Growing Season - Ecology Plus Diversity - Lake Harding Association

Growing Season – Ecology Plus Diversity

Growing Season – Ecology Plus Diversity

By Micah Moen 0 Comment February 25, 2020

hello my name is Grant Thompson today
I’ll be talking about ecology and diversity explore how to create plant
communities that mimic nature in urban spaces for an outline of what I’ll be
talking about today I’ll will give you a little bit of
background on myself once we get going here and for most of today we’ll be
talking about the book planting in a post wild world designed plant
communities by Thomas Rainier and Claudia West I’ll talk a little more
about this book and why I am using it to organize this talk I’ll talk about the
five key principles of designed plant communities and talk about how this
works in design and practice I’d also like to acknowledge Lisa Orgler at Iowa
State University department of horticulture for some of today’s content
I’ll also make a quick plug Kelly Norris of the greater Des Moines Botanical
Garden as well as Lisa Orgler put on a more intensive Hort ecology design
workshop so if you like what you hear about today you want to get more of an
opportunity to get hands-on guidance actually work with some design they do
some workshops that expand on this a little bit further and I’ll put this up
at this slide up again at the end of the talk if you want to take down any more
information so as I mentioned my name is grant Thompson I’m an assistant
professor of horticulture at Iowa State University primarily I’m involved with
our teaching program I teach woody plant materials landscape and hard scape
installation and our plant propagation course I also have a research program in
sustainable landscape management I’m an Iowa native my research background is in
urban ecology both above ground and below ground so I’m interested in plants
and soils microorganisms and how we can use all of these to design more
sustainable spaces I’m also a professional landscape architect and
horticulturist when I was a practicing landscape architect I worked on projects
throughout the state of Iowa including many different ecological areas wetlands
rain gardens some shoreline restoration as well as some therapy gardens and
other commercial and residential landscapes so as I launch into today’s
talk I want you to consider native landscapes on the left we have
the Loess Hills in western Iowa on the right we have a typical upland woodland
understory landscape take a look and see what you see here in nearly all of these
landscapes there’s complete plant coverage different species are
intermixed overlapping the landscapes are really lush even when they’re
dormant bottom line here we see are lots and lots of plants now consider these
kind of more traditional residential or commercial horticulturally design
landscapes we have individual plants that take up distinct spaces lots of
mulch not a whole lot of community plants interacting with one another
they’re all kind of individual and lonesome in these landscapes now
consider this approach this is an approach to landscape design and plant
design of what we call designed plant communities plants are selected to
coexist mingle spread out and exist in conjunction with
one another these types of landscapes are inspired by natural settings and
they rely on ecological principles at work in unmanaged landscapes but these
plant selections and the plant communities are adapted for managed
urban conditions quite a bit different than the horticultural landscapes we saw
in the previous slide so in planting in a post wild world Rainier and West call
these designed plant communities and the definition that they like to use is that
they’re translating wild plant communities into a cultural language
things that are easily understood by humans as well as just generally
accepted in terms of their overall aesthetic and how we take care of those
different plant communities and bottom line they represent a hybrid of ecology
and horticulture so this is taking what we know works in the natural world using
them with cultivated plants and making these designed urban spaces and I’m
using this book as a guide to this conversation it’s not the only book to
suggest the style of planting design but I think it does a pretty good job of
explaining it in a way that works for experienced landscape designers as well as
those who were maybe new to thinking about landscape design or thinking about
designed plant communities it’s a good starting point for a book but again it’s
not the only one that covers this kinds of topic so when we think about designed
plant communities we start by taking cues and making observations in native
communities these are unmanaged landscapes and these
design plant communities require two basic things first all of the plants
that exist here must thrive under similar environmental conditions so if
the plants don’t work together if they don’t need the same requirements then
it’s really hard to have them exist as a community the second primary requirement
is that they’re compatible in terms of their competitive strategies this means
that plants grow at a similar rate one is not going to become totally dominant
over another and again that they will exist under the same environmental
conditions so here we had an example of an oak savannah habitat you can see the
overstory Oaks some sparse shrubs lots of open space that are filled in by
different kinds of grasses and forbs so this is one kind of plant community that
we can use as a reference when we start to develop what a designed plant community
would be so what kinds of plants should we use in a designed plant community again
we can look at natural landscapes as inspiration and then figure out how we
translate those into other design communities so for example we can be
inspired by unmanaged or naturalistic landscapes but we’re not necessarily
tied to the exact same plant palette nor do we have to use native plants
necessarily in these designs we’re gonna observe what we see in these native
landscapes and then translate them into what that means for our design gardens
so I mentioned there for a moment maybe not always thinking about native plants
so I want to take a moment here to think about what are native plants
you probably have talked about this in previous discussions through Master
Gardeners or different gardening workshops or resources you’ve been
involved with but I want to think about this clearly in terms of Iowa so in the
past 15,000 years different parts of what is now Iowa have been covered by
glaciers that it bulldozed away topsoil and dropped little bits of
Canada across the state as the glaciers receded parts of Iowa have been fire
adapted prairies in Savannah grazed by different large megafauna which no
longer roam these areas parts of Iowa have received windblown soil from
Nebraska and the flood plains of the Missouri River and this now forms what
is the Loess Hills along Iowa’s western edge many parts of Iowa have been plowed
farmed and developed into cities and of course flooding is constant in Iowa as a
landscape we’re surrounded by rivers and rivers and creeks flow through it and
deposit soil whenever these floods occur so when we think about native plants in
this context given that there’s so much change that has occurred over history in
Iowa how do we define what are native plants to whear, to when, and is that
relevant now take a moment and consider this amongst yourselves
maybe think to yourself for a moment and turn to a neighbor and discuss this but
I want you to think about what challenges or problems might there be
with the concept of native plants or what constraints might there be to
native plants in urban landscapes and when I say urban that can be downtown
Des Moines that can be an area in your own backyard it’s developed it’s no
longer the natural landscape that it would have been before humans have
developed it so take a few moments and think about these topics so a few things that I’d like to point
out about native plants in these landscapes is first of all much of what
we know having existed in Iowa comes from early survey records during the
early and mid 1800s when Iowa was settled by Europeans we do have records
of older native plants from different means but when we develop what is called
a native plant list for a particular region we’re usually confined to roughly
a hundred and fifty or 200 years or so when we have documented records saying
what plants used to be here so that’s a pretty narrow range in terms of
ecological or geological time you know if 200 years isn’t an appropriate time
span to consider what’s native then how far back in or should we go to consider
whether a plant was native to a region and if we go back further and further in
time how do we know that it was here we can also think about urban areas so
these are already so greatly altered from what they would have been in their
native state the soils are different the hydrology or the way that water moves
across the landscape is different and even the climate is different in urban
areas we have lots of different hardscapes that receive and reflect heat
back out into the environment so the question is is what is native to these
environments and you don’t even have to be in a major city to experience what
this happens anywhere that we disturb soils we do different kinds of
development we’re affecting what those landscapes are and the plants that can
then thrive in those disturbed landscapes and in the bottom right here
I have a scene from the field of dreams and I want to point out this kind of
I’ll call it a myth or so of native plants in the bottom right here I have
this image from the field of dreams and what I’d like to point out is this
general perception that if you plant native plants things will come back that
somehow just planting a plant that used to grow here fixes everything an often
that’s not the case even though native plants can be extremely important in
terms of habitat restoration there’s so much more that goes into it
we have to work with the soils that are on the site and do different kinds of
soil remediation we have to make sure that the plants that we plant and then
propagate and grow themselves we need to attract pollinators which may no longer
be in the area or other animals that both rely on and use these native plants
and continue their propagation so there’s a lot more than just goes into
planting so instead of if you build it they will come
it’s if you build it will they come if we plant native plants does that solve
everything I would say not entirely so when we think about designed plant
communities we should place an emphasis on a plant’s ecological performance not
at center of origin so what is it doing for us not necessarily where it’s from
native plants are good but adapted non invasive plants can also be suitable
choices particularly if the places we want to put them are harsher and those
plants are better suited than some of the plants that we would consider native
to our region and the bottom line that I’d like you to take away here is that
it’s not a black or white issue but it’s often treated as such
it’s go native or gone home but I think that there is lots of opportunity to use
plant materials that can be suitable for these sites so when we think about this
there’s probably three parts to this equation the right plant the right place
depending upon the different site conditions you’re working with and the
right reasons ultimately when we think about planting design we want to know
what are those plants doing for us both aesthetically what did they look like in
the landscape and functionally what are they getting us when we put these in and
I actually like to think about this when I teach my students I flipped this
around and this becomes the equation of how we pick our plant materials what do
we want it to do so what’s our reason what are the site constraints that we
have to work with so what is the right point what is the place and then finally
using those to help us pick what is the right plant for that situation so
instead of starting as with the plants we use the other constraint
to help us develop a plant list for this site and this kind of thought process is
also supported by the Rainier and West book so I’ll begin here’s talking about
the five principles that Rainier and West put forward in their book and the
first principle is related populations not isolated individuals so here you can
see this image of a lush planting here to the right and so let’s explore what
Rainier and West say about this first principle first of all they suggest not
placing plants like objects that they’re not furniture in a room we don’t compose
them that way and that we should use plants in masses so plants should be
grouped together in a way that they interact with each other and with the
site so the plants are grouped based on their environmental needs where they’re
going to grow well and finally that each plant is part of the larger puzzle so
the equation that I shared with you a moment ago the right reason the right
place and ultimately those defining the right plant that’s part of the
underlying message that Rainier and West like to convey so let’s explore this in
a little more detail on the Left we have traditional planting design what might
be considered a horticultural arrangement of isolated individuals you
can see lots of mulch here and maybe the massings are of the same plant or
similar plants different cultivars but they’re all kind of placed individually
in the landscape they’re all standing alone as if they’re in their own
furniture in a room or sculpture on display on the right we have a design
plant community that Rainier and West highlight in their book and they have
different focal point or arrangements of plants throughout this landscape so
there’s different pops of color there’s different forms there’s different
textures there’s not a lot of open space between the plants they get kind of
messy they bump right up to one another but still it’s confined within this
orderly frame of these gravel paths so clearly someone cares about this
landscape it’s maintained but the plants within those orderly
frames are kind of messy there’s not a lot of mulch here either it’s plants
full and full of plants here another couple of examples so on this left we
have this fairly urban courtyard and again there’s sprawling plant materials
no bare ground the plants are often not in neat or tidy rows they’re
interspersed with one another and you have clumps or pockets of different
plants of the same species but they’re not in drifts like some other planting
designs but overall this space still looks fairly managed and that has to do
with the paving elements the furniture the different boardwalk so again there’s
a cue that someone cares about this kind of landscape and on the right we have a
more naturalized planting design including these granite steppers there’s
creeping ground cover that moves in and amongst the cracks of these different
steppers and taller herbaceous and grasses that overlap between the stones
and form these dense pockets of lush vegetation and again not a lot of bare
ground not a lot of mulch in either one of these examples Rainier and West set
out principle two and here they say that stress is an asset so for example in
this right image here we have a blooming cone flower prairie this happens to be
on calcium rich soils that were developed from a limestone bedrock and
some species are not adapted to this really higher alkaline pH so if we spent
a lot of time trying to quote unquote improve these soil conditions to make
them more neutral that would actually open up the plant palate and allow a lot
more different kinds of plants that like that more neutral range to be planted
and along with the desirable plants that we might get in this landscape we would
actually probably see an increase in the incidence of weeds weeds that are maybe
more adapted to those neutral conditions as opposed to the alkaline conditions
here so digging into this Rainier and West say to accept the environmental
constraints of a site don’t add richer soil don’t prune your trees to increase
Sun don’t plant things to increase shade
provide irrigation just basically work with what you have and let the plants
that you select fit that site and what they also say is that you can embrace a
more limited plant palette that that tolerate those particular conditions and
that different plants will prefer different conditions and so across even
a small backyard garden you may have a shady wet area a sunny dry area you may
have areas that get different amounts of heat because of how close they are to a
building or a driveway or a dryer vent and that we can use these different
pockets even in a small landscape these different stresses to help us pick
different and adapted plant materials and that actually creates pockets of
diversity within these landscapes different plants prefer different
environments and we can take advantage of that so let’s take a look at a couple
more examples of how this might work on the Left we have a fairly dry sunny site
there’s a lot of reflected heat from the pavement and the masonry of the
buildings and so plants that are adapted to those drying hot environments or
chosen and again that looks really lush not a lot of mulch the plants are
grouped together you can see how principal one is also acting on this
site on the right we actually have a low angle image of the Elings Hall green
roof here at Iowa State University this is a manufactured green roof it’s rather
dry sunny it’s in a hot location it’s on the roof of the building and the soil or
substrate profile here is actually pretty thin and so we have a plant
community that tolerates those different stressful conditions these plants were
seated across the landscape and grown in on the green roof and how they end up
massing and appearing here is totally a function of what plants survived in
which places across this green roof we can also see how this might work in a
more residential setting so here on the Left we have a moderate to dense shade
backyard probably some fairly high moisture you
can see how the plants are layered together there’s lots of
different interests from the hydrangea up front some of the ferns and the mid
in the back you can see a pool of sunlight back behind the bench towards
the garden shed so lots of different opportunities within this landscape that
takes advantage of the different gradient of sunlight and probably
moisture that works through this backyard garden on the right we have a
different example of what a high moisture landscape might look like but
in this case these irises growing by this garden pond
they’ll take full Sun so we can play with sunlight we can play with moisture
and we can use these different gradients these different stresses to our
advantage principle three that Rainier and West put out is that we should cover
the ground densely by vertically layering plants so they point out that
rarely do we see bare soil in the wild we see this where there’s been some kind
of disturbance a tree falls down rips up the soil or a fire moves through or
something else but that bare ground doesn’t exist for very long plants
immediately start to grow and populate and within a season or two there’s no
bare ground to be seen and they also point out that if we don’t fill these
bare spaces weeds will there’s constantly as a pressure of different
weed seeds maybe they’re coming from a neighbor’s yard or your own yard or in
different situations but if there is bare soil that’s opportunity and if we
don’t put something desirable there weeds will fill it in and they point out
that we should arrange plants not just side by side as if you were arranging
furniture in a house which we mentioned in principle one but that you should
actually arrange plants on top of one another to form layers of plants so we
have things growing low to the ground we have some things that grow up or over
the top of those and so on so usually our ground covers are somewhat shade
adapted but overall we have this layering of plants vertically that makes
for these designed plant communities so if we take a look at maybe a traditional
residential planting how long does it take before this newly mown
bed becomes weedy and how often do you end up weeding your mulch even when we
use landscape fabrics or newspaper or cardboard we’re developing an area
suitable for weeds to grow on top of that and they will they’ll grow on top
of the cardboard landscape fabric whatever we put down and so we add more
mulch year after year we add more mulch because it breaks down and because we’re
trying to deal with the weeds that we have and so yes organic mulches can
improve our soil quality but mulching is actually a short for short term form of
weed control and if you don’t keep adding it you have to keep weeding and
eventually the weeds can take over these nicely arranged beds and I’ll also point
out there’s emerging research in terms of how soil organic matter is developed
and this research actually emphasizes the role of microorganisms and how they
break down different plant residues to form soil organic matter and what this
research is indicating is that fine roots that die and turn over in a year
so our plants are still living but they produce root systems and some of those
roots turnover and the exudates that roots put out into the soil so these are
simple sugars other compounds these actually feed the microbes and they’re
really good food sources they’re highly digestible but things like wood mulch
are less digestible to these microorganisms so yes while mulching can
and does improve our soil quality we actually have to put in a lot of effort
to sustain these landscapes we can also see here where we have exposed areas we
can get different weeds growing so this is purslane growing next to a
gravel sidewalk and why would purslane grow here I mean it’s a pretty harsh
environment it’s really hot and dry but there’s space there’s nutrients there’s
no competition so weeds in general are opportunistic and anytime that there’s
space that they can be competitive in they will take over so when we look back at native
landscapes we can see how densely planted that they typically are how
dense the plants grow in these landscapes on the Left we see a dense
understory of a coniferous forest it’s full of plants not a lot of bare soil
and even the senescent ferns dying and turning brown in the foreground adds
seasonal interest to this landscape so even though it’s green we don’t see a
whole lot blooming at the moment we can still have different visual interest in
these kinds of spaces on the right we have a restored Iowa Prairie full of
different plants growing densely over the top of one another
leaving little ground for weeds to get established and even if we had weed
seeds coming into this system seeds need good soil seed to soil contact to begin
to germinate and grow so the plant material itself can actually intercept
those weed seeds and prevent that seed soil contact so again a dense vegetation
helps us out so let’s take a moment and think about how this works in a design
setting oftentimes designers and even if you’re sketching something for your own
backyard you might start with what’s called a plan view this is a bird’s eye
view or otherwise looking down on the landscapes and so plants are usually
drawn as different sized circles or maybe other graphical symbols to
indicate how they look so this is a plan view and the canopy looks super full we
can see that the circles are overlapping and we don’t see or we don’t perceive
rather that there’s a whole lot of bare ground here another way we can think
about design is in what’s called section so this is looking if we were to cut
through the landscape and see the plants growing vertically and this is the exact
same design but instead of looking down on it now we’re looking at it in section
and we can see that there’s actually a lot of bare ground under those tree
canopies areas that would be available for weeds to begin to grow and
furthermore if we take a look instead of using 2d representations of our design
if we look in a 3d dimension whay so in a perspective drawing we can
actually see that there is a whole lot of bare ground even though in plan this
looks like a very densely planted landscape so even just the graphical
ways we represent this as designers kind of trick our perceptions into how
densely planted these landscapes are the bottom line is there’s a lot more room
for plants than we give ourselves credit for so Rainier in Westwood suggests that
instead of using different kinds of mulch we can use plants themselves that
they can be the green mulch that covers our soil so ground cover can be a
diverse mosaic of plants we can have multiple species with similar
requirements they’ll all take a bit of shade because we have other plants
growing up over the top of them but if we plant them densely the need for us to
continuously remulch these landscapes is greatly reduced that actually increases
the sustainability of these sites because we’re having to do less we’re
adding less in order to maintain them here is an example of a streetside
garden in a residential setting and it’s rife with lush dense plantings and it
creates an oasis even though just on the other side of those plantings is a small
neighborhood street again not a lot of bare soil not a lot of mulch and layers
of plants but at this point you might start to ask yourself well what about
competition if we have all of these plants growing in and among and over one
another do we have problems our plants able to get the water the nutrients
the light that they need and I’ll point out that plants have adapted different
strategies for tolerating stress and competition and even below ground plants
have developed lots of different strategies what we would call root
morphologies or the root architecture of plants to deal with some of these
different stresses and competitions so roots will go to different depths they
occur at different densities and they have different symbiosis with soil
microorganisms such as mycorrhizal fungi and all of these help with below ground
competition let alone all of the different strategies plants have adapted
to compete above ground but not only are plants able to compete in space above or
below ground they can also compete with each other in time so plants have
different needs of different resources and can grow at different parts of the
growing season so for example the spring ephemerals that we see across a forest
understory things like Trillium or trout Lily they’re growing where the tree is
above them haven’t leafed out yet they can still get the sunlight they need and
complete their growing cycle before everything else is leafed out so they’re
competing when others aren’t and that strategy is actually one that a lot of
weeds use as well so growing early in the growing season
these are overwintering annuals things that we can try to manage depending on
how we plant our landscapes principle four of Rainier and West book they say
that we should make our landscapes attractive and legible they point out
that humans have a preference for orderly landscapes things that are easy
to understand so if you can look at a landscape even
if you don’t totally understand plants if you’re not a plant person you can see
that there’s care you can see where there’s areas of safety that you’re not
being obscured by plant materials and you can start to understand what’s in
the distance so here on the right I’ve shown this image before this is our
granite paver path way we have low growing ground covers grasses and forbs
in the foreground we have some evergreens in the background that kind
of points interest and draws our eyes back into the landscape but we can see
there’s a clear path it looks like there is interest back there that it’s drawing
our eye into this landscape and so it’s attractive and it’s legible Rainier and
West point out that spaces must be beautiful in order to be valued
no one wants or will pay for a less than desirable or an ugly landscape so of
course we need to make them beautiful why not and they point out that cues for
caring are often necessary in these landscapes so they say that using
orderly edges or frames can help and even when you have
messy and layered plant material if you have these little cues throughout the
garden like the granite pavers in this pathway that can help again people
understand that this is in fact a maintained landscape so here on the left
we have two different angles of the same house and in the top image we can see a
very lush dense planting and that to some people may actually look weedy I
think it actually looks pretty nice but that’s that’s my interest but from a
different angle we can see that there is a very clean neat sidewalk and we can
see that another part of the landscape is actually closely maintained lawn and
so this is that signal to care to people in the neighborhood that this house know
that that high growing landscape on the left is actually intentional that there
is that cue to care that it is maintained and that makes this
acceptable to the neighbors may not care what the neighbors think but it’s one
way that you can show that you are actually maintaining this landscape now
in the image on the right we do have a very closely maintained lawn behind this
border planting but I would say even without the lawn this border planting is
very clearly a maintained or a developed landscape all of the different hues of
purple and pink and blue those wouldn’t naturally assemble in that so again
that’s a cue to care someone organized and put those plants together and pick
that color palette and there is an intention to it and so showing that cue
for care or that intention in the landscape helps create that legibility
factor that Rainier and West Point out the fifth and final principle that they
point out is that we should work for management not maintenance of these
landscapes they go in a pretty good detail in the book talking about how
maintenance is often trying to keep something in a static state maintaining
it to a certain quality a certain situation but that management actually
allows for change and so we’re not worried about
maintaining an individual plant this tree or that shrub or that masses of
grass but that we want to manage things at a community level we want to make
sure that all of the plants are doing reasonably well or just that the whole
community on average is doing well and so management allows for change some
plants will struggle year-to-year some will thrive depending on what the season
brings us and yearly the garden may look better sometimes and not others but
overall when we do our management we’re trying to preserve the community we’re
trying to keep the layers and the general balance of species and this
allows for some variation so on the image on the right you can see these
strip plantings I’ve shown this before there’s the gravel pathways between them
and so we have these pockets of flowering forbs and grasses these pops
of color but again we’re not worried about is an
individual plant in one spot right in the center of one of those strips doing
well we’re worried about how it works over all season after season how we
manage this and not worry about maintenance and so if we dig into a
little bit of plant ecology here we can actually start to understand in greater
detail what Rainier and West mean so in this top image on the bottom axis we
have a light gradient so on the Left we have full Sun and on the right we have
full shade and on the y-axis we point out the number of individuals in a
population and so the left curve is our little bluestem and we can see that in a
full Sun setting little bluestem is pretty happy we’ll have lots of little
blue stems but as we have more and more shade their population tapers off and on
the right curve we have Pennsylvania sedge and that is we get increasing
amounts of shade that sedge will take over so there’s an optimum depending on
what the sunlight gradient is between these two plants and that’s just two
plants we could have lots of different plants on the same sunlight gradient and
depending on what that individual species or cultivars needs our that population optimum will change we can also think about this
in terms of other gradients so in a given garden you may have a different
soil moisture gradient a different fertility gradient different heat
loadings and on and on and on you can probably think of many different
gradients in your own landscape and that if we’re choosing plants to exist in
these different communities they’ll experience different Optima depending on
what the season brings so a design plant community has different species that can
take advantage of these different gradients and take advantage of them to
different degrees so if we think about this in a little more detail we remember
that principle to stress is an asset in principle five management not
maintenance so if we abstract the diagrams that we saw in the previous
slide we end up with something like this so on the x-axis we have some
environmental gradient could be moisture could be light could be fertility the
list goes on on the y-axis we have still the number of species in a given
population and to either side of this gradient either side of this bell curve
becomes increasingly more stressful so we have fuller and fuller sun or fuller
and fuller shade lots of water very very dry conditions and so on so the number
of plants that like things in the middle just the right amount of Sun just the
right amount of moisture are pretty high and that’s the top of our bell curve but
as we moved in our gradient to either direction either right or left we
increase the amount of stress and fewer and fewer plants are going to like those
more and more stressful situations so resource inputs that try to change this
environmental gradient our maintenance practices and they often require ongoing
efforts so think about this if you have a low fertility site and you’re trying
to increase the fertility you have to keep fertilizing year after year as
those nutrients are used up or leached or otherwise no longer available to the
plants same thing with irrigation or liming to change pH
their ongoing efforts and the more effort you have to put into that the
less sustainable your landscape is we can also think about this in different
ways so this is the same curve that we have on that top image now we have it
down here at the bottom and if we put in different kinds of inputs to alleviate
those stresses and so we add water or we add fertility we change the range of
plants that will exist in that zone so we’re moving it to a more moderate or
more neutral condition that more plants might tolerate but not only more
desirable plants we also increase the potential for weed pressure so if we
work at the margins if we embrace the stress of our site it narrows our plant
palette but it also narrows the weeds that will be competitive in that same
environment so with principle five Rainier and west
stress management not maintenance so things like watering mulching spraying
pruning and even leaf litter removal we generally don’t do once the plants are
established and so there’s a couple of important points that I want to make
here first of all once the plants are established we certainly do need mulch
in the beginning we need water in the beginning and we need to get our plants
the desirable plants in these design plant communities growing well only once
we have a community growing well are they going to be competitive against
weeds and are they going to give us the outcomes that we want so yes there is
some upfront work we need to do to get these going well the other thing is that
they’re generally avoided if you’re used to watering or mulching or fertilizing
year after year you may do it occasionally you may water in the
really-really droughty years you may do some of these things but the degree to
which you do them is going to be much much less than in a typical landscape
that you’re used to working with and so ultimately management is necessary to
keep the ground covered so to keep bare soil away and keep the plants that we
want healthy and vibrant to preserve the overall aesthetic of the plants and to
prevent aggressive plants so aggressive invaders from dominating
these landscapes and not just aggressive invaders even sometimes we may find that
plants that we wanted there initially are maybe just too successful and they
end up out competing the other plants in our community so ultimately a manager is
more of a referee than a prison guard we’re trying to make sure that everyone
is competing fairly with each other then trying to keep them strictly maintained
the way that we originally intended another way that we can think about this
is that management is necessary to keep the portfolio diverse if you’re using to
think about this in financial terms you might be pretty familiar with a
diversified stock portfolio being beneficial so here on the top image we
have a diverse stock portfolio it’s going to be well buffered against
different shocks to the economy overall if the economy is doing well this
portfolio is going to do well we can think about our plant communities the
same way if we have diverse communities one season stress so a summer that’s a
little wetter or a little drier than another you’ll have a shift in which
species in that community are more dominant so you may have species a doing
very well in under dry conditions but species C doing much better in a little
bit wetter year and so on and in the biodiversity literature we actually call
this the portfolio effect and so that a diverse portfolio on average does better
certainly just like with a financial portfolio you could have all of your
money in one stock that does really really well that one year and you make a
boatload you can also have a lot of money in one stock that does really
poorly so the same way with plants in the landscape some years there are
winners some year there are losers but on average the long-term average a
diverse portfolio is better we also in the diversity literature see that this
is called the insurance effect and so in the literature it says that the greater
diversity means a greater likelihood of community stability so again one year a
particular plant may not due to well but if we have lots of
plants in our design community overall the community survives and looks pretty
good so how does this work in terms of working with designed plant communities
what is this actual design process so first we’re going to utilize landscape
archetypes as references and inspiration we’re going to break down those
inspirational landscapes into different vertical layers of plants so we’re going
to start to organize and understand what we observe in these native landscapes
and lastly we’re gonna identify multiple plants for each layer and then combine
those to make our design plant community so what do we mean by landscape
architypes well the essence of a place things that
elicit emotional responses from these different kinds of landscapes the most
basic and memorable vegetation patterns of that place
and rather than imitating a native plant community we’re going to be inspired by
those patterns so again what do we mean by landscape archetypes well I’ve
listed here three different archetypes that you might be familiar with a
Midwestern Prairie a Pacific northwestern woodland or an eastern
hardwood forest and for a moment I want you to close your eyes and envision what
those landscapes look like and I have intentionally not added images to this
slide because I want you in your mind’s eye to see what that looks like so go
ahead and close your eyes for a moment what are the dominant forms that you see
in this landscape what are the colors that are popping out at you what are the
different textures in the foliage in the woody material what’s the quality of
light if you know specific plants in this
landscape what are they if you don’t know specifically what they
are what are they like in general now that you’ve had a moment to envision
these landscapes open your eyes so with these different landscape archetypes
that we have we can start to Zone in or zoom in on those different aspects so
take a look at the chosen archetype that you have the Midwestern Prairie the
Pacific northwestern woodland or the eastern hardwood forest start to group
the plants by height which ones are really tall these are going to be our
overstory plants which ones are moderate height these are our understory plants
and which ones are very near the soil surface these are our ground covers
notice how these different archetypes are all very different from one another now think about your own home what
archetype might be most appropriate for your house and maybe there’s not one
here that’s most like your own home if that’s the case then what is the right
archetype what’s the natural analog for the landscape that you have and consider
that in terms of your site conditions and the stresses present in your site so
now we can start to break this into layers Rainier and West talked about a
structural layer a seasonal theme layer and a ground cover layer and so we can
actually think about those top two layers the structural layer and the
seasonal layer as our design layers and the ground cover layer is our functional
layer and I’ll explain what those mean here so our design layers create
legibility in the landscape these are those dominant patterns that we see what
makes the Pacific Northwest forests different than the eastern hardwood
forests they give our seasonal interest these layers contain our Pow or our Wow
plants the things that just make you stop and take your breath away so those
are structural and our seasonal layers in our functional layer or a ground
cover layer this is where we have an opportunity to create a really diverse
landscape so these are ground covers this is our green mulch this is what’s
keeping everything intact and letting those seasonal layers and the structural
layers really stand out and be spectacular so choose the archetype that
you are familiar with the Midwest Prairie the Pacific Northwest woodland
or the eastern hardwood forest and now begin to break these apart into these
different layers take a few minutes here and visualize describe or list how these
layers work in your landscape if you know specific plants go ahead and note
them out and after you’ve had a few moments to work on this compare with
your neighbor if you have the same landscapes note how your lists are
similar or maybe different or if you have different archetypes how does their
archetype compare to yours take a few moments with that here after you’ve had a few minutes to talk
with one another to share your archetypes and maybe compare and
contrast which you have this is the exact same process that you can go
through with residential design as well so you’re gonna choose an archetype
that’s appropriate to the site conditions and the stresses that you
have you’re gonna translate that natural landscape that unmanaged landscape
archetype into how that works for your own home garden so here are some
different layering examples in this example from Rainier and West book we
have a structural layer so those are the overstory trees that we have in the
background our seasonal theme layer comes in purples and yellows and pinks
here we can see some iris blooming in the mid ground and various plants and
leaf textures so this is overall a very green landscaper it was when this
photograph was taken but you have very fine textured grasses against the very
coarsely textured plants there in the mid ground and finally we have our
ground cover layer so things that are low growing grasses or sedges in this
case next to this pond we have emergent aquatic vegetation so again we’re
working with our three layers we’re looking at different plants within them
and depending on what the archetype is how that’s going to work is going to be
different here we have another example this is a design garden by Roy Block in
the structural layer we have an overstory tree in the mid ground we have
some background evergreens and a stone wall that kind of add that structure to
the garden so these are the things that are going to be there over the winter
when the herbaceous layer is maybe died back or not looking so great we have our
seasonal themed layer these are yellows purples and Pink’s we have some what
look like Allium bulbs we have some other aster type plants in the
foreground we also have our ground cover layer so again low growing grasses and
sedges other low growing herbs that complement the seasonal layer so we have
again these light lavender flowers in the foreground that they reference the
strong purple that we have in the mid-ground so again
our ground cover layer can still be attractive can still have flour but
importantly they reinforce what’s going on with our seasonal themed layer so
this is the design plant community is presented by a Rainier and West in
planting in a post wild world their key principles are populations not
individuals stress as an asset denseley layered plants and remember that’s
vertically not just side-by-side attractive and legible landscapes and
management not maintenance and so with these principles they’re showing us how
we can look at native landscapes how we can translate those archetypes into
designed Gardens and how ultimately we can work with different plant communities
and create these new and exciting landscapes that still reference what’s
working in native landscapes and ultimately that we use principles of
plant ecology and biodiversity as design tools to mimic nature but in designed
and intentional ways so ecology doesn’t change just because we were working with
it it is a designer and in fact does a ecology and stress are designed tools
that we can use to specifically help us pick plant communities I’ll mention
again a quick plug if you’re interested in learning more about this and
receiving some hands-on guidance with how this works and particularly at
residential scales Kelley Norris of the Greater Des Moines Botanic Garden and
Lisa orgler with Iowa State University put on a series of these workshops I
have here the tentative 2019 dates listed but if you’re interested please visit the
greater Des Moines Botanical Gardens website for more information
that’s the hort ecology design workshop lastly thank you very much it’s been a
pleasure presenting this today and I hope you’re interested in learning more
about design plant communities and thinking about how these can work to
enhance the sustainability of your own landscapes thank you

Add Comment

Your email address will not be published. Required fields are marked *