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Biodiversity net gain – the wood wide web pitfall?

#tldr The Environment Act 2021 requires development to deliver – and maintain for 30 years –  biodiversity improvement. Soil fungi connect trees over wide distances. Protecting, restoring and quantifying such underground biodiversity will be challenging and require new information.

Social networks have come a long way since the launch of Friends Reunited (2000 – 2016). Facebook, Twitter, LinkedIn, Instagram and even MySpace (2003 – to date) connect us, inform us, empower us, sell to us, frustrate us, anger us. But if you go down to the woods today, you may be walking on a social network older – much older – even than Usenet’s Newsgroups.

The “wood-wide web” neatly summarised an experiment that showed the two-way exchange of carbon between trees and fungi. Professor Suzanna Simard’s 1997 paper in Nature demonstrated this give-and-take and prompted the aphorism on the 7 August 1997 front cover of the prestigious journal.

As the three men and a woman Artemis II astronauts prepare for humanity’s return to the moon, colonising outer space is a step closer. In Avatar, James Cameron’s 2009 film, the forests of Pandora, colonised by humans in search of scarce resources, formed Eywa – a mind with electrochemical connections between tree roots functioning as neurons. Fiction may once again be following reality. It seems that Earth’s rich diversity of soil invertebrates and microbes allows trees to… network. Soil’s biodiverse ecological communities are linked to soil biogeochemistry. However it seems that these communities are also linked to – and may direct – the growth and nature of entire forests.

Back to Earth… with a bump.  Biodiversity net gain (BNG) is seen by Defra as a way for development to contribute to the recovery of nature by “making sure the habitat for wildlife is in a better state than it was before development”. The Environment Act 2021 introduced a requirement for development in England to deliver 10% BNG and maintain it for 30 years. Later this year a new calculation tool will start to be used to determine biodiversity. The Biodiversity Metric 4.0 was published by English Nature back in 2021 for calculating biodiversity net gain.

English Nature advise that assessments of current and, hence needed, future biodiversity on sites being put forward for development will need information (my thoughts added in italics) on:

  • the types of habitat – on-site and off-site, potentially including underground
  • the size of each habitat parcel in hectares, or kilometres if it is linear (rivers and streams, hedgerows and lines of trees), or potentially cubic metres if it is underground
  • the condition of each habitat parcel
  • whether the sites are in locations identified as local nature priorities

The BNG calculator recognises the importance of soil as a source of nutrients and a chemical environment in which trees grow but makes no obvious reference to the diversity of soil life or its significance to the trees ability to communicate with each other. Perhaps a case of not seeing the wood for the trees?

Article Written by Paul Nathanail.

Paul Nathanail is a Chartered Geologist and Specialist in Land Condition writing in a personal capacity.

Follow up reading:

Suzanne Simard et al. 1997. Nature 388: 579-582. (Open Access)

Defra. 2023. Information you need for biodiversity net gain (BNG).

Article original source: Biodiversity net gain – the wood wide web pitfall?