Acacias as weed or miracle plant?

By Christian Kull

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 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.

According to Stephen Midgley, there are now about 900,000 ha of Australian acacia plantations in Vietnam (about the same area as the Californian Pinus radiata in Australia). Just last year, an estimated 120 000 ha of acacias were planted in Vietnam – some 70% by smallholders. 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:

“One 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.”

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 milliion ha), 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.

Acacia trees and cucumber field, Vietnam. Photo: Chris Harwood

Acacias in landscape, Yen Bai, Vietnam. Photo: Chris Harwood

Acacia mangium as a shade plant in tea plantation, Phu tho, Vietnam. Photo: Chris Harwood

[Reblogged from, originally posted in December 2012. If images or links don’t work, or you want to make a comment, please visit the original blog post.]

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