A woodland creation hierarchy

Do we need to plant nursery-grown ‘whips’ in our UK woodland creation projects, or can we allow nature to create woodlands by standing back (natural regeneration), perhaps with a subtle helping hand (assisted natural regeneration)?

I’ve been having a bit of a debate on Twitter about the relative merits of tree planting and natural regeneration as an approach to woodland creation in the UK. This was sparked by frequent pro-planting posts from the Woodland Trust, World Wildlife Fund-UK and the Rivers Trust.

Tweets from the Woodland Trust, celebrating its woodland creation endeavours, always seem to be illustrated with photos of plastic tree tubes, affixed to treated wooden posts with a couple of plastic ties. I posed the question: why not allow either natural regeneration (where one simply stands back and allows natural woodland growth to take its course) or assisted natural regeneration (in which we can give nature a helping hand by clearing grasses and scrub from around tree seedlings that appear naturally, or plant seedlings grown by school kids).

In response, the Woodland Trust stated that planting whips in tubes is necessary to ensure trees get away in the face of grazing and browsing voles, rabbits and deer. They also alluded to photo-ops and funder preference for planting.

Barbara Young, the Chair of the Woodland Trust who I hold in great esteem, suggested in a tweet that planting is needed now because natural regeneration wont be quick enough to deliver carbon sequestration benefits, which need to be delivered within the next twelve years.

Now, don’t get me wrong. I accept that planting of small whips (nursery transplants) can be an effective approach to getting native trees and shrubs going and is sometimes needed. It’s also a great way to engage communities in woodland establishment.

But I fear that planting of imported whips is the default approach adopted by organisations like the Woodland Trust.

So what’s wrong with planting?

For starters, should we be using tens of thousands of plastic planting tubes and plastic ties? These will remain in the environment fo thousands of years, far longer than the tree they encase, even if a given tree does survive to live a ripe old age. How long can an oak really hope to live?

Think about that: the plastic ties and tubes will probably outlive the tree they’re protecting, even if it lives its full term, to a ripe old age of a few hundred years!

Plastics could be recovered and an attempt made to recycle them. But they are often degraded by the sun, caked in muck and often just collapse to be lost among emergent shrubs and leaf litter. And surely woodland creators should observe the ‘Reduce, Reuse, Recycle’ rule: surely we should look to Reduce avoidable plastic waste, only using plastic when it simply cannot be avoided – then re-using it if possible, and recycling it as the last resort?

What of the statement that woodlands cannot regenerate in the presence of voles, rabbits and (over-abundant) deer? This is true in some situations. But a look at the Northern Forest region, in which the Woodland Trust is planting hundreds of thousands of trees, reveals a network of tree and shrub lined railway corridors. The fact that these are celebrated wildlife corridors – with deer not an infrequent sight from the train – suggests that trees and shrubs are quite capable of getting away throughout the area without much planting.

What of Barbara Young’s assertion that planting is needed urgently because natural regeneration cannot deliver carbon sequestration quickly enough? I can see the argument: planting whips at least guarantees that a mix of native trees will establish at a given plot quickly. I’m not convinced, though, that assisted natural regeneration wouldn’t do the job just as well, and just as rapidly.

The Woodland Trust also state that planted trees form natural woodlands. My experience is the opposite. It’s very easy to tell a planted oak wood, 100 years later, from a naturally regenerated woodland. That’s my experience, at least. The science may reveal otherwise.

So, what do I suggest? How about a new Woodland Creation Hierarchy? I suggested this back in 2018, and the concept was picked up by Rewilding Britain.

Briefly, rather than assume the default position that planting is best, we might consider a series of options in turn, at each site:

First option, assume natural regeneration, unless the site is so far away from seed sources that trees and shrubs simply won’t arrive, and establish, any time soon. One needs to consider both ‘dispersal limitation’ and ‘establishment limitation’. Tree and shrub seeds may arrive at the site, but factors such as a dense thatch of grasses, or nibbling voles, or browsing deer, may prevent their establishment.

If unassisted, natural regeneration is demonstrably not possible…

Second option, undertake assisted natural regeneration, in which naturally-appearing seedlings are ‘liberated’ by keeping competitors at bay in their immediate vicinity, and with some planting of small seedlings of, say, oaks, grown on by kids at school. Only plant widely distributed clumps. Avoid wall-to-wall planting across a whole site. This is because wall-to-wall planting leads to a thicket stage very quickly, and completely bypasses the more open, biodiverse grassland-scrubland mosaic stage of natural regeneration.

If neither of those two options are demonstrably appropriate at the site in question…

Final option, plant nursery whips of trees and shrubs. But, again, try to avoid wall-to-wall planting. Plant discrete groups of trees and shrubs with unplanted areas separating them. This will speed-up the formation of grassland-shrubland mosaics, a habitat so important to, for example, Turtle Dove, Red-backed Shrike, Grass Snake, Duke of Burgundy etc etc.

It would be relatively easy for natural woodland creators to adopt such a Hierarchy approach.

And funder attitude? Avoid being funder-led. Educate funders as to what’s best for biodiversity, rather than what’s best for the photo-op and grant form-filling. Besides, it’s easy to involve volunteers in seedling cultivation and planting. No need for wall-to-wall whip-in-tube planting.