SAEON, CIRAD and SANParks team up to resist the alien invasion of the Kruger National Park

Some of the common alien plant species invading Kruger National Park rivers. Clockwise from the top left: Senna occidentalis (Coffee senna), Verbesina encelioides (Wild sunflower), Acanthospermum hispidum (Upright starbur), Bidens bipinnata (Spanish blackjack), Xanthium strumarium (Large cocklebur), Argemone mexicana (Yellow-flowered Mexican poppy), Datura stramonium (Common thornapple), and Lantana camara (Common lantana) (Pictures: Rob Taylor) The user-friendly identification platform utilises a series of simple diagrams to guide the user in selecting the morphological, habit and habitat characteristics associated with the plant in question (Picture: AdvenRun V.1.0) A cleanly pressed Senna pendula (Easter cassia) specimen and herbarium information sheet. The project’s specimen collection will be housed at Skukuza herbarium in the Kruger National Park (Picture: Rob Taylor) SAEON Technician Thembi Marshall examines an Argemone mexicana (Yellow-flowered Mexican poppy) flowering on the banks of the Letaba River. Several plant characteristics as well as the abundance and location are recorded for each species (Picture: Rob Taylor) An infestation of Datura innoxia (Downy thornapple) hand-pulled on the southern bank of the Limpopo River in northern Kruger National Park. An identification tool for this species and advice on its recommended method of eradication will be supported by the Pl@nt-Inv Kruger project (Picture: Rob Taylor)

Invasion biology has become a hugely important scientific field worldwide as invasive species increasingly threaten to decrease biodiversity and modify ecosystems. The same is true in South Africa, where plants establishing outside of their natural distribution ranges represent one of the major threats to ecosystems and their functioning.

For these reasons, SAEON considers alien organisms - both plant and animal - to be among the most important agents of anthropogenic change.

Areas dedicated to the protection and conservation of natural ecosystems and biodiversity, such as the Kruger National Park (KNP), are particularly threatened by alien plants which establish along watercourses, ‘escape’ into the protected area from adjacent gardens and are inadvertently introduced through road hardening. It is therefore imperative that more be done to recognise and prevent the spread of alien plants in this, and other, parks.

SAEON’s Ndlovu Node is collaborating with members of Scientific Services (South African National Parks) and the French Centre for International Cooperation in Agronomic Research for Development (CIRAD) in compiling a database of the 400+ alien plant species - from notorious Category 1 invaders to ornamentals currently restricted to gardens - which are known to occur within KNP. The outcomes of this collaboration will be detailed descriptions (including their invasiveness, habitat, origin, vernacular names and documented control methods) of as many of these alien plants as possible, supported by clear photographs and illustrations of various diagnostic plant features.

Interactive identification tool

Unique to this project will be the Phase 2 development of an interactive identification tool (IDAO) from the 400-odd species accounts. The IDAO technology (a multimedia approach to computer-aided identification) was developed by members of the CIRAD team and uses an identikit to reconstitute species identity. This process has already been used to produce similar resources for the weeds of the Indian Ocean Islands (Principales mauvaises herbes des îles de l’Océan Indien; Advent-OI) and for other places such as Central Africa, Laos, Cambodia and New Caledonia.

The ‘Pl@nt-Inv Kruger’ collaboration is a further refinement and validation of this technology. Ultimately the simple platform produced will guide users towards identifying an unknown alien plant through a series of step-wise choices and simple schematics concerning morphological, habit and habitat characteristics. Final identification is based on the similarity (expressed as a ranked percentage probability) of the unknown specimen to so-called ‘type’ specimen information databased during Phase 1 of the project. Pictures and text can then be accessed to confirm the identity of the alien plant.

Open source and user friendly

In keeping with the mandates of SAEON, KNP and CIRAD, the IDAO-associated software and ‘raw’ database will be open-source and freely available online to all interested parties and potential users. It is also planned for the application to be compatible with a range of mobile electronic storage devices such as smart phones, PDAs and tablets, thus allowing for easy and convenient use under field conditions.

Further, it will be linked to a web-based collaborative platform where people can share information, knowledge and questions on invasive plants. This ‘one-stop’ product will assist managers, conservationists and technical crews within Kruger Park and beyond, to identify alien plants and will suggest appropriate methods for eradication in situ.

Alien control in other vulnerable systems

The Pl@nt-Inv Kruger project has the capacity to educate people on the ground regarding the full range of alien plants found in the savannas of north-eastern South Africa as well as stressing the very severe threat posed by these invaders. As a validation of a valuable technology, this collaboration will pave the way for similar alien awareness and control initiatives in other vulnerable systems (many of which are of interest to SAEON, such as grasslands and fynbos) and also in a range of sectors outside of conservation. The reference specimens of all the alien plant species included in the project database will be lodged in the Skukuza Biological Collection in the Kruger National Park.

Currently Phase 1 of the Pl@nt-Inv Kruger project, which is scheduled to last for 18 months, is underway at the SAEON Ndlovu Node. Two dedicated Project Technicians, Rob Taylor and Thembi Marshall are being kept busy collecting reference specimens and photographs during field trips into the KNP, and populating a database with the relevant supporting information sourced from printed and electronic sources.

In addition, these collecting trips – which include time spent in heavily impacted tourist camps and staff villages, along major rivers, and also in some wilderness areas - have extended the known distributions of specific alien plant species within the KNP, and in several cases have turned up alien species previously not recorded in the Park.

¹Contact Dr Dave Thompson: dave_at_saeon.ac.za