The following interview was broadcast on Earthbeat
on ABC (Australian Broadcasting Corporation) Radio National on
Saturday 26 July 2003
Summary:
Earthbeat
gathers a group of urban ecologists together to discuss the challenges
facing the often ignored animals competing for space in our towns
and cities.
Transcript:
Alexandra
de Blas: Australia is now one of the most urbanised countries
on the planet, with most of us living in cities and towns along
the coastline. Also living there though are numerous plant and
animal species that my next guests believe are too often overlooked.
The study
of urban ecology was up for discussion at a forum at the University
of Melbourne during the week, and joining me in the studio to
discuss some of the key issues are leading scientists from here
and overseas.
Dr Gee Chapman
is Deputy Director of Sydney University's Centre for Research
on Ecological Impacts of Coastal Cities. Also with me is Dr Richard
Pouyat, a team leader with the Baltimore Ecosystem Study, a project
of the US Forest Service. Dr Glen Guntenspergen is a landscape
ecologist with the US Geological Survey; and finally, Dr Mark
McDonnell is with us from ARCUE, the Australian Research Centre
for Urban Ecology, a division of Melbourne's Royal Botanic Gardens.
Welcome to
you all, and if I can start with you, Mark McDonnell, what is
urban ecology and why should we be studying it?
Mark McDonnell:
Urban ecology is the application of the science of ecology, which
is the study of the interaction between plants and animals and
their environment. In this case it actually focuses on where people
live, the ecology of cities and towns.
Alexandra
de Blas: So what research is your centre doing to develop
the field and to understand the urban ecology of the cities here
in Australia?
Mark McDonnell:
We have a lot of different research projects. What we really
need to know is the structure of a city, the pattern of open space,
the pattern of housing, the pattern of roads, the patterns of
remnant vegetation. How do those patterns influence what lives
in cities and towns.
Alexandra
de Blas: How important is it that we do science in the city?
Mark McDonnell:
Well that's really one of our key points, is that because ecologists
haven't been studying cities, we haven't actually had a lot of
information, and certainly without the information we're not very
visible, we're not apparent to people making decisions or people
planning cities. The issue is that we don't have enough scientific
information to actually manage with understanding and our point
here is we have to increase our understanding in order to be better
managers.
Alexandra
de Blas: Well Gee Chapman, you're working at the interface
between the city and the coast; what does urban ecology have to
offer in this area?
Gee Chapman:
Well I think that one of the problems is as Mark said, urban ecology
is a relatively new science and we don't know much about how humans
do maintain ecology in a very altered system. But what we do know
has largely been done in the terrestrial habitats, and most of
our big cities around the world are on the coast, and they have
a very big impact on the edge, the interface between the sea and
the land, one of the main reasons being because they tend to honour
it, they tend to replace natural habitat with artificial habitat,
vertical sea-walls, runways in the middle of Sydney Harbour, docks,
piers, marinas.
Alexandra
de Blas: And what's the problem with that?
Gee Chapman:
Well the problem is it's not natural habitat, that it actually
does support a sub-set of biodiversity so when people look at
it, it looks at first sight as if it's all right, because there's
quite a lot of animals and plants living on it, but it's actually
not the complete set of biodiversity and the numbers of the different
species are very different in their patchiness, and their spacing
is very different from their natural habitats, and we have no
idea what will be the long term of such subtle changes.
Alexandra
de Blas: What can urban ecology do then to help better inform
people who are managing what happens at this interface? And what
are some of the research projects that may give people insights
into how to allow nature to survive better in this new environment?
Gee Chapman:
Well a lot of these artificial habitats are managed by local
councils, so in a place such as Sydney Harbour, different parts
of the harbour are managed by different people, but we're finding
it very successful to work with engineers and environmental people
in some of the councils around Sydney Harbour, and in actual fact
when they are repairing sea walls, they are allowing us to get
in there and actually manipulate how the walls are built, so they'll
allow us to drill holes in the face of the walls to make additional
habitat, to make rock pools half way up vertical sea walls that
octopus and things like that can live in.
Alexandra
de Blas: Well Richard Pouyat, it seems that the field of urban
ecology is actually more developed in the United States. You've
worked at both the local and the national level; what are the
key issues you've been grappling with there?
Richard
Pouyat: Well in the United States we have national policies
that have been enacted since the 1970s, many of which have affected
cities and major metropolitan areas, and two in particular are
the Clean Air Act and the Clean Water Act, and both put the onus
on the local municipalities to make sure that there is a quality
environment for people to live in, in our major cities. And of
course many of our cities in North America, actually exceed these
requirements, and so the municipalities are all struggling right
now to reach what we call attainment. And so they're beginning
to turn to urban ecologists who help them deal with these issues,
and a good example would be the Clean Air Act. Originally the
Act was written to deal with sources, and that makes sense. We
had belching smokestacks bellowing out black smoke in the '60s
in the United States, and there was an obvious problem. And the
Clean Air Act did a good job taking care of those issues. But
there are other air quality problems that we have that are less
visible and much more difficult to deal with, in particular automobile
exhaust. And what we've learned is that trees are very good filters
of atmosphere pollutants and trees are particularly important
because they're not much taller than people, so they can clean
the air where people are. So now there's a big movement to use
trees to fulfil these national standards for air quality, and
we're working very closely with the EPA right now to do that.
Alexandra
de Blas: So you're actually doing the research to determine
how many trees need to be plant so people can determine whether
they reach attainment or not?
Richard
Pouyat: Yes, we still haven't totally convinced the EPA of
this, but we're working with them. Then we could do it by species,
different species of trees are actually more effective than others,
and obviously some species of trees can survive in urban environments
better than others. So it's a combination of factors that we have
to account for in doing that.
Alexandra
de Blas: I believe there's also been some very interesting
research done on the impact of lawns, and how the nitrogen applied
to lawns is actually impacting on waterways. What's been looked
at here?
Richard
Pouyat: Yes. This kind of reminds me when we think about urban
areas, we often think about the major metropolitan downtown business
district or something like that, but in the United States, and
unfortunately what I'm seeing here in Melbourne as well, I took
a field trip the other day for this workshop, is that we have
what we call in the US urban sprawl, some people call it the suburbs,
have lots of grass. So what we're very interested in the States
is what is the impact of a conversion of say, a forested landscape
and in some cases an agricultural landscape, to one that's dominated
by lawns. Well we've learned in our work in the Baltimore city
areas that the fertiliser application rates actually are very
similar to what they do in agricultural systems and even more,
people like to fertiliser their lawns quite a bit. So there's
a tremendous amount of nitrogen being applied on this landscape,
and in fact if you look in a global scale, due to agricultural
practices and now of course the suburbanisation of the landscape,
we've more than doubled the amount of nitrogen coming into our
ecosystems. So that's a tremendous amount of nitrogen coming into
the system. And also with lawns, the other issue is phosphorous,
and we also have, due to air pollution, we have a process called
nitrogen deposition from air pollution, and many of our forests
are receiving lots of nitrogen, but most forests can take that
nitrogen and actually use it, so you get more growth and it doesn't
come out of the system. Lawns are a very interesting subject for
us, because we don't know the retentive capabilities of lawns,
so we're very interested in how this tremendous input of nitrogen
into these systems is going to potentially affect our surface
waters.
Alexandra
de Blas: What sort of impact do you suspect?
Richard
Pouyat: Nitrogen in the form of nitrate is very mobile, so
it can leach through the soil, and ends up in our surface waters.
And nitrogen in coastal systems is eliminating nutrients, so if
you get a lot of nitrogen in your coastal estuaries or bays we
get algal blooms, and in the United States the area I live in
the Chesapeake Bay, which is a very beautiful estuary, and nitrogen
is the chief nutrient loading problem in the Bay. If this nitrogen
that we're applying to the landscape even if a small fraction
of it ends up in the Bay, we can have serious ecological problems.
Alexandra
de Blas: Glenn Guntenspergen, you're a landscape ecologist
with the US Geological Survey; sometimes people argue that OK
it's fine if we remove this wetland because we're going to build
another wetland somewhere else, and so everything's OK, it's in
balance. Do you agree that things can be weighed up in that way?
Glenn Guntenspergen:
That's a very controversial topic in the United States right now,
because not all wetlands are the same. There are a variety of
different types of wetland systems, and destroying a wetland in
a particular setting is not necessarily mitigated by creating
another wetland in another system. And oftentimes in the United
States what tends to happen is that very rare types of wetlands
are proposed to be eliminated, and the wetland that they tend
to create for the mitigation is an entirely different wetland,
and that wetland does not have the same properties and characteristics
as the one that's been destroyed.
Alexandra
de Blas: So how problematic is that then?
Glenn Guntenspergen:
It's quite a problem. We have a set of rules and regulations in
the United States that does allow for mitigation, but the science
behind doing mitigation proves that it's not as straightforward
and simple as people would like to make it out to be.
Alexandra
de Blas: What's the potential to use wetlands for pollution
mitigation in cities in Australia?
Glenn Guntenspergen:
I would urge those interested in doing such a thing in Australia
to be very cautious, and I would make a recommendation that natural
wetlands would be the last thing that you would want to use for
such a purpose. The science of creating artificial wetlands is
probably a much better way to go. There are too many other inherent
qualities that natural wetlands have; in the United States for
instance, a vast majority of the endangered and threatened species
that we have in the country are found in wetland systems. There's
a study in the United States where a group of scientists determine
that natural systems provide upwards of $33-trillion in services
that society can make use of, and wetland systems contribute up
to $7-trillion worth of those services.
Alexandra
de Blas: When you look at the images of the globe at night
the major cities of the world are covered in a bright light haze.
But what impact does this have on the wildlife living in those
places? Mark McDonnell.
Mark McDonnell:
That's an interesting question and I think it's one of those impacts
of cities that has been overlooked, and there's a number of scientists,
particularly one, Gerhard Eisenbeis in Germany, has been looking
at cities around the world, in Germany and in Europe, and he examined
Los Angeles. And what we don't realise is that there's a whole
suite of species that are out at night. In Australia there'd be
quite a few insects and we all know when we leave our porch light
on, that we see just a lot of insects at night, particularly moths
and beetles. He's got a very long term study in Europe and he's
gone back to sight settler studied 10, 15 years ago and they had
collections of insects, and he's gone back to them, done the same
exact study and found a significant reduction. I mean with literally
only a third or less than a third of the species that were present
10 years earlier had disappeared. We have to realise that as we
create light, the light goes in all directions, and we could still
light paths, and we could still light roads, without having that
light go in all directions and control it. He also has done studies
that suggest different lighting actually has different effects,
and you can ameliorate the effect of lighting by using different
light sources.
Alexandra
de Blas: I suppose the Councils and various bodies would actually
be saving energy too, if they were using more specific lighting.
Mark McDonnell:
Yes, exactly. Or maybe not leaving them on as long.
Alexandra
de Blas: Yes. So if you're having an impact on the insects,
is that then having a wider impact on the predators of those insects?
Mark McDonnell:
Yes. The things that eat them.
Alexandra
de Blas: There was a theory at one stage the Melbourne's flying
foxes were actually being attracted to the Botanic Gardens into
the centre of the city because of the light, as if they were flying
down an illuminated highway and being attracted to the city. Your
centre has actually been researching the flying fox problem; what
actually are you finding?
Mark McDonnell:
Well I think that they grey-headed flying foxes are an amazing
animal. The thing though that's apparent to me is a lack of ecological
understanding of the flying foxes and of the city, has contributed
to a misunderstanding on why they're there and how to manage them.
The basic ecological principles our centre applied to looking
at the bats, why are they in Melbourne, why are they at the Botanic
Gardens? Well they actually, as many people know, they go out
to feed at night. They travel as much as 60 kilometres from the
city to feed, which is pretty phenomenal, and return. And they
return to the Botanic Gardens. The Botanic Garden is where they
camp, they've created a camp there, and since around the 1995,
they've been there year-round. Last year was our peak year with
30,000 individuals in the middle of summer, which is a lot of
animals in the Botanic Gardens. The issue that we have is that
they're very important animals to Australia but they're in the
wrong place. 30,000 of anything. And then as we know that there's
a group that have a caring, and they care about the conservation
of them, and they talk about well the reason that they're in Melbourne
is because we've destroyed all their other habitats. Well our
research suggests that in fact those habitats were destroyed many
many years ago, and in fact ecologically that wouldn't be the
legitimate cause of them coming to Melbourne. The reason they're
in Melbourne is very simple: and that is that since the '70s,
Melburnians have planted street trees and garden trees and park
trees that are from New South Wales and Queensland. Those trees
are the common and standard food resources for the grey headed
flying fox. Our estimates at the centre suggest that even just
looking at street trees, there's over 600,000 trees, mature trees,
on the streets of Melbourne which can be a food resource for flying
foxes. No wonder they're here. The other thing we've done ecologically
is study their behaviour, and we've come up with a system to disperse
them without harming them, and that's actually been very successful.
We still need to manage them because they need to be in an appropriate
place, because that's what the ecology of cities is all about.
There's appropriate places for things, and I know people think
differently about that, but certainly ecologically, for health
reasons, for historic reasons, the quality of our landscapes and
cityscapes, we have natural areas close by, and that's where we
would like to get them and keep them there.
Alexandra
de Blas: As a group, you've been calling for an increase in
the study of urban ecology, but some people might argue that we
should adopt more of a triage approach, that there's plenty of
space for nature outside the city and why spend money and effort
trying to keep it everywhere. Shouldn't we just keep it in the
country where it belongs?
Mark McDonnell:
The unique Australian flora and fauna still exists within
our cities, within 10 kilometres of our central business district.
In all of our major cities, all of our capital cities in Australia.
That is not true in Europe, that's not true in many cities in
the United States. So first and foremost, we actually still have
some of the most precious plants and animal communities that exist
and are part of our natural heritage, so that's Number 1. Number
2 is that for people to care about the environment, they have
to be exposed to it, and I mean the environment, the plants and
animals living, and I think this has been very clear with work
by E.O. Wilson a professor at Harvard University, this concept
that he has of biophilia. Many of the reasons people move into
the suburbs is that they feel they want to be closer to nature,
to animals, to see the birds and the plants and it is actually
going to help them understand why we have to do certain things,
like preserving wetlands, preserving coastal areas, or manage
them effectively for biodiversity. And last but not least, I think
it's a crime that if we want to teach our students about the city,
which is not just the cultural and the economic and the architectural,
but the natural history of cities, we have to actually drive two
hours out of the city to show that to them. So I think there's
a tremendous need to maintain these areas in cities as environmental
education centres, if for anything, living laboratories.
Alexandra
de Blas: Dr Mark McDonnell, with the final word on urban ecology
for today's program anyway. He's the Director of the Australian
Research Centre for Urban Ecology. Thanks also to Gee Chapman,
from Sydney University and visiting U.S. urban ecologists, Glen
Guntenspergen and Richard Pouyat.
Thanks as
always to the production team of Jackie May and Janita Palmer.
I'm Alexandra de Blas, and next week as Australian troops settle
in on the Solomon Islands, we'll look at how pressing environmental
concerns in that country are being dealt with. Hope you can join
me then.
Guests on
this program:
Dr. Mark
McDonnell
Director
Australian Research Centre for Urban Ecology
Royal Botanic Gardens
Melbourne
markmc@unimelb.edu.au
Dr Gee Chapman
Deputy Director,
Centre for Research on Ecological Impacts of Coastal
Cities (EICC)
University of Sydney
gee@bio.usyd.edu.au
Dr Richard Pouyat
Forest Ecologist
USDA Forest Service
Baltimore Ecosystem Study
University of Maryland
U.S.A
rpouyat@aol.com
Dr Glenn Guntenspergen
Landscape Ecologist
U.S Geological Survey
Patuxent Wildlife Research Centre
University of Wisconsin
Glenn_Guntenspergen@usgs.gov
Further information:
Australian
Research Centre for Urban Ecology
(ARCUE)
http://arcue.rbg.vic.gov.au
Reporter:
Alexandra de Blas
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