DESKTOP BOTANICAL IMPACT ASSESSMENT FOR A CONSTRUCTED DAM AND ASSOCIATED INFRASTRUCTURE ON MELKBOOM, FARM 384 PORTIONS 213 & 220, VANRHYNSDORP

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1 DESKTOP BOTANICAL IMPACT ASSESSMENT FOR A CONSTRUCTED DAM AND ASSOCIATED INFRASTRUCTURE ON MELKBOOM, FARM 384 PORTIONS 213 & 220, VANRHYNSDORP Compiled by : Johlene Krige Botanical Ecological Specialist - Boland Enviro cc, Worcester Client: Sigma-Boerdery (PTY) Ltd. Date: December

2 SUMMARY An area of approximately 24 ha of natural vegetation has been transformed by the construction of an earth dam and associated infrastructure (pump in the Doring river and pipeline towards the dam) on the farm Melkboom, Farm 384, Portions 220&213, Vanrhynsdorp. The development site comprised an ecotone (transitional area) of Klawer Sandy Shrubland and Vanrhynsdorm Gannabosveld (SA Vegetation Map 2006). Both vegetation types are least threatened. It is not certain whether any rare or endangered plant species were impacted by the development since the transformation activities were conducted and completed prior to this assessment. The constructed dam site largely falls within a terrestrial CBA on the property, identified under various criteria including: vegetation type thresholds (although least threatened), priority sub-catchment and edaphic (soil) interphase. Soil interfaces are regarded as ecologically important, as this is often one of the driving forces in terms of evolution of species. The constructed dam on Melkboom farm did not result in the obstruction of a natural landscape corridor. Natural vegetation within the newly constructed dam footprint has been completely transformed (approximately 24 ha) and removed from the site. A large section of the development site appeared partially disturbed prior to the development (network of tracks), by apparent historical vehicle use on the property. Significant areas of natural vegetation are still intact within the areas surrounding the development site, including transitional areas, with Klawer Sandy Shrubland towards the NW and SW and Vanrhynsdorp Gannabosveld along the NE and SE. It is expected that the currently bare footprint of the pipeline will be covered by spring annual regrowth (similar to naturally bare patches of this sandy habitat). Natural re-vegetation is highly likely due to the small diameter of the pipeline footprint area and presence of surrounding natural areas. A pump was installed within the Doring river, recognised as an aquatic CBA.The pump appears to have had limited impact on vegetation within and along the riverbed. Instability and soil erosion of the river bank may be an impact associated with the operational phase. From a botanical/ecological perspective continued use of the dam and associated infrastructure is recommended. The rehabilitation potential of the site to its original habitat is very low, due to the extensive earth moving and excavation activities associated with the construction of the dam. 2

3 Contents 1. INTRODUCTION TERMS OF REFERENCE LIMITATIONS AND ASSUMPTIONS METHODOLOGY MAIN FINDINGS Mapped Ecosystems Special Plant Species Critically Biodiversity Areas Vegetation and Habitat Condition on Site Biodiversity Significance IDENTIFICATION OF IMPACTS RECOMMENDATIONS REFERENCES

4 1. INTRODUCTION This desktop botanical assessment was commissioned in order to help inform decisions regarding the illegal (without environmental authorisation) clearing of indigenous vegetation and the construction of a dam and associated infrastructure on the farm Melkboom, Farm 384/213 & 384/220, Vanrhynsdorp. The properties are located in the Matzikama Municipal Area, approximately 13 km southsouth-east of Klawer. The development site lies in a flat open valley, immediately south of the Doring River. The Olifants River is located directly towards the south-east. An existing dam, known as the Zypherfontein dam, is located directly east of the development site. This dam is currently leaking. A new dam (known as the Sigma dam) was required in order to compensate for the cost of electricity to continuously collect/pump seepage back into the existing dam or to repair the leakage in the dam wall. Land uses and prominent features of the surrounding area are predominantly agricultural related and include vineyards, farm dams, canals, farm workers housing, and farm homesteads on neighbouring properties and natural areas. The development comprised the following: 1. The completed construction of a new dam (Sigma dam) on Farm 384 Portion 213, next to another dam on the property (Zypherfontein dam) 2. A pump was placed on the banks of the Doring River, on Farm 384 Portion An underground water pipeline was installed, which runs from the pump to the dam. The dam has a maximum wall height of 10 m and a full capacity footprint area of 16 ha. The entire development resulted in the transformation of approximately 24.5 ha of indigenous vegetation. The transformation and construction activities were conducted and completed without the required environmental authorisation in terms of the EIA Regulations 2010, of NEMA. The landowner is currently applying for the necessary authorisation (post construction) and continued use of the dam and associated infrastructure in terms of S24G of NEMA. 4

5 N Doring river Olifants river Figure 1. Satellite image showing the location of Melkboom farm (black polygon) and the constructed dam site (star). N Figure 2. Aerial photograph showing the completed Sigma Dam on Farm 384 Portion 213, Vanrhynsdorp. (Photograph date: March Photograph source: Marizanne Vos, BolandEnviro) 5

6 2. TERMS OF REFERENCE This basic desktop botanical assessment was conducted post-construction of the dam. The TOR includes: Determine original vegetation type and sensitivity of the site through Biodiversity Maps. Assessment of vegetation type, land cover and habitat condition using site photographs. This assessment does not include a site visit. Site photos taken by Boland Environmental Consultants after the dam was constructed, as well as images taken by the dam engineer before and during construction will be utilized for the botanical assessment. Provide a specialised opinion on the biodiversity significance of the site. Determine sensitivity of the site and identification of impacts within the development area. This assessment was limited to a desktop study for the following reasons: The entire development area has already been completely transformed. All activities associated with the construction of the dam and relevant infrastructure has been completed. No further transformation of indigenous vegetation will occur within the development areas. 3. LIMITATIONS AND ASSUMPTIONS This assessment does not include a site visit. Site photos taken by Boland Environmental Consultants after the dam was constructed, as well as images taken by the dam engineer before and during construction was utilized for the botanical assessment. The desktop study, however, proofed to be sufficient to identify the impacts that the construction of the dam is likely to have had on vegetation and terrestrial ecosystems. The assessment was conducted post-construction of the dam. The dam development site has thus been entirely transformed and no natural vegetation remains on site. It is unknown whether any rare or endangered plant species occurred within the development site, prior to the transformation. 4. METHODOLOGY An overview of the existing land use, vegetation, ecosystem status and occurrence of sensitive areas on the identified land parcels were obtained through SANBI GIS, The Vegetation Map of South Africa, Lesotho and Swaziland (Mucina and Rutherford 2006), the National Ecosystem Status Maps (2011) and the most recent Google Earth imagery. In addition, the CAPE Fine Scale Biodiversity Planning Project, Critical Biodiversity Areas Map (Pence, G. Q. K, 2008) for the Matzikama Municipal Area was consulted. 6

7 Site photos taken by Boland Environmental Consultants after the dam was constructed, as well as images taken by the dam engineer before and during construction were utilized for the botanical assessment. 5. MAIN FINDINGS 5.1 Mapped Ecosystems The constructed Sigma dam is located within the NW Sandveld Region, which forms part of the Succulent Karoo Biome. According to the SA Vegetation Map, the area transformed by the Sigma dam comprised an ecotone (transitional area) of Klawer Sandy Shrubland and Vanrhynsdorm Gannabosveld (Figure 3). These ecosystems are NOT listed in the National List of Threatened Ecosystems 2011 (G 34809, GoN 1002). Klawer Sandy Shrubland is found on deep neutral to acid sands with occasional loamy sands, within the Lower Olifants River Valley in close surrounds of Klawer. The vegetation comprise sparse to moderately dense shrubland dominated by Montinia caryophyllacea, with an abundance of the spinescent grass (Cladoraphis spinosa) in the undergrowth. Annuals and geophytes are very common in spring including various species of Dimorphotheca, Oncosiphon, Osteospermum, Senecio, Ursinia, Zaluzianskya, Albuca and Lachenalia. Special plant species include the herbs/shrublets Pelargonium nephrophyllum (Endangered), Steirodiscus schlechteri (Vulnerable), Selago inaquaefolia (Endangered) and the geophytes Haemanthus pubescens ssp. leipoldtii (Vulnerable) and Sparaxis auriculata (Endangered) (Mucina & Rutherford 2006; Helme 2007). Vanrhynsdorm Gannabosveld occurs on deep silty loams that are often slightly saline with a saline or biogenic crust. It is a typically low, sparse succulent shrubland, with spectacular geophyte and annual displays in good rainfall years. The vegetation is dominated by gannabos (Salsola spp.) and very sparse and dull in summer. Special plant species include the succulent shrub Euphorbia fasciculate (Vulnerable), succulent herb Brownanthus glareicola (Vulnerable), herb Cotula pedunculata (Threatened) and the geophyte Eriospermum eriophorum (Critically Endangered). 5.2 Special Plant Species From a desktop assessment of the ranges and habitat preferences of special plant species occurring within the particular ecosystems present within and around the development site (see 5.1), only Selago inaquaefolia (Endangered) and Haemanthus pubescens ssp. leipoldtii (Vulnerable) are likely to occur within the local area. Selago inaquaefolia (Endangered) grows on sandy flats around Klawer. Its extent of occurrence is <100 km² and this species is known from two locations. Its habitat is continuously being converted for vineyard, tomato or onion cultivation (Raimondo 2007). 7

8 Haemanthus pubescens ssp. leipoldtii (Vulnerable) occurs in a mixture of sand plain fynbos, succulent karoo and strandveld, in areas with an accumulation of loose, windblown sand. It is known from three locations, in the range from Vanrhynsdorp to Klawer. Although not declining currently, this subspecies remains potentially threatened by expanding agricultural activities along the Olifants River, driven by the introduction of irrigation schemes (Snijman & Victor 2004). It is not certain whether any rare or endangered plant species were impacted by the development since the transformation activities were conducted and completed prior to this assessment. SA VegMap 2006 Vanrhynsdorp Gannabosveld Klawer Sandy Shrubland Namakwaland Riviere Figure 3: Extract from the South African Vegetation Map (Mucina & Rutherford 2006) indicating the boundaries of Melkboom farm (black dotted polygon), the constructed dam footprint (red polygon) and pipeline (red dotted line). 5.3 Critically Biodiversity Areas Figure 4 represent aquatic and terrestrial Critical Biodiversity Areas (CBAs) and Ecological Support Areas identified through the systematic assessment conducted by the C.A.P.E. Fine- Scale Biodiversity Planning (FSP) project. These areas require safeguarding to ensure the continued existence of biodiversity, its ecological processes (e.g. animal migration, pollination, seed dispersal etc.) and its ecosystem services e.g. water supply. The map also delineates Other Natural Areas and No Natural Remaining/Developed areas (Pence 2008). The network of CBAs reflected on the CBA Map indicates the most efficient (i.e. least landhungry) selection and classification of land portions (a network of natural sites) requiring 8

9 safeguarding in order to meet national biodiversity thresholds. The overall aim is to avoid the loss of natural habitat in Critical Biodiversity Areas (CBAs) and prevent the degradation of Ecological Support Areas (ESA), while encouraging sustainable development in Other Natural Areas. The following criteria were used to identify terrestrial CBAs: all remaining patches of Critical Endangered vegetation all known point localities of Species of Special Concerns (e.g. Rare/Endangered plant or animal species) Endangered, Vulnerable or Least Threatened vegetation required to meet national thresholds (target area) landscape corridors required to meet the predefined thresholds for spatially explicit ecological processes (e.g. upland-lowland corridors, coastal-and-sand movement corridors, etc.) CBAs on site: The constructed dam site largely falls within a terrestrial CBA on the property (Figure 4), identified under various criteria including: vegetation type thresholds (although least threatened), priority sub-catchment and edaphic (soil) interphase. A large section of this CBA is already transformed by the Zypherfontein dam. The southernmost section of the dam site is identified as Other Natural Areas on the CBA map. The pump was installed within the Doring river, recognised as an aquatic CBA. The northernmost section of the site may have extended into the upper sections of a Critically Ecological Support Area buffer (part of a small drainage line that originates ± 20 m NE of the development site). The management objectives for terrestrial Critically Biodiversity Areas are to maintain natural land and to rehabilitate degraded to natural or near natural and manage for no further degradation (Maree and Vromans 2010). For ecological support areas, biodiversity processes should be maintained. Figure 5 shows the CBA maps in a broader context. A number of CBAs were identified as natural landscape corridors in the area. The site does not form a direct link between other terrestrial CBAs. The constructed dam on Melkboom farm did not result in the obstruction of a natural landscape corridor (Figure 5). It is however important as it is connected to an aquatic CBA and comprises an edaphic interphase (ecotone of Klawer Sandy Shrubland and Vanrhynsdorp Gannabosveld). Figure 6 shows the habitat condition of terrestrial sites identified in the CBA Map. According to this map, the constructed dam site predominantly comprised of natural areas with a few near-natural patches. 9

10 Doring river Olifants river Figure 4: Extract from the CAPE Fine Scale Project: Critical Biodiversity Areas Map for the Matzikama Municipality. Olifants river Doring river Figure 5: Extract from the CAPE Fine Scale Project: Critical Biodiversity Areas Map indicating CBAs of the surrounding area in the broader context of the Matzikama Municipality. 10

11 Figure 6: Extract from the CAPE Fine Scale Project: Critical Biodiversity Areas Map indicating the habitat condition of terrestrial CBAs and other natural areas within the constructed dam site on Melkboom farm. 5.4 Vegetation and Habitat Condition on Site The development site comprises a transitional area. From the pre-construction aerial photographs, a significant edaphic (soil) interface is clearly evident, which cuts directly through the development site (Figure 7). Open sandy areas were a prominent feature within the SW parts of the site. Such open sandy areas are typical of the Klawer Sandy Shrubland ecosystem during summer months that are covered with spring annuals after good rains. Apart from generally open sandy areas, the SW parts of the site comprised areas that appeared partially disturbed by apparent historical vehicle use on the property (network of tracks evident on 2010 aerial photographs). The NE portions of the site comprised natural vegetation which appeared to be in a good condition, prior to the dam construction activities. The remaining areas within the immediate surroundings of the dam comprise denser vegetation dominated by a low succulent shrubland (Vanrhynsdorp Gannabosveld) with many sandy elements of adjacent Klawer Sandy Shrubland vegetgation. 11

12 Natural vegetation within the newly constructed dam footprint has been completely transformed (approximately 24 ha) and removed from the site. Overall, the vegetation within the immediately surrounding areas (post construction of the dam) appears sparse and dull. Open sandy areas can be interpreted incorrectly as disturbed/near natural areas, while this is typical of the particular ecosystems during summer months (site photos were taken during March 2013, prior to winter rains). Significant areas of natural vegetation are still intact within the areas surrounding the development site, with Klawer Sandy Shrubland towards the NW and SW and Vanrhynsdorp Gannabosveld along the NE and SE. The path of the underground water pipeline is largely bare (sandy) with little or no vegetation re-growth. The pump installed in the Doring river appeared to have had limited impact on vegetation within and along the river. Legend Farm boundary Dam footprint Pipeline Pump Soil interphase N Doring river Klawer Sandy Shrubland Vanrhynsdorp Gannabosveld Zypherfontein dam Figure 7. Satellite image showing the Sigma dam site, pipeline and pump, pre-construction. 12

13 Figure 8. Looking north towards the newly constructed Sigma dam wall, showing Klawer Sandy Shrubland south of the dam site. (Photograph date: March Photograph source: Marizanne Vos, BolandEnviro) Figure 9. Looking north, from the completed Sigma dam towards the Doring River (not visible) and cultivated fields beyond. Natural Klawer Sandy Shrubland is evident in the NW, with natural Vanrhynsdorm Gannabosveld in the NE. (Photograph date: March Photograph source: Marizanne Vos, BolandEnviro) 13

14 Figure 10 a & b. Water pump installed on the bank of the Doring River, to abstract water from the river and pump it to the completed dam. (Photograph source: Floris Visser (Sigma Boerdery)) 5.5 Biodiversity Significance The vegetation on site is Least threatened. A large section of the development site appeared partially disturbed prior to the development (network of tracks), by apparent historical vehicle use on the property. In addition significant natural areas were evident on and surrounding the site. These may incorrectly appear disturbed/near natural in the field, due to sparse vegetation cover during summer months, which is typical of the particular ecosystems. The development site lies within a transitional area (soil interface). Soil interfaces are regarded as ecologically important, as this is often one of the driving forces in terms of evolution of species. The largest portion of the development site comprises a terrestrial CBA. The particular CBA borders an aquatic CBA (Doring river). The site does not form a direct link between other terrestrial CBAs and does not form part of a natural biodiversity corridor. The small drainage line that origins within the area directly north of the dam site appears still intact and functional. 14

15 From a botanical/ecological perspective, the dam site was of moderate-high biodiversity significance, prior to the development. The area is regarded as sensitive, not as a result of the vegetation type or specific plant species that grows on the site, but due to the location in the landscape (transitional area, natural area adjacent to a river). A significant natural area, which also comprises the Klawer Sandy Shrubland Vanrhynsdorp Gannabosveld transitional area, is still intact within the immediate surrounding area, towards the south of the Sigma dam. Additionally, a portion of the transitional habitat is still intact towards the north of the dam site, all the way to the Doring river. The remaining natural areas within the immediate vicinity of the completed Sigma dam thus remain a priority in terms of biodiversity significance. 6. IDENTIFICATION OF IMPACTS 6.1 Impact on vegetation and habitat The construction of a new dam on Melkboom farm resulted in the permanent transformation of a localised area (approximately 24 ha) of Least Threatened vegetation and natural / near natural habitat. Significant areas of natural vegetation are still intact within the areas surrounding the development site, with Klawer Sandy Shrubland towards the NW and SW and Vanrhynsdorp Gannabosveld along the NE and SE. Most of the fauna and other organisms that naturally occured within and around the development area will have other similar habitat still available to them. The installation of a pipeline from the Doring river towards the dam site resulted in the temporary disturbance / transformation of natural vegetation (±0.5 ha). It is expected that the currently bare footprint of the pipeline will be covered by spring annual regrowth (similar to naturally bare patches of this sandy habitat). Natural re-vegetation is highly likely due to the small diameter of the pipeline and presence of surrounding natural areas. Table 1. Impact on vegetation and habitat Extent Duration Intensity Probability Status Confidence Significance Site Permanent Low Definite Negative High Low Potential mitigation during construction: This impact could not have been avoided. The dam was constructed within the most disturbed site on the property. 6.2 Impact on indigenous plant species The constructed dam resulted in the localised impact on populations of indigenous plant species. It is however not certain whether any rare or endangered plant species were impacted by the development since the site has been completely transformed prior to this application. 15

16 It is unlikely that the development caused the permanent loss of plant species, as other similar habitat that are in a fairly good or even better condition, are available within the immediate surroundings of the dam site. Natural Klawer Sandy Shrubland is evident towards the NW and SW and Vanrhynsdorp Gannabosveld along the NE and SE of the development site. Adjacent natural habitats include a transitional area of these ecosystems towards the north and south of the site. Table 2. Loss of indigenous plant species Extent Duration Intensity Probability Status Confidence Significance Local Permanent Medium Unlikely Negative Medium Low Potential mitigation during construction: A detailed Botanical Assessment prior to the construction of the Sigma dam could have avoided potential impacts on indigenous plant species through relocation of individuals. It is however unlikely that the development caused permanent loss of entire populations of special plant species. 6.3 Impact on Ecological Support Areas A small, ephemeral drainage channel originates ±20 m north-east of the northernmost edge of the constructed dam, flowing into the Doring river. The drainage channel is recognised as a Critical Ecological Support Area to maintain ecological processes (according to the C.A.P.E. Fine-Scale Biodiversity Planning Project). The northernmost section of the transformed site may have extended into the buffer area of the upper sections of the mapped Critically Ecological Support Area (maximum 0.5 ha), but not into the drainage channel itself. From the satellite images and site photos it appears that the drainage channel is still intact and functional. Table 3. Impact on ecological support areas Extent Duration Intensity Probability Status Confidence Significance Site Medium term Low Low Negative High Low Potential mitigation during construction: It is unlikely that the impacts (Low) could have been reduced. 6.4 Reduction of terrestrial CBAs Any development within CBAs will have the cumulative impact of an irreversible reduction or fragmentation of a network of natural sites identified to meet pattern and process thresholds of biodiversity. The construction of the Sigma dam had a direct impact on a transitional area of two ecosystems (Klawer Sandy Shrubland and Vanrhynsdorp Gannabosveld). The site is thus 16

17 largely regarded a CBA due to an edaphic/soil interphase over most of the site. Soil interfaces are regarded as ecologically important, as this is often one of the driving forces in terms of evolution of species. Other criteria of the particular CBA within the immediate surroundings of the development site include vegetation type thresholds (although least threatened) and priority sub-catchment that will be impacted by the development. Table 4. Impact on terrestrial CBAs Extent Duration Intensity Probability Status Confidence Significance Regional Permanent Medium Definite Negative High Medium Potential mitigation during construction: It is unlikely that the impacts could have been avoided / mitigated, apart from finding another locality or the no-go option which would have had significant practical and economic implication and most likely additional biodiversity implications. 6.5 Impact on aquatic CBAs A pump was installed within the Doring river, recognised as an aquatic CBA. The installation of the pump appeared to have had limited impact on vegetation within and along the riverbed (construction phase). The most significant impacts associated with the pump are impact on the stability of the river bank and potential erosion (operational phase). Table5. Impact on aquatic CBAs (stability of river bank and erosion) Extent Duration Intensity Probability Status Confidence Significance Site Long term Medium Likely (without mitigation) Negative High Medium (without mitigation), Low (with mitigation) Proposed mitigation: Effective measures should be implemented to control erosion of the river bank, particularly when it is required to remove the pump from the river during heavy rains and flooding. The site should be inspected immediately after heavy rainfall for any erosion damage. Any erosion sites should be repaired and stabilised as soon as possible. 17

18 7. RECOMMENDATIONS From a botanical/ecological perspective continued use of the dam and associated infrastructure is recommended. The rehabilitation potential of the site to its original habitat is very low, due to the extensive earth moving and excavation activities associated with the construction of the dam. The desktop study proved adequate to assess the impacts of the development on biodiversity. A detailed botanical assessment, including a site visit is not recommended. In addition, the following recommendations are made: Natural areas within the immediate surroundings of the constructed dam should be maintained to conserve the remnants of the transitional area and habitat of local plant species. No development or disturbances should be allowed within adjacent natural CBA of the dam site. Effective measures should be implemented to control erosion of the river bank where the pump is installed. Measures should be implemented for the ongoing control of soil erosion on the dam s earth walls, which may impact on adjacent natural areas. The development area should be kept clear of alien invasive trees at all times. 8. REFERENCES Brownlie, S Guideline for involving biodiversity specialists in EIA processes: Edition 1. CSIR Report No. ENV-S-C C. Provincial Government of the Western Cape: Department of Environmental Affairs and Development Planning. De Villiers, C.C. et al Fynbos Forum Ecosystem Guidelines for Environmental Assessment in the Western Cape. Fynbos Forum, Cape Town. Helme, N. (2007) Botanical Report: Fine Scale Vegetation Mapping in the Sandveld, report to CapeNature as part of the C.A.P.E. FineScaleBiodiversity Planning Project. Mucina, L. and M. Rutherford. Eds The Vegetation of South Africa, Lesotho, and Swaziland. Strelitzia 19. South African N ational Biodiversity Institute, Pretoria. Pence, Genevieve QK C.A.P.E. Fine-Scale Systematic Conservation Planning Assessment: Technical Report. Produced for CapeNature as part of the GEF-funded C.A.P.E. Fine-Scale Biodiversity Planning Project. Cape Town, South Africa. Raimondo, D Selago inaequifolia Hilliard. National Assessment: Red List of South African Plants version Accessed on 2013/12/11 Snijman, D.A. & Victor, J.E Haemanthus pubescens L.f. subsp. leipoldtii Snijman. National Assessment: Red List of South African Plants version Accessed on 2013/12/11 National Environmental Management: Biodiversity Act: National list of ecosystems that are threatened and in need of protection, (G 34809, GoN 1002), 9 December