Public reactions to conferences on invasive species are always illuminating

I am publishing a guest post by Jacques Tassin, who tells us of his personal experiences with presenting his findings about invasive species in public forums.  Jacques Tassin is a French ecologist. He has been working on invasive species for more than twenty years, especially on islands in the West Indian Ocean and Pacific Ocean.

Jacques Tassin

Dr.Tassin agreed to tell us about his interactions with the public because he believes the public’s views of invasive species are poorly understood and that improved understanding of the public’s views would improve communication about this controversial topic. 

I must add that my personal experiences with such interactions have revealed the same themes.  The public feels strongly that it is possible—even necessary—to control nature.  And much of that sentiment is based on guilt about the damage that humans have done to nature and a desire for redemption.  I prefer to respond to that viewpoint by informing the public of the damage being done in the name of “restoration.”  We cannot redeem ourselves by doing yet more damage.  However, I share Dr. Tassin’s frustration with scientists who are unwilling to speak to the public in ways that the public can comprehend.

Jacques Tassin is a new voice on Million Trees.  I am grateful for his participation in our discussion of invasion biology.

Million Trees

It takes much energy for a scientist to go down to the arena to meet the general public, for example in the form of a conference. But it is well worth it. On the one hand, because it allows scientists to hear a different kind of discourse than media coverage of the issue. On the other hand, because the comments and questions from the public are often very significant.

Following the publication of my book La Grande invasion: qui a peur des espèces invasives ? (The Great Invasion: Who Fears Invasive Species?) published in editions Odile Jacob in 2014, I was often invited to such meetings. I can distinguish several types of public reactions to my conferences.

The main one is the public’s seeming intolerance of the idea that we can agree to do nothing about the progression of an invasive species, even if it is proven that nothing can be done about it, or that the species in question does not have a clearly negative ecological or economic impact. Farmers and hunters are particularly opposed to this view of not intervening and therefore not controlling the environment. For these people, it is a question of putting nature in its place.

The public also strongly rejects the possibility that we cannot redeem our faults, or that we may not be able to undo what we have done, if we do not deal with invasive species. This reaction is the result of an activist stance that is particularly present in nature conservation associations. The remark that comes up most often is “we’re not going to sit back and watch.”

Finally, the third most frequent reaction is the belief that each invasive species introduced somewhere necessarily takes the place of another species. This principle of musical chairs seems deeply rooted in everyone’s mind. It is not certain that this is due to the theories of Robert MacArthur and E.O. Wilson’s about island biogeography. It seems much more likely that, deep in our imagination, the arrival of an intruder will end up with the departure of one of us.

In any case, it seems to me that the debate about invasion biology is far more concerned with social psychology than with the science of invasions. I am now certain that those who focus their discourse on the biological and ecological dimension of invasive species are headed in the wrong direction. Today, invasion biology is more in the field of psychology and beliefs than it is a question of a rational discourse. But it is clear that scientists are particularly ill-suited for this dialogue. Journalists who are used to talking to hundreds of thousands of listeners on the radio or in the press are much better equipped to do so. Scientists must learn from journalists how to communicate with the public about invasive species, whatever the public’s opinion of invasive species.

Jacques Tassin

Further Reading:

Tassin J., Thompson K., Carroll S.P., Thomas C.D. (2017). Determining whether the impacts of introduced species are negative cannot be based solely on science: a response to Russell and Blackburn. Trends in Ecology and Evolution, 32 (4) : 230-231.

Tassin, J. and C. Kull (2015). Facing the boader dimensions of biological invasions. Land Use Policy 42 : 165-169.

Tassin, J. (2014). La grande invasion. Qui a peur des espèces invasives ? Editions Odile Jacob. Paris, 216 p.

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. 


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.


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.