Ecosystem Guidelines for Environmental Assessment

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SUCCULENT KAROO INCORPORATING VYGIEVELD, BROKEN VELD & QUARTZ PATCHES SUCCULENT KAROO ECOSYSTEMS SUCCULENT KAROO Nick Helme What are the key ecological “drivers” in terms of maintaining ecosystem function, pattern or structure Variations in soil type (such as depth, moisture capacity, rockiness, mineral composition and acidity) largely determine plant community composition and occurrence of rare species. Many of the rare localised species are restricted to distinctive habitats such as quartz patches and rocky outcrops. Total rainfall, and rainfall seasonality, have important effects on community structure and diversity. Low but fairly reliable winter rainfall and hot, dry summers characterise the Succulent Karoo. Rainfall ranges from 20 to 290 mm p.a., with more than 40% of precipitation occurring in winter. Seaward-facing slopes and sites that catch the sea fogs are often very rich in localised endemics. Altitudinal gradients and topographic variation are very important in the Richtersveld and Kamiesberg, and along the Namaqualand escarpment. Small patches (~1 ha) could be viable for a long time, given that most succulents have very small dispersal distances (often no more than a few metres) and that many habitats (e.g. quartz patches) are naturally < 1 ha in extent. Maximum rain water infiltration is vital for plant growth and groundwater availability and its rate is largely determined by plant cover, plant litter and condition of biogenic soil crust (lichens and mosses). Termitaria (’heuweltjies’) often are an important feature in lower-lying areas with loamy soils. Besides supporting distinctive plant communities, they are important browsing "hotspots" for smaller fauna. Grazing, especially by small resident antelope, may be an important factor in regulating competitive interactions between plants. Certain species (especially Pteronia spp.) act as important "nursery" plants for smaller species. They are also important for successional development after disturbance. Tortoises and mammals such as the bat-eared fox are important seed dispersal agents. Fires occur in only a few of the wetter Succulent Karoo types and at very low frequencies (> 50 years), but are usually of a very high intensity. Annuals and Hermannia species dominate post-fire vegetation and some of them seem to be fire-dependent. What are the key issues, vulnerabilities and threats Rare species tend to be concentrated in small specific habitats, often in rocky areas, hence their pronounced vulnerability to mining and quarrying. Heavy grazing pressure (by both domestic stock and extra-limital game species) and trampling of the biogenic crust are a significant cause of habitat degradation. There are a number of invasive plant species that have infested Succulent Karoo habitats and ecosystems, such as Nerium oleander (mostly in watercourses abutting the Fynbos Biome), Mesquite (Prosopis spp.) prickly pear (Opuntia spp.) and saltbush (Atriplex spp.). Watercourses and drainage lines are particularly vulnerable to invasion. Agricultural transformation is a major threat along most of the major river and floodplain systems. COLIN PATERSON-JONES 58 : SUCCULENT KAROO ECOSYSTEMS
Variations in soil types and topography largely determine the composition of Succulent Karoo plant communities. SUCCULENT KAROO
Page 1:
ECOSYSTEM GUIDELINES FOR ENVIRONMEN
Page 4 and 5:
CHARL DE VILLIERS (EDITOR) Conserva
Page 6 and 7:
CONTENTS 7 : 8 : 10 : 14 : 22 : 24
Page 8 and 9:
“Environmental Assessment provide
Page 10 and 11: PREFACE Charl de Villiers These gui
Page 12 and 13: INTRODUCTION Susie Brownlie Purpose
Page 14 and 15: The drafting process, which was co-
Page 16 and 17: INCLUDING BIODIVERSITY CONSIDERATIO
Page 18 and 19: UNEP's voluntary guidelines on biod
Page 20 and 21: Breede River valley: CAPE and SKEP
Page 22 and 23: STEP 4: WHEN SIGNIFICANT IMPACTS AR
Page 24 and 25: A NOTE ON FIRE All fynbos types req
Page 26 and 27: COASTAL ESTUARIES COASTAL ECOSYSTEM
Page 28 and 29: COASTAL non-linear manner over wide
Page 30 and 31: COASTAL SANDY BEACHES & DUNE SYSTEM
Page 32 and 33: COASTAL What are the “bottom line
Page 34 and 35: COASTAL INCORPORATING WEST AND SOUT
Page 36 and 37: COASTAL Strandveld is also increasi
Page 38 and 39: What are the critical things to mai
Page 40 and 41: LOWLAND FYNBOS INCORPORATING SAND F
Page 42 and 43: LOWLAND FYNBOS Veld clearance for r
Page 44 and 45: NICK HELME LOWLAND FYNBOS Leipoldtv
Page 46 and 47: MIDLAND & MOUNTAIN INCORPORATING AL
Page 48 and 49: MIDLAND & MOUNTAIN Altered fire reg
Page 50 and 51: MIDLAND & MOUNTAIN What are the cri
Page 52 and 53: MIDLAND & MOUNTAIN will move in fro
Page 54 and 55: RENOSTERVELD INCORPORATING COAST &
Page 56 and 57: RENOSTERVELD Urban expansion is a p
Page 58 and 59: RENOSTERVELD What, if any, reliable
Page 62 and 63: SUCCULENT KAROO Quarrying for grani
Page 64 and 65: MAINLAND THICKET INCORPORATING THIC
Page 66 and 67: MAINLAND THICKET appear to recover
Page 68 and 69: MAINLAND THICKET What are the criti
Page 70 and 71: FRESHWATER FRESHWATER ECOSYSTEMS: W
Page 72 and 73: FRESHWATER What are the key issues,
Page 74 and 75: FRESHWATER exotic garden escapees i
Page 76 and 77: FRESHWATER INCORPORATING MINOR DRAI
Page 78 and 79: FRESHWATER Introduction to the syst
Page 80 and 81: SCEPS SPATIAL COMPONENTS OF ECOLOGI
Page 82 and 83: JAN VLOK SCEPS Quartz patches can s
Page 84 and 85: SCEPS those characterised by mosaic
Page 86 and 87: TABLE 4: EXAMPLES OF SPATIAL COMPON
Page 88 and 89: SCEPS ecosystems (e.g. Granite Fynb
Page 90 and 91: REFERENCES & RESOURCES There is a w
Page 92 and 93: APPENDIX 1 SOUTH AFRICAN VEGETATION
Page 94 and 95: APPENDIX 2 RECOMMENDED TERMS OF REF
Page 96: SALDANHA CAPE TOWN VANRHYNSDORP CER
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Ecosystem Guidelines for Environmental Assessment

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