Prosopis invasions in South Africa: A blessing or curse?

Barriers to the management of Prosopis - mesquite, a widespread invasive tree
Species have been move around the world for many reasons and have led to the rise of biological invasions which are a major driver of ecological and social change globally. One such species, Prosopis (mesquite), has been introduced to over 100 countries globally, both accidently and purposefully to act as an agroforestry tree.
Prosopis was introduced into the arid parts of South Africa to help farmers with fodder and shade for livestock and as a source of firewood. It has since become the second most widespread invasive tree species in South Africa.
The negative effects of Prosopis and other invasive species has led to the initiation of programs to manage these invasions across the world and are a key need as highlighted in the Convention on Biodiversity . In South Africa, the Working for Water program drives management on state and private land along with input from private land owners. Management initiatives aim to reduce impacts and in some cases improve the benefits that some invasive species can provide.
A study by C·I·B post-doctoral researcher, Ross Shackleton, assessed the barriers that hinder the effective management of Prosopis invasions in South Africa amongst different stakeholder groups. “To date, we are unaware of the systematic investigation into barriers faced by natural resource management programs, making this study important. We used questionnaire surveys and focussed workshops to identify barriers and adaption responses in four key stakeholder groups involved in different stages of Prosopis management,” explains Shackleton.
More than 100 barriers to effective management of Prosopis were identified, most of them relating to social issues. Key barriers related to limited knowledge, economic factors, conflicts of interest, the ecology of the genus and the nature of the invaded land, as well as poor planning, co-ordination and co-operation, and a lack of prioritisation. There were marked differences in how stakeholders perceived the importance of some barriers. Most Farmers placed high importance on a lack of strategic planning and poor control implementation as important barriers, while a few managers regarded these as important. Managers suggested that poor partnerships between stakeholders was a major barrier and Academics suggested that inadequate monitoring was a problem which were factors was not raised as important by other stakeholders. This reflects different views about the context in which management projects operate and shows the importance of engaging multiple stakeholder groups to get a holistic picture.
Key adaption responses to address these barriers include the use of more effective clearing methods (mechanised options and biological control), raising awareness, building partnerships, improving monitoring, reducing inefficient management and incorporating strategic planning at various levels to improve the effectiveness of control programs with the funding available.
Contact Details
Dr Ross Shackleton
DST-NRF Centre of Excellence for Centre for Invasion Biology, Stellenbosch University
Email: [e-mail] or [e-mail]
Website: www.sun.ac.za/cib

[@edialbert8035]

I don’t see the negative impact of Prosopis sp. all I see is degraded landscape. A gold medal 🥇 should be given to this tree for being able to initialize the process of repair and succession. Prosopis sp. are pioneers and nitrogen fixing legumes, that will enable the planting of other more productive species.

[@awilgiire5355]

Great work Dr. Ross Shackleton

[@anotherhuman8211]

Prosopis, really ones from NA and a few from SA & Caribbean(For instance P. Juliflora) are 'over-adapted' in terms of how it has drought tolerance, but prosopis has evoloutionary pressures to stay leafed out by using up water in the surface soil as quickly as possible and for some, using a taproot which in Africa, contributes to rapidly decreasing ground water reserves. There is evidence that north and mid American species evolved like this because of creosote jumping from SA to NA. Creosote bush/shrub itself in one of the few species in NA that actually is better at tapping out the soil of any water quickly than Mesquite which makes sense. When mesquites grow, not many native species are able to keep up with prosopis' quick water depleting trait. In Africa, it ecologically is more damaging, despite it flowering more. Prosopis being a nitrogen fixer isn't good or bad, it is just a characteristic that almost any other legume in Africa has, which Africa is dominated by legumes that fix nitrogen. So many legumes in Africa fix nitrogen, that some specifies of legumes(like some senegalia sp.) don't even need to fix nitrogen because there is so much to go around. While they do help with succession, so does any native species, but grazing causes seedlings of them to die. Mesquite seedlings just like longer due to it being avoided because animals eating the foliage eventually get sick, and stay away from it after.

[@edialbert8035]

@@anotherhuman8211 , very interesting. We also should remember that the amount of water on earth, was and is the same amount, the problems with drought is not contributed to Prosopis sp. , as far as I know, the drought problems is contributed to human activity, more than anything else. I have witnessed the most hostile place on earth being being used to grow trees and other food crops, with the help of legumes, the dead soil transforms into rich soil full of life...

[@beorntwit711]

I think prosopis was a fine choice for Lawton - because it already grows in Jordan, and he gets rid of it eventually. But that's a small site, easily controlled. In the wild, its a different matter, and financing the removal of such a species is beyond the capacity for most African states, especially in low density areas. I have also read that most nitrogen fixing legumes are in arid areas. And Africa, consequently can be expected to have a bunch of similar native trees that do most if not all the functions, so that would be preferable.

[@beorntwit711]

@@anotherhuman8211 do you know by chance any African native arid nitrogen fixing trees with a strong shading effect? (Other than Senegalia, though I don't know how much canopy cover that gives?)

[@JornSilverblade]

With more then 8000 endemic plant species unique to South Africa the Prosopis is a huge curse if you ask me! South Africa has a lot of native species that survive the harsh climate, Prosopis will inhibit the growth of other plants and turn the land into a 'green desert'.

[@josemcabralrmz173]

Hello from México 🇲🇽: You should harvest Honey Bees from the mathenge flower, it’s very well paid in Europe. And in order to change from bush in to a Tree just apply formation prune Regards

[@kalleleman]

You shouldn't be grazing that landscape anyway. Or at least minimally and in a very controlled manner. The trees are a start of a process, you need to continue it

[@grahamdanney4000]

statement on the wood is not what we have experienced, the wood is very hard and long burning producing excellent coals for cooking.

[@don.timeless4993]

Same happening to my country. The only good & native to Africa/Middle East prosopis is Koelziana & Cineraria

[@ismailadabo2907]

Here in Sénégal, west africa , we use it for traditional medication...❤