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PRIORITISING QUATERNARY CATCHMENTS FOR INVASIVE ALIEN PLANT CONTROL WITHIN THE WORKING FOR WATER NORTH WEST REGION: PROJECT REPORT
March 2011
Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West 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/2011/0027/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 North West 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 North West 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 North West 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. 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 North West 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 ground water recharge, aggressiveness of invading species and the extent of invasion, surface water yields, quality and riparian habitat variables, ecosystem function, grazing potential and degradation.
•
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 North West Regional area A total of 70 quaternary catchments occur within three primary catchments that make up the WfW North West region, and were used in this assessment. The five quaternary catchments with the highest relative importance are A31D, C23F, A21H, C23K, and C23J. The area in the eastern section of this region just north and east of Ventersdorp and south of Rustenburg is a key region for targeting invasive alien plant clearing operation. This area is especially important for ground water recharge and ground water yield. Surface water yield is also relatively high in this region, but some quaternaries here received a low weighting due to their geological composition. The aggressiveness of invasive aliens and grazing potential were also weighted high in this area. In general the highest priority catchments are those which have high ground water recharge, and surface yield, aggressive aliens and are presently invaded.
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West region
Acknowledgements We thank the Working for Water Programme of the Department of Water and Environment Affairs for funding this work. We thank Mr Xola Morris Tsobo 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 North West Working for Water Region: Hendrik Ferreira, F. Jordaan, Hennie Roux, Henry Segome, Sipho Jiviadava, Potso Mphephu, Favida Nkhwashu, Zamisile Mabato, K.P. Mapoitshego, Benadictos Mdaka, Maurice Valaya, Piet Theron, Pieter H. Roodt, Xola Tsobo, Gralvome Moseki,Nomsa Mosete, Lufuno Netangaheni, Rens Botha, Jonathan Modiba, Hlamalang Come, Elvis Moyo, Nokuzola Mchunu.
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West 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
5 5 5 5 7 7
3.4
3.4.1 Water resources 3.4.1.1 Ground water 3.4.1.2 Surface water 3.4.2 Potential to spread 3.4.2.1 Existing extent 3.4.2.2 Potential extent 3.4.2.3 Aggressiveness 3.4.3 Biodiversity 3.4.3.1 Ecosystem function and services 3.4.3.2 Critical biodiversity conservation 3.4.4 Grazing and browsing 3.4.4.1 Grazing potential 3.4.4.2 Grazing induced degradation 3.4.5 Fire regimes 3.4.6 Poverty relief 3.4.7 Human and animal health effects
7 7 7 7 8 8 8 8 9 10 10
3.5
SPATIAL DATA SETS USED IN THE PRIORITISATION
10
3.6
CALCULATING THE WEIGHTS USED BY THE EXPERT CHOICE SOFTWARE
11
4. RESULTS
11
4.1
GOAL AND CRITERIA
11
4.2
NORTH WEST PRIORITY QUATERNARY CATCHMENTS
14
5. CONCLUSIONS
21
6. RECOMMENDATIONS
22
7. REFERENCES
23
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West region
Appendix 1
Priority invasive alien plants in the moist savanna and grassland biomes for the North West province
Appendix 2
Agenda for North West region
Appendix 3
Participants in expert workshops
Figures Figure 1:
A map showing the regional boundaries of the Working for Water program in the North West region, the biomes, Savanna (arid and moist) and Grassland, and the major towns in the region. ________________________________________________ 3
Figure 2:
A map showing the regional boundaries of the Working for Water programme in the North West region, major towns and the primary catchments found in this region. ____ 3
Figure 3:
The relative importance and ranking of the 46 top priority quaternary catchments out of the 70 in the North West Region. These values have been normalised. ______ 15
Figure 4:
The relative importance of quaternary catchments in the North West region for each of the eight criteria that were assigned the highest importance in the model. The importance or weight is shown in parentheses. ___________________________ 16
Figure 5:
The relative importance of quaternary catchments in the North West region for the th th 9 to 16 most important criteria in the model. The importance or weight is shown in parentheses.________________________________________________________ 17
Figure 6:
The priority quaternary catchments identified according to priority classes within the North West Region. Priority weightings reflect the scores for each catchment. ______ 19
Figure 7:
The expenditure allocated to invasive alien plant clearing projects in the North West 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 12 priorities) if the allocation went to the 12 catchments with the highest priority.________________________________________________________ 20
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West region
Tables Table 1:
Grazing potential ranges and associated midpoints in large livestock units (LSU) per km2 (Scholes 1998).__________________________________________________ 8
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. _______________________________________________________ 11
Table 4:
Identified criteria and descriptions of the attributes that they incorporate. __________ 12
Table 5:
Nested criteria, together with the relative weightings, identified as significant for the purposes of prioritising quaternary catchments in the North West region for the clearing of invasive alien plants. __________________________________________ 13
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West 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. Mr Xola Morris Tsobo 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 North West 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 North West 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: •
Mr Xola Morris Tsobo (Department of Water and Environment Affairs – Working for Water Programme, North West)
•
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 three biomes that dominate the region, grassland, arid savanna and moist savanna (Figure 1).
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West region
•
The work would entail prioritising areas to clear at a quaternary catchment scale within the portions of the Limpopo catchment (A), the Upper Vaal catchment (C), the Orange river (D) which occur in the Working for Water regional boundaries of the North West 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 Rustenburg.
•
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 both the moist and dry Savanna and the Grassland (see Appendix 1) by the recent CSIR study (van Wilgen et al., 2008). In the North West 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 North West 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 North West 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.
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West region
Figure 1: A map showing the regional boundaries of the Working for Water program in the North West region, the biomes, Savanna (arid and moist) and Grassland, and the major towns in the region.
Figure 2: A map showing the regional boundaries of the Working for Water programme in the North West region, major towns and the primary catchments found in this region.
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West region
3. APPROACH 3.1 WORKSHOP TO DETERMINE RANKING CRITERIA A one day workshop was held at the Hunter’s Rest Hotel, near Rustenburg on 19th January 2011. The workshop agenda is provided in Appendix 2. A total of 23 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 North West 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 North West 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).
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West 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 North West 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 Ground water Ground water data for the prioritisation studies were taken from the Groundwater Resource Assessment Project of the Department of Water Affairs (DWA 2005). The study included estimates of the groundwater recharge, groundwater exploitation potential and the groundwater demand at various spatial scales including quaternary catchments.
3.4.1.1.1
Ground water recharge
Groundwater recharge was estimated from mean annual rainfall and hydrogeological data, and information from recharge studies by Groundwater Resource Assessment Phase 2 study (DWA 2005). Summary data are available for quaternary catchments which give estimates of the mean annual recharge (millions of m3 per year). These data were converted to millimeters to give the relative recharge of the catchment. The recharge (mm) was used as the weight for each catchment, with the greatest weight going to catchments with the greatest depth of recharge.
3.4.1.1.2
Ground water yield
The volume of groundwater yield was estimated from data on the recharge, the storage capacity and the transmissivity of the aquifers that store the water (DWA 2005). Only a proportion of this water is available on a sustainable basis when allowance is made for drought years and periods. In addition, only some of the groundwater is also potable. The sustainable yield of potable water is called the potable groundwater exploitation potential and estimates of the annual volume are available in millions of m3 per km2 per year. These values were used to give with catchments a weight based on their potable groundwater exploitation potential.
3.4.1.2 Surface water 3.4.1.2.1
Surface 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.
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West region
3.4.1.2.2
Flood attenuation
We used the riparian invasion dataset from the National Invasive Alien Plant Survey (Kotze et al. 2010) that contains records for all species occurring within a 1 kilometre buffer on either side of each mapped river. We reduced this buffer to 125 metres on each side of rivers which is the minimum width that the data can be used at because of its spatial resolution. We did this because most rivers do not have floodplains that are 1 kilometre wide (500 metres on each side). The data were expressed as condensed hectares where, for example, an area of 100 hectares with a 50% cover of a species is equivalent to 50 condensed hectares (i.e. with 100% cover). We then summed the “condensed” hectares for all the species occurring in each quaternary catchment and then divided the sum by the total area of each catchment to arrive at an area weighted score for each catchment. Catchment having dense riparian invasions, many or long rivers will receive the greatest score. The sum of these scores was then calculated and each quaternary catchment’s score was divided by this sum to arrive at a proportional weight for each catchment in this region.
3.4.1.2.3
Riparian habitat
We determined areas of conservation significance from the NFEPA 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.
3.4.1.2.4
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 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.
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West region
3.4.2
Potential to spread
3.4.2.1 Existing 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.
3.4.2.2 Potential extent 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.
3.4.2.3 Aggressiveness To derive an aggressiveness score we developed the equation below, with the following values. A = Sd*Gr*Ns*S Where:
Sd = seed dispersal
(3 = Long range (wind, bird, water), 2 = Short range; 1 = No seeds); Gr = growth rate (3= fast, 2= moderate, 1= slow) Ns = numbers of seeds produced (3 = high, 2 = moderate; 1 = low or none) S = sprouting (2 = sprouter; 1= non-sprouter).
Scores ranged from 72 for species like Acacia mearnsii, to 4 for Populus species. These scores were multiplied by the condensed invaded area for each priority species in each quaternary catchment based on the national invasive alien plant survey (Kotze et al. 2010) This was divided by the total condensed invaded area for that catchment to give an area weighted mean aggressiveness score.
3.4.3
Biodiversity
3.4.3.1 Ecosystem function and services In assessing ecosystem function and services we used areas of natural land cover as an surrogate measure. We calculated the area of untransformed land in each quaternary catchment from the 2000 national land cover dataset (Van den Berg et al. 2008). This was done by removing all transformed land classes from the dataset, which included all cultivated land and improved grassland; all urban and industrial areas, mining and quarries and water storage dams. We
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West region
calculated the area of natural vegetation in each quaternary catchment and expressed this as a proportion of the area of the catchment
3.4.3.2 Critical biodiversity 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.
3.4.4
Grazing and browsing
3.4.4.1 Grazing potential 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.
3.4.4.2 Grazing induced degradation In assessing grazing induced degradation we calculated the area of degraded and eroded veld within each quaternary catchment from the 2000 national land cover dataset (Van den Berg et al. 2008). The total area of degraded and eroded land was calculated for each quaternary catchment and this was then expressed as a proportion of the quaternary catchment. The sum of all degraded area proportions was calculated for the region and a weight per quaternary calculated based the proportional weight for each catchment for this region.
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West region
3.4.5
Fire regimes
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). This criterion identifies the potential to reduce the risks associated with increased fuel loads by controlling invasive alien plants in catchments where they have the greatest biomass and fuel load. We used the priority species for the North West region from the national invasive alien plant survey (Kotze et al. 2010)(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. 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.
Species or group
Fuel Score
Species fuel weight
Arundo donax
3
0.0625
Chromolaena odorata
3
0.0625
Eucalyptus spp.
3
0.0625
Pinus spp.
3
0.0625
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
Wattle species (mearnsii, dalbata, decurrens, baileyana)
2
0.0417
Agave spp.
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
Salix babylonica
1
0.0208
Senna didymobotrya
1
0.0208
Solanum mauritianum
1
0.0208
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3.4.6
Poverty relief
To prioritise catchments with regard to the need for socio-economic development we made use of data contained in the South African Geo-spatial Analysis Platform (Naudé et al. 2007). This database contains 25000 irregularly shaped meso-scale analysis units, called meso-zones, which are approximately 7 x 7 km in size. Meso-zones have been designed so as to nest within administrative and physiographic boundaries. Each meso-zone contains a variety of socioeconomic data including the number of people living below the mean living level. We used the proportion of the population living below the mean living level in each meso-zone to calculate an average value for each quaternary catchment by summing these proportions of the population up and dividing by the total area of the catchment. The quaternary catchments with the highest proportion of their population living below the mean living level were allocated the greatest weight. This calculated proportion per quaternary catchment is considered to be a reasonable surrogate for the proportion of unemployed and people requiring poverty relief interventions.
3.4.7
Human and animal health effects
We have been unable to develop a valid method of calculating the effects that alien invasive species are having on human and animal health from a spatial prioritisation perspective. We have therefore weighted all quaternary catchments within this region as being equal with regards to this criterion.
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).
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West region
Table 3: Spatial datasets used to rank quaternary catchments in relation to selected criteria and sub-criteria.
Spatial data
Sub-criterion
Water resources
Ground water recharge
GRA II 2005 (Available from DWAF)
Ground water yield
GRA II 2005 (Available from DWAF)
Surface water yield
Water Resources 2005 (Middleton & Bailey 2008)
Flood attenuation
National Invasive Alien Plant Survey (Kotze 2010) National freshwater ecosystem priority areas (Nel et al. 2011) Impacts of Invasive Alien Plants on Water Quality (Chamier et al. 2011; CSIR 2011)
Riparian habitat Water quality Potential to spread
Existing extent
National Invasive Alien Plant Survey (Kotze 2010)
Potential extent
Rouget et al. (2004) and Mgidi et al. (2007)only of potential
Aggressiveness Biodiversity
Ecosystem function and services Critical biodiversity conservation
Grazing and browsing
South African Plant Invaders Atlas (Henderson 1998 and revisions) - copy of database March 2010 National Land Cover Database 2000 (Van den Berg et al. 2008) National Vegetation Map (Mucina and Rutherford 2006) updated with the 2009 threatened ecosystem list (DEA 2009). Environmental Potential Atlas (ENPAT 2001)
Grazing potential
Areas of homogenous grazing potential (Scholes, 1998)
Grazing induced degradation
National Land Cover Database 2000 (Van den Berg et al. 2008)
Fire regimes
National Invasive Alien Plant Survey (Kotze 2010)
Poverty relief
CSIR GAP data (Naudé 2007)
Human and animal health effects
1
1
Criterion
None available
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 Rustenburg workshop was “To manage invasive alien plants to maintain ecosystem functioning”. Goal setting was followed by the identification of six criteria for prioritising the clearing of quaternary catchments within the North West region.
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West region
The criteria identified were: water resources, the potential of aliens to spread, biodiversity, grazing and browsing, fire regimes, poverty relief and human and animal health. Descriptions of these criteria are provided (Table 4). Many of the criteria were further divided into sub-criteria, for example, the criterion “water resources” was divided into the sub-criteria of ground water and surface water, and these were both further sub divided into sub-sub-criteria. The final ranking for prioritisation, considering all the criteria, sub-criteria and sub-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, these being both surface and ground water. This includes water yield, water recharge, water quality, riparian habitats and flood attenuation. The objective behind this criterion was to secure the sustainable provision of water.
Potential to spread
The actual presence of invaders and their future invasion potential. 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, and the aggressiveness of invasive species.
Biodiversity conservation
The degree to which the alien species are able to displace indigenous species, in particular their impact on protected areas, terrestrial, wetland, and riparian systems, and the biodiversity they contain. The objective behind this criterion was to protect biodiversity priority areas.
Grazing and browsing
The degree to which the alien species are able to displace indigenous species which are important for grazing and browsing. The objective behind this criterion was to retain and restore land capability for animal production.
Fire regimes
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.
Poverty relief
The degree to alien clearing operations can be directed towards area with a high proportion of poor people, thereby creating employment. The objective behind this criterion was to identify the areas with this highest number of poor people so that poverty relief initiatives such as working for water clearing projects could be directed to these area above others that has few or no poor people.
Human and animal health effects
The degree to which the alien species affect animal and human health through poisoning, allergies. The objective behind this criterion was to identify areas where invasive alien species were having significant health effect based on the presence of certain toxic and allopathic species.
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West region
Table 5: Nested criteria, together with the relative weightings, identified as significant for the purposes of prioritising quaternary catchments in the North West region for the clearing of invasive alien plants.
Ground water
Water resources
0.278
0.417 Surface water
Existing extent Potential to spread
Biodiversity
0.205
0.133
Grazing and browsing
0.129
Fire regimes
0.059
Poverty relief
0.034
Human and animal health effects
0.022
0.139
0.232 0.046 0.068 0.008
Riparian habitat
0.04
Water quality
0.023
0.053
Potential extent
0.021
Aggressiveness
0.131
Ecosystem function and services Critical biodiversity conservation
Ground water recharge Ground water yield Surface water yield Flood attenuation
0.111 0.022
Grazing potential
0.086
Grazing induced degradation
0.043
The most important criterion to be identified was water resources, this was given a weighting of 41.8%, followed by the potential of invasive alien plants to spread 20.5% and biodiversity conservation (13.3%). Gazing and browsing accounted for 12.9%. These four criteria accounted for 88.5% of the model. The remaining three criteria accounted for 11.5% of the weighting in achieving the goal. Fire regimes, poverty relief, human and animal effects were assigned weightings of 5.9%, 3.4% and 2.2% respectively. The last two criteria relate to socio-economic factors concerning the location of poor people with respect to prioritising areas, and the negative impacts of invasive species on health (in particular poisonous plants and large volumes of pollen). The most important sub-criterion identified overall is ground water recharge. This carries a weighting of 23.2% (Table 5). Next in order of importance is the aggressiveness of invasive alien species (13.1%), ecosystem function and services (11.1%) and grazing potential (8.6%) (Table 5).
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West region
4.2 NORTH WEST PRIORITY QUATERNARY CATCHMENTS Within the North West region the ten catchments with the highest relative importance rankings are: A31D, C23F, A21H, C23C, C23J, C23H, A31B, A21K, A21J, A22G (Figures 3). All criteria have been mapped according to quaternary catchments indicating priorities for each of these (Figures 4 & 5). Of the 70 quaternary catchments investigated, the first 10 accounted for just under 30% of the total weight of the priorities in the model. The prioritisation exercise indicates that the area in the eastern section of the province, just north and east of Ventersdorp and south of Rustenburg is a key region for targeting invasive alien plant clearing operation (Figure4-6). This area is especially important for ground water recharge and ground water yield and this is a function of its geology with this area being underlain by dolomite (Figure 4). Surface water yield is also relatively high in this region, with some exceptions, again underlying geology is likely to play a role, with surface water moving below ground in places (Figure 4). The aggressiveness of invasive aliens criterion, and the areas with the highest grazing potential are also dominant in this same eastern area. It is worth noting that this region is adjacent to the Gauteng Working for Water region with the quaternaries with the highest priority (Figure 4). The central and southern areas were considered important from a water quality and biodiversity conservation perspective (Figure 4 & 5). Poverty relief, critical biodiversity, ecosystem function and grazing induced degradation were criteria that scored relatively high in the western quaternary catchments (Figure 4 & 5).
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West region
A31D C23F A21H C23K C23J C23H A31B A21K A21J A22G C23E A31A A31E A31C C24D A31F A22A C23G A22B A22E C24C A21L A23K A22C C24E A22H C24F A31H C24A C31A A31G A23F A22D A31J A22F A10A A24A C25A C24H C24G A23L A22J A23J C31C C31D C32A
1.000 .903 .886 .843 .788 .692 .648 .631 .596 .588 .583 .576 .528 .517 .509 .494 .483 .471 .469 .462 .459 .441 .412 .409 .406 .399 .398 .394 .377 .375 .354 .347 .341 .330 .328 .323 .321 .321 .316 .315 .310 .308 .298 .294 .294 .294
Figure 3: The relative importance and ranking of the 46 top priority quaternary catchments out of the 70 in the North West Region. These values have been normalised.
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West region
Groundwater recharge (0.198)
Aggressiveness (0.146)
Surface water yield (0.099)
Ecosystem function and services (0.094)
Grazing potential (0.091)
Existing extent (0.059)
Riparian habitat (0.058)
Grazing induced degradation (0.046)
Figure 4: The relative importance of quaternary catchments in the North West region for each of the eight criteria that were assigned the highest importance in the model. The importance or weight is shown in parentheses.
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West region
Fire regimes (0.042)
Ground water yield (0.040)
Water quality (0.033)
Potential extent (0.024)
Poverty relief (0.024)
Critical biodiversity conservation (0.019)
Human and animal health effects (0.016)
Flood attenuation (0.012)
Figure 5: The relative importance of quaternary catchments in the North West region for the 9th to 16th most important criteria in the model. The importance or weight is shown in parentheses.
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West region
The quaternary catchments with the highest prioritisation scores for the North West Region are shown in Figure 6. The highest priority catchments are mainly those which have high levels of ground water recharge, and surface water yields, contain aggressive invasive aliens, have areas which area intact retaining their ecological function and the services that flow from this, and those areas with a high grazing potential. Of the 12 quaternary catchments which currently have clearing projects in operation, six of these catchments is in the top ten priority quaternary catchments. Figure 7 indicates that the majority of clearing projects are in catchments with a relatively high priorities, and only three clearing projects is in low priority areas.
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West region
Quaternary catchment prioritisation final result
Figure 6: The priority quaternary catchments identified according to priority classes within the North West Region. Priority weightings reflect the scores for each catchment.
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West region
2.5
Budget (Millions of
2
1.5
1
Current expenditure Exp. According to priority Top 12 priorities
0.5
0 0
10
20
30
40
50
60
70
80
Quaternary catchment priority ranking (1= most important to 70 =least important) Figure 7: The expenditure allocated to invasive alien plant clearing projects in the North West 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 12 priorities) if the allocation went to the 12 catchments with the highest priority.
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West region
5. CONCLUSIONS This study has identified the highest priority quaternary catchments for managing invasive alien plants within the Limpopo, Upper Vaal, and Orange river primary catchments which are managed by the Working for Water North West 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. 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.
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West region
6. RECOMMENDATIONS 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 North West 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 ground water recharge, water yield, aggressiveness of invaders, ecological function, grazing potential and restoration of degraded area following poor grazing practices, riparian habitat management, fire regimes and the extensiveness of current invasions. 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.
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West 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. DWAF (2005) Groundwater Resource Assessment. Phase II. Department of Water Affairs and Forestry, 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.
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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. Lötter, M.C. and Ferrar, A.A. (2006) North West Biodiversity Conservation Plan Map. North West 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.
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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. 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.
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West region
APPENDIX 1: PRIORITY INVASIVE ALIEN PLANTS IN THE MOIST SAVANNA AND GRASSLAND BIOMES FOR THE NORTH WEST PROVINCE The invasive alien plant taxa selected for prioritisation in the Savanna (Moist and Arid) and the Grassland biome. A # indicates those species identified by van Wilgen, Forsyth and Le Maitre, (2008) as a threat but not regarded by the North West 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) Arundo donax (Giant reed) Campuloclinium macrocephalum (Pom-pom weed) Cestrum laevigatum (Inkberry)* Chromolaena odorata (Triffid weed) # Cirsium vulgare (Scotch thistle)* Cotoneaster franchetii and pannosus ( and silver-leaf cotoneasters)# Eucalyptus camaldulensis (Gum) Eucalyptus cinerea (Florist gum)# Gleditsia triacanthos (Honey locust)* Ipomoea indica (Morning glory) Jacaranda mimosifolia (Jacaranda)* Melia azedarach (Syringa)* Morus alba (Mulberry)* Nerium oleander (Oleander)* Opuntia sp. (Cactus pear)* Pinus elliottii (Slash pine)# Pinus patula (Patula pine)# Populus x canescens and alba (Grey and white poplars) Prosopis glandulosa var. torreyana (Miskeet)* Pyracantha angustifolia (Yellow firethorn) Robinia pseudoacacia (Black locust) Rubus cuneifolius (American bramble) Salix babylonica (Weeping willow) Salix fragilis (Crack willow)# Sesbania punicea (Red Sesbania)* Solanum elaeagnifolium (Satan’s Bos) Solanum mauritianum (Bugweed) Xanthium spinosum (Boetebos)*
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West region
Moist Savanna species Acacia mearnsii and the rest (Black wattle) Agave sp (agave group of species)* Arundo donax (Giant reed) Bamboo (various species) * Caesalpinia decapetala (thorn)# Celtis orientalis Cereus jamacaru (Queen of the night) Cestrum laevigatum (Inkberry) Chromolaena odorata (Triffid weed)# Cirsium vulgare (Scotch thistle)* Crofton weed* Gleditsia triacanthos (Honey locust)* Jacaranda mimosifolia (Jacaranda) Lantana camara (Lantana) Macfadyena unguis-cati (Cats-claw creeper)* Melia azedarach (Persian lilac) Morus alba (Mulberry)* Opuntia sp. (Cactus pear)* Parthenium hysterophorus (Parthenium)# Pereskia aculeata (Barbados gooseberry)# Pinus spp. (elliottii and patula)# Populus x canescens and alba (Grey and white poplars)* Prosopis glandulosa var. torreyana (Miskeet)* Psidium guajava (Guava)# Pyracantha angustifolia (Yellow firethorn) Rubus cuneifolius (American bramble) Schinus terebinthifolius (Brazilian pepper tree) Senna spp. (Peanut butter cassia and others) Sesbania punicea (Red Sesbania)* Tecoma stans (Yellow bells)* Arid Savanna species Arundo donax (Giant reed) Cereus jamacaru (Queen of the night) Eucalyptus camaldulensis (Gum)* Melia azedarach (Persian lilac) Nerium oleander (Oleander)* Opuntia spp (Prickly pear) Populus x canescens (Grey poplars) Prosopis x glandulosa (Mesquite) Robinia pseudoacacia (Black locust) Schinus molle (Pepper tree)
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West region
APPENDIX 2: AGENDA FOR NORTH WEST REGION AGENDA: NORTH WEST REGION
RANKING THE IMPORTANCE OF CRITERIA TO USE IN PRIORITISING QUATERNARY CATCHMENTS TO CLEAR OF INVASIVE ALIEN PLANTS IN NORTH WEST
Working for Water Office Hunter’s Rest Hotel 12 km outside Rustenburg on R24
Wednesday 19th January 2011 1. 2. 3. 4. 5. 6.
Welcome (08h45) Introduction: Aims of workshop and AHP methodology (09h00) Results of previous prioritisation studies (09h15) Discuss current rankings of important invasive alien species in North West (09h35) Tea (10h00 – 10h20) Agree on goal, criteria (objectives) and sub-criteria (sub-objectives) for prioritising quaternaries catchments in North West (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 North West (14h30) 11. Workshop ends at approximately 15h00
Enquiries: Xola Morris Tsobo Tel: 012 253 1787 Cell: 082 800 4813 Email:
[email protected]
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Prioritising quaternary catchments for invasive alien plant control within the Working for Water North West region
APPENDIX 3: PARTICIPANTS IN THE EXPERT WORKSHOP Participants in the workshop held at the Hunter’s Rest Hotel, near Rustenburg on 19th January 2011 to determine criteria and rank these to use in prioritising the clearing of invasive alien plants from quaternary catchments within the North West Region. #
Name
1
Greg Forsyth
2
Hendrik Ferreira
3
F. Jordaan
Organisation
Telephone
E-mail
CSIR
021 888-2400
[email protected]
Midvaal Water Company
018 482-9523
[email protected]
Dept of Agric NW
018 299 6702
[email protected]
4
Hermien Roux
NW - DACERD
082 466-5966
[email protected]
5
Henry Segome
Working for Water
082 807-5655
[email protected]
6
Sipho Jiviadava
Working for Water
082 323-2779
[email protected]
7
Potso Mphephu
8
Favida Nkhwashu
Working for Water
082 833-2970
[email protected]
DEA – Dr R Mampati DM
053 927-0681
[email protected]
9
Zamisile Mabato
10
K.P. Mapoitshego
DEA – Dr K. Kaunda DM
079 81-7206
[email protected]
DAFF – Dr K. Kaunda DM
053 927-3141
11
Benadictos Mdaka
DAFF - LUSM
018 294-3343
[email protected]
12
Maurice Valaya
DAFF - LUSM
018 294-3343
[email protected]
13
Piet Theron
DAFF - LUSM
018 294-3343
[email protected]
14
Pieter H. Roodt
Working for Water
012 253-1787
[email protected]
15
Xola Tsobo
Working for Water
[email protected]
16
Gralvome Moseki
Working for Water
[email protected]
17
Nomsa Mosete
Dr K. Kaunda DM
018 473-8000
[email protected]
18
Lufuno Netangaheni
SANBI – NFNet NW
082 593-3262
[email protected]
19
Rens Botha
DWA – NW Region
012 392-1308
[email protected]
20
Jonathan Modiba
Dr Ruth S. Mampati DM
072 343-7133
[email protected]
21
Hlamalang Come
DEA – Bojanala Office
082 337-5885
[email protected]
22
Elvis Moyo
Working for Water
076 732-2667
[email protected]
23
Nokuzola Mchunu
Working for Water
072 501-2823
[email protected]
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