Plant some trees and save the world…?

I’m cautiously positive about a new initiative to plant a belt of woodland across the North of England. It should, hopefully, be a good thing, creating new habitat for a variety of birds, woodland insects (maybe Aleyrodes lonicerae and its predators and parasitoids? I’d love that!) and woodland understorey plants. And the ecosystem services outlined in the news report will definitely be a wonderful thing. If it truly is a “belt”, i.e. continuous habitat with connectivity, the value will be even higher.

But I worry about the planning process, and the legacy. What land is going to be used for this? Will the biodiversity losses as a result of destroying the old habitat be counterbalanced by the biodiversity gains of replacing it with young secondary woodland? (I would hope in every case the answer would be “yes”, by selecting overgrazed fields, unused amenity grassland, etc. – but in cases like scrubland and brownfield, I’d rather they checked the data first!).

What trees will be selected? Will they be both appropriate to the environment and also chosen with a long-term view (e.g. slow-growing pillars of ancient woodland) or will the focus be on fast-growing species of early-stage woodland? Will imported nursery stock of non-native subspecies be used – and is this necessarily a problem?

My biggest concern, though, is the legacy. If you plant a load of trees in some wasteland then go away and leave it untouched, you won’t come back in 100 years to find something comparable to Cromers Wood or Hayley Wood. Humans have been interacting with woodland for centuries (if not longer) and the species assemblages you get are a result of that interaction. A good example is to chase up some of the Millennium woodlands planted in 2000. In a lot of cases, the money ran out and the maintenance slowed or stopped, and the original vision hasn’t really been carried through.

Earlier this year I did visit a few Millennium woodlands in Kent. It was a pleasant day out and we saw a few good noteworthy invertebrates – a Stelis bee species, a wasp spider, and so on. But the sites seemed to suffer a bit from haphazard maintenance and the species lists weren’t really comparable to what we’d get from an older site under more proactive management. A example from Medway is Bloors Lane Community Woodland. From the point of view of a public amenity for a bit of fresh air, dog-walking or (in the case of some local teenagers) having a private smoke away from parental observation, these types of sites are all well and good; even low-quality habitat benefits people1. But habitatwise, it doesn’t get a lot of love much of the time. The trees are, in my opinion, getting too dense, the areas of unbroken canopy are shading out the ground, it suffers from frequent vandalism, and last time I checked there was very little growing at the understorey level. It’s home to a few common species of bird and bumblebee, but to help significantly with rare stuff it would probably need much more money poured into it for management. For decades. And I can’t see that happening any time soon.

Replicate that up to 20% of land around northern urban cities and we’re talking about a large team of full-time woodland wardens needing to be employed indefinitely (which would be excellent if it happened) alongside volunteers. The woodlands are going to need at least some periodic pruning/coppicing/thinning if you want to support a range of woodland flora2 (though different stages of a coppice cycle can give rise to unique and rare species assemblages at all points, even the late/neglected ones3) – requiring human labour, suitable equipment and means of disposing of or selling the material removed. At the moment the plan seems to fund it predominantly via charity. Charities like the Woodland Trust do a lot of really fantastic work and there are many dedicated people out there working their socks off on different patches of habitat, but they all seem to be spread very thin and underpaid. It seems to me that a lot is being assumed about the reliability of those charity funds over the next 200 years.

I’d really love to see fantastic high-quality habitat crossing the north of England. But I admit I don’t, at this time, have a lot of faith in the longevity of the idea. Somebody please reassure me!

1Agbenyega, O., Burgess, P. J., Cook, M., & Morris, J. (2009). Application of an ecosystem function framework to perceptions of community woodlands. Land use policy, 26(3), 551-557.
2Mason, C. F., & MacDonald, S. M. (2002). Responses of ground flora to coppice management in an English woodland–a study using permanent quadrats. Biodiversity & Conservation, 11(10), 1773-1789.
3Broome, A., Clarke, S., Peace, A., & Parsons, M. (2011). The effect of coppice management on moth assemblages in an English woodland. Biodiversity and Conservation, 20(4), 729-749.

Advertisements