Assessing the effectiveness of invasive alien plant management in a large fynbos protected area
Tineke Kraaij1, Johan A. Baard2, Diba R. Rikhotso2, Nicholas Cole3, Brian W. van Wilgen4
1 Nelson Mandela Metropolitan University, School of Natural Resource Management – Nature Conservation, Private Bag X6531, George, 6530
2 South African National Parks, Garden Route Scientific Services, P.O. Box 3542, Knysna, 6570
3 South African National Parks, Biodiversity Special Projects, Private Bag X6531, George, 6530, South Africa
4 Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland, 7602
Concern has been expressed about the effectiveness of invasive alien plant (IAP) control operations of Working for Water (WfW). Recommended remedial measures included improved planning and prioritisation, and efficiency and professionalism of operations. We assessed the effectiveness of IAP management practices in a large fynbos protected area, the Garden Route National Park. We found that although substantial effort was invested in sound planning and prioritisation, implementation was poorly aligned with plans. Field surveys in 103 management units (4280 ha) suggested that the general quality of treatments was poor, with work done to standard in only 23% of the area. Deviations from acceptable work standards included a complete absence of work despite payment of contractors (occurring in 33% of assessed area), partial work done (38%), not all the IAP species (11%) or age classes (8%) present being treated, wrong choice of treatment method (9%), and treatments not being applied to standard (7%). Field surveys and interrogation of WfW’s database suggested that inaccurate (or lack of) in-field estimation of IAP cover prior to contract generation resulted in erroneous estimation of effort required, and expenditure disparate with industry norms. Successive follow-up treatments furthermore did not necessarily effect reductions in IAP infestations. We advocate rigorous, compulsory, in-field assessment of IAP cover prior to contract allocation, and assessment of the quality of treatments applied prior to contractor payment. In line with legislative requirements, this will enable tracking of both the state of invasions and the effectiveness of interventions, and improve the efficiency of control operations.