A Larry Weaner garden in New England. To be featured in the October issue of Gardens Illustrated. Photo credit: Claire Takacs |
Who remembers that
wonderful Gil Scott-Heron rap song “The Revolution Will Not BeTelevised”
The
revolution will not give your mouth sex appeal
The
revolution will not make you look five pounds
Thinner,
because The revolution will not be televised.
I feel like coming up
with something similar for 'ecological planting'.
There is much talk of
ecological planting? Is anyone actually doing any? Or is it all talk?
What is ecological
planting anyway?
And does it matter?
Well, it is always
nice when words convey meaning we can all agree on, and in this case
we are not just talking about something with the equivalence of an
artistic movement but also something that a direct impact on
biodiversity. There is always the ever-present danger of 'greenwash',
something sounding green and good for the environment but in fact
just a trendy feel-good facade.
Years ago (late 1990s)
Nigel Dunnett and James Hitchmough had made the distinction between
'naturalistic' planting and ecological functioning, i.e. you can have
1) something that looks natural but is either completely static or
dependent on quite intense management or 2) a planting that is to
some extent dynamic, i.e. its components are going through active
processes of seeding, spreading, dying. An ecologically functioning
planting should have some level of stability, so it can continue to
exist without too much human intervention. One example might be a
meadow, which is dependent for its long-term survival on annual
mowing but otherwise is relatively stable from year to year.
Now, it should be
pretty obvious that there is a lot of good planting design that falls
into the former category, natural looking to most observers but in
fact not in the remotest sense a dynamic self-sustaining plant
community. Anyone with any knowledge of basic plant ecology would not
be fooled, and more importantly neither would most invertebrates
seeking a habitat.
Compare such a
planting to a natural or semi-natural habitat like a meadow and it is
immediately obvious that any horticultural planting is almost
absurdly low density. In a wild habitat, gaps between plants are
often difficult to see, whereas in a human-created planting they are
usually pretty obvious. It is possible to get tens of species in one
square metre in the wild, whereas most artificial plantings have 4 or
5 plants (never mind species) to the square metre, or 9 at the most
(this figure is significant, as we shall see).
Six species in shot, but could do better, BUT much greater species density than most gardeners aim at: close-up of one of my old trial plots in Herefordshire |
Think about this
disparity in density in habitat terms – the artificial planting
will be almost inevitably far poorer. So, before doing too much
slapping ourselves on the back about what a good turn we are doing
for nature, let's just consider the absurdity of thinking that just
because we've got something that looks rather natural, and/or is
composed of locally-native species we've created something that is
any way equivalent to a natural habitat. If it's got gaps between
plants its ecological functioning will be below par, and it will be
unstable (space for weeds). Ecological planting it is not.
To go back to Gil
Scott-Heron:
The revolution is not
because you got the right plants for the habitat conditions,
The revolution hasn't
happened because you've gone all native
The revolution isn't
ticking all the species on the list of bee-friendly plants from Home Depot
The revolution is not
just about looking all wild and woolly,
The revolution will never be bought at the garden centre.
Above all, because the
whole 'perennial revolution' has happened alongside the interest in
naturalistic planting there tends to develop the thought in too many
heads that “it's all perennials therefore it must be ecological”.
No!
At the same time
however, let's remember the much-quoted Owen research which
showed just how many insect species an average (i.e. not in the
remotest sense ecological) British garden contains. This shows us the
exciting possibilities! Imagine how much biodiversity a garden could
contain if it had something approaching the density of real habitat
AND the range of diversity that most gardens include anyway (trees
and shrubs and perennials and climbers).
How do we measure
garden biodiversity? Not easy. Never is. Owen simply counted species
not their frequency of occurrence in comparison to 'nature', and if
you look through the academic literature it rapidly becomes apparent
that there is no easy, or for that matter difficult, way to measure
overall health of ecological functioning. What sometimes is done by
researchers is to take one particular aspect, usually a category of
insect, and use that as an indicator. Trouble is, it will be
different for different types of habitat. Currently there is much
focus on pollinators. And much trendy nonsense spoken; trouble is -
where there are marketing opportunities, pseudoscientific gibberish
soon follows. Pollinators could a relatively easy group to use as an
indicator for ecosystem health. The trouble is though that I could
imagine a garden planted with pollinator-friendly plants buzzing with
bees etc, but which actually supported very little else such as
ground-level invertebrate biodiversity.
How much do we want to
create gardens that are genuine biodiversity reserves? If we really
want to create plantings with an ecological functionality that
approaches equivalent natural environments, then we must be honest in
making clear the distinctions between these and plantings that merely
look a bit wild.
Anyone who sows a
meadow or prairie and got it to a point of reasonable stability will
have created a functioning ecosystem. BUT, this won't be a garden but only a habitat restoration. In the
US however, practitioners such as Larry Weaner have started to tweak
seed mixes to create what are essentially ornamental versions of
natural ecosystems. The much richer flora of North America (compared
to much of Europe) allows this. But it still is not what most people
would regard as a garden. BTW there's a great example of his work coming up in Gardens Illustrated soon.
So, any other, more
garden-like, examples?
The best can be seen
in lightly shaded habitats where light levels knock back grass
growth, the main enemy of plant diversity (dense north European
grassland could possibly be worse in ecosystem functioning than your
average garden). Or indeed other, slightly stressed habitats.
Established gardens sometimes have amazingly dense and varied
combinations of woodland species in such places. One of my favourite
such areas is the woodland garden at Wisley (the one near the new
glasshouse): a whole range of rather competitive woodland edge
species, native and introduced fight for supremacy, and with the
possible exception of one patch of comfrey, nobody seems to be
winning. Maintenance seems to be limited to the odd clear-out and
re-plant, which I suspect has the effect of 're-setting the clock'.
A spectacular example
I saw recently was as Innisfree in NY State, where a shaded rocky
slope is home to a bewildering variety of naturalised garden plants,
mostly non-native species, but mixed with natives. According to Kate
Kerin, the Landscape Curator there, this would have been planted up
between the 1930s and the early 2000s and gets only limited
maintenance – mostly pulling of grass and tree seedlings. One of
the sights in this fascinating, but also rather precipitous, place is
a big patch of Coreopsis verticillata and
Convallaria majalis growing completely intertwined, two species
of very different habitats (sun, dry and shade) no gardener would
have put together.
Nigel Dunnett's
planting at the Barbican in London may be only a few years old but
shows enough self-seeding to suggest to me that it could stabilise as
a genuinely ecologically functioning planting. It's essentially a
green roof planting, so seasonal drought will limit grass and weed
growth.
James Hitchmough's
various plantings, all created from seed, should theoretically, lead
to semi-stable ecosystems, but I have personally not seen one that convinces me,
yet, although some of the Queen Elizabeth Olympic Park ones may yet
do so, and I have heard good reports of others.
In two gardens in
Herefordshire, I feel I have got pretty close to achieving small
areas of genuine ecological planting, with really dense species
intermingling. In my last garden I ran a trial for seven years which
went someway to convincing me that, in the most challenging situation
of all: fertile moist soil, full sun, this might be possible. These
conditions favour the growth of strongly competitive plants which
could possibly swamp everything else and most dangerously, favour
weedy grass growth. This never happened (success!), but somewhat
disappointingly, an analysis of every 10cms square after seven years,
revealed that there were still a lot of gaps. In reality these could
probably be filled with ground-level creeping species and more
seeding short-lived species. More species need to be packed in to
really create a dense multi-layer habitat. I, like everyone, have a lot to learn here.
What about
Oudolf-style perennials or German Mixed Planting systems, which use
long-lived perennials at around 8-9 plants per square metre? They are
designed to be relatively stable, but also allowing for a certain
amount of self-seeding. They seem like a very good starting point for
a genuinely ecological planting. Not TOO stable though, as that can
preclude any ecological functioning (think prostrate cotoneaster
ground cover).
And, on the subject of Piet Oudolf, he has created one of the most interesting and successful combinations of an ecological planting (native grasses and wildflowers) and non-native perennials. See here: This approach is certainly one which deserves much more research: but very dependent on having low fertility soils.
And, on the subject of Piet Oudolf, he has created one of the most interesting and successful combinations of an ecological planting (native grasses and wildflowers) and non-native perennials. See here: This approach is certainly one which deserves much more research: but very dependent on having low fertility soils.
Piet Oudolf perennial meadow at Hummelo, not typical of his work but possibly one of the most interesting things he's ever done; combining genuine ecological functioning and good looks |
The fact is that we
have hardly begun to explore the possibilities of what ecologists are
now calling Novel Ecosystems: “a system of abiotic, biotic, and
social components (and their interactions) that, by virtue of human
influence, differs from those that prevailed historically, having a
tendency to self-organize and manifest novel qualities without
intensive human management.” quoted here.
From now on I'm going
to talk about: NOEs: Novel Ornamental Ecosystems.
Where do we go from
here?
How do we assemble
plantings that look good, with species from multiple origins that are
so dense that they can offer wildlife as many opportunities as
natural/semi-natural plantings, and which are stable enough to make
maintenance easy?
This is now the
challenge. Let's raise the bar.
Wrong time of year for the flowers but a shaded bank at Innisfree which includes a bewildering range of Novel Ornamental Ecosystem biodiversity |