Concern has been expressed about the effectiveness of invasive alien plant (IAP) control operations carried out by Working for Water (WfW). South African legislation now also requires reporting on the effectiveness of IAP management interventions.
We assessed the effectiveness of IAP management practices in a large fynbos protected area, the Garden Route National Park, South Africa.
We undertook field surveys of pre-clearing IAP composition and the quality of treatments applied by WfW during 2012–2015 in 103 management units, covering 4280 ha. We furthermore assessed WfW data for evidence of change in IAP cover after successive treatments, and adherence to industry norms.
Despite the development of detailed management plans, implementation was poorly aligned with plans. The quality of many treatments was inadequate, with work done to standard in only 23% of the assessed area. Problems encountered included (1) a complete absence of treatment application despite the payment of contractors (33% of assessed area); (2) treatments not being comprehensive in that select areas (38%), IAP species (11%) or age classes (8%) were untreated; (3) wrong choice of treatment method (9%); and (4) treatments not applied to standard (7%). Accordingly, successive follow-up treatments largely did not reduce the cover of IAPs. Inaccurate (or lack of) infield estimation of IAP cover prior to contract generation resulted in erroneous estimation of effort required and expenditure disparate with WfW norms.
We advocate rigorous, compulsory, infield assessment of IAP cover prior to contract allocation and assessment of the quality of treatments applied prior to contractors’ payment. This should improve the efficiency of control operations and enable tracking of both the state of invasions and effectiveness of management.
Invasive alien plants (IAPs) are globally considered to be a significant threat to biodiversity conservation and the sustained delivery of ecosystem services (Dukes & Mooney
Strategic assessments of WfW have repeatedly expressed concern about the efficiency of the programme at various levels of operation (Common Ground
Globally, inadequate attention has been paid to assessing the effectiveness of control interventions (Kettenring & Adams
We report here on a case study in a large protected area of the Cape Floristic Region, the Garden Route National Park (GRNP), where we assessed the efficiency of WfW’s IAP management practices in the field. Parts of the GRNP have a long history of WfW operations, while comprehensive, strategic planning, prioritisation and improved monitoring have only recently been initiated. In particular, we considered the following aspects:
the alignment of implementation with management plans
the effectiveness of alien plant clearing practices in the field
the relationships between IAP species, age classes and cover, and treatment effort.
These investigations allowed us to identify challenges experienced by WfW projects during different stages of implementation (planning, costing and execution) and to produce recommendations towards improving the effectiveness of IAP management practices, which may be widely applicable.
The study area is the GRNP (33.80°S 22.50°E – 34.15°S 24.20°E), situated along the southern Cape coast of South Africa between the Indian Ocean in the south and the watershed of the Outeniqua and Tsitsikamma Mountains in the north. The park extends over 152 500 ha of which ca. 78 000 ha comprise fire-prone fynbos shrublands and ca. 41 500 ha comprise Afrotemperate forest. A more detailed biophysical description of the park is given by Kraaij, Cowling and Van Wilgen (
WfW has been involved in IAP control in the area of the GRNP (prior to proclamation) since the programme’s inception in 1995 albeit initially at a small scale (Hosking & Du Preez
Since 2014/2015, the scientific services department of South African National Parks (in consultation with park and WfW staff) developed a strategic medium-term plan for clearing IAPs from the GRNP. This plan was based on the principles of sound prioritisation of area and IAP species (Forsyth et al.
Principles associated with a strategic medium-term plan to control invasive alien plants in extensive and often remote fynbos areas of the Garden Route National Park.
Principle | Rationale |
---|---|
Fynbos at post-fire ages of 1–2 years should be given first priority. |
- At 1–2 years after fire, treatment occurs before reproductive maturity of most IAPs and, thus, largely prevents seed set. - 2 years allows for some seedling mortality because of self-thinning (Geldenhuys - Young vegetation is readily accessible and treatment methods are cheaper, thus reducing the cost. |
Fynbos at post-fire ages of 3–10 years are given second priority. |
- At 3–10 years post-fire, vegetation is still reasonably accessible, reducing the cost. - Some alien species may have reached reproductive maturity, but seed banks will be relatively smaller than in older vegetation. |
Follow-up treatments should take place at 4-year intervals where pines are the dominant invaders. |
- Pines are the dominant invaders in large tracts of mountain fynbos (Van Wilgen et al. - 4 years after the previous treatment, the regrowth is still small enough that simple treatment methods and equipment can be used. |
Follow-up treatments should take place at 2-year intervals in areas where acacias or other re-sprouters with large persistent soil-stored seed banks are the dominant invaders (in addition to ensuring that biological control agents are present, if available). |
- 2 years allows for some seedling mortality because of self-thinning (Geldenhuys - After 2 years, seedlings are still small enough and total biomass low enough that the required treatment methods are simple and relatively cheap; biomass does not yet cause a high fuel load and fire risk, neither does it have to be removed from riparian zones. - Although many invasive acacias reach reproductive maturity within a year, they usually do not produce large numbers of seeds at an early age, that is < 2 years (Milton & Hall - Follow-up intervals of < 2 years (albeit potentially more effective to treat acacias) would result in less resources being available for clearing of extensive catchment areas with low-cover pine invasions (Van Wilgen et al. |
Fell mature pines with chainsaws instead of ringbarking, as an initial clearing treatment (at densities where felled biomass does not create excessive fuel loads). |
- Ringbarking facilitates wind dispersal of pine seeds from slow-dying, standing trees, whereas seeds do not disperse from felled trees. - Felling results in 100% mortality (in the non-sprouting species, - Felling enables rapid verification of the extent and the quality of work done after treatment application, whereas it is difficult to assess whether ringbarking has been done properly, especially in inaccessible areas. - Felling (unlike dead standing trees) enhances landscape aesthetics (Barendse et al. |
Prioritising areas where IAPs occur at low levels of cover. |
- Provides the best return for investment (Van Wilgen et al. |
IAP, invasive alien plant.
We briefly outline the procedures involved in implementation of WfW projects by implementing agents, including SANParks, but more detail is provided by Loftus (
We restricted our analyses to the areas covered with fynbos vegetation within the GRNP, and to work carried out by WfW between 2004 and 2015 with an emphasis on the 2014/2015 financial year (1 April 2014 to 31 March 2015). Our unit of assessment was the management unit as spatially delineated by WfW and reported on as cases in their information system [see Working for Water Programme (
To assess whether implementation was aligned with the strategic medium-term plan, we compared, in terms of geographic overlap and total extent, the areas that were planned to be treated during 2014/2015 with those included in the 2014/2015 APO. We furthermore compared the strategic medium-term plan and APO with records of areas cleared during 2014/2015 according to the WfW information system.
To evaluate the effectiveness of clearing practices, we inspected 103 management units in the field (covering 4280 ha worked by WfW during 2012–2015) where we (1) estimated pre-treatment cover and size classes of IAP species and (2) assessed the quality of IAP management treatments. Field surveys were mostly done within 6 months after the execution of control treatments, which then provided information on both these aspects (as ringbarked and felled trees and shrubs remain
Types of deviations from acceptable standards of treatment application, and their rates of incidence in terms of the number of management units affected, and by area. A total of 103 management units, and 4280 ha, were assessed. More than one deviation type could pertain to a management unit.
Type of deviation | Incidence (% of number of units examined) | Incidence (% of total area examined) |
---|---|---|
Inaccurate estimation of alien plant cover, causing inaccurate allocation of person days and cost | 25 on par; | 40 on par; |
5 underestimated; | 7 underestimated; | |
70 overestimated | 53 overestimated | |
Incorrect identification of dominant species (often listing re-sprouters, requiring greater treatment effort, instead of non-sprouters) | 22 | 36 |
No evidence of work done during last treatment – Aliens present were not cleared, yet contractor paid – No aliens present, yet contract generated and contractor paid |
44 | 33 |
Some individuals of target species or part of management unit not treated | 34 | 38 |
Some age groups of target species not treated (e.g. adults treated, saplings untreated) | 5 | 8 |
Some species not treated (e.g. |
11 | 11 |
Wrong choice of treatment method (e.g. ringbarking of trees < 10 cm diameter; ringbarked AND felled trees; ringbarking of dead trees) | 11 | 9 |
Treatment not applied to standard
– Ringbarked strip too narrow – Ringbarked on only one (the most visible) side of the tree – Re-sprouting plants felled but no herbicide applied, or wrong choice/concentration of herbicide |
7 | 7 |
Work done well | 15 | 23 |
We also assessed whether IAP cover recorded in WfW’s information system decreased with successive follow-up treatments. For these analyses, we considered the complete treatment history (spanning the period 2004–2015) of management units (
The large and persistent soil-stored seed banks of the dominant
To assess whether allocation of effort to treatments was aligned with the dominant IAP species, age classes and cover, we compared the relationship between these variables with the WfW norms (Neethling & Shuttleworth
The work carried out during the 2014/2015 financial year deviated to a large degree from the agreed priorities in the medium-term strategic plan. Only 47% of the area on the strategic medium-term plan for that year was carried forward to the APO. Furthermore, there was a failure to complete all of the work scheduled in the APO. Only 19% of the area on the strategic plan for 2014/2015 and 37% of the area on the APO were actually carried out (see
We found evidence for widespread ineffective treatment of IAPs in the field. Field surveys of recently treated areas (103 management units, total area 4280 ha) showed that in 85% of the assessed units (77% of the assessed area), work was not done to standard (
We found evidence that cover was regularly overestimated prior to the awarding of contracts. The IAP cover estimates recorded by WfW (mean 54.8% ± SD 56.5%; median 32.5%) prior to contract allocation were more than double (
Cover (%) of IAPs as estimated by Working for Water prior to contract allocation and during our field surveys in the same 103 management units (total area 4280 ha).
Frequency distribution of cover (%) of IAPs estimated by WfW in 764 management units last treated between 2012 and 2015 (total area 21 760 ha).
We also found, contrary to expectation, that repeated treatments of management units more frequently led to increases, rather than decreases, in cover. In addition, and also contrary to expectation, we found no significant difference (
(a) Absolute and (b) proportional change in cover of IAPs effected by successive follow-up treatments, as recorded by Working for Water in 764 management units (21 760 ha). Absolute change was calculated as the difference between cover before a specific treatment and cover before the prior treatment; proportional change was calculated as the ratio of cover before a specific treatment to the cover before the prior treatment. Treatment = 0 represents the effect of the initial treatment. Outliers are not shown in (a) to enhance figure clarity, while the y-axis in (b) is spaced on a log-scale to accommodate outliers.
The effort required to control IAPs increased with IAP cover (
The relationship between actual allocated treatment effort (expressed as person days per hectare) and IAP cover estimates, compared to Working for Water norms. Distinction is made between
A lack of planning had previously been identified as a factor reducing the effectiveness of control (Van Wilgen et al.
The GRNP proved exemplary in having heeded the calls (Van Wilgen et al.
Our assessments of the quality of infield treatment applications revealed equally disappointing results with no evidence of work done over a third of the assessed area, and deviations from acceptable standards of treatment application occurring over an additional 44% of the area. Treatments have, thus, been applied to standard in less than 15% of the assessed units. Our findings are similar to those of McConnachie et al. (
Overall, less than 10% of the strategic medium-term plan that was designed to ‘effectively’ reduce IAP infestations in the fynbos of the GRNP has been achieved, when considering that approximately a third of the area targets as per the planning products have been ‘implemented’, of which less than a quarter has been treated to standard. Although better planning and prioritisation are often recommended to improve the efficiency of IAP management practices, our case study suggests that sound planning by itself does not ensure efficiency. Accordingly, Van Wilgen et al. (
IAP cover mostly appeared to be overestimated by WfW. A substantial proportion of the IAP cover records in WfW’s information system greatly exceeded 100% (
Inaccurate IAP cover estimation is likely exacerbated by the lack of a clearly defined method for determining cover (or density), inconsistent application of any such method and observer subjectivity that may account for up to sevenfold variances in cover estimates for the same area (Loftus
The observed relationship between workload/effort allocations and IAP cover estimates did not reflect a close correlation or stringent adherence to norms, with three- to fivefold deviations from the norms being common (
The lack of a discrepancy observed in the effort – IAP cover relationship between two main IAP species groups (
Interventions essential to improving the effectiveness of IAP management practices at project level largely relate to (1) improvement in IAP cover estimations, (2) additional quality control in terms of infield operations and (3) auditing of data captured in the WfW information system. In particular, we recommend the following:
Increased alignment of project level annual plans and implementation with strategic planning.
Implementation of effective protocol for IAP cover estimations that are relevant to specific biomes/regions and IAP species to be managed (cf. Loftus
Compulsory infield assessments of IAP cover prior to contract generation and increased investment (in terms of travel, time, staff skills/training allowances) to this end. Outsourcing of this function should be considered as that may reduce subjectivity and scope for fraud, improve professionalism, specialisation and standardisation of this function, and yield data that are more comparable in space and time.
Auditing of field data submitted for generation of contracts through the WfW information system, and in particular in terms of deviations from historical data in IAP cover.
Ensuring that the WfW information system correctly applies the norms when calculating effort allocations in relation to IAP infestation attributes.
Compulsory infield inspections of the quality of treatments applied during contract implementation, that is, mid-term and prior to contract payment.
Allocation of funding by WfW to implementing agents specifically for monitoring and research, including compliance monitoring, ecological monitoring, and applied research applicable to the challenges faced by conservation agencies in the management of IAPs.
Many challenges experienced in the management of IAPs as revealed by this study relate to functions performed at WfW project management level. These include the development of annual plans that are aligned with the medium-term strategic plan, coordination of different processes involved in implementation, infield identification of IAP species and age classes, IAP cover estimations, application of norms in the generation and costing of contracts, choice of best treatment methods and infield inspections of the standard of treatment applications. In reality, the project management function in WfW is a daunting task, requiring a considerable and varied skillset and experience, including ecological, social and financial, with project managers typically managing annual budgets of ZAR 3–8 million. Due to poor remuneration, most applicants for project manager positions do not meet the tertiary education requirements, resulting in managers appointed being inadequately skilled. Furthermore, the mechanisms necessary to mentor and support these positions are not present within the implementing agents (cf. Coetzer & Louw
We strongly advocate greater involvement of implementing agents (particularly in the case of conservation agencies) in all the major processes involved in IAP management, including planning, monitoring of IAP distributions, quality control of infield operations and training of all staff involved. The current approach that uses poverty-relief funds for alien plant control projects is politically attractive, and it has been the main reason that the control projects have received high levels of funding. However, as currently configured, the model imposes exacting requirements and demands that employment be maximised. These demands come at the cost of effectively achieving ecological goals that in the longer term would arguably support greater economic development (Van Wilgen & Wannenburgh
We thank Working for Water for providing access to data and the anonymous reviewers for their suggestions which enabled improvement of the manuscript.
Funding was provided by South African National Parks, the Nelson Mandela Metropolitan University, the DST-NRF Centre of Excellence for Invasion Biology and the National Research Foundation (grant no. 87 550 for B.W.v.W.).
The authors declare that they have no financial or personal relationship(s) that may have inappropriately influenced them in writing this article.
T.K. was the project leader. T.K., J.A.B. and D.R.R. undertook field data collection. T.K., J.A.B. and N.S.C. were responsible for data processing and analyses. All authors, including B.W.v.W., made conceptual contributions.
Geographic correlation between strategic medium-term plan (‘Strategic Plan’), annual plan of operation (‘Annual Plan’), and work recorded in Working for Water information system as contracted and paid (‘Paid’) during the 2014/2015 financial year in the Garden Route National Park (‘GRNP’).