Conservationists are “fighting a losing battle” against invasive plant species such as Lantana (Lantana camara L.). That is the conclusion of a team of researchers
from the University of Oxford and the University of Bergen in their article entitled: “A Battle Lost? Report on Two Centuries of Invasion and Management of Lantana camara L. in Australia, India and South Africa.” According to the authors this means the “established paradigm” of eradication of invasive species must be abandoned in favor of “adaptive management.”
I discussed the article with two people who have been working for years on invasive plant species in Australia and Africa. Rod Randall and Arne Witt. Rod Randall works for the Department of Agriculture and Food, Western Australia. Arne Witt works for CABI based in Nairobi, Kenya. (See biographies below.)
The very first thing that Randall and Witt questioned about the Lantana article was the existence of any “established paradigm of eradication” for entrenched invasive species such as Lantana. As Randall observes, “it shows a certain naivety on the part of the authors that anyone would consider control attempts in Australia, India or South Africa as eradication efforts.” Lantana first invaded in the 19th century. Back then, control efforts only occurred after invasive plants had become massive problems. It is now so well established that eradication of an established invasive such as Lantana is out-of-the-question – at least with current means.
Both Randall and Witt argue that control is the key with well-established invasives like lantana. And both agree that control is not a lost cause. Interestingly, they contend the problem is not so much the invasive species as it is the people in charge. As Witt says, “a wise man once told me that the problem is not managing invasive species but managing people to manage invasive species. This is so true if you look at past efforts that have been made to manage infestations around the world.”
As Witt relates, “I was personally involved in a project in Zambia where the government made $450,000 (U.S. dollars) available to clear Mimosa pigra from a floodplain in a National Park.” The national implementing agencies had no real structured plan or strategy for follow-up activities, but the government promised to make more funding available when current funds were depleted, so, as Witt notes, “nobody was too concerned.” After more than 900 ha. of a 3,000 ha. infestation were cleared, funds dried up and the area is being re-invaded. “Without knowing the details someone may say that the management of Mimosa pigra in Zambia has been an absolute failure,” and “the weed is impossible to control.” According to Witt, however, “this is far from the truth – it was a failure of management/people, but important lessons have been learned in this process. There are many examples where we can effectively control weeds if we develop long-term control strategies coupled to long-term sustainable funding – it is not a lost cause.”
Randall describes just such a success: involving Kochia (Bassia scoparia (L.) A.J.Scott). This effort worked “because the critical people, the landholders . . . were right behind the program and worked well with our agency to remove Kochia from over 2700 acres and hundreds of widespread sites.” (Note this eradication program cost less than $500,000 (Australian dollars) and was deemed successful after 10 years of monitoring with no finds.)
In short, there really is no “established paradigm” of eradication according to Witt and Randall for established invasives like lantana. It is a straw man that distracts and discourages decision-makers such as government agencies.
And what do the Oxford and Bergen researchers mean by “adaptive management” of invasive plant species? In a future article, Invasive Plant News will address this topic.
Arne Witt: Arne has been working on the management of invasive plants, particularly biocontrol, for the past 18 years. He has worked for CSIRO (Australia), Queensland Department of Natural Resources and Mines (now Biosecurity Queensland), the Plant Protection Research Institute of the Agricultural Research Council (South Africa), and is currently the Regional Coordinator (Africa and Asia) for IAS for CABI. He has been the International Project Coordinator and/or Technical Advisor for GEF-UNEP IAS Projects in Africa, SE Asia and the Caribbean assisting in the strengthening/development of IAS policy, creating awareness, building IAS capacity and the development and implementation of control programmes for IAS.
Rod Randall: A biologist by training, Rod started his career with the Western Australian Agriculture Protection Board in 1985 moving to the Department of Agriculture’s Weed Science group in 1987. In 2002 he published A Global Compendium of Weeds the most comprehensive document on the status of the worlds weed flora. Rod has worked extensively on weed biology and ecology for a quarter century and for the past 16 years has assessed all plant introductions into Western Australia for their weed potential. In that time he has assessed over 10,000 species and extensively reviewed the weed status of many hundreds of others.