Despite the crucial role earthworms and other soil invertebrates play for healthy ecosystems and fertile soils, there has historically been a lack of monitoring of their populations. Now, by collecting nearly 100 years of scientific studies on soil invertebrate abundance, a team of scientists led by the British Trust for Ornithology (BTO) has found evidence that earthworm populations have significantly declined over the past decades.
“Changes in the UK countryside over the last century, such as extensive drainage, pesticide use, and inorganic fertilizer application, are likely to have negatively affected earthworm populations,” reported study lead author Ailidh Barnes, a research ecologist at BTO.
“Any large-scale decline in soil biodiversity – particularly the loss of earthworms – would sit alongside concerns about ‘insectaggedon’ and the wider biodiversity crisis,” added James Pearce-Higgins, the Director of Science at the same organization. “We need to be concerned about what is happening to biodiversity below the ground in order to protect the biodiversity that we see above ground. We need to look after earthworms.”
According to the scientists, thrushes, starlings, and waders which rely on soil invertebrates are experiencing long-term declines, partly due to changes in the availability of their food sources. These declines appear to be greatest in southeast England, where hotter and drier summers are also likely to reduce the availability of earthworms to foraging birds.
“Whilst these data do not come from a proper monitoring scheme, our hope is that publishing this work will stimulate others to investigate what is happening to our soil invertebrates and establish proper monitoring. Given their importance, we need to monitor changes in the status of our soil invertebrates better than we have in the past,” Pearce-Higgins concluded.
The findings of this study will be presented by Professor Pearce-Higgins at the British Ecological Society’s annual meeting in Edinburgh on Monday 19th December.
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