The New Nature: Winners and losers in wild Australia

In The New Nature, Australian ecologist Tim Low takes us on a tour of his continent/country to make the point that every nook and cranny has been impacted by the activities of humans.  (1) It is a dizzying adventure because it challenges many of our assumptions about nature:

  • Human civilization has benefited many plant and animal species in Australia.  For example, places such as garbage dumps and sewage treatment plants are sources of food for many species, from the bottom of the food web to the top.  Many animals hang out in the company of humans where they find housing, food, and protection from their predators.
  • However, there are “winners” and “losers” in the changed environment.  Not all species benefit equally from the resources provided by humans and not all species are equally adaptable to change.
  • When “winners” dominate at the expense of rare species, the “winners” are nearly always native species, according to Low.  Non-native “invaders” are hardly mentioned in Low’s tour of Australia.
  • Low defines “conservation” as active management of ecosystems, including aggressive culling (AKA killing) of native species as needed to prevent extinction of rare species.  He acknowledges that these massive killings are controversial in Australia, which was some comfort to us.
  • Eucalyptus forests in Australia are in serious trouble.  There is no evidence in Australia that they are the aggressive “invaders” they are labeled in California.
The Australian eucalyptus forest as painted by Hans Heysen:  Mystic Morn, 1904
The Australian eucalyptus forest as painted by Hans Heysen: Mystic Morn, 1904

As ecologists tend to do in the United States, Low uses pre-European Australia as the baseline from which changes in ecosystems are judged.  The Aborigines of Australia were hunter/gatherers, like many Native American tribes in North America.    Like our Native Americans, they used fire to support their hunting.  Periodic burning of grassland promotes the growth of new grass which attracts the grazing animals they hunted.  In Australia, the grazing animals were marsupials, such as kangaroos, rather than the ungulates in North America.  Periodic burning also prevented natural succession from grassland to forests.

When Europeans arrived, the population of Aborigines plummeted as it did in North America and the remaining population was displaced from most of their homelands.  Their way of life was radically altered and hunting was no longer their primary means of living.  That was the end of the annual grassland fires that had maintained the grassland.

Australian eucalyptus forest as painted by Frederick McCubbin:  The Pioneer, 1904
Australian eucalyptus forest as painted by Frederick McCubbin: The Pioneer, 1904

The Europeans brought sheep and cattle that partially replaced the function of the Aboriginal fires to maintain grassland.   However, there is a fine line between over-grazing and grassland maintenance.  Many native grasses were replaced by annual grasses introduced with the livestock of the Europeans, just as it was in North America.  Europeans in Australia actively suppressed fire for safety reasons.

Here is a brief summary of the consequences of these changes in human use of the land:

  • Koala and joey.  Creative Commons
    Koala and joey. Creative Commons

    There were few koala bears in Australia when Europeans arrived at the end of the 18th century.  They were easy marks for Aboriginal hunters because they sleep in the canopy of trees during the day.  When Aboriginal hunting stopped, the population of koalas skyrocketed.  Because they are so cute, humans love them and they want them everywhere, so they have been introduced into parks where they had not lived in the past.  Now they are killing eucalyptus forests in those parks.  Park managers want to cull them and sometimes they do, but Australians strenuously object to these efforts to balance the population of koalas with available resources.  When managers are prevented from culling, the forests die and the koalas eventually starve.  This makes for disturbing reading.

  • Kangaroos in native grassland
    Kangaroos in native grassland

    Kangaroo populations have benefited from both the disappearance of Aboriginal hunters and the eradication of dingoes by cattle and sheep ranchers.  The large species of kangaroos now have no natural predators so their populations have destroyed much of the grassland that they graze.  Kangaroos are also aggressively culled and Australians aren’t happy about that either.

  • Insect predators of eucalyptus forests have increased because they are “fed” by the fertilizer in stock paddocks.
  • The absence of fire has also radically altered many ecosystems.  Where kangaroos and stock have overgrazed, the fires that start aren’t sustained because there isn’t sufficient fuel.  When there are no fires to reduce the understory, the forest retains more moisture.  The forest gradually converts from dry forests to tropical forests and the trees cannot regenerate in the wet, dense understory:  “If you take eucalypt forest, add fertilizer and water, you have the recipe for rainforest.”   This is another factor in the decline of the eucalyptus forest in Australia.
  • The changes in these ecosystems reverberate throughout the food web.  The insects, birds, and animals that lived in one type of ecosystem aren’t necessarily adapted to the changes.  Some species disappear and others arrive that often compete with their predecessors in the ecosystem, further diminishing rare species.

Although there are North American counterparts to most of these changes in the environment, the concluding chapters of Low’s remarkable book are entirely foreign to us.  He is unequivocal in his assessment that human attempts to compensate for the damage that has been done to Australian ecosystems in their residential gardens inflicts even greater damage by helping “winners” displace “losers.”  Bird boxes and feeders benefit only the most aggressive birds which give them an even greater advantage over the forest birds that are in decline.  Likewise, garden ponds are occupied by only a few species of the toughest frogs.   His assessment of native plant gardening is so surprising that we will quote it directly:

One tenet of wildlife-friendly gardening is that native plants be used, but often that’s not what animals want.  Growing native plumbago for native butterflies doesn’t help as much as growing the exotic equivalent, which sprouts hundreds more flowers.  And switching native animals over to native plants is often harder than it sounds.”

We visited Australia as tourists for a month, but that is nearly the limit of our understanding of its ecology.  It felt much like home inasmuch as it’s another of the five Mediterranean climates in the world.  We can’t claim that this experience is sufficient to question Tim Low’s description of Australian ecology.  So, until we learn otherwise, we must say that the drivers of environmental change in Australia are primarily anthropogenic and the existence of non-native species plays little role.  However, we can’t help but wonder if a difference of perception accounts for the radically different assessment of American ecologists.  In other words, are American ecologists blaming non-native species for environmental changes that are just the consequence of human activities?   That seems another equally logical explanation for the radical difference in American and Australian assessments of non-native species.

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(1)    Tim Low, The New Nature:  Winners and Losers in Wild Australia, Penguin Books Australia, 2002

Acacia: Another Australian tree caught in the cross hairs of nativism

Webmaster:  We are republishing, with permission, a post from the website of Christian Kull, Associate Professor of Geography and Environmental Science at Monash University in Melbourne Australia.  He is also Adjunct Professor at the University of the South Pacific.  He is presently based in Suva, Fiji, where his wife is employed by a division of the Secretariat of the Pacific Community.  (We have added a few edits for an American audience.)

We have read the debate in scientific journals between Professor Kull and his colleague, Jacques Tassin, with Tim Low, which is described in this post.  It sounded very familiar to us.  On the one hand, Kull and Tassin wish to consider the economic and environmental benefits of acacia.  Their pragmatic evaluation of acacia is attacked by Tim Low, using the same alarmist arguments that we hear in the San Francisco Bay Area about another Australian tree, the eucalyptus. 

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Are Australian acacias planted overseas miracle plants for rural development, or are they the worst kind of environmental weeds?  The battle lines appear rather stark at times.  At least when one reads environmentalist Tim Low’s rebuttal to a critique that Jacques Tassin and I wrote of his views.  We thought our statement to be tempered and tried to build a reasonable case for responsible use of exotic agroforestry trees (see also previous blog).  But Low calls us “in denial about dangerous aid,” flogs a misplaced example about mesquite in an argument about acacia, all the time preaching his argument to the converted in the journal Biological Invasions.  Low has even taken his views to an online editorial on the Australian Broadcasting Corp website and has promoted his views to the Herald Sun (link).

Meanwhile, in Vietnam, an entirely different story is developing.  On 2 November, there was a small seminar and dinner in Hanoi, Vietnam celebrating the contributions of Australian and Vietnamese scientists to the forestry sector, primarily through the promotion of Australian acacia species.  The Vietnamese Government awarded medals to Sadanandan Nambiar, Chris Harwood, Khongsak Pinyopusarerk, Rod Griffin and Stephen Midgley for “contributions to Vietnam’s forest development.”  Australian acacias are now a common part of Vietnam’s rural landscape, rehabilitating denuded landscapes, and providing wood for industry and fuel.  Australian aid (via CSIRO, AusAID, and ACIAR) played a role in supporting such initiatives since 1987, working together with Vietnamese partners like the Research Centre of Forest Tree Improvement and the Forest Science Institute of Vietnam.

Tea grown in shade of acacia in Vietnam.  Photo by Chris Harwood
Tea grown in shade of acacia in Vietnam. Photo by Chris Harwood

According to Stephen Midgley, there are now about 900,000 hectares of Australian acacia plantations in Vietnam (about the same area as the Californian Pinus radiata [Monterey pine] in Australia).  Just last year, an estimated 120,000 hectares of acacias were planted in Vietnam – some 70% by smallholders [private property owners].  Acacias have been used as nurse crops to rehabilitate native forest areas; examples include the protection forests of Hai Van Pass and the Perfumed River catchment behind Hue.  Acacias are now a valuable commercial asset, as hardwood woodchips and as furniture wood.  Product value exceeded US$1.5 billion in 2011, with some US$400 million returning directly to the pockets of the growers, leading to improvement to livelihoods among acacia-growing communities.

An ecologist may look at this situation and worry that the acacias in Vietnam are going to ‘explode’ in the future, becoming problematic pests or replacing ‘natural’ forest.  That is, they will become too successful for their own good.  Indeed, apparently the weediness of acacias will be addressed to some extent at the upcoming IUFRO acacia sylviculture working party meeting in Vietnam.  Chris Harwood, of Australia’s research agency CSIRO, wrote to me:

“On my just-completed trip to Vietnam I had a careful look (as I always do) in the farming landscapes of northern, central and southern Vietnam for signs of acacias spreading as weeds.  There are no such signs.  All the farming land is too intensively cultivated (Vietnam has a land area of 33m ha and a population of 87m), and  all the acacias in the landscape are planted rather than naturally regenerated, except for very occasional patches of vacant ground which may have a few ‘volunteer’ acacia seedlings but which will soon go under cultivation.  Quite large areas formerly under acacia plantations in southern Vietnam have been converted to rubber plantations during the last 5 years, with no evident difficulty.  In the north, tea is successfully grown under Acacia mangium.  The only caveat regarding weediness in Vietnam is that care must be taken when planting adjacent to native ecosystems to ensure that acacias do not spread into them.  But this is a manageable potential problem and is just not an issue for the vast majority of acacia plantations that do not abut natural ecosystems.”

Acacia and cucumber field in Vietnam.  Photo by Chris Harwood
Acacia and cucumber field in Vietnam. Photo by Chris Harwood

In addition to ecological questions about invasion potential, social scientists may ask about how access to land and other rural power relations are altered by such forestry development.  Indeed they have already (link).  But the point here might be that shouting from diametrically opposed ideological camps is probably not the best way to move forward.  In this case, there is a will to plant acacias (what combination of government diktat and social consensus I don’t know) and they are already deeply incorporated into the physical and socio-economic landscape.  In addition to shaping the already very anthropogenic landscape by farming rice, other crops, and tree crops like rubber (over 1 million hectares), the Vietnamese are farming acacias.  The question then, instead of “go acacia go” or “doom is coming,” is how farmers, foresters, villager leaders, government agents, and scientists might each in their own way address the questions of the future of Vietnam’s regional landscapes – what values are important, what are the options, what are the constraints and potential problems, what does the evidence show.  It is this kind of measured approach Jacques Tassin and I tried to make in our response to Tim Low.

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Webmaster:  We believe that the debate we are engaged in with native plant advocates should be a land-use decision.  This should be a civil debate, which in a democratic society should result in a decision that reflects the wishes of an entire community.

Unfortunately, native plant advocates seem to believe that their demand that non-native trees and plants be destroyed is a moral imperative.  Although they claim environmental damage from non-native trees, they are unable to provide the scientific evidence to support that claim.  In the absence of such evidence, their demands are just an imposition of their gardening preferences on the public.  The tactics they use to impose their will are inconsistent with their claim that they are on the moral high-ground and the methods they use to eradicate non-native species are also inconsistent with their claim that they are benefiting the environment.