Vegetation Assessment for the Proposed Olifantsfontein Landfill Waste Management License
Total Page:16
File Type:pdf, Size:1020Kb
Vegetation Assessment for the proposed Olifantsfontein Landfill Waste Management License September 2020 Ina Venter Pr.Sci.Nat Botanical Science (400048/08) M.Sc. Botany trading as Kyllinga Consulting 53 Oakley Street, Rayton, 1001 [email protected] i Executive Summary Introduction Kyllinga Consulting has been appointed by EcoPartners to review the vegetation on the indicated areas on Portion and 41 and a portion of the Farm Olifantsfontein 410, Tembisa. The project includes the review of the vegetation assessment conducted by Natural Scientific Services on site in March 2011 as well as a desktop assessment and site visit to verify whether the assessment is still applicable to the site or whether the situation changed. The purpose of the assessment was to determine any changes to the vegetation since the last vegetation assessment and to provide updated empirical information related to the vegetation on the site. Methods The desktop assessment included review of the vegetation report by NSS (2011), various databases and the investigation of aerial photographs of the site, with the identification habitat units. The site visit took place on 8 September 2020 to ground truth the data obtained through the desktop assessment. The vegetation in each habitat unit was recorded along random transect walks. The assessment focused on the grassland unit since this is the most intact vegetation unit, but the vegetation in the disturbed areas dominated by alien species were also recorded. The results of the assessment were compared to the NSS assessment of 2011. Results The density of invasive woody species on site has increased since the assessment in 2011 and the site has formally been authorised as a landfill site. In addition, landfill cell construction (cells 1 and 5) on the western portion of the site commenced. A portion of the site has also recently been cleared in preparation of cell 7 of the landfill. The following vegetation units are currently present on site: • Alien dominated vegetation • Grassland • Disturbed grassland • Historically excavated (opportunistic wetland species) Several portions of the site have been cleared of vegetation through construction of the authorised landfill cells or roads. These areas are almost completely bare of vegetation and should therefore not be considered to be vegetation units and are of no conservation importance. The grassland and disturbed grassland units have similar dominant species, but the grassland unit have a much higher species diversity. None of the vegetation units are pristine, but different levels of disturbance are present in the various patches of grassland. The observed species composition of the grassland units on site is very similar to species composition recorded during the 2011 assessment. Several additional species were recorded, while a number of others were not observed. This is mostly due to the season of the assessment. A number of early flowering species were ii observed during the site visit, but it is likely that several species were still dormant at the time of the 2020 assessment. Although the identified vegetation units are still fairly similar to the 2011 assessment, the disturbance on site increased significantly. The density of invasive trees is higher and the infestation expanded significantly. The new authorised landfill construction activities also contributed significantly to the disturbances on site. Although remnants of grassland are present none are pristine and the units are largely isolated. Conclusion and Recommendations The disturbances on the site increased since the 2011 assessment and the alien dominated woody component took over the alien dominated herbaceous component. The northern portion of the site is therefore now almost completely covered by alien and invasive tree species. The dominant trees include Acacia mearnsii and Acacia decurrens, but a wide variety of other invasive tree, forb and shrub species are also present. This unit is of low conservation importance and is very suitable for use as a landfill as authorised. The control of invasive species in this area is however required to prevent the spread of invasive species from the site to surrounding areas. Construction of the authorised landfill Cell 5 has commenced on the western portion of the site and the vegetation is completely cleared in this area. The vegetation has also been cleared for cell 7 of the landfill. Various other areas are affected by land clearing, such as roads. All of these areas are of low conservation importance. Some historical excavations are present across the site and water are accumulating in some of the excavations, resulting in the presence of opportunistic wetland species on site. These areas are not wetland areas and are not of conservation importance. Some grassland units representing the Egoli Granite Grassland vegetation unit remain in the southern portion of the site. These units are affected by disturbance and are no longer pristine but will improve if sufficient management measures are applied. The units are however small and fairly isolated, representing an ecological cul de sac. The unit is therefore of moderate conservation importance. The disturbance in the surroundings affect the remaining grassland and wetland unit to the south of the site, further isolating the remnant patches on site. Small grassland units are unlikely to persist without sufficient management and connectivity to surrounding areas. The impact of the proposed amendment on the grassland is therefore considered to be of medium significance. The landfill on site has already been licenced to receive inert waste. Changing the facility to receive general waste will not alter the impact on the environment significantly. iii Table of Contents 1 Introduction .................................................................................................................................. 1 1.1 Limitations ............................................................................................................................ 1 1.2 Details of the Authors ........................................................................................................... 1 1.3 Existing authorisations .......................................................................................................... 1 2 Site ................................................................................................................................................ 2 2.1 Location and site description ................................................................................................ 2 3 Desktop information ..................................................................................................................... 2 3.1 Gauteng C-Plan and NBA ....................................................................................................... 2 3.2 Vegetation............................................................................................................................. 2 3.3 Water resources .................................................................................................................... 2 4 Methods ........................................................................................................................................ 7 4.1 Vegetation Assessment ......................................................................................................... 7 4.2 Ecological Sensitivity ............................................................................................................. 7 4.3 Impact Assessment ............................................................................................................... 8 5 Results......................................................................................................................................... 11 5.1 Vegetation........................................................................................................................... 11 5.1.1 Description .................................................................................................................. 11 5.1.2 Invasive species ........................................................................................................... 17 5.1.3 Species of conservation importance ........................................................................... 18 6 Results of the Environmental Screening Tool ............................................................................. 19 7 Sensitivity .................................................................................................................................... 20 8 Impact assessment and mitigation recommendations ............................................................... 20 9 Conclusion & Recommendation .................................................................................................. 23 10 References & further reading ................................................................................................. 24 List of Figures Figure 1: Location of the site. ............................................................................................................... 3 Figure 2: Important areas according to the Gauteng C-Plan. ................................................................ 4 Figure 3: Terrestrial remnants according to the NBA (2018) database. ................................................ 5 Figure 4: Wetland areas according to the National Wetland Map 5. ...................................................