NFEPA Atlas 5.3_20111025_FINAL.indd - Biodiversity GIS - SANBI

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4.3 Wetland ecosystem typesWetland ecosystem types were used for representing natural examples of the diversity ofwetland ecosystems across the country. Wetlands of the same ecosystem type are expectedto share similar functionality and ecological characteristics. For example, seeps functiondifferently to valley-bottom wetlands; valley-bottom wetlands in the mesic highveldgrassland have different characteristics to valley-bottom wetlands in sandstone fynbos. Asexplained in Section 1.5, the biodiversity target for freshwater ecosystems in South Africais 20%, which means that we should keep at least 20% of each wetland ecosystem type ina natural or near-natural condition. This serves to conserve many common species andcommunities, and the habitats in which they evolve. The coarse-filter surrogate providedby wetland ecosystem type was supplemented with information on Ramsar status (http://ramsar.wetlands.org/), known threatened frog (http://www.adu.org.za/; http://www.adu.org.za/docs/FrogData.csv) and waterbird occurrences (http://cwac.adu.org.za/cwac_map.php?Pv=GP) and expert knowledge on biodiversity importance. These additional datasources helped in identifying wetland FEPAs (see Section 2.2 of the atlas).Planning for wetlands at the landscape level (rather than on a site-by-site basis) ischallenging. The best national information available prior to NFEPA was the SANBI NationalWetland Map 3 (completed in 2009; http://bgis.sanbi.org), which maps the extent ofDepressionMountain seepPeter Chadwick/WWF-SAKate Snaddon25 kmSeepValleyhead seepUnchannelled valley-bottomChannelled valley-bottomFloodplainDepressionFlatsome 100 000 wetland systems. The delineations are based largely on remotely-sensedimagery and therefore do not include historic wetlands lost through drainage, ploughingand concreting. Irreversible loss of wetlands is especially high in some areas, such as urbancentres and intensively cultivated areas.NFEPA augmented the National Wetland Map 3 with finer scale wetland maps that wereavailable from various sub-national biodiversity planning exercises. This produced an NFEPAwetland map of almost 200 000 wetlands. Sub-national wetland data included:• Wetlands for the entire KwaZulu-Natal Province (available from Ezemvelo KZN Wildlife);• Cape Action for People and the Environment (C.A.P.E.) fine-scale biodiversity planningwetlands of Saldanha/Sandveld, Riversdale plain and Upper Breede River Valley(available from http://bgis.sanbi.org);• Overberg, Niewoudtville and Kamieskroon wetlands (available from http://bgis.sanbi.org);• Selected wetlands of conservation importance in Mpumalanga Province (available fromMpumalanga Parks and Tourism Agency).Although there are still gaps in mapping wetlands in South Africa, enormous progresshave been made over the last several years. SANBI has an ongoing wetland inventoryingprogramme that is improving the GIS layer for national wetlands to support futureplanning and management.Another important advance towards landscape-level planning for wetlands was thecompletion of the national wetland classification system (SANBI 2009). Levels 1 to 4of the classification system identify broad groups of wetlands sharing similar regionalcontext, landform and broad hydrology. Levels 5 and 6 describe site characteristics suchas hydroperiod, geology, vegetation, substratum, salinity, pH and naturalness. Wetlands inthe NFEPA wetland map were classified into wetland ecosystem types according to Level4 of the national wetland classification system.Level 4 wetland ecosystem types were derived using the landforms (Section 4.5) andwetland vegetation groups (Section 4.6). First the four landform classes (benches, slopes,plains and valley-floors) were used in conjunction with the 1:50 000 pans GIS layer(Department of Land Affairs: Chief Directorate Surveys and Mapping 2005-2007) and1:500 000 river network GIS layer to classify each wetland into one of seven ‘hydrogeomorphictypes’ (Figure 4.8):• Seep• Valleyhead seep• Unchannelled valley-bottom• Channelled valley-bottom• Floodplain• Flat• DepressionSecond, each wetland was assigned the wetland vegetation group that occupied themajority of its area, to characterise the regional context (e.g. climate, soil, geology) withinwhich the wetland occurs. For each wetland, the hydrogeomorphic type was combinedwith its corresponding wetland vegetation group, producing 791 distinct wetlandecosystem types across the country. Although there are many gaps and challenges withthe NFEPA wetland ecosystem types, they represent a major achievement and provide asignificant new national product that can now be further refined and debated.FloodplainKate SnaddonFigure 4.8: An example of the hydrogeomorphic types used to derive wetland ecosystem types in South Africa. The inset mapshows the location of the area on the main map. The hydrogeomorphic type of a wetland was used together withthe wetland vegetation group in which it was embedded (Section 4.6) to determine its wetland ecosystem type.DepressionKate SnaddonInput data layers- 52 -
4.4 Wetland conditionWetland condition describes the extent to which a wetland has been modified by humanactivity. There are many approaches to assessing wetland condition in the field. However,in the absence of field survey data for most wetlands across the country, wetlandcondition was modelled by NFEPA to serve as a relative measure for informing choices inselecting wetland FEPAs. As explained in Section 2.2, choices in the selection of wetlandFEPAs were made using wetland ranks, which were based on a combination of specialfeatures and wetland condition. Wetlands with known special features (e.g. presence ofrare plants and animals, extensive intact peat wetlands) were selected as the first choicefor achieving biodiversity targets for wetland ecosystem types. Any remaining targets wereachieved first in wetlands of good condition, proceeding only if necessary to wetlands ofprogressively modified condition (Table 4.2). Wetland FEPAs did not have to be in a goodcondition to be chosen as a FEPA, but those wetland FEPAs currently in less than goodcondition should be rehabilitated to the best attainable ecological condition.Wetlands that had the majority of their area coinciding with 1:50 000 artificial water bodies(Department of Land Affairs: Chief Directorate Surveys and Mapping 2005-2007) wereassigned a heavily- to critically-modified wetland condition (equivalent of D, E or Fecological category for rivers: Table 4.1). For the remaining wetlands, the percentagenatural land cover in and around the wetland was used as a surrogate measure of wetlandcondition. The same land cover data as used for modelling condition of tributaries wasapplied (Section 4.2). Percentage natural land cover was calculated within four areas:the wetland itself, and the wetland surrounded by GIS buffers of 50 m, 100 m and 500 mfrom the edge of the wetland. The lowest of these four resulting percentages of naturalland cover was used to guide the condition category of the wetland (Table 4.2; Figure 4.9),using the following rules:Natural or goodModerately modifiedHeavily to critically modified• Non-riverine wetlands were considered to be in a good, moderately modified orheavily modified condition if the lowest percentage natural land cover in and aroundthe wetland was 75% or more, 25-75%, or less than 25% respectively.• This same rule was applied to riverine wetlands associated with natural or moderatelymodified rivers (i.e. in an A, B, or C ecological category) because in such cases thesurrounding land use is more likely to be a driver of wetland ecosystem degradationthan the condition of the associated river.• Riverine wetlands associated with a largely modified, seriously modified or criticallymodified river (i.e. in a D, E or F ecological category) were assigned a heavily modifiedcondition irrespective of the surrounding natural land cover.• Several riverine wetlands are associated with rivers too small to be included onthe 1:500 000 river network GIS layer – in these instances, the river condition wasunknown and the wetland was assigned a condition based on the lowest percentagenatural land cover.It is very difficult to assess accurately how much of South Africa’s wetland area hasalready been irreversibly lost. However, we know it is substantial, especially in urbanareas and intensively cultivated areas. Over and above this irreversible loss that hasalready taken place, approximately 45% of our remaining wetland area in South Africa isin a heavily or critically modified condition, owing to human impacts such as damming,draining and bulldozing of wetlands. This is of immense concern given the importantregulating ecosystem services that healthy wetlands provide, such as purifying water andregulating floods.Figure 4.been accentuated to make them more visible.500 kmTable 4.2: Wetland condition categoriesWetland condition Assessment criteria * % of total wetland area **Good Natural land cover ≥ 75% 44Moderately modified Natural land cover 25-75% 18Heavily modified Riverine wetland associated with a D, E, F or Z category river 9Critically modified Wetland where the majority of its area coincides with a 1:50 000artificial inland water body, or where natural land cover < 25%* Percentage natural land cover was calculated within four areas: the wetland itself, and the wetland surrounded byGIS buffers of 50 m, 100 m and 500 m from the edge of the wetland. The lowest of these four percentages wasused.** Note that this excludes the extent of wetlands that have already been irreversibly lost due to draining, ploughingand concreting.36Input data layers - 53 -
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Front Cover: Clanwilliam and Fiery
Page 4 and 5:
AcknowledgementsThe development of
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Table of ContentsPart 1:Introductio
Page 8 and 9: Part 1: IntroductionThis section de
Page 10 and 11: 1.2 Guiding principles for managing
Page 12 and 13: 1.3.3 Destruction or degradation of
Page 15 and 16: 1.5 History of freshwater biodivers
Page 17 and 18: Part 2: FreshwaterEcosystem Priorit
Page 19 and 20: Box 2.1. Policy mechanisms supporte
Page 21 and 22: WMA 1LegendLIMPOPOTownSub-quaternar
Page 23 and 24: WMA 3CROCODILE(WEST) AND MARICOLege
Page 25 and 26: WMA 5INKOMATILegendSabieTownSub-qua
Page 27 and 28: WMA 7THUKELALegendBuffaloTownSub-qu
Page 29 and 30: WMA 9MIDDLE VAALMiddle VaalRhenoste
Page 31 and 32: WMA 11MVOTI TO UMZIMKULUMvotiLegend
Page 33 and 34: WMA 13UPPER ORANGERiet/ModderLesoth
Page 35 and 36: WMA 15FISH TO TSITSIKAMMALegendFish
Page 37 and 38: WMA 17OLIFANTS/DOORNSandveldKnersvl
Page 39 and 40: WMA 19BERGLegendTownSub-quaternary
Page 41 and 42: % Area of WMA selected as FEPA10213
Page 43 and 44: 3.3 Free-flowing riversA free-flowi
Page 45 and 46: The Mtentu River: An ecotourism ass
Page 47 and 48: The Elands River: A unique biodiver
Page 49 and 50: For species and species lineages co
Page 51 and 52: The map of high water yield areas w
Page 53 and 54: 0 10 20 30 40 50BERGBREEDECROCODILE
Page 55 and 56: 4.1.2 Flow variability categoriesTh
Page 57: % River length0 20 40 60 80 1004.2
Page 61: 4.6 Wetland vegetation groupsWetlan
Page 64 and 65: Nel, J.L., Roux, D.J., Cowling, R.M
Page 66 and 67: Fish Support Area: Fish sanctuaries
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NFEPA Atlas 5.3_20111025_FINAL.indd - Biodiversity GIS - SANBI

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