Thread by @sophusticated

As mandatory Biodiversity Net Gain inches closer, update all on what the data says the impacts of #BNG will currently be on England's nature, without further changes. 📢📢📢Updated results of our database of all development projects within councils with Net Gain policies 📢📢 /1

Database now spans ~6000 new homes & industrial, research, transport, energy, & health/social care infrastructures; ~800 individual habitat patches. It's now a pretty good picture of where #BNG is leading. Built with @wildbusiness & team of wonderful forward-thinking planners /2

Headline results: #BNG currently associated with a 36% loss of area devoted to non-urban habitats (so urban habitats cover 16% of total footprint of development boundaries under baseline, and 50% under post-dev scenario). BUT, urban is mostly replacing croplands & pasture /3

To compensate for these pretty huge losses in area of open space / habitat, developers proposing to increase area (slightly) & condition (a lot) of habitats such as neutral grasslands, mixed scrub, & woodlands. /4

Now if we look at total 'units' delivered under #BNG, we can see these promised small area (& large condition) increases in these more ecologically valuable habitats is apparently more than compensating for losses; overall database gives a 20% Net Gain /5

For those interested in the 'biodiversity unit market'... so far, units purchased from LPAs (who can generate them themselves through local nature investments or buying from brokers) equal just 5% of total units. No sign of a thriving market yet. Vast maj gains are on-site. /6

Also, hedgerows: there are 8.5km hedgerows under the baseline, and 14km post-development, so good news for the hedgerow afficionados. /7

OK, so: positives? The big one for me is no impacts to highly distinctive habitats in our data; which *may* be evidence of avoidance of biodv impacts initially (although to know for sure, you need to quantify avoidance before the policy too and compare - we're working on it). /8

Worries: a) it's a pretty epic land-take associated with new infra. That's a whole lot of concreting over open space happening under the banner of 'Biodiversity Net Gain' (albeit less biodiverse open space than it could be). /9

No movement as far as I'm aware on the brewing hurricane of the problem that is governance of gains delivered on-site to ensure that promises to deliver condition gains in the future materialise in reality. We discuss that in our pre-print here: osf.io/preprints/soca…. /10

I have spoken with tens of planners about #BNG, & very few think s106 agreements & planning conditions have enough 'bite' to enforce gains in the long-run; especially as setting s106 agreements up takes a lot of time & expertise so is unsuitable for small habitat patches. /11

Also another big concern is very little of the compensation proposed ticks the boxes 'more, bigger, better, connected' of the famous Lawton report. The vast majority is landscaping measures within development footprints. /12

These might deliver 'Net Gains' measured by the Metric... but do they really deliver the restoration of higher-level ecological processes required for thriving wildlife? My guess is not - & if we want that, we'll need much more investment in strategic gains delivered off-site /13

I'll be doing these little updates on what the data says about the progress of #BNG every few months; so feel free to follow me if interested. /fin

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