F
PRIORITISING QUATERNARY CATCHMENTS FOR INVASIVE ALIEN PLANT CONTROL WITHIN THE WORKING FOR WATER GAUTENG REGION: PROJECT REPORT
March 2011
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng Region
Greg G. Forsyth, Patrick J. O’Farrell and David C. Le Maitre (authors in alphabetic order) Reviewer: Brian W. van Wilgen CSIR Natural Resources and the Environment P.O. Box 320 Stellenbosch 7599, South Africa.
Report number: CSIR/NRE/ECO/ER/2011/0029/B March 2011
Prepared for: Andrew Wannenburgh Working for Water Programme Private Bag X4390 Cape Town 8000 Tel: 021 441-2738 E-Mail:
[email protected]
Contact person: Gregory Forsyth Tel: 021 888-2406 Fax: 021 888-2684 Email:
[email protected]
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
Executive Summary Introduction Invasive alien plant control requires the allocation of limited resources to control operations to maximise benefits. The priorities for such allocation are based on a mixture of fact and opinion, interpreted either subjectively or objectively, and often not transparent or repeatable. This project develops an approach that could assist managers and planners in the Working for Water Programme’s Gauteng Region to prioritise their activities with a degree of transparency.
Conclusions and recommendations This study has successfully applied the approach developed by van Wilgen et al. (2008) at a quaternary catchment scale in the Gauteng Province. However, a number of follow-up actions will be needed if this approach is to deliver its full potential in terms of assisting the Working for Water Programme to improve its operations and its impact. We recommend the following: •
That the techniques developed at this quaternary catchment scale be adopted by Working for Water’s national and regional planning offices to assist with prioritisation, planning, and the allocation of resources to both existing and new projects on an ongoing basis.
•
The priorities identified here be used to guide the allocation of funds between quaternary catchments and subcatchments of Gauteng region.
•
That a spatial database be developed to underpin effective comparisons of areas. This database could contain data relating to most of the criteria identified here, including water yield, erosion and water quality variables, terrestrial and fresh water biodiversity conservation, protected areas, carrying capacity, cultivation potential, cultural and tourism use features and the abundance and potential spread of invasive alien species.
•
Each Working for Water region should maintain existing datasets and revise them on a regular basis. This period between revisions should not be longer than 3 years so as to coincide with the medium term expenditure framework of government.
We used the Analytic Hierarchy Process (AHP) to facilitate prioritisation. AHP is a multiple criteria decision-making tool for setting priorities when both qualitative and quantitative aspects of a decision need to be considered, and for achieving group consensus.
Priorities in the Gauteng Regional area A total of 49 quaternary catchments occur within three primary catchments that make up the WfW Gauteng region, and were used in this assessment. The five quaternary catchments with the highest relative importance are A21G, A21F, A21E, B20B, and B20A. An area to the north west, north, and north east of Krugersdorp, and just south of the Hartebeespoort dam contained six of the top ten identified priority catchments. This area is important for water yield and river conservation, this the Witwatersrand draining this region into the Hartebeespoort dam. It also contains important provincial, municipal reserves, conservancies and eco-tourism and cultural features with the Sterkfontien caves and the “Cradle of Human kind” found here. There are three alien clearing projects in this area. In general the highest priority catchments are those which have high water yields, contain areas that are considered to important for river and terrestrial conservation and are vulnerable alien invasion.
p. i
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
Acknowledgements We thank the Working for Water Programme of the Department of Water and Environment Affairs for funding this work. We thank Ms Linda Mabuza and Mr Andrew Wannenburgh of the Working for Water Programme of the Department of Water and Environment Affairs for supporting the project and serving on the reference group. The following managers, implementing agents and researchers are thanked for their informed and enthusiastic participation in the workshop aimed at developing a model for assessing the priority quaternary catchments to clear in the Gauteng Working for Water Region: Linda Mabuza, Lenesse Tshikovhi, Tshepo Seale, Ivy Duba, Mariam Dickinson, Sizwe Sogaxa, Johannes Majuta, Concilence Samba, Charles Ngwenya, Nacy Matloko, Phillemon Shibambo, Zacharia Mokoana, Phyllis Serumula, Anill Govender, Kelebogile Kekana, Lindelani Mthembu, Phyllystas Mmakola, Esther Mampane, Thapelo Loobile, Christopher Mthombeni, Petrus Links.
p. ii
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
Contents Executive Summary ........................................................................................................................................................... i Acknowledgements........................................................................................................................................................... ii Contents........................................................................................................................................................................... iii Figures ............................................................................................................................................................................. iv Tables ............................................................................................................................................................................... v 1. INTRODUCTION
1
2. SCOPE OF WORK
1
3. APPROACH
4
3.1
WORKSHOP TO DETERMINE RANKING CRITERIA
4
3.2
SPECIES SELECTION
4
3.3
GOAL AND CRITERIA
4
SELECTING APPROPRIATE DATA 3.4.1 Water resources 3.4.1.1 Water yield 3.4.1.2 Erosion 3.4.1.3 Water quality 3.4.2 Biodiversity conservation 3.4.2.1 Terrestrial conservation 3.4.2.2 Fresh water conservation 3.4.3 Agricultural potential 3.4.3.1 Grazing capacity 3.4.3.2 Crop potential 3.4.4 Presence of priority invasive alien plants 3.4.4.1 Invasive potential 3.4.4.2 Current extent 3.4.5 Protected areas 3.4.6 Eco-tourism and cultural sites 3.4.7 Fuel loads
5 5 5 5 5 6 6 6 6 6 7 7 7 7 7 8 8
3.5
SPATIAL DATA SETS USED IN THE PRIORITISATION
9
3.6
CALCULATING THE WEIGHTS USED BY THE EXPERT CHOICE SOFTWARE
3.4
4. RESULTS
10 10
4.1
GOAL AND CRITERIA
10
4.2
GAUTENG PRIORITY QUATERNARY CATCHMENTS
12
5. CONCLUSIONS
18
6. RECOMMEDATIONS
19
7. REFERENCES
20
p. iii
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
Appendix 1
Priority invasive alien plants in the moist savanna and grassland biomes for the Gauteng province
Appendix 2
Agenda for Gauteng region
Appendix 3
Participants in expert workshops
Figures Figure 1:
A map showing the regional boundaries of the Working for Water program in the Gauteng region and the two biomes, Savanna and Grassland which dominate this region. ____________________________________________________________3
Figure 2:
A map showing the regional boundaries of the Working for Water programme in the Gauteng region, major towns and the primary catchments found in this region.________________________________________________________________3
Figure 3:
The relative importance and ranking of the 45 top priority quaternary catchments out of the 49 in the Gauteng Region. These values have been normalised. ___________________________________________________________13
Figure 4:
The relative importance of quaternary catchments in the Gauteng region for each of the eight criteria that were assigned the highest importance in the model. The importance or weight is shown in parentheses. _____________________14
Figure 5:
The relative importance of quaternary catchments in the Gauteng region for the 9th to 14th most important criteria in the model. The importance or weight is shown in parentheses. __________________________________________________15
Figure 6:
The priority quaternary catchments identified according to priority classes within the Gauteng Region. Priority weightings reflect the scores for each catchment. _____16
Figure 7:
The expenditure allocated to invasive alien plant clearing projects in the Gauteng region in 2010/11, in relation to priorities identified in the study (Current exp.). Clearly, most quaternary catchments, including several of high priority, do not receive any funding. The figure also shows the amount of funding that would be allocated to each catchment if the allocations were proportional to priorities (Exp. according to priority), as well as the funding that would be allocated to each catchment (Top 13 priorities) if the allocation went to the 13 catchments with the highest priority. __________________________________17
p. iv
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
Tables Table 1:
Grazing potential ranges and associated midpoints in large livestock units (LSU) per km2 (Scholes 1998). __________________________________________________6
Table 2:
Invasive alien species identified and assessed in the national invasive alien plant survey (Kotze 2010), and the fuel score allocated to each of these based on biomass and structure. Species fuel weights are proportional to the individual fuel divided by the total fuel score for all species. ______________________________9
Table 3:
Spatial datasets used to rank quaternary catchments in relation to selected criteria and sub-criteria. _________________________________________________10
Table 4:
Identified criteria and descriptions of the attributes that they incorporate.___________11
Table 5:
Nested criteria, together with the relative weightings, identified as significant for the purposes of prioritising quaternary catchments in the Gauteng region for the clearing of invasive alien plants.___________________________________________11
p. v
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
1. INTRODUCTION Invasive alien plant control requires the allocation of limited resources to control operations to maximise benefits. The priorities for allocating resources typically are based on a mixture of fact and informed opinion and this information may be interpreted either subjectively or objectively. However, the information and the rationale behind the resulting priorities are rarely made explicit so it is difficult to assess the validity of the resulting priorities. The Council for Scientific and Industrial Research (CSIR) has recently completed studies on the prioritisation of primary catchments for the purposes of guiding invasive alien plant control operations. These included an assessment of the terrestrial biomes of South Africa and the established national priorities (van Wilgen et al., 2008), and others that have focused on quaternary catchment scale and established priorities for the Northern Cape and Western Cape (Forsyth et al., 2009, Le Maitre & Forsyth 2010). These studies developed an approach and method that enables managers and planners in the Working for Water Programme to prioritise their activities in a way that is transparent, logical and defensible. A biome-level study has also been undertaken and developed methods for the identification of a priority list of (i) invasive alien plants, and (ii) areas (primary catchments) within the terrestrial biomes of South Africa that should be targeted for control by the Working for Water Programme. Ms Linda Mabuza of the Department of Water Affairs and Forestry (DWAF) asked the CSIR to assist in prioritising areas to clear within the Working for Water region in the Gauteng province by applying the methods developed for the biomes and the quaternary catchment scale studies. This report presents the results of this study to determine the priority quaternary catchments to clear within the Gauteng region. We also make recommendations for further improvements to the prioritisation process and its implementation by the Working for Water Programme.
2. SCOPE OF WORK This project is conducted as part of a collaborative agreement between the DWAF and the CSIR. The work was guided and reviewed by a reference group, appointed by DWAF at the initiation of the project, in terms of the collaborative agreement. Members of the reference group are: •
Ms Linda Mabuza (Department of Water and Environment Affairs – Working for Water Programme, Gauteng)
•
Mr Andrew Wannenburgh (Department of Water and Environment Affairs – Working for Water Programme)
It was agreed at the outset of the study that the planned scope of activities would be as follows: •
The work would focus on the dominant biomes found in the region, the grassland and moist savanna (Figure 1).
Page 1
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
•
The work would entail prioritising areas to clear at a quaternary catchment scale within the portions of the Limpopo catchment (A), Olifants catchment (B), the Upper Vaal catchment (C), which occur in the Working for Water regional boundaries of the Gauteng Province. We selected all the quaternary catchments which fall within this boundary (Figure 2).
•
The Analytic Hierarchy Process (AHP)1 would be used to facilitate the prioritisation of quaternary catchments using Expert Choice 11.5 decision support software (Anon. 2009).
•
The criteria to use for prioritising the quaternary catchments for the clearing of invasive alien plants would be identified and agreed to at an expert workshop to be held in or near Roodeplaat.
•
An obvious criterion was whether or not priority alien invasive species are present or likely to spread in a quaternary catchment. In this regard it was agreed that we would start with the list of priority species identified for the Moist Savanna and the Grassland (see Appendix 1) by the recent CSIR study (van Wilgen et al., 2008). In the Gauteng Province study we used data from National Invasive Alien Plant Survey (Kotzé et al. 2010) for prioritising quaternary catchments based on the current extent and density of invasions. The National Invasive Alien Plant Survey (NIAPS) was undertaken by the ARC and used an ecotope classification to extrapolate from the point samples to landscapes.
•
The work of Rouget et al. (2004) and Mgidi et al. (2007) would be used if necessary to identify areas that are likely to become invaded by the species identified in the CSIR study as priority species for clearing.
•
Where applicable and available we would also made use of river (Nel et al. 2007; Nel et al. 2011) and terrestrial (Driver et al. 2005) conservation prioritisation datasets for various spatial scales.
•
The assessment would focus on (a) the criteria and (b) the relative weighting of those criteria that will be used in prioritising the quaternary catchments and not on direct pair-wise catchment comparisons. The primary reason for this is that the AHP approach requires a pairwise ranking and there are too many quaternary catchments in the primary catchments of the Gauteng Province to make this feasible. We would therefore apply the procedures which we developed for automating these comparisons for the Western and Northern Cape Studies (Forsyth et al. 2009, Le Maitre & Forsyth 2010).
The Working for Water Programme’s strategic plan for 2008 – 2012 lists “the reduction of impact of existing priority invasive alien plant problems” as one of three primary goals relating to natural resource management. The other two are related to preventing problems, and building capacity to address problems. This project will assist in the identification of such priorities at a quaternary scale in the Gauteng region, which are not clearly defined at present.
1
AHP is a multiple criteria decision-making tool for setting priorities when both qualitative and quantitative aspects of a decision need to be considered. It involves setting a goal, breaking it down into its constituent parts and then assigning relative weights to each of these, thereby progressing from the general to the specific. Scoring is on a relative basis comparing one choice with another. Relative scores for each choice are computed with each level of the hierarchy. Scores are then synthesised through a model contained in Expert Choice. This yields a composite score for each choice at every level as well as an overall score.
Page 2
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
Figure 1: A map showing the regional boundaries of the Working for Water program in the Gauteng region and the two biomes, Savanna and Grassland which dominate this region.
Figure 2: A map showing the regional boundaries of the Working for Water programme in the Gauteng region, major towns and the primary catchments found in this region.
Page 3
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
3. APPROACH 3.1 WORKSHOP TO DETERMINE RANKING CRITERIA A one day workshop was held at the Department of Water Affairs Training Centre, Roodeplaat Dam on 18th January 2011. The workshop agenda is provided in Appendix 2. A total of 22 people from the key economic sectors, including, Conservation, Agriculture and Water Affairs as well as the Working for Water representatives responsible for implementing Working for Water projects, participated in the workshop (see Appendix 3). The topics addressed at the workshop were: •
Findings from previous studies conducted by the CSIR at a regional or porovinceial level in the Northern Cape and the Western Cape (Forsyth et al. 2009; Le Maitre & Forsyth 2010)
•
An explanation of the Analytic Hierarchy Process
•
Current priority invasive alien plants for the savanna and grassland biomes (See Appendix 1)
•
The goal, criteria (objectives) and sub-criteria (sub-objectives) for prioritising quaternary catchments. These were captured on paper and using the Expert Choice software
•
Pair-wise comparisons (ranking) of the agreed criteria and sub-criteria using the Analytical Hierarchy Process approach in the Expert Choice software
•
Identifying the datasets that will allow for the objective comparison of quaternary catchments with regard to particular criteria
3.2 SPECIES SELECTION Workshop participants undertook a species verification exercise. Here local experts examined and commented on the lists of invasive species identified by van Wilgen et. al (2008; 2010) for the Savanna and Grassland biomes. A consolidated list was created which included those verified species as well as additional species which participants felt were problematic. The result was a complete list of the most important alien species for the Gauteng Province. These are presented according to the regions biomes in Appendix 1.
3.3 GOAL AND CRITERIA The workshop participants established a goal for prioritizing the clearing of catchments in within the Gauteng region. Criteria for meeting this goal were also developed and weighted in relation to one another. The AHP was used to compare each individual criterion to each other and to assign weightings to each of these according to their relative importance (Saaty, 1990). The Expert Choice software package, which uses an Analytical Hierarchical Processes, was used to facilitate this process (Anon 2009).
Page 4
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
3.4 SELECTING APPROPRIATE DATA A summary of the data sets used, the rationale for using these to address the criteria underlying the hierarchy mode and methods are provided below. We were limited in our choice to those datasets that were readily available (in the public domain) and covered the entire working for water Gauteng region. We did not rely on expert opinion in palace of data sets. Where no data was available we used surrogate measures or related variables. Where this was not possible we gave all quaternary catchments the same value.
3.4.1
Water resources
3.4.1.1 Water yield Surface water yield information was obtained from the Water Resources 2005 quaternary catchment dataset (Middleton and Bailey 2008). Information relating to the annual run-off was used (coded as “naturalized run-off” in this database). To compare catchments directly we used the mean annual runoff to rank catchments with catchments with higher water yields assigned higher weights in proportion to their area.
3.4.1.2 Erosion We used the soil erodibility factor defined by Schulze and Horan (2007), who assigned each soil type within South Africa an erodibiltiy factor (K), ranging from 0.1 (soils with a low erodibility) to 0.7 (soils with a high erodibility). This erosion factor was developed for assessing dryland erosion, not river bank stability, however we felt this to be an appropriate surrogate in the absence of more suitable data. We developed a soil erodability data layer for the quaternary catchments, after removing all transformed areas. We multiplied the area under each of the soil classes by the erodibility factor, summed these scores for the quaternary catchments and divided by the area of the quaternary catchment. Catchments with the highest score were most vulnerable to erosion and received the greatest weight.
3.4.1.3 Water quality This criterion identifies the potential to improve water quality by controlling invasive alien plants in catchments where the quality is poor. Water quality is a problematic variable to deal with at the regional and national scale. The DWA has been collecting water quality data at a number of sites on rivers throughout this region. However, this record is not necessarily representative. Only a small sample of the rivers is actually monitored, so the coverage is very uneven. The sample is taken at a particular point but the source of the problem may be located well upstream and it is not necessarily well identified. In many cases the reported problems are high total dissolved solids but these may not be affected by plant invasions or their control. A recent national overview of the state of water resources in South Africa (CSIR 2011) highlighted a number of water quality issues that affect different parts of the country, notably eutrophication (nutrient enrichment) and the occurrence of toxic cyanobacteria blooms in major water storage dams (storage capacity > 1 Mm3). In both cases clearing of invasive plants could increase inflows and help dilute the pollutants that cause the problems. We have developed a simple scoring system where the catchments feeding dams are given a score of zero where there are no problems to six for
Page 5
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
hypertrophic and an additional score of one was added where there was at least one report of a cyanobacteria bloom (Chamier et al. 2011). Catchments contributing to more than one dam with such problems have been a summed score, where all storage dam values were added together.
3.4.2
Biodiversity conservation
3.4.2.1 Terrestrial conservation We used vegetation status as a measure of the requirements for terrestrial conservation in this region. Vegetation conservation status based on the most recent conservation status assessment (DEA 2009) was used to update the 2004 status used in the national vegetation map (Mucina and Rutherford 2006). Once all transformed areas had been removed from the region, the total area of each vegetation status class was expressed as a proportion of the total area of each quaternary catchment. The catchments with the highest proportion of threatened vegetation received the higher weights.
3.4.2.2 Fresh water conservation We determined areas of conservation significance from the national freshwater ecosystem priority area data (Nel et al. 2011). Areas identified as Fresh water Ecosystem Priority Areas and Fish Support Areas were selected and their area calculated as a proportion of each quaternary catchment. Catchments with the highest proportional area of these conservation areas were given the greatest weight.
3.4.3
Agricultural potential
3.4.3.1 Grazing capacity The relative value of the land for livestock production was estimated by calculating the grazing potential of quaternary catchments. This potential was derived from Scholes’ (1998) estimates of sustainable mean domestic livestock production (Table 1). This approach may underestimate the carrying capacity for browsing antelope but as game farming only occurs in limited areas this would not significantly affect the outcome. Table 1: Grazing potential ranges and associated midpoints in large livestock units (LSU) per km2 (Scholes 1998).
LSU range LSU mid‐point
0 – 1 0.5
1 – 2 1.5
2 – 3 2.5
3 – 4 3.5
4 – 6 5
6 – 8 7
8 – 10 9
10 – 14 12
14 – 18 16
18 – 22 20
We assumed that only untransformed (natural) vegetation would support livestock, and subtracted the area of transformed vegetation, using the National Land Cover Database 2000, (Van den Berg et al. 2008) from the carrying capacity layer (Scholes 1998) in each catchment before the above calculation was made. We took the midpoint of each class, and multiplied it by the remaining area in that class in each quaternary catchment to get an area weighted mean grazing capacity. The catchments with the highest grazing capacity were given the greatest weights.
Page 6
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
3.4.3.2 Crop potential We used the Land capability data (ARC 2002) to determine the cultivation potential of areas within this region. This database divides the national land surface into eight classes, ranging from 1 = Very high agricultural potential to 8 = Very low agricultural potential. We unioned the quaternary catchments with the land capability database after removing all transformed areas. We multiplied the area under each of the classes by the number of the class (1 to 8), summed these scores for the quaternary catchments and divided by the area of the quaternary catchment. We then subtracted all values from highest category value (8), to reverse the order of scores, making the area with the highest score as having the most potential for cultivation and visa versa.
3.4.4
Presence of priority invasive alien plants
3.4.4.1 Invasive potential We estimated the potential invasions by priority species using the combined list that was generated at the workshop which was based on those identified by van Wilgen et al. (2008) and supplemented by participants in the workshop. Data on the potential ranges (invasion envelopes) have been developed for a range of species by Rouget et al. (2004), and we made use of this data. We determined the number of priority species that could invade the remaining natural vegetation in a quaternary catchment based on the biome composition of that catchment (grassland and savanna). We assigned the highest of these two values to the catchment. The quaternary catchment with the highest number of species received the weight based on this species number.
3.4.4.2 Current extent Condensed invaded area was extracted for each priority species from the NIAPS data (Kotze 2010) and expressed as a proportion of the area of the respective quaternary catchment. Whilst we note that not all invasive alien species have been captured in this survey the dominant species which make up most of this density are captured. Quaternary catchments with a greater proportion of condensed hectares of invasive alien plants received the higher weights.
3.4.5
Protected areas
We used the protected areas, both formal and informal, from the recent update of the national protected areas database prepared for the National Protected Areas Expansion Strategy (Biodiversity GIS 2011). These areas include those managed by South African National Parks, provincial nature conservation authorities and local municipalities, private nature reserves, conservancies and water management areas. We allocated protected areas to each of the following categories: Provincial reserves and world heritage sites, municipal reserve and conservancies. The total extent of each category of protected area was expressed as a proportion of the total area of the quaternary catchment. Catchments with a greater proportion of total extent of protected areas received the higher weights for each of these protected area categories.
Page 7
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
3.4.6
Eco-tourism and cultural sites
From the environmental potential atlas (ENPAT 2001), we selected all shape files that related to cultural features and tourism features (these included protected areas, cultural sites, gardens, heritage sites, hiking areas, ramsar sites, resorts, rock art, routes, cultural interest, historic battle fields). A single data layer of these features was created, the areas of each of these calculated, and proportioned according to quaternary catchments. Quaternary catchments with higher proportional areas of cultural and tourism features received the higher weights.
3.4.7
Fuel loads
This criterion identifies the potential to remove the risk of increased fuel loads by controlling invasive alien plants in catchments where they have the greatest biomass and fuel load. We estimated this using the cover of individual invasive species within the Gauteng region (Table 2). Each species was allocated a score of between 1 and 3 based on their biomass, life history traits and structure. Species with a high fuel load got a 3, moderate fuel load 2, and low fuel load, 1. A fuel weight was then calculated for each of these species as the proportional contribution to the sum of all scores for all species considered. The total condensed area for each species for each quaternary catchment was multiplied by their fuel weight, and then all species fuel weights were summed up for each quaternary catchment. This summed total was then proportioned according to the quaternary catchment area.
Page 8
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
Table 2: Invasive alien species identified and assessed in the national invasive alien plant survey (Kotze 2010), and the fuel score allocated to each of these based on biomass and structure. Species fuel weights are proportional to the individual fuel divided by the total fuel score for all species. Fuel Score
Species fuel weight
Acacia cyclops
3
0.0625
Arundo donax
3
0.0625
Chromolaena odorata
3
0.0625
Species or group
Eucalyptus spp.
3
0.0625
Hakea spp.
3
0.0625
Pinus spp.
3
0.0625
Acacia melanoxylon
2
0.0417
Acacia saligna
2
0.0417
Caesalpinia decapetala
2
0.0417
Lantana camara
2
0.0417
Populus spp.
2
0.0417
Prosopis spp.
2
0.0417
Sesbania punicea
2
0.0417
Tamarix chinensis
2
0.0417
Wattle species (mearnsii, dalbata, decurrens, baileyana)
2
0.0417
Agave spp.
1
0.0208
Atriplex nummularia subsp. nummularia
1
0.0208
Cereus jamacaru
1
0.0208
Cestrum spp.
1
0.0208
Jacaranda mimosifolia
1
0.0208
Melia azedarach
1
0.0208
Opuntia spp.
1
0.0208
Psidium guajava
1
0.0208
Rosa rubiginosa
1
0.0208
Salix babylonica
1
0.0208
Senna didymobotrya
1
0.0208
Solanum mauritianum
1
0.0208
3.5 SPATIAL DATA SETS USED IN THE PRIORITISATION The prioritisation of the catchments relies on matching of criteria data sets that either provide a direct measure of the criterion, or a surrogate measure where direct data are not available (Table 3).
Page 9
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
Table 3: Spatial datasets used to rank quaternary catchments in relation to selected criteria and sub-criteria. Criterion
Sub-criterion
Water resources
Water yield Water quality Erosion
Biodiversity conservation
Land (biodiversity) Rivers (biodiversity)
Agricultural potential
Spatial data
1
Water Resources 2005 (Middleton & Bailey 2008) Impacts of Invasive Alien Plants on Water Quality (Chamier et al. 2011; CSIR 2011) South African Atlas of Climatology and Agrohydrology (Schulze & Horan 2007) National Vegetation Map (Mucina and Rutherford 2006) updated with the 2009 threatened ecosystem list (DEA 2009). Environmental Potential Atlas (ENPAT 2001) National freshwater ecosystem priority areas (Nel et al. 2011)
Grazing capacity
Areas of homogenous grazing potential (Scholes, 1998)
Crop potential
National land capability (ARC 2002); National Land Cover Database 2000 (Van den Berg et al 2008)
Presence of priority species
Current extent
National Invasive Alien Plant Survey (Kotze 2010)
Invasive potential
Rouget et al. (2004) and Mgidi et al. (2007)only of potential
Protected areas
Provincial reserves world heritage sites
National Protected Areas Database (SANBI)- (Biodiversity GIS 2010)
Municipal reserves
National Protected Areas Database (SANBI)- (Biodiversity GIS 2010)
Conservancies
National Protected Areas Database (SANBI)- (Biodiversity GIS 2010)
Eco-tourism and cultural sites
Environmental Potential Atlas (ENPAT 2001)
Fuel loads
National Invasive Alien Plant Survey (Kotze 2010)
1
See reference section for complete references
3.6 CALCULATING THE WEIGHTS USED BY THE EXPERT CHOICE SOFTWARE The Expert Choice software (Anon 2009) calculates the weights of alternatives (quaternary catchments in this case) as proportions that sum to one. For each of the criteria and sub-criteria used by the AHP model we calculated the sum of the values for each variable for each quaternary catchment. Each quaternary catchment’s value for that variable was then divided by the corresponding total to give the final weight.
4. RESULTS 4.1 GOAL AND CRITERIA The goal that that was agreed on at the Roodeplaat workshop was “To control invasive alien plants so as to minimize their negative impacts on natural resources and ecosystem services”. Goal setting was followed by the identification of six criteria for prioritising the clearing of quaternary catchments within the Gauteng region. The criteria identified were: Water resources, biodiversity conservation, agricultural potential, protected areas, presence of priority invasive alien species, eco-tourism and cultural features, and fuel loads. Descriptions of these criteria are provided in Table 4. Many of the criteria were further
Page 10
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
divided into sub-criteria, for example, biodiversity conservation was divided into the sub-criteria of terrestrial conservation and fresh water conservation. The final ranking for prioritisation, considering all the criteria, and sub-criteria is provided Table 5. Table 4: Identified criteria and descriptions of the attributes that they incorporate. Criterion
Description of criteria attributes
Water resources
The degree to which alien species affect our limited water resources. This includes water quantity, water quality and erosion effects. The objective behind this criterion was to secure the sustainable provision of water.
Biodiversity conservation
The degree to which the alien species are able to displace indigenous species, in particular their impact on protected areas, terrestrial and riparian systems, and the biodiversity they contain. The objective behind this criterion was to protect biodiversity priority areas.
Agricultural potential
The degree to which the alien species are able to displace indigenous species which are important for grazing and the cultivation potential of the land. The objective behind this criterion was to retain land capability.
Protected areas
The degree to which the alien species is able to displace indigenous species, within protected areas. The objective behind this criterion was to maintain protected areas of varying status including provincial reserves, world heritage sites, municipal reserves and conservancies.
Presence of priority invasive alien species
The actual presence of invaders and their potential to invade further and more extensively in the future. The objective behind this criterion was to identify both areas with a large scale presence of invasive alien species and those likely to become invaded in the future.
Cultural and tourism sites and routes
The degree to which the alien species is able to displace indigenous species, negatively affecting cultural and tourist features and sites, e.g. restricting access, impacting views and restricting recreation opportunities and cultural practices. The objective behind this criterion was to maintain these important cultural and tourism sites and routes.
Fuel load
The degree to which the alien species is able to increase the vegetation fuel load posing a potential risk to natural and built capital. The objective behind this criterion was to identify the potential to remove the risk of increased fuel loads by controlling invasive alien plants in catchments where they have the greatest collective biomass and therefore fuel load.
Table 5: Nested criteria, together with the relative weightings, identified as significant for the purposes of prioritising quaternary catchments in the Gauteng region for the clearing of invasive alien plants.
Criterion
Weighting assigned (%)
Sub-criterion
Weighting assigned (%) 0.259 0.049
Water resources
0.373
Water yield Water quality Erosion
0.065
Biodiversity conservation
0.248
Land (biodiversity)
0.083
Rivers (biodiversity)
0.165
Agricultural potential
0.146
Grazing capacity
0.049
Crop potential
0.097
Presence of priority species
0.124
Current extent
0.018
Invasive potential
0.106
0.049
Provincial reserves world heritage sites
0.036
Municipal reserves
0.009
Conservancies
0.004
Protected areas
Eco-tourism and cultural sites
0.039
Page 11
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
Fuel loads
0.021
The most important criterion to be identified was water resources, this was given a weighting of 37.4%, followed by the biodiversity conservation (24.8%) and agricultural potential (14.6%) (Table 5). The presence of priority species accounted for a further 12.4 %. These four criteria accounted for 89.2% of the model. The remaining three criteria accounted for 10.8% of the weighting in achieving the goal. Protected areas, eco-tourism and cultural sites and fuel loads were assigned weightings of 4.9%, 3.9% and 2.1% respectively (Table 5). The most important sub-criterion identified overall is improving the water yield. This carries a weighting of 25.9% (Table 5). Next in order of importance is river conservation (16.5%), invasive potential (10.6%) and cropland potential (9.7%) (Table 5). Socio-economic factors were discussed, in particular the location of poor people with respect to prioritising areas. It was decided that, given the pervasive nature of poverty within South African society, all areas of this region contained many more unemployed poor people than the Working for Water programme would be able to employ. Such a criterion would therefore be unhelpful in deciding between priorities. Nevertheless, we believe that social and economic criteria are relevant and should be revisited when revising these priorities.
4.2 GAUTENG PRIORITY QUATERNARY CATCHMENTS Within the Gauteng region the ten catchments with the highest relative importance rankings are: A21G, A21F, A21E, B20B, B20A, A21C, A21D, C22C, C12G, A23A (Figures 3). All criteria have been mapped according to quaternary catchments indicating priorities for each of these (Figures 4 & 5). Of the 49 quaternary catchments investigated, the first 5 accounted for more than 30% of the total weight of the priorities in the model. The prioritisation exercise indicates that there are five specific areas within this region that emerge and key areas in terms of the goal set in this exercise (Figure 6). Firstly the area to the north west, north, and north east of Krugersdorp, and just south of the Hartebeespoort dam. This area contains six of the top ten priority catchments. It is an important area for water yield and river conservation, this the Witwatersrand draining this region into the Hartebeespoort dam (Figure 4). It also contains important provincial, municipal reserves, conservancies and eco-tourism and cultural features with the Sterkfontien caves and the “Cradle of Human kind” found here. The second most important area is found to the north east of Springs, having both high water yield (feeding the Bronkhorstspruit dam), and high cropping potential (Figure 4). The area to the south west of Springs is important for water yield, terrestrial conservation and grazing capacity. Suikerbosrand nature reserve is found here. The area to the south east of Springs and north west of Standerton is has a high priority because of water yield, invasion potential, river conservation, and terrestrial conservation (Figure 4). The final area which this analysis highlighted as a priority was the in the vicinity of Mamelodi (north and south), because of it prtential vaulnerability to invasion, erosion and water quality issues (Figure 4).
Page 12
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
A21G A21F A21E B20B B20A A21C A21D C22C C12G A23A A23D A23B C12F C21F C22D B20G C22A C22E B20D B20H A21B B20C B20F A21A A23E C21E B20J B31A C22B C21C B32G B31F C21G C12L B20E B31C C21A B31D C12H C21D C83M C12K C21B C23D C22J
1.000 .774 .640 .358 .352 .284 .271 .270 .237 .215 .198 .197 .191 .184 .182 .181 .180 .179 .178 .178 .172 .172 .169 .167 .164 .160 .159 .151 .151 .149 .145 .141 .141 .140 .138 .137 .137 .135 .134 .130 .129 .126 .123 .122 .121
Figure 3: The relative importance and ranking of the 45 top priority quaternary catchments out of the 49 in the Gauteng Region. These values have been normalised.
Page 13
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
River conservation (0.165)
Water yield (0.259)
Invasion potential (0.106)
Crop potential (0.097)
Terrestrial conservation (0.083)
Erosion (0.065)
Water quality (0.049)
Grazing capacity (0.049)
Figure 4: The relative importance of quaternary catchments in the Gauteng region for each of the eight criteria that were assigned the highest importance in the model. The importance or weight is shown in parentheses.
Page 14
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
Eco-tourism and cultural sites (0.039)
Provincial reserves (0.036)
Fuel loads (0.021)
Current extent of invasion (0.018)
Municipal reserves (0.009)
Conservancies (0.004)
Figure 5: The relative importance of quaternary catchments in the Gauteng region for the 9th to 14th most important criteria in the model. The importance or weight is shown in parentheses.
The quaternary catchments with the highest prioritisation scores for the Gauteng Region are shown in Figure 6. The highest priority catchments are mainly those which have high water yields, contain areas that are considered to important for river and terrestrial conservation, and are vulnerable invasion. Of the 13 quaternary catchments which currently have clearing projects in operation, two of these catchments is in the top ten priority quaternary catchments, and five in the top 15 priority catchments identified here. Figure 7 indicates that whilst there some clearing projects (approximately half) in catchments with relatively high priorities, the remainder are in catchments which have medium to low priorities.
Page 15
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
Quaternary catchment prioritisation final results
Figure 6: The priority quaternary catchments identified according to priority classes within the Gauteng Region. Priority weightings reflect the scores for each catchment.
Page 16
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
4.0 Current expenditure 3.5
Exp. According to priority Top 13 priorities
Budget (Millions of
3.0
2.5
2.0
1.5
1.0
0.5
0.0 0
10
20
30
40
50
60
Quaternary catchment priority ranking (1= most important to 49 =least important) Figure 7: The expenditure allocated to invasive alien plant clearing projects in the Gauteng region in 2010/11, in relation to priorities identified in the study (Current exp.). Clearly, most quaternary catchments, including several of high priority, do not receive any funding. The figure also shows the amount of funding that would be allocated to each catchment if the allocations were proportional to priorities (Exp. according to priority), as well as the funding that would be allocated to each catchment (Top 13 priorities) if the allocation went to the 13 catchments with the highest priority.
Page 17
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
5. CONCLUSIONS This study has identified the highest priority quaternary catchments for managing invasive alien plants within the Limpopo, Olifants, and the Upper Vaal, primary catchments which are managed by the Working for Water Gauteng Region and compared them with the current budget allocations. There is some alignment between identified priority areas and the location of existing projects, however there is only one clearing project in the top five identified quaternary catchments. The regional Working for Water management team needs to assess how best to improve the current alignment between budgets and priority catchments over time. The techniques we have developed to determine the priority areas for clearing invasive alien plants at a quaternary catchment scale are workable but it is not really clear whether the results correspond with what the managers and experts would intuitively expect. The difference that this new approach makes is that the managers can now evaluate the roles of the individual data elements which contribute to each score assigned by the Expert Choice (AHP) software and adjust them where necessary. An advantage of using AHP is that it can handle a large number of alternatives enabling comparisons to be made on any number of quaternary catchments. The results are as good as the underlying spatial datasets but as new or revised datasets become available they can easily be accommodated by the hierarchical model and used to generate a revised set of rankings (catchment scores). On the other hand, as understanding improves, the weightings assigned to the criteria and sub-criteria in the hierarchical model can be adjusted, and criteria and sub-criteria added or removed. This study has identified a number of shortcomings regarding the available spatial data and, in other instances, the lack of appropriate spatial data to represent the criteria and sub-criteria that were considered important by the experts. We are however still limited in our ability to determine impacts on: cultural features and natural resource use, and are unable to identify water stressed catchments.
Page 18
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
6. RECOMMEDATIONS This study has been successful in applying the approach developed by van Wilgen et al. (2008), Forsyth et al. (2009) and Le Maitre and Forsyth (2010), at a quaternary catchment scale in the Gauteng Region. However, a number of follow-up actions will be needed if this approach is to deliver its full potential in terms of assisting the Working for Water Programme to improve its operations and its impact. With this in mind, we recommend the following: •
That the techniques developed at the primary and quaternary catchment scale be adopted by Working for Water’s national and regional planning offices to assist with prioritisation, planning, and the allocation of resources to both existing and new projects on an ongoing basis. This would assist in establishing a uniform approach to prioritisation across the organization and allow for regular reassessments as needed and when new or improved datasets become available.
•
Future funding should be channelled into establishing invasive alien clearing projects in catchments that have been identified as having high priorities. In addition projects in low priority catchments should be brought to a conclusion.
•
Each Working for Water region should maintain existing datasets and revise them on a regular basis. This should not be longer than 3 years so as to coincide with the medium term expenditure framework of government.
•
That a spatial database be developed to underpin effective comparisons of areas. This database could contain data relating to most of the criteria identified here including water yield, erosion and water quality variables, terrestrial and fresh water biodiversity conservation, protected areas, carrying capacity, cultivation potential, cultural and tourism use features and the abundance and potential spread of invasive alien species. The Working for Water Information Management System should be used to store the necessary data.
•
The results are as good as the underlying spatial datasets but as new or revised datasets become available they should be incorporated into the hierarchical model and used to generate a revised set of rankings (catchment scores). In addition as understanding improves, the weightings assigned to the criteria and sub-criteria in the hierarchical model can be adjusted, and criteria and sub-criteria added or removed.
Page 19
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
7. REFERENCES Anonymous (2009) Expert Choice 11.5. Expert Choice Inc., Pittsburgh, PA, United States of America. Agricultural Research Council (2002) A System for Soil and Land Capability Classification for Agriculture in South Africa. Department of Agriculture and Environmental Affairs. Biodiversity GIS (2010) South African National Biodiversity Institute's spatial biodiversity planning information system. http://bgis.sanbi.org. Accessed: November 2010. Chamier, J. Schachtschneider, K., Le Maitre, D.C., Ashton, P. and van Wilgen, B.W. (2011) Impacts of Invasive Alien Plants on Water Quality. Report number CSIR/NRE/ER/2011/0007/A, CSIR, Stellenbosch. CSIR (2011) A CSIR perspective on water in South Africa – 2010. Report No.: CSIR/NRE/PW/IR/2011/0012/A, January 2011. Compiled by Wilma Strydom, Natural Resources and the Environment, CSIR, Pretoria. DEA (2009) List of threatened terrestrial ecosystems for South Africa (2009) [DRAFT] Notice 1477 of 2009, Government Gazette No 32689, 6 November 2009. Driver, A., Maze, K., Rouget, M., Lombard, A.T., Nel, J., Turpie, J.K., Cowling, R.M., Desmet, P., Goodman, P., Harris, J., Jonas, Z., Reyers, B., Sink, K. and Strauss, T. (2005) National Spatial Biodiversity Assessment 2004: Priorities for biodiversity conservation in South Africa. Strelitzia 17, South African National Biodiversity Institute, Pretoria. ENPAT (2001) Environmental Potential Atlas. Department of Environmental Affairs and Tourism, South Africa. Forsyth, G.G., Le Maitre, D.C. and van Wilgen, B.W. (2009) Prioritising quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province. CSIR Report CSIR/NRE/ECO/ER/2009/0094/B. Natural Resources and the Environment, CSIR, Stellenbosch. Henderson, L. (1998) Southern African Plant Invaders Atlas (SAPIA). Applied Plant Science 12, 3132. Kotzé, I., Beukes, H., van den Berg, E. and Newby, T. (2010) National Invasive Alien Plant Survey. Report No. GW/A/2010/21, Agricultural Research Council – Institute for Soil, Climate and Water, Pretoria. Le Maitre, D.C. and Forsyth, G.G. (2010) Prioritising quaternary catchments for invasive alien plant control within the Savanna, Nama and Succulent Karoo biomes of the Northern Cape province. CSIR Report CSIR/NRE/ECO/ER/2010/0015/B. Natural Resources and the Environment, CSIR, Stellenbosch.
Page 20
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
Lötter, M.C. and Ferrar, A.A. (2006) Gauteng Biodiversity Conservation Plan Map. Gauteng Parks Board, Nelspruit. Mgidi, T.N., Le Maitre, D.C., Schonegevel, L., Nel, J.L., Rouget, M. and Richardson, D.M. (2007) Alien plant invasions – incorporating emerging invaders in regional prioritization: a pragmatic approach for southern Africa. Journal of Environmental Management 84, 173-187. Middleton, B.J. and Bailey, A.K. (eds) (2008) Water Resources Of South Africa, 2005 Study (WR2005). Report TT 380/08, Water Research Commission, Pretoria. Mucina, L. and Rutherford, M.C. (2006) The vegetation of South Africa, Lesotho and Swaziland. Strelitzia. South African National Biodiversity Institute, Pretoria. Naudé, A.H., Badenhorst, W., Zietsman, H.L., Van Huyssteen, E., Maritz, J., (2007) Technical overview of the mesoframe methodology and South African Geospatial Analysis Platform. CSIR, Pretoria. (Report number CSIR/BE/PSS/IR/2007/0104/B). Nel, J.L., Roux, D.J., Maree, G., Kleynhans, C.J., Moolman, J., Reyers, B., Rouget, M. and Cowling, R.M. (2007) Rivers in peril inside and outside protected areas: a systematic approach to conservation assessment of river ecosystems. Diversity and Distributions 13, 341–352. Nel J.L., Driver A., Strydom W., Maherry A., Petersen C., Roux D.J., Nienaber S., van Deventer H, Smith-Adao LB and Hill L. (2011) Atlas of Freshwater Ecosystem Priority Areas in South Africa: Maps to support sustainable development of water resources. Atlas and accompanying data available from CSIR or WRC. Rouget, M., Richardson, D.M., Nel, J.L., Le Maitre, D.C., Egoh, B. and Mgidi, T. (2004) Mapping the potential ranges of major plant invaders in South Africa, Lesotho and Swaziland using climatic suitability. Diversity and Distributions 10, 475 – 484. Saaty, T.L. (1990) How to make a decision: The analytic hierarchy process. European Journal of Operational Research 48, 9-26. Scholes, R.J. (1998) The South African 1:250 000 maps of areas of homogenous grazing potential. Report ENV-P-C 98190, CSIR, Pretoria. Schulze, R.E. and Horan, M.J.C. (2007) Soils: Hydrological Attributes. In: Schulze, R.E. (Ed). 2007. South African Atlas of Climatology and Agrohydrology. Water Research Commission, Pretoria, RSA, WRC Report 1489/1/06, Section 4.2. Van den Berg, E.C., Plarre, C., Van den Berg, H.M. and Thompson, M.W. (2008) The South African National Land Cover 2000. Agricultural Research Council (ARC) and Council for Scientific and Industrial Research (CSIR), Pretoria. Report No. GW/A/2008/86. van Wilgen, B.W., Forsyth, G.G. and Le Maitre, D.C. (2008) The prioritization of species and primary catchments for the purposes of guiding invasive alien plant control operations in the terrestrial biomes of South Africa. CSIR Report CSIR/NRE/ECO/ER/2008/0070/C. Natural Resources and the Environment, CSIR, Stellenbosch.
Page 21
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
van Wilgen, B.W., Le Maitre, D.C., Forsyth, G.G. and O’Farrell, P.J. (2010) The prioritization of terrestrial biomes for invasive alien plant control in South Africa. CSIR Report CSIR/NRE/ECO/ER/2010/0004/C. Natural Resources and the Environment, CSIR, Stellenbosch. WSAM (2003) Water situation assessment model, Version 3.002. Department of Water Affairs and Forestry (DWAF), Republic of South Africa.
Page 22
Page 23
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
APPENDIX 1: PRIORITY INVASIVE ALIEN PLANTS IN THE MOIST SAVANNA AND GRASSLAND BIOMES FOR THE GAUTENG PROVINCE The invasive alien plant taxa selected for prioritisation in the Savanna and Grassland biome. A # indicates those species identified by van Wilgen, Forsyth and Le Maitre, (2008) as a threat but not regarded by the Gauteng experts as a threat. An * denotes species regarded as problematic and added to the list during the workshop by the local experts. Grassland species Acacia mearnsii, dealbata and decurrens (Black, silver and green wattle) Argemone mexicana (Mexican poppy)* Arundo donax (Giant reed) Campuloclinium macrocephalum (Pom-pom weed) Cardiospermum grandiflorum (Balloon vine)* Chromolaena odorata (Triffid weed)# Cotoneaster franchetii and pannosus (Orange and silver-leaf cotoneasters)# Eucalyptus camaldulensis (Red river gum) Eucalyptus cinerea (Florist gum) Ipomoea indica (Morning glory) Macfadyena unguis-cati (Cat's claw creeper)* Pinus elliottii (Slash pine) Pinus patula (Patula pine) Populus x canescens and alba (Grey and white poplars) Pyracantha angustifolia (Yellow firethorn) and red Ricinus communis (Castor-oil plant)* Robinia pseudoacacia (Black locust) Rubus cuneifolius (American bramble) Salix babylonica (Weeping willow) Salix fragilis (Crack willow)# Sesbania punicea (Red Sesbania)* Solanum mauritianum (Bugweed) Solanum seaforthianum (Potato creeper)* Solanum sisymbriifolium (Wild tomato)* Xanthium spinosum (Boetebos)*
Page 24
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
Moist Savanna species Acacia mearnsii (Black wattle) Arundo donax (Giant reed) Caesalpinia decapetala (Mauritius thorn)# Campuloclinium macrocephalum (Pom-pom weed)* Cereus jamacaru (Queen of the night) Cestrum laevigatum (Inkberry) Chromolaena odorata (Triffid weed)# Eucalyptus camadulensis (Red river Gum)* Eucalyptus grandis* Jacaranda mimosifolia (Jacaranda) Lantana camara (Lantana) Melia azedarach (Persian lilac) Parthenium hysterophorus (Parthenium)# Pereskia aculeata (Barbados gooseberry)# Pinus spp. (patula)# Populus x canescens and alba (Grey and white poplars)* Psidium guajava (Guava) Schinus terebinthifolius (Brazilian pepper tree)# Senna spp. (Peanut butter cassia and others) Sesbania punicea (Red Sesbania)* Solanum mauritianum (Bugweed)* Tecoma stans (Yellow bells)*
Page 25
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
Appendix 2: AGENDA for GAUTENG REGION AGENDA: GAUTENG REGION
RANKING THE IMPORTANCE OF CRITERIA TO USE IN PRIORITISING QUATERNARY CATCHMENTS TO CLEAR OF INVASIVE ALIEN PLANTS IN GAUTENG
Tugela Conference Room Dept. Of Water Affairs Training Centre Roodeplaat Dam
Tuesday 18th January 2011 1. 2. 3. 4. 5. 6.
Welcome (08h30) Introduction: Aims of workshop and AHP methodology (08h45) Results of previous prioritisation studies (09h15) Discuss current rankings of important invasive alien species in Gauteng (09h35) Tea (10h00 – 10h20) Agree on goal, criteria (objectives) and sub-criteria (sub-objectives) for prioritising quaternaries catchments in Gauteng (10h20) 7. Pairwise comparisons of criteria and sub-criteria (11h30) 8. Lunch (13h00 – 13h45) 9. Continuation of pairwise comparisons of criteria and sub-criteria (13h45) 10. Discussion of relevant and available datasets for Gauteng (14h30) 11. Workshop ends at approximately 15h00
Enquiries: Linda Mabuza Tel: 012 392 1400 Cell: 082 317 2921 Email:
[email protected]
Page 26
Prioritising quaternary catchments for invasive alien plant control within the Working for Water Gauteng region
APPENDIX 3: PARTICIPANTS IN THE EXPERT WORKSHOP Participants in the workshop held in the Tugela Conference Room, DWA Training Centre, Roodeplaat Dam on 18th January 2011 to determine criteria and rank these to use in prioritising the clearing of invasive alien plants from quaternary catchments within Gauteng. # 1
Name Greg Forsyth
Organisation
Telephone
E-mail
CSIR
021 888-2400
[email protected]
2
Linda Mabuza
Working for Water
082 317-2921
[email protected]
3
Lenesse Tshikovhi
Working for Water
082 876-1574
[email protected]
4
Tshepo Seale
Working for Water
073 955-1603
[email protected]
5
Ivy Duba
Working for Water
078 460-5578
[email protected]
6
Mariam Dickinson
Working for Water
082 807-5092
[email protected]
7
Sizwe Sogaxa
Working for Water
082 317-5758
[email protected]
8
Johannes Majuta
Working for Water
078 460-5580
[email protected]
9
Concilence Samba
Working for Water
082 763-0201
[email protected]
10
Charles Ngwenya
WfW - IDT
083 341-6375
[email protected]
11
Nacy Matloko
Working for Water
083 607-0276
[email protected] [email protected]
12
Phillemon Shibambo
WQM - S
073 975-6108
13
Zacharia Mokoana
Working for Water
082 801-5173
[email protected]
14
Phyllis Serumula
Rand Water (RWF)
083 763-3873
[email protected]
15
Anill Govender
Working for Water
082 612-1232
[email protected]
16
Kelebogile Kekana
Working for Water
082 317-3150
[email protected]
17
Lindelani Mthembu
Working for Water
083 430-1363
[email protected]
18
Phyllystas Mmakola
DAFF - LUSM
082 404-3054
[email protected]
19
Esther Mampane
DAFF - LUSM
076 561-6891
[email protected]
20
Thapelo Loobile
DAFF - LUSM
084 261-1064
[email protected]
21
Christopher Mthombeni
Ekurhuleni DM
083 239-7774
[email protected]
22
Petrus Links
Gauteng DARD
076 993-3887
[email protected]
Page 27
