching any that fly within a set distance of me and my poised-for-action insect net. Once I’ve successfully managed to catch a bee or butterfly, I try to identify it by eye so that I can quickly release it. Beetles are collected via simple, ground-based traps called pitfall traps.
While bumblebees and butterflies are relatively easy to ID, many solitary bee species are tricky to tell apart without the use of a microscope and a detailed identification key.
Insect sampling will continue until the end of September, with a second round starting next March. Over the autumn, I’ll be writing; researching and reviewing the findings of other earlier, relevant studies; and returning to each of my study sites to collect additional measurements of things like tree density, and extracting soil cores.
Back in the lab, I’ll use a special machine to calculate the amount of carbon that these cores contain, then use these measurements to produce estimates of the total amount of carbon stored within the soils of different-aged orchards.
By improving our understanding of the features that boost insect diversity and carbon storage capacity in urban orchards, this study will hopefully help urban planners, community groups, and charities like The Orchard Project design and manage these unique habitats in ways that make them even more effective at conserving species and combatting climate change.
Most importantly, being able to quantify the biodiversity and carbon storage value of urban orchards will provide us with an even stronger argument for their continued creation, restoration, and management.
I’ll be sharing more updates here later in the year, but for now, feel free to follow along with my urban orchard adventures over on Instagram @lucyhouliston
by Lucy Houliston