Australian acacias: weeds or useful trees?

Abstract

By promoting Australian acacias to the developing world, aid and development agencies are failing to learn from the mistakes made with mesquite (Prosopis juliflora) and jatropha (Jatropha curcas)two plants with weedy attributes that have done more harm than good when promoted in Africa as aid. The belief in ''miracle'' plants that can lift people quickly out of poverty is problematical, because such plants have the attributes of weeds-vigorous growth in degraded conditions-and often escape human control, degrading rather than improving land. Other problems are costs that are less obvious than benefits, discounting of the future, and a belief that anything green is good. The main biological problem with Australian acacias is copious crops of long-lived seeds which make eradication very difficult, binding future generations to acacia-dominated landscapes. Drawing on papers presented at a workshop on Australian acacias as introduced species around the world held at Stellenbosch University, I examine the different perceptions of Australian acacias by invasion biologists and the aid and development community. The latter has redefined ''sustainability'' to give it social rather than ecological goals. To manage Australian acacias sustainably, precautionary risk assessment should take precedence over adaptive management, because mistakes are often irreversible and can take many decades to become obvious.

Stakeholder perceptions and practices regarding Prosopis (mesquite) invasions and management in South Africa

“…Research is needed to evaluate stakeholder knowledge, perceptions, practices, awareness, and wants and needs relating to biological invasions (Shackleton et al 2007;Eiswerth et al 2011;Kull et al 2011;Rai and Scarborough 2014). This is particularly important for invasive species that were introduced for specific purposes and where complex conflicts of interest now exist due to the provision of valuable consumptive and nonconsumptive services (Shackleton et al 2007;Low 2012a;Dickie et al 2014;van Wilgen and Richardson 2014).…”

Identification of invasion status using a habitat invasibility assessment model: The case of Prosopis species in the dry zone of Myanmar

“…The intentional introduction of alien woody species for restoration projects in arid ecosystems has led to widespread biological invasions (D'Antonio and Meyerson, 2002;Low, 2012). These invasions are often detected too late, making eradication unfeasible (Milton and Dean, 2010).…”

Invasive Acacia mearnsii De Wilde in Kunming, Yunnan Province, China: a new biogeographic distribution that Threatens Airport Safety

“…Explanations for A. mearnsii invasions have received attention in some studies (Dodet and Collet 2012;Donaldson et al 2014;Lamarque et al 2011;Low 2012). We identify a number of factors that are possible for the successful invasion by A. mearnsii at the Changshui airport, and group them into environmental factors, human disturbance and weed characteristics.…”

“…Meanwhile, interference by construction activities enhances invasion ability of A. mearnsii, because it can help break seed dormancy underground. Finally, the weedy characteristics are also key drivers of invasive success (Gibson et al 2011;Low 2012), such as long-lasting inflorescences, a variety of dispersal pathways, the ability to re-sprout and germinate in abundance following disturbance, and high growth rates. All result in the emergence of a large number of tree seedlings after environmental adaptation in grass-planting area at the airport.…”