Bothalia 34,2: 141-153 (2004)
Vegetation of high-altitude fens and restio marshlands of the Hottentots Holland Mountains, Western Cape, South Africa
E.J.J. SIEBEN* f, C. BOUCHER* & L. MUCINA*
Keywords: canonical correspondence analysis. Cape Wetlands Fynbos. phytosociology, plant communities, svntaxonomy
ABSTRACT
Seepages occurring at high altitudes in the Hottentots Holland Mountains (HHM) (Western Cape Province. South Africa) were subject to a phytosociological survey. Relevé sampling method and classification procedures of the floristic-sociological (Braun-Blanquet) approach as well as numerical data analyses (numerical classification and ordination) were used to reveal syn- taxonomic patterns and characterize the position of the syntaxa along major environmental gradients. Nine plant communities were recognized, three of which were classified as associations, following formal syntaxonomic and nomenclatural rules of the floristic-sociological approach Most of the studied mire communities were dominated by low-growing clonal restios (Restionaceae). whereas some consisted of other types of graminoids. The most important species determining the structure (and function) of the mire communities on sandstones of the HHM include restios Anthochortus crinalis, Chondropetalum deustum. C. mucronatum, Elegia intermedia. E. thyrsifera. Restio subtilis. R. purpurascens. cyperoids Epischoenus villosus. Ficinia argy- ropa, grasses Ehrharta setacea subsp. setacea. Pentameris hirtiglumis as well as shrubs Berzelia squarrosa. Cliffortia tricuspi- data. Erica intenallaris and Grubbia rosmarinifolia. Protea lacticolor and Restio perplexus dominate a rare shale band seep age community. There are two major groups of communities—the fens (dominated by carpets of Anthochortus crinalis and other low-growing species) and the restio marshlands (mosaics of low tussocks of Restio subtilis and tall Chondropetalum mucrona tum). The degree of soil (and water) minerotrophy was found to be the most important differentiating feature between the mire (fen and restio marshland) communities studied. The soils in the centre of mires were found to have high contents of peat and showed very little influence from the underlying sandstone. The soils along the mire margins had a greater admixture of miner al soil derived from the sandstone or shale bedrock.
INTRODUCTION These are defined as wet. swampy habitats characterized by peat> soils, regardless of the chemico-physical properties of The Cape mountain ranges are important catchments the peat and water captured in the peaty soils. Concepts such for high-quality drinking water. A vast quantity of this as bogs and fens refer to specific types of mires (Gore 1983). water is stored in the basement rocks before it is released The term bog refers to the strictly ombrotrophic (rain-fed) into river systems via seepages (Hewlett 1982). Seepage and usually oligotrophic mires found in places with high pre is a very general term for an area where water percolates cipitation. whereas fens are the mires (minerotrophic or tran through the upper soil layers (mostly lying over a layer sitional ) that are fed to a larger extent by water that has per of impenetrable rock) and usually forms the source of colated through the mineral substrate. The Cape high-altitude rivers. It includes the majority of wet slopes as well as mires generally qualify as fens; true bogs are rare in the south many mires of the Cape mountains. The quality of water ern hemisphere, although they do occur on some steep south- is largely determined by the soil conditions that percolat facing slopes in Western Cape mountains. In the mountains, ing water encounters prior to its emergence at the surface mires are found at the sources of the rivers and in watersheds. and on its way to a river, hence seepages are of great Riparian mires can be formed in places where the floodplain importance to river ecosystems (Bosch el al. 1986). is very wide and the area remains inundated long after a flood However, the total surface area of seepages that influ has receded. ence the water quality of rivers is variable and many seepages can be out of touch with the river system for a long time. This was called the Variable Source Area There are four types of seepages linked to the drainage Concept by Hewlett (1961). After heavy rains the Source network of rivenne systems recorded in the Cape moun Area of a river expands and much water, that was stored tain ranges, namely; in basement rocks or in fens for a long time, moves into the river. During its storage in the seepage areas, water is 1. well-drained slope seepages supporting soils of the stained by tannins leached from decaying plant litter. Femwood form (Fry 1987); this type shows a high level This explains the brown colour that is characteristic of of variability and can be characterized by the increased many of Western Cape rivers, particularly after heavy presence of Bruniaceae; Campbell (1986) in his structur rains (King & Day 1979; Dallas & Day 1993). al classification of the Fy nbos Biome. classified the veg etation of these seepages as Wet Ericaceous Fy nbos; Some seepages located in high-altitude areas supporting fynbos vegetation have soils rich in peat —accumulated organ 2. low-altitude valley seepages characterized by high soil ic material (Gore 1983)—they can be classified as mires. water levels and peaty Champagne soils (Fry 1987); Boucher (1978) described the Erica-Osmitopsis Seepage Fy nbos in this habitat in the Kogelberg Biosphere Reserve. * Department of Botany & Zoology. University of Stellenbosch. A subty pe of the low-altitude valley seepages occurs on Private Bag X1. 7b02 Matieland. Stellenbosch. South Africa. + author for correspondence; E-mail: e.j.j.siebenCa buwa.nl temporarily wet sandy soils. It is dominated by Elegia MS. received: 2001-10-15. filacea (Tay lor 1978); 142 Bothalia 34,2 (2004)
3, the high-altitudefens, situated at the sources of rivers: Stellenbosch, Franschhoek and Grabouw in Western Campbell (1986) has classified the vegetation of this Cape, South Africa—the region with the highest rainfall habitat as Sneeukop Azonal Restioid Fynbos and in Western Cape and possibly also in the entire South Otterford Wet Proteoid Fynbos; Africa. There are many peaks reaching above 1 000 m altitude, where numerous and extensive mires have 4, in order to distinguish between the different degrees of developed. We have added some additional vegetation minerotrophy in the mires described in this study, we samples from the Du Toitskloof Mountains, which are want to introduce the term restio marshlands for the bet located to the north of the HHM and some from the ter-drained sites at the edges of mires of the Fynbos Groenland Mountains, southeast of the HHM. Biome, in contrast to the ‘fens’ being situated in the cen tre of the mire. The restio marshland supports a vegeta Most of the fens in the HHM are found in the Palmiet tion structural type called Sneeukop Azonal Restioid River catchment, although the Riviersonderend and Fynbos (Campbell 1986). Eerste Rivers are fed by water from fairly extensive mire systems. Two other rivers originating in the area, the Most of the African swamps (including mires and Berg River and the Lourens River, barely receive water other types of marshlands) are dominated by grasses and from mires as they originate on very steep mountain sedges (Van Zinderen Bakker & Werger 1974; Weisser & headwalls. Howard-Williams 1982; Thompson & Hamilton 1983; Rogers 1995, 1997). The fens and restio marshlands of The climate of the Fynbos Biome in the southwestern the Fynbos Biome are conspicuously different due to the Cape is classified as mediterranean, with hot, dry sum dominance of (often endemic) Restionaceae (Campbell mers and mild, wet winters. In the Kóppen (1931) system 1986). Despite their peculiarity, the wetland ecosystems the climate of the area is classified as Csb—having of the Cape mountain ranges have received little atten mesothermal (C) climate with a warm, dry summer and tion (Boucher 1988; Rogers 1997) and hence deserve a average temperatures above 22°C and relatively wet win closer look. ters (sb). Most mountains of the Fynbos Biome have a rainfall between 1 000 and 2 000 mm mean annual pre This study describes vegetation types found in the cipitation (MAP), but in the wettest areas (such as the rare and poorly studied high-altitude fens and restio HHM) it might exceed 3 000 mm (Schulze 1965). Most marshlands located in the region of richest precipitation low-lying localities receive much less—up to 750 mm in Western Cape—the Hottentots Holland Mountains near the coast, and mostly less than 400 mm MAP in the (HHM). The floristic composition of these vegetation intermontane valleys (Fuggle & Ashton 1979). The types and their relationship to major ecological factors mountains in the Fynbos Biome play a major role in are the main foci of this paper. influencing precipitation and evaporation. Extremely high regional variation in precipitation (Figure 1) occurs due to the windward-leeward geomorphological dichoto MATERIAL AND METHODS my in the mountains and the fact that winds can sweep unhindered over the coastal plains (Deacon et al. 1992). Study area: location, climate, geology and soils Schulze (1965) described a strong gradient in rainfall with increasing altitude—50 mm of precipitation The majority of vegetation samples used for this increase per 300 m increase in altitude. The regional paper were recorded from the HHM (between 33° 56' S rainfall pattern in the mountains is variable, depending and 34° 03' S latitude and 18° 57' E and 19° 09' E longi on aspect of slope as well as frequency and strength of tude). This area is situated between the towns of northwesterly and southwesterly winds. Mountains can
Mean Annual Precipitation (MAP)
18*4ff 19*12- Rainfall (in mm)
0-800
801 -1200
1201 -1600
1601 -2000
2001 - 2400 34*00"—' 2401 - 2800 FIGURE l .—Grid with Mean Annual 2801 - 3600 Precipitation in Hottentots No Data Holland Mountains (Source: Computing Centre for Water Research; grid data comput N ed from weather data from nine official weather stations 17 in vicinity, extrapolated using methodology of Dent et al. 1987). Bothalia 342 (2004) 143 also receive much precipitation (not registered in the rain Methods of data collection gauges) from mist (Kerfoot 1968; Fuggle & Ashton 1979) associated with the summer trade winds, locally Vegetation was studied by means of plot sampling. known as ‘southeasters’. The plots were laid out in selected fen and marshland Sixty per cent of the precipitation falls in the wettest habitats in a representative way (Westhoff & Van der four months spanning June to September. This precipita Maarel 1978). The size of most of the plots was 10 x 10 tion is mostly in the form of rain, but snow regularly m (sometimes less in the case of small vegetation occurs in winter on the mountain peaks (Fuggle & stands), as this was considered to be sufficient to record Ashton 1979). Wind speeds are the highest in winter on the species richness. In each plot, each plant species the mountain tops (Fuggle 1981). This is in contrast with was recorded and the cover-abundance of each was esti the wind patterns in the surrounding lowlands, showing mated using the modified Braun-Blanquet sampling the highest speed in summer. scale (Barkman et al. 1964). Thirty-three plots were recorded in the HHM. We also added a further two sam The geology of the HHM is dominated by sandstones ples from the Du Toitskloof Mountains merely to point and shales of the Table Mountain Group, especially at the out that similar communities also occur in the neigh higher altitudes. Some of the valleys are underlain by bouring mountain ranges (Appendix 2). Soil samples Achaean Cape Granite and Malmesbury Group shales, were only collected from the topsoil (A-horizon). The but no mires were recorded on these latter substrates. The particle size distribution of the soils is determined for Table Mountain Group sandstones (TMS) are mainly the fractions finer than 2 mm 0. After drying and grind from the Nardouw Formation (De Villiers et al. 1964). ing the soil to break up any coagulation, the soils were High-altitude shale bands of the Cederberg Formation shaken through a set of sieves. The sieves of the fol accompanied by tillites of the Pakhuis Formation occur lowing raster size were used: 500 ^m (to separate throughout the area. The shale bands are situated at high coarse sand), 106/vm (to separate medium sand) and 63 er altitudes than most of the seepage areas and virtually pirn (to separate fine sand). The fraction that passes all the vegetation types (with one exception) described in through all the sieves is composed of silt and clay. this study, are reported from sandstone. Acidity and resistance were measured in water-saturat Soils of the mires are classified as belonging to the ed soils using a pH meter (Orion 420A) and a conduc Champagne Form (Soil Classification Working Group tivity meter (YSI 3200). The fraction of organic matter 1991). The amount of peat is variable; towards the outer was measured by titration according to the Walkley- edges of seepages, the soil contains a greater portion of Black method (Walkley 1935; Non-Affiliated Soil minerotrophic material (mainly sand) originated from Analysis Work Committee 1990). sandstone. Here the prevailing soil form is the Femwood Form. In this study, we have used soils as a major crite A list of environmental variables and other relevant rion for the location and delimitation of the fens. information is presented in Table 1.
TABLE I —Explanatory variables used in the canonical ordination. Data type: 1: interval scale: R: ratio-scale variables. N: nominal-scale variable
Name of variable Data Methods of measurement estimation, scales, type and identity of states for the nominal variables
Soil reaction (pH) I Measured in H-0 using pH-meter ORION 420A. Organic matter (ORGANIC) R Percentage calculated by titration using the Walkley-Black method (Walkley 1935). Slope (SLOPE) R Angle measured by slope-meter in degrees. Geology N Determined using geological map (SACS) and by field observations. States: Sandstone (San). Tillite (Til). Shale (Sha). Granite (Gra). Alluvium (Qua). Soil type N Determined after Fry (1987) and Soil Classification Working Group (1991) and on basis of field obser vations (character of lop soil layer and soil depth). States (Soil Forms): Mispah. Magwa. Oakleaf. Femwood. Glenrosa. Champagne. Aspect N Measured by compass and classified into quadrants. States: N.W. S& E. Altitude (ALTITUDE) R IX*termined from orthophotographic maps (scale 1:10 000); expressed in m. Resistance (RESISTAN) R Resistance to an electrical current (£2) measured using a YSI model 3200 conductivity meter. Gravel (GRAVEL) R °tc of coarse material (>2 mm) in soil sample. Coarse sand (CSAND) R of coarse sand (0.5-2 mm) in soil sample. Medium sand (MSAND) R of medium sand (106-500 //m) in soil sample. Eine sand (ESAND) R of tine sand (63-106 //m) in soil sample. Silt (SILT) R of silt (< 63 //m) in soil sample. Soil depth (SOILDEPT) R Depth of soil until bedrock; estimated average expressed in cm. Bedrock cover (BEI)R(X'K 1 R Estimate of cover (%) of bedrock. Large cobbles (LG_COBB) R Estimate of cover (%) of large cobbles (13-25 cm O). Small cobbles (SM .COBB) R Estimate of cover (9t) small cobbles (6-13 cm 0). Pebbles (PEBB) R Estimate of cover (%) pebbles (2-6 cm O). 144 Bothalia 34,2 (2004)
Methods of data handling and presentation taxomic nomenclature (Weber et al. 2000). Vernacular names, using a combination of important taxa and veg The vegetation samples were stored in a database in the etation structure (Edwards 1983), were coined for all format of the National Vegetation Database (Mucina et al. plant communities as well. 2000) and using the database-management software Turboveg (Hennekens 1996b; Hennekens & Schaminée RESULTS 2001). The original cover-abundance data was trans formed into percentage format using Turboveg. The data The fens (and most of the restio marshlands) of the were classified using Two-way Indicator Species Analysis region have a high cover of Restionaceae. Only a few seep (TWINSPAN) (Hill 1979) followed by manual table-sort- age types are dominated by grasses or sedges, such as ing using MEGATAB 2.0 (Hennekens 1996a), aimed at Carpha glomerata, Epischoenus spp., lsolepis prolifer and improvement of coincidence between the groups of Pennisetum macrourum. Some Restionaceae typically relevés and groups of species. Differential species for occurring in the seepages are Anthochortus crinalis, communities and their groups were identified on the basis Chondropetalum mucronatum, Elegia thyrsifera and Restio of fidelity. The differential species, constant companions subtilis. Two graminoids such as Ehrharta setacea subsp. and the dominant species are identified in each case. A dif setacea and Epischoenus villosus are also common. ferential species is a species that can be used to differenti ate between one community or a group of communities The following Community Groups and Communities and the rest at the same syntaxonomic level (Westhoff & have been revealed in our data: Van der Maarel 1978; Mucina 1993). The difference in the frequency of more than two presence classes (40%) was Community Group A: Fens taken as sufficient for a species to be considered to be dif ferential for one of the communities under comparison. Fens form the wettest parts of the seepages—they are However, a species can also be ranked as differential on poorly drained and contain much peat. The low-grown restio the basis of distribution of cover values (dominant versus Anthochortus crinalis is usually dominant and forms dense non-dominant) among relevés of the communities under mats in between the tussocks of cyperoid Epischoenus villo comparison. A dominant species is a species that is con sus. Five fen communities were distinguished: the stant and has an average cover of more than 25% Communities A 1 and A2 occur on steep slopes and experi (Westhoff & Van der Maarel 1973). A constant companion ence somewhat better drainage than the flat-habitat fen com is a species that occurs in more than 60% of all the sam munities (Communities A3, A4 and A5). ples in a community and is not considered differential at the same time. Less frequent species recorded in plots are listed in Appendix 1. The communities are described here Community Al: Protea lacticolor-Hippia pilosa Tall at the level of association or rankless vegetation type com Shrubland parable to the level of association. We refrained from defining units of the higher syntaxonomic ranks due to (Table 2, relevés 1, 2) limited extent of the data and local character of the study. We have used only two informal groups of the communi The Community Al is peculiar due to its link to shale ties based on the habitat characteristics (fens vs. restio bands. Protea lacticolor is the dominant species and forms marshlands). a dense shrubbery 2-4 m tall. This is the only form of pro- teoid fynbos recorded on the slope seepages in HHM. The The relationship between the environmental data and herb layer covers over 80% and is dominated by tussocks the vegetation data was determined using multivariate of Epischoenus villosus and mats of Restio per plexus. techniques. We follow 0kland (1996), who made a case Other important species include Senecio umbellatus, for validity of use of both ordination and constrained Seriphium plumosum ( = Stoebe plumosa), Hippia pilosa ordination as complementary approaches, both direct and and Oxalis truncatula. The stands of this community were indirect gradient analyses were performed The four vari recorded on the eastern slopes of Somerset Sneeukop at a ables, coarse sand, medium sand, fine sand and silt, very high altitude (about 1 400 m). The habitat receives a together comprise 100% in every soil sample so they are very high annual rainfall (more than 3 300 mm), some of it not independent from each other. According to the rec in the form of snow, which might persist longer on the ommendations of Ter Braak & Smilauer (1998) this sort southern than on the northern slopes of the mountain. A of (compositional) data, has to be log-transformed prior dense mist blanket covers the mountain especially in sum to analysis. Correspondence Analysis (CA) was adopted mer. It is purported to contribute a considerable additional as the indirect gradient analysis technique, while amount of ambient precipitation (Marloth 1903). Campbell Canonical Correspondence Analysis (CCA) was used to (1986) refers to this vegetation (in structural terms) as perform the direct gradient analysis (see Ter Braak 1986; Otterford Wet Proteoid Fynbos. Jongman et al. 1987 for details on the techniques). The Canoco 4 program suite (Ter Braak & Smilauer 1998) C ommunity A2: hlegia thvrsifera-Centella eriantha was used to perform CA and CCA. Short Closed Herbland
Nomenclature of taxa and plant communities (Table 2, relevés 3,4)
The nomenclature of plant species follows Germis- This community is found near the sources of the huizen & Meyer (2003). Three of the well-sampled plant Lourens River on the western slopes of Somerset communities were named according to the rules for syn- Sneeukop (1 1 (X) m) at high altitudes and receives a high Bothalia 342 (2004) 145 precipitation. The upper herb layer is formed by the dom community also represents a typical form of what is inating Elegia thyrsifera, whereas the lower herb layer is described by Campbell (1986) as Sneeukop Azonal formed by a multitude of species, such as Senecio umbel- Restioid Fynbos. In one relevé. Carpha glomerata was latus. Hippia pilosa and Erica curviflora. This communi recorded as the dominant species—a situation usually ty, like the Protea lacticolor-Hippia pilosa Tall Shrub- encountered in wet habitats at lower altitudes. land, is quite atypical for the seepages of the studied area. The differential species, Carpacoce spermacocea. Centella Community A5: Restio bifurcus-Anthochortus crinalis eriantha, Othonna quinquedentata and Ursinia eckloniana, Short Closed Restioland are all more common in typical ericaceous fynbos (Sieben 2003). The Elegia thyrsifera-Centella eriantha Commu (Table 2. relevés 15-18) nity occurs on steep slopes on sandstone. A further seepage type is also dominated by Community A3: Anthochortus crinalis-Elegia inter Anthochortus crinalis. Floristically and structurally this media Tall Closed Kestioland community resembles the previous one closely and it might also be considered as a subassociation of the (Table 2, relevés 5-8) Ficinio argyropae-Epischoenetum villosi. The main dif ference is in the absence of Senecio grandiflorus and Scientific name: Anthochorto crinalis-Elegietum inter Ficinia argyropa. but this community also has some dif mediate ass. nova hoc loco ferential species of its own, such as Gladiolus carneus, Restio bifurcus. Restio corneolus, Tetraria capillacea Holotypus: Table 2, relevé 7 and Chondropetalum mucronatum (the last-named This is an extremely species-poor seepage communi reaches far above the dominant herb layer). Notable is ty, which is limited to the Dwarsberg Mountains in the the occurrence of Prionium serratum — a typical shrub in Berg River catchment. The dominant vegetation stratum Cape mountain streams (Sieben 2003). is a dense layer of Elegia intermedia, which grows 1.2 to 1.5 m tall. Linder (1987) has not recorded this species Community Group B: Restio Marshlands outside the Cape Peninsula, but Kruger (1978) found it on the Dwarsberg. In this study, it was recorded in several The habitats supporting all four communities of Com other locaties in the HHM. The lower herb layer of the munity Group B are better drained than those of Com community is dominated by Anthochortus crinalis and is munity Group A. The soils are largely of minerotrophic less dense. Dwarsberg receives more than 3 000 mm origin and the peat content is low. They are often found rainfall per annum and the community is found in the on the edges of the mires and the water drains into the wettest, extremely peaty habitats, surrounded by stands fens. The restio marshlands are richer in species than the of the Ficinio argyropae-Epischoenetum villosi and Tetra- fens. The Communities B1 and B2 show transitional fea rio capillaceae-Restietum suhtilis. Epischoenus villosus, tures between restio marshlands and fens, through occur Senecio crispus and the moss Campylopus stenopelma as rence of species such as Senecio crispus. well as the species mentioned above are the only species present in the vegetation. Community Bl: Platycaulos depauperatus Short Closed Restioland Community A4: Ficinia argyropa-Epischoenus villo sus Short Closed Restioland (Table 2.relevés 19-21) (Table 2, relevés 9-14) This is the only seepage type dominated by restio Platycaulos depauperatus. which forms dense green Scientific name: Ficinio argyropae-Epischoenetum mats and is the most conspicuous differential species of villosi ass. nova hoc loco this community. The tussock-forming Restio subtilis is Holotypus: Table 2. relevé 9 the co-dominating element. Together they form the lower herb stratum. One emergent 1.5 m tall restio. Chondro This is one of several seepage communities dominat petalum mucronatum. forms its own stratum. Epischoe ed by the restio Anthochortus crinalis. This clonal spe nus villosus. Elegia neesii and Tetraria capillacea are cies forms dense mats and is often found intertwined significantly shorter. Apart from the eponymous, the with Ehrharta setacea subsp. setacea, Cliffortia tricuspi- only other differential species of this community are the data and Senecio crispus. The vegetation is much short grass Pentameris hirtiglumis and the geophyte Kniphofia er than in the previous communities. The tallest restio tabu laris, flowering after a fire. We believe that this present is Elegia grandis. which grows taller than 0.5 m community, although only recorded in our study in three together with the tussocks of Epischoenus villosus. In the samples, due to being visible after a recent fire, is quite limited open spaces, low-grown Ficinia argyropa and common in the Palmiet River catchment. It seems to Anthoxantum tongo can be found. This community as occupy an intermediate ecological position between the well as the Community A5. resemble similar vegetation Ficinio argyropae-Epischoenetum villosi Association described from the Table Mountain (Glyphis et al. 1978: (from peaty soils) and the Tetrario capillaceae-Restie Erica mollis Fynbos Community; Laidler et al. 1978: tum subtilis Association (from more minerotrophic Restio-Hypolaena Subcommunity). Both communities soils). The localities of this community receive less rain are associated with peaty soils that are waterlogged for fall than other seepage types, with a MAP of just over most of the time. Ficinia argyropa-Epischoenus villosus 2 (XX) mm. 146 Bothalia 342 (2(X)4)
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W 1 ^ 1 1 ^ a»a.< a: ac ki Uji l ac < < 148 Bothalia 34,2 (2004) Bothalia 342 (2004) 149 Community B2: Erica autumnalis-Restio purpuras- amongst others, Brunia alopecuroides. Berzelia squar cens Tall Closed Restioland rosa. Erica fastigiata, Grubbia rosmarinifolia and Restio bifidus. (Table 2, relevés 22, 23) Community B4: Tetraria capillacea-Restio subtilis This is one of the two communities described from Short to Tall Closed Restioland riparian mires. From the point of view of hydrology and species composition these communities are closely relat (Table 2, relevés 27-35) ed to the Restio Marshlands, hence they are classified as such in this study. These communities occur along the highest reaches of the rivers (in this study all were sam Scientific name: Tetrario capillaceae-Restietum sub pled in the Palmiet River catchment) and have a mixture tilis ass. nova hoc loco of seepage and riparian elements making up very species-rich communities, both in comparison with other Holotypus: Table 2. relevé 27 seepage types as well as with riparian communities. The Erica autumnalis-Restio purpurascens community has a This is the most common type of seepage community more prominent tall herb layer than most of the seepage in the area, which can be characterized by the absence of communities. The dominant species is Restio purpuras Senecio crispus. The dominant restio is Restio subtilis, cens, but Elegia racemosa and E. thyrsifera are also with Anthochortus crinalis and Restio aff. versatilis as abundant. In the lower stratum. Anthochortus crinalis is co-dominants. A typical characteristic is the mosaic conspicuous. Some species such as Hippia pilosa and formed by patches of low vegetation of small restios and Senecio crispus are shared with Community Group A. sedges (Restio subtilis, R. aff. versatilis. Tetraria capil- This type can best be described as a Restioland. because lacea and Epischoenus villosus) and patches of tall veg small and big restio species are its most important struc etation consisting only of Chondropetalum mucronatum. tural constituents. It is difficult to determine the differen This species does not resprout after fires, like many other tial species in a situation where relevés are few. but seepage species, but regenerates from seed. It tends to Aristea baker i, Cliffortia ova I is, Elegia racemosa. Hippia dominate the community, because the old plants form a pilosa and an unidentified species of Asteraceae. might thick litter layer on the soil beneath it. which seems to serve as possible candidates. Eponymous Erica autum- prohibit other (aggressively spreading) clonal species nalis is endemic to the HHM. The community occurs in from growing there. the highest reaches of the Wesselsgat River, where river- banks are steep and rocky. Differential species of this community are few. because most species are shared with the Grubbia ros marinifolia-Restio aff. versatilis Closed Shrubland. Community B3: Grubbia rosmarinifolia-Restio aff. Diagnostic features are mostly the dominance of Restio versatilis Medium Closed Shrubland subtilis and the occurrence of Chrysithrix species. As in the case of the riparian seepage types, this community (Table 2. relevés 24-26) contains numerous shrub species, such as the differential species Grubbia rosmarinifolia and Berzelia squarrosa. This is the other type of riparian mire found along but they do not grow very tall. high altitude streams. The main difference from the pre vious type is the shape of the banks, which are tlatter and This community occurs on more minerotrophic soils less rocky in this vegetation. The dominant small restio than the former communities. Nevertheless, the soils are here is Restio aff. versatilis. compared with Antho very acidic and highly organic. In one case it was found chortus crinalis in community B2. in a riparian zone and it is closely related to the riparian seepage types described above. The community This community has a tall herb stratum (reaching described by Boucher (1978) as Chondropetalum-Restio 1.0-1.5 m), dominated by the shrubs Berzelia squarrosa, Tussock Marsh seems to be quite similar, but the domi Brunia alopecuroides and Grubbia rosmarinifolia and nant small restio in the Kogelberg is not Restio subtilis restioids Restio purpurascens and Chondropetalum but R ambiguus and many other species are absent in the mucronatum. The most closely related riparian commu Kogelberg community. nity is the Erico-Tetrarietum crassae (Sieben 2003), which shares many Erica species with the Grubbia ros (Gradient analyses marinifolia-Restio aff. versatilis Closed Shrubland. The most closely related seepage community is the Tetrario The most important environmental factors that come capillaceae-Restietum subtilis. A species that is shared out of the CCA (Figure 2) are slope and altitude. This is with this community is Restio aff. versatilis. which is the mainly due to the outlier communities of Al and A2. dominating element of the ground layer. The Grubbia which are located at a higher altitude and on steeper rosmarinifolia-Restio aff. versatilis Community is typi slopes than any other of the mire communities. They also cal of situations where river banks are not steep and there have, together with the riparian mire communities B2 is a lot of lateral seepage. It can be described as a shrub and B3. the highest values for rockiness. It is interesting land because of the high cover of shrubs of Ericaceae and to see that there is a sharp contrast in the fraction of soil Bruniaceae. There are many differential species, most of particle sizes: the fraction of coarse sand is an important which are shared with ericaceous fynbos and the environmental variable and the communities with a high Erico-Tetrarietum crassae in particular. These are. fraction of coarse sand are the riparian mires (B2 and B3) 150 Bothalia 34.2 (2004) FIGURE 2,—Biplot of constrained ordination (CCA) of mire vegetation of Hottentots Hol land Mountains, featuring Axes 1 and 2 with position of community samples and se lected environmental vari ables. Comm. AI and Comm. A2,0;Comm.A3,+; Comm. A4, □; Comm. A5, ▼: Comm. B2 and Comm. B3, X; Comm. B3, A; Comm. B4. o. and restio marshlands (B4) which are the most brotrophic mire. Ombrotrophic mires can only exist in minerotrophic mires in the mire system. On the other very humid climates such as the blanket bogs of the hand, there are the communities which have a high frac British Isles and the elevated bogs of northern Europe; tion of fine sand and silt, which represent the fens in the they are quite rare in the southern hemisphere. Actually, middle of the mire system where peat formation occurs the distinction between ombrotrophic and minerotrophic (especially A3, but also A4 and A5). The axis that is mires is more like a gradient, an idea expressed by Sjors formed by the variable of coarse sand, fine sand and silt (1983). Ombrotrophic mires are on the one extreme of reflects a gradient in minerotrophy or in waterlogging. this gradient and all mires that do not feed exclusively on The fens (A3, A4 and A5) have the highest values for rainwater make up the rest of this gradient. organic matter contents and soil depth. They are also mainly found at the higher altitudes because this is where Sjors (1983) also gives a more detailed subdivision of the highest rainfall occurs. European mires: topogenous mires (influenced by stag nant water), soligenous mires (influenced by seepage), limnogenous mires (influenced by floodwaters) and DISCUSSION ombrogenous mires (influenced by rainwater). Solige nous and limnogenous mires are both associated with One of the most important questions that is raised rivers. Soligenous mires form around springs and lim from the results of this study is where the high-altitude nogenous mires occur in the floodplains along the lower mires of the Fynbos Biome fit into the world-wide typol reaches of rivers. The mires described in this study are all ogy of fens and mires. Although the mires regularly form of the soligenous type. The different communities the sources of the rivers, they are clearly very different described in this study are situated along a gradient from from the European spring ecosystems (Zechmeister & dry to moist. In the Ficinio argyropae-Epischoenetum Mucina 1994). Swamps and bogs with a high graminoid villosi Association, occurring in the centre of the mire, cover are found extensively in the boreal zone of the water stagnates more because the drainage is slow. On northern hemisphere (Sjors 1983) and the vegetation the edges, the Tetrario capillaceae-Restietum subtilis cover of swamps and bogs in Africa is also mostly domi Association, which has a faster drainage, will prevail. nated by graminoids (Thompson & Hamilton 1983). Further towards the margins, communities dominated by Chondropetalum deustum can occur, but these were not Gore (1983) distinguishes between ombrotrophic and recorded during this study. Two communities can occur minerotrophic mires, based on the origin of the water. In towards the centre of very wet mires, namely the ombrotrophic seepage, a thick layer of peat has devel Anthochorto crinalis-Elegietum intermediae Association oped and there is no more contact with the mineral sub or the I sole pis prolifer-Bulbinella nutans Tall Closed strate. The water originates exclusively from rain, which Sedgeland described from the Du Toitskloof Mountains. results in very oligotrophic conditions. The water from Both communities are extremely poor in species, minerotrophic mires seeps through the mineral substrate because of the specific stresses that occur under water into the mire, so it is richer in nutrients than the om logged conditions. It is clear that this gradient, from Bothalia M2 (2004) 151 well-drained to poorly drained or from the edge to the DALLAS. H.F.& DAY.J.A. 1993. The effect of water quality variables centre of the mire, is also very prominent in the ordina on riverine ecosystems: a review. Water Research Commission tion diagrams. This gradient was also found by Bragazza Report TT 61/93. Pretoria. DEACON. H.J.. JURY. M.R. & ELLIS. F. 1992. Selective regime and & Gerdol (1999) in some mires in the southeastern Alps. time. In R.M. Cowling. The ecology of fynbos; nutrients, fire The other distinguishing feature that shows clearly in the and diversity: 6-22. Oxford University Press. Cape Town. ordination diagrams is the importance of the substrate, as DENT. M.C.. LYNCH. S.D. & SCHULZE. R E. 1987. Mapping mean can be seen from the Protea nmndii-Hippia pilosa Tall annual precipitation and other rainfall statistics over southern Africa. Agricultural Catchments Research Unit Report No. 27. Shrubland from the shale band. Water Research Commission Report No. 109/1/89. DE VILLIERS. J.. JANSEN. H. & MULDER. M.P. 1964. Die geolo- A conspicuous thing about the vegetation of mires of gie van die gebied tussen Worcester en Hermanus. Geological the Fynbos Biome is that they are dominated by the clon Survey, Pretoria. al restios A. crinalis, P. depauperatus and R. subtilis EDWARDS. D. 1983. A broad-scale structural classification of vegeta tion for practical purposes. Bothalia 14: 705-712. (Linder 1985). Because these species tend to cover FRY. M. ST. L. 1987. A detailed characterization of soils under differ everything, the vegetation is relatively poor in species. ent fynbos-climate-geology combinations in the southwestern Clonal reproduction is often coupled to environmental Cape. M.Sc. thesis, University of Stellenbosch. plasticity, so the species can tolerate slight differences in FUGGLE, R.F. 1981. Macro-climatic patterns within the Fynbos Biome Final Report. National Programme for Environmental Sciences, the environment. The diversity of microsites is much Fynbos Biome Project. Cape Tow n. bigger than the species richness suggests (Price & FUGGLE. R.F. & ASHTON. E.R. 1979. Climate. In J. Day, W.R. 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Amsterdam. grasses take the place of the clonal Restionaceae record HENNEKENS. S.M. 1996a. MEGATAB—a visual editor for phytosoci- ological tables. Version 1.0. User's Guide. Giesen & Geurts. Ulft. ed in this study. It is generally accepted that the clonal HENNEKENS. S.M. 1996b. TVRBOVEG: software package for input, growth form is an adaptation to the stress of waterlog processing, and presentation of phytosociological data. Version ging. This is confirmed by the investigations by Souku- July 19%. User's guide. IBN-DLO & Lancaster University, pová (1994) of three clonal graminoids. After waterlog Wageningen & Lancaster. ging there is an increase in clonal modules. Specht HENNEKENS. S.M. & SCHAMINÉE. J.H J. 2001 TURBOVEG. a comprehensive data base management system for vegetation (1981) reviews many of the problems that sclerophyllous data. Journal o f Vegetation Science 12: 589-591. plants have to overcome in seasonally waterlogged areas. HEWLETT. J .D. 1961. 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Een taksonomiese sisteem vir Suid-Afrika. Department springs: high-rank syntaxa of the Montio-Cardaminetea. of Agriculture Affairs. Pretoria. Journal o f Vegetation Science 5: 385-399. APPENDIX 1. List oi less frequent species having one or two occurrences in the relevé table. Sequence: name of species, the field code of the relevé(s) and cover-abundance (in brackets) Agathosma pentachotoma 262 (2a) Kogelbergia verticillata 127 (+) Askidiosperma chartaceum 262 (2a) Lobelia jasionoides 134 (+) Askidiosperma esterhuyseniae 164 (2b), 202 (+) Lycopodiella caroliniana 123 (+) Berzelia lanuginosa 262 (+) Osmitopsis afra 241 (+) Blechnum tabulare 131 (+) Oxalis nidulans 202 (+) Bobartia gladiata 259 (+) Pentameris thuarii 233 (2b) Chironia decumbens 262 (r) Pentaschistis pallida 135 (+) Cliff or tia gramine a 165 (1) Protea cynaroides 128 (+), 233 (r) Cliffortia ruscifolia 233 (2a) Psora lea aculeata 241 (2a) Corymbium congestum 131 (1) Raspalia virgata 136 (2a) Corymbium cymosum 131 (+) Restio bifarius 131 (+) Dicranoloma billardieri 123 (2a) Restio intermedins 128 (3) Disa tripetaloides 123 (2m), 127 (2a) Restio obscurus 262 (1) Edmondia pinifolia 131 (+) Restio pedicellatus 259 (+), 262 (3) Ehrharta ramosa 259 (1) Schizaea tenella 127 (1) Ehrharta setacea subsp. uniflora 111 (2m) Senecio coleophyllus 134 (2a) Epischoenus complanatus 131 (1), 201 (+) Senecio pubigerus 233 (1) Epischoenus gracilis 262 (2a) Senecio rigid us 131 (+) Erica longifolia 262 (r) Sonchus oleraceus 259 (+) Euchaetis glabra 201 (1) Staberoha cernua 234 (1) Euryops abrotanifolius 232 (2m), 233 (1) Staberoha vaginata 124 (+), 189 (+) Felicia cymbalariae 111 (1) Seriphium plumosum (juvenile) 188 (r) Ficinia cf. involuta 259 (3) Tetraria pillansii 201 (1), 259 (2a) Ficinia sp. 233 (1) Tetraria thermal is 124 (r) Fissidens plumosus 111 (2m) Todea barbara 111 (1), 259 (2a) Geissorhiza umbrosa 131 (+) Ursinia dentata 233 (1), 241 (+) Helichrysum cymosum 233 (2a) Utricularia bisquamata 163 ( + ) Hymenophyllum peltatum 131 (2m) Villarsia capensis 163 (1), 164 (+) Hypochaeris radicata 259 (+) Wahlenbergia procumbens 201 (D.241 (2b) Ischyrolepis triflora 262 (1) Watsonia borbonica 241 (r). Isolepis digitata 135 (2m) Bothalia 34,2 (2004) 34,2 Bothalia APPENDIX 2 Selected data on sampled vegetation properties and geographical location of two relevés in Du Toitskloof Mtns and relevés in Hottentots Holland Mms. No., releve number; Com., community; FC, field code; As., aspect; SI., slope in degrees; Area, sampled area (m~); CE2. cover of shrub layer (%); CE1, cover of herb layer (7r); CB). cover of moss layer (%); HE2, height of shrub layer (m); HE 1, average height of herb layer (m); SR. species richness r*“, n , r y O 3 3 T3 "3 -3 •O 5 o c £ S £ Cr.Cn UJ UJ vd O ' O ' O c o c o c o c ^ ' O ' O ' O ' O ' O o o o o c o c o - ( f Ii T IT, IT) ITi fN (N — r- . 0 C/5 C/5 0> W *—•rr* d. uuuuuajuoowijsjop; E E E E y u W t> . & K. 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