Almost all urban landscapes are contrived and designed, due to their artificial nature and short timescales of development and use. We see increasing use of mature rootballed trees and extensive hard landscape and this is normal for intense inner urban areas; I do get concerned that the increasing complexity of urban planting systems divorce trees particularly from their natural functions and prevent the occurrence of the biological interactions/communities that go to make up an ecosystem. For example, I have seen trees planted whose surface levels are around a metre below the surrounding paving level. No matter how well designed, this seems fundamentally wrong to me.
So I’m thinking that there must be a way of dealing with the majority of less intense landscape zones (especially where there isn’t the financial budget that a high-end development attracts) to provide urban regeneration, ecological restoration and biophilic connection, all on a modest budget. This would create a new method to allow for wide-spread adoption in urban and suburban zones. I think the solution comes from Nature’s own process of natural regeneration and a developed philosophy of minimal (but specific) preparation.
silver birch are pioneering species for natural regeneration
Starting from the observation that Nature is very efficient at regenerating itself, what can we do? Too often, I have seen unnecessary interference in this process. I still recall that a few years after the great storm of 1987, I walked through some nearby National Trust woodland of pines and birch. A great deal of damage had been done with many trees blown over. Birch had however, regrown abundantly from dormant seed and was already three or four foot tall. The NT then sent in the bulldozers to clear out the fallen wood so the area could be – replanted. I watched them tracking over all the natural regeneration. Why didn’t they just leave well alone? The restoration of the woodland was only slowed down by such clumsy interference and this was not even a productive forest.
If we simply broke up paving in our urban centres and loosened up the sub-base, what would happen? Nature would soon find a footing and things would start to grow; however, that process would be too slow and unpredictable for human sensibilities. So what if we did a little more, adding a small amount of topsoil to the rubble, planting small (1+1 year transplants) bare root trees and shrubs, with plugs of understory forbs, ferns and grasses. Starting so young, we’d generate a successful community in no time. These could be designed as narrow ribbons – two to four metres wide, inserted into suitable wider areas of paving.
An urban area suitable for natural regeneration
The above area was one I thought would be suitable for such an approach; there are many such areas throughout all urban spaces. They cry out for regeneration, yet seldom can this be done for lack of adequate finance. Below is a quick sketch showing how it might look.
Sketch showing regenerative planting
The benefits of such an approach would be huge. It would cost far less than using a traditional approach to landscaping such an area, maybe half (I haven’t costed it!). The care would move from maintenance to management, using a rotational coppice methodology, rather than trim and tidy (which always ruins a plants natural habit. Biodiversity would be hugely enhanced, air pollution mitigation would increase, wind buffering, urban heat island reduction, stormwater runoff (they would act as rain gardens) and of course, our biophilic needs, our connection to nature.
Someone needs to be bold and try it; talk to me…
Posted in Arboriculture, Biophilia, Climate Change, Design, Ecosystem Services, Environment, landscapes, Regenerative Planting, Trees Tagged with: adaptive landscapes, biodiversity, biophilia, eco-system services, ecology, garden, gardens, landscape, native plants, pm10, pollution entrapment, rain gardens, sustainability, sustainable, trans-migrational landscapes, trees, urban greening, urban heat island, wildlife
Curiously, I’ve never really written about green roofs, yet they are an important part of the urban greening scene and definitely a part of my “building biomembrane” concept. Perhaps it’s because the subject is so well covered by the commercial sector and various organisations; far better than green walls but then, they have a twenty year head start.
And twenty years ago, I was putting green roofs into some of the landscapes I designed and built. Here’s one in my own garden, on a wood store: the one at the back is an 18 year old turf roof, with soil and grasses, such as was common in those days. There’s a lot of Sedums, Sempervivum, bulbs etc that have been added over the years, or found their own way there. The roof to the front is about two weeks old, consisting mostly of Sedum album, which was growing prolifically in a graveled part of my garden where I didn’t want it. I put a layer of soil and compost under it and slapped the darn stuff down!
I also have another Sedum/succulent roof over my porch, which is much more akin to a modern extensive green roof, with a mix of compost and expanded clay pellets (ie lightweight aggregate). It is much less prolific and to my mind, less successful therefore. I used to be quite adept at building hobbit-like turf-roofed garden structures from chestnut and reclaimed timber, such as this one, built for a show:
These days I like to do rustic with a contemporary feel, such as my current summerhouse, which I built last year. It doesn’t have a green roof, simply because it faces away from us so we’d never see it. It’s insulated and timber-lined inside, so stays fairly warm with a little help. The windows all came from a house up the road, so fitting my desire for recycling. Double-glazed too…
Of course, the best kind of green roofs are the ones you can use as garden or green space. I’m designing one right now which overlooks the Thames; an early concept modeled below. I’ll put more up on this as things progress…
Posted in Environment, green roof, landscapes, My Garden Tagged with: garden, green roof, sedum, summerhouse, turf roof