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Did Frogger Reach the Other Side?

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Did Frogger Reach the Other Side?

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In the mid 1990s, I owned a used BBC Micro computer. With its command line green on black text interface, and simple pixel art graphics, it was my gaming pride and joy for many years.

Frogger was a firm favourite – the basic game where you hop across a busy road through moving traffic as a green frog, then jump from log to log over a river. Each vehicle and log moves at a different speed, so you have to time it just right to cross from one side to the other, without being squashed or drowning.

Why Frogger?

What on earth, you might well ask, has Frogger got to do with ecosystem restoration? Well the new approach which we’re taking to biodiversity credits is very similar to Frogger.

Restored habitats will pop up across our landscape – they’re maintained for years or decades, then they change hands, or priorities change, and the habitat may disappear again.

Like frogger, animals, plants, fungi etc must hop from one restored island of biodiversity to another, to stay alive. And, just like in the game, sometimes these species don’t make it in time and they disappear from the area altogether.

Rewilded garden
Five years ago, this garden was a large concrete driveway, but what will it be five years from now?

What is BNG?

Biodiversity Net Gain is a new system where developers must deliver at least 10% more biodiversity at the end of a project than they have on their land at the beginning. But this doesn’t necessarily mean that all biodiversity is protected during development. And the new habitats may not reach their full potential for a long time after they’re created.

In fact, the BNG system specifically discourages destruction of woodland, because it’s so hard to create a new, healthy woodland to replace it, within a 30 year timespan. It may take many more decades, or even centuries, for it to reach its full potential.

What Selling Biodiversity Credits Means

As a landowner, BNG and similar systems of biodiversity credits may be a tempting opportunity. You can make a decent amount of money by restoring an ecosystem and selling the ‘uplift’ back into the market. This can create a mosaic of thriving habitats across your land, and it’s hard to see how this is a bad thing.

However, it’s worth bearing in mind that selling your credits essentially neutralises most of the gains you’ve made (except that 10%). While on your land there is a patchwork of biodiversity, elsewhere that biodiversity has been lost. The developer is paying to offset their losses by purchasing the improvement of your land.

The system is an interesting one – it reminds me of how Catholics used to pay the Church to forgive their sins. In one way it’s fantastic, because it put a monetary value on biodiversity and allows people to invest in nature. In another way it’s terrible, because landowners often ‘double-count’ – with the gut feeling that this biodiversity comes ‘for free’, as they don’t see the resulting destruction of ecosystems elsewhere.

Grassland habitat with late successional scrub
The dense stands of scrub at Knepp have allowed Nightingales to increase in abundance.

Knepp's Resurgence

But these islands of biodiversity are not necessarily a bad thing. They’re certainly a positive change from the system we used to have, where ecosystems were constantly destroyed. And in an unchanging, unmanaged landscape, habitats tended to revert to high canopy woodland. This is great for some species, but not all of them.

The reason that rewilding projects like Knepp became so famous is that they contained a lot of early successional habitats. These were bits of land which were in the process of shifting from grassland to scrub to young woodland. These habitats have been lost from a lot of our landscape, along with the species which depend on them.

At Knepp, dense stands of scrub drew in nightingales, while rich supplies of agricultural weeds were food for turtle doves, and young willow stands alongside mature hedgerow oaks created habitat for purple emperor butterflies. Elsewhere in England, you’d be hard-pushed to find any of these species in the wild. The sudden creation of new habitats supported lost diversity and abundance.

Mushroom
It may take decades or centuries for fungi like this Fly Agaric to become established in a new woodland.

Your Own Project

This is why, even if your garden, smallholding or farm is likely to change hands in a few years’ time, it’s still worth thinking about rewilding and ecosystem restoration. Even short fallow periods can create huge biodiversity and abundance, while improving the soil quality as an added benefit.

It’s like you’re building a log for Frogger to leap onto. It may not be a long term solution, but it helps the species in the area to hang around for a little bit longer.

But there are some habitats which need long periods to get established, and must be conserved and maintained over centuries. These include our ancient woodlands, which are not just home to old trees, but to an intricate web of diversity which is impossible to recreate by hand.

You can’t just transplant a tree and expect the soil organisms, bird species, bats and fungi to come along with it. But we can use our understanding of the value of this biodiversity to help speed-along woodland restoration projects.

Soil Transplants

The soil in a woodland is dominated by fungal species, whereas grassland soils are dominated by bacteria. Switching between these two regimes takes a considerable amount of time. But you can speed up the process by dumping woodchip onto newly planted ‘forest’ floors on former pastures.

Woodchip can often be acquired for free, as local landscapers are desperate to dump their waste. It’s just worth checking that it isn’t contaminated with herbicides. You’re may also get diseased trees in the mix, so check that it’s not a rare disease which you could be responsible for spreading.

If you know the landowner of an existing healthy woodland, then taking soil samples and digging them into your own plot can introduce beneficial fungal spores, invertebrates and microorganisms. This ‘soil transplant’ strategy is taking hold as a popular method in rewilding.

Frogger game
What lay on the other side of the river?

Frogger's Dream

Frogger may have dreamed of a day when they could finally reach the other side. Perhaps there was a restored island of biodiversity awaiting them on the far bank. Many animals and plants are migratory in their nature, and this new model of habitats popping up and disappearing simply harkens back to the ancient landscape, when the same thing happened all the time.

But it’s important that we recognise the distinction between these high value, temporary, transitional habitats, and the long term biodiverse ecosystems which act as refuges for a diverse network of species over many centuries.

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