Victoria Burton, Postgraduate researcher at Natural History Museum talks about the importance of soil and some of our lesser-known soil invertebrates.
Soils, and the life they contain support humans by growing most of our food, filtering water and recycling nutrients. We know that 56% of species studied in the UK have declined in recent decades (State of Nature Report 2016) but almost all of this knowledge is on plants and animals that live above-ground, particularly birds and mammals. It’s important to know if there are similar losses in the soil since this could affect soil health. My research at Imperial College and the Natural History Museum, London is finding out how soil and leaf-litter life such as earthworms, insects and microbes are affected by different land uses.
There has been lots of research on earthworms in farmland because they are important in helping us grow food but not so much in gardens, parks and other urban green spaces. I wanted my research to include these habitats, and also to share their amazing underground world with others. To do this I developed Earthworm Watch with the Earthwatch Institute and the Natural History Museum - anyone can to take part and help me with my work.
I also love to get outside and get my hands dirty researching soil invertebrates! Last year I had permission to collect invertebrates and soil samples from six different habitats in the New Forest, Hampshire, with the aim to see what patterns there are. I used a variety of different methods to find soil animals but my favourite is surveying leaf-litter. There is a huge amount of life in dead leaves – I found over 18,000 invertebrates!
Victoria Burton at an Earthworm Watch event. (Credit: Earthwatch Institute / Natural History Museum, London)
My favourite soil invertebrates
These tiny animals are around the size of a full stop and as their name implies, have an appendage folded under their body which they can use to launch themselves into the air and away from danger - you may have seen them pinging about in compost or dead leaves. Springtails are very numerous - there can be 100,000 individuals per square meter! They graze on fungi or dead plant material and are important for fragmenting dead leaves and speeding up decomposition. There are about 250 species in the UK and they come in a wonderful range of shapes, sizes and colours. Some of my favourites are the (relatively!) large 4mm long and fantastically hairy Orchesella villosa, the blue, fuzzy and dumpy Neanura muscorum, and the rounded, yellow and red patterned Dicyrtomina ornata.
Assorted springtails (Credit: Andy Murray CC BY-SA 2.0 via Flickr)
Assorted soil mites (Credit: from British Oribatiae via Biodiversity Heritage Library (public domain))
These belong to the same class of animals as spiders – arachnids. Mites are mostly maligned as causing allergic reactions (dust mites) or itchy skin infections (mange and scabies) but there are hundreds of beneficial species in soil which help recycle nutrients by breaking down dead leaves. There are at least 600 species in the UK - some can roll up for protection like an armadillo, others cover themselves with a blob of soil and many have intricate patterns of scales, hairs or ridges.
It’s an exciting day for me when I find a false-scorpion! Like mites they are arachnids and as their name suggests they look like scorpions but without a stinging tail. They are tiny (2-8mm) ferocious hunters of springtails and other small soil animals. There are only 28 different species in the UK and you have to look hard for them in soil, leaf-litter, rotting wood and compost heaps. Curiously they sometimes hitch a lift (called phoresy) on flying insects such as beetles and flies.
What I most about soil invertebrates is the sheer quantity and variety, nearly a quarter of known species live in the soil, yet most people wander around unaware of all this life underneath their feet. Unfortunately, most soil animals are small and need a lens or microscope to really appreciate them but these and macro photography are more available than ever before and opening up another world.
Pseudoscorpion with finger for scale. (Credit: Marshal Hedin CC BY-SA 2.0 via Flickr)
Victoria Burton, Postgraduate Researcher at The Natural History Museum