**3. Results and discussion**

of this vegetation type stretching from Bloemfontein in the south-west to the Willem Pretorius Nature Reserve in the north-east. The plot data were grouped into the five groups namely the Bloemfontein stand, the Winburg stand, the Willem Pretorius Nature Reserve stand, the Skoongesig stand and the Kareefontein stand. Habitat as well as floristic data was captured using TURBOVEG (Hennekens 1996; Hennekens & Schaminee 2001) and exported to JUICE (Tichý 2002) from where a raw table (Table 1-Annexure 1) was created for basic floristic interpretation. No formal phytosociological classification was done since the purpose of this study was not to obtain a formal classification, but to compare the different groups in terms

Many people regard species richness and diversity as similar to species diversity. Species richness however refers to the number of species within an area or community (Kent & Coker 1992; Magurran 1988; Magurran 2005; Spellerberg & Fedor 2003). For this study species richness was calculated by determining the total number of species in each stand surveyed.

Species diversity refers to the diversity that occurs within a plant community or area and incorporates both species richness and the evenness of species' abundances (McGinley 2013). Species diversity is one component of the concept of biodiversity and is influenced by the relative abundances of different plant species present within the community. Various indices exist that measure both evenness and species richness into a single measure of species diversity (Stirling & Wilsey 2001). For the purpose of this study the Simpsons Index (Simpson 1949) as well as the Shannon-Wiener Species Diversity Index (Smith & Wilson 1996) was used to determine species diversity for each stand of the Bloemfontein Karroid shrubland surveyed

*<sup>D</sup>* <sup>=</sup> <sup>∑</sup> ( *ni ni* - <sup>1</sup>

Species richness (S), Simpson index if diversity (-ln (D)) and the the Shannon-Wiener index of

D=Simpson's index of diversity. It represents the likelihood that two randomly chosen

A the Chi-Square Test (Welman *et al.* 2007) was performed on the data to determine whether

*H* ' = - ∑ i=1 *S*

pi=is the proportion of individuals of a species (relative proportion)

significant associations exist between the different stands.

*<sup>N</sup> <sup>N</sup>* - <sup>1</sup> ) (1)

*pi*(ln *pi*) (2)

of species richness and diversity.

332 Biodiversity - The Dynamic Balance of the Planet

Simpson Index:

Shannon-Wiener Index:

in this study as expressed in the following formulas:

diversity (H') were calculated for each stand:

individuals will be different species.

S=Richness (Number of species per community)

#### **3.1. Habitat and growth forms**

In 1937, Potts and Tidmarch published an article recognizing a vegetation type near Bloem‐ fontein which has "marked affinities with the Karoo". In 1991, Du Preez and Bredenkamp (1991) named this vegetation unit the *Oropetium capense* community on rock sheets and classified it as a separate vegetation class. Dingaan and du Preez (2002) surveyed this vegeta‐ tion unit near Bloemfontein and identified three different plant communities, namely the *Eragrostis trichophora–Aristida congesta, Heliophylla carnosa–Senecio radicans* and the *Stomatium braunsii–Avonia ustulata* Communities. In Mucina and Rutherford (2006) this vegetation unit, although small in size, is recognized as a separate vegetation type and has been described as the Bloemfontein Karroid shrubland (Gh8). Due to the presence of the scattered dolerite sheets this vegetation type has an archipelago appearance that occurs mainly in the Dry Highveld grassland.

Dolerite is of igneous origin and forms extensive sheets which vary in thickness. During the cooling process various horizontal cracks develop (Duncan and Marsh 2006; Holmes 2012). These cracks create areas where water infiltrates the rock. This allows chemical weathering to take place which in turn allows more water infiltration. Eventually the cracks develop into crevices into which soil and organic matter accumulates. Areas with deeper soil (50mm – 250mm) accommodate deep rooted species such as shrubs, perennial grasses and geophytes. Depressions occur on the exposed dolerite sheets where soil accumulates, These areas, although very shallow (10mm – 50mm), house a few species especially succulents and annuals. The two main environmental factors that differentiate the different plant communities on these dolerite outcrops are soil depth and soil moisture availability.

These dolerite sheets create an unusually arid habitat in a relatively high rainfall area due to the high loss of potentially available water. The loss of rainwater is caused by the poor water retention abilities of the coarse textured soil, poor infiltration, high evaporation tempos and high runoff. This unique habitat creates physiological drought conditions (Snyman 1984). The presence of these archipelagos of dolerite sheets with their shallow soils in a "sea" of deep soil and grass covered plains create a mosaic of scattered and isolated patches of arid habitats (Figure 2) which are relatively hostile environments for typical grassland species.

The physiological drought environment that is being created by the dolerite sheets and the shallow soil, is unsuitable most of the Grassland biome species but for a number of Namakaroo biome species, which can tolerate the high temperatures and arid conditions present on these dolerite sheets, it creates a suitable habitat. This habitat can therefore be regarded as unique and in a certain sence can be regarded as an azonal vegetation type, Due to the lack of water, it is deviating strongly from the typical surrounding zonal vegetation (Mucina & Rutherford 2006)

The percentages of the number of plant species present per growth form recorded on these rocky sheets are indicated on Figure 3.

The percentages of the number of plant species present per growth form recorded on these rocky sheets are indicated on Figure 3. **Figure 2.** Typical appearance of the Bloemfontein Karroid shrubland vegetation type (Gh8). Succulents are limited to shallow crevices in the dolerite sheets while the grasses and low shrubs occur on slightly deeper soil.

Figure 3. A pie chart that It is interesting to note that number of succulents (30%) is the highest out of a total of 111 plant species noted on these dolerite sheets. This differs from the surrounding grasslands where less than 10% of the species are succulents. The second most important growth form is grasses (23%) followed by Karroid shrubs (12%). Perennial forbs make up 10% of the total species list while annuals and geophytes represent almost the same percentage (9%). Shrubs (3%), sedges and ferns (2%) struggle to survive on these arid habitats and are not well represented.

The percentages of the number of plant species present per growth form recorded on these rocky sheets are indicated on

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335

A number of species are endemic to this arid habitat. They are the succulents *Anacampserus filamentosa, A. telephiastrum, Avonia ustulata, Crassula tetragona, Euphorbia catervifolia, Hereroa species, Othonna protecta, Rabiea species, Ruschia unidens, Stomatium braunsii*, the *geophytes Brachystelma dimorphum subsp. gratum, Strumaria tenella subsp. orientalis* and the drought tollerant sedges *Cyperus bellus* and *Mariscus indecorus* (Annexure 1). It is only Brachystelma dimorphum subsp. gratum which is currently listed as a Red data species. According to POSA

ferns (2%) struggle to survive on these arid habitats and are not well represented.

Skoongesig stand with the Winburg and Kareefontein stands the lowest (Figure 4).

Figure 4. Species richness of the different stands of the Bloemfontein karroid shrubland (Gh8).

**Figure 4.** Species richness of the different stands of the Bloemfontein Karroid Shrubland (Gh8).

35

**Species richness (S)**

17

the third most diverse. These results are confirmed in the Simpsons Index (Figure 6).

According to the Shannon-Wiener Index (Smith & Wilson 1996) values the Willem Pretorius Nature Reserve population of the Bloemfontein Karroid shrubland vegetation type (Gh8) has the highest diversity followed by the Bloemfontein population (Figure 5). They are significantly different from the other three populations with the Kareefontein population

According to the Shannon-Wiener Index (Smith & Wilson 1996) values the Willem Pretorius Nature Reserve population of the Bloemfontein Karroid Shrubland vegetation type (Gh8) has the highest diversity followed by the Bloemfontein population (Figure 5). They are signifi‐

Kareefontein Willem Pretorius NR

Figure 3. A pie chart that indicates the percentages of the number of plant species per growth form present on the dolerite sheets.

It is interesting to note that number of succulents (30%) is the highest out of a total of 111 plant species noted on these dolerite sheets. This differs from the surrounding grasslands where less than 10% of the species are succulents. The second most important growth form is grasses (23%) followed by Karroid shrubs (12%). Perennial forbs makes up 10% of the total species list while annuals and geophytes represent almost the same percentage (9%). Shrubs (3%), sedges and

A number of species are endemic to this arid habitat. They are the succulents Anacampserus filamentosa, A. telephiastrum, Avonia ustulata, Crassula tetragona, Euphorbia catervifolia, Hereroa species, Othonna protecta, Rabiea species, Ruschia unidens, Stomatium braunsii, the geophytes Brachystelma dimorphum subsp. gratum, Strumaria tenella subsp. orientalis and the drought tollerant sedges Cyperus bellus and Mariscus indecorus (Annexure 1). It is only Brachystelma dimorphum subsp. gratum which is currently listed as a Red data species. According to POSA (2009) its

The Bloemfontein stand of the Bloemfontein Karroid Shrubland vegetation type (Gh8) has the highest species richness (81) with the Willem Pretorius Nature Reserve stand the second most namely 68 different species. That is followed by the Skoongesig stand with the Winburg and

The Bloemfontein stand of the Bloemfontein Karroid shrubland vegetation type (Gh8) has the highest species richness (81) with the Willem Pretorius Nature Reserve stand the second most namely 68 different species. That is followed by the

81

18

Winburg

68

(2009) its status is rare.

status is rare.

Figure 3.

**3.2. Species richness and diversity**

**3.2. Species richness and diversity** 

Kareefontein stands the lowest (Figure 4).

Skoongesig

indicates the percentages of the number of plant species per growth form present on the dolerite sheets. **Figure 3.** The percentages of the number of plant species per growth form present on the dolerite sheets.

and ferns (2%) struggle to survive on these arid habitats and are not well represented.

the Skoongesig stand with the Winburg and Kareefontein stands the lowest (Figure 4).

status is rare.

**3.2 Species richness and diversity.** 

It is interesting to note that number of succulents (30%) is the highest out of a total of 111 plant species noted on these dolerite sheets. This differs from the surrounding grasslands where less than 10% of the species are succulents. The second most important growth form is grasses (23%) followed by Karroid shrubs (12%). Perennial forbs makes up 10% of the total species list while annuals and geophytes represent almost the same percentage (9%). Shrubs (3%), sedges

A number of species are endemic to this arid habitat. They are the succulents *Anacampserus filamentosa, A. telephiastrum, Avonia ustulata, Crassula tetragona, Euphorbia catervifolia, Hereroa* species*, Othonna protecta, Rabiea*  species*, Ruschia unidens, Stomatium braunsii*, the geophytes *Brachystelma dimorphum* subsp. *gratum*, *Strumaria tenella* subsp. *orientalis* and the drought tollerant sedges *Cyperus bellus* and *Mariscus indecorus* (Annexure 1). It is only *Brachystelma dimorphum* subsp. *gratum* which is currently listed as a Red data species. According to POSA (2009) its

The Bloemfontein stand of the Bloemfontein Karroid shrubland vegetation type (Gh8) has the highest species richness (81) with the Willem Pretorius Nature Reserve stand the second most namely 68 different species. That is followed by It is interesting to note that number of succulents (30%) is the highest out of a total of 111 plant species noted on these dolerite sheets. This differs from the surrounding grasslands where less than 10% of the species are succulents. The second most important growth form is grasses (23%) followed by Karroid shrubs (12%). Perennial forbs make up 10% of the total species list while annuals and geophytes represent almost the same percentage (9%). Shrubs (3%), sedges and ferns (2%) struggle to survive on these arid habitats and are not well represented. Figure 3. A pie chart that indicates the percentages of the number of plant species per growth form present on the dolerite sheets. It is interesting to note that number of succulents (30%) is the highest out of a total of 111 plant species noted on these

A number of species are endemic to this arid habitat. They are the succulents *Anacampserus filamentosa, A. telephiastrum, Avonia ustulata, Crassula tetragona, Euphorbia catervifolia, Hereroa species, Othonna protecta, Rabiea species, Ruschia unidens, Stomatium braunsii*, the *geophytes Brachystelma dimorphum subsp. gratum, Strumaria tenella subsp. orientalis* and the drought tollerant sedges *Cyperus bellus* and *Mariscus indecorus* (Annexure 1). It is only Brachystelma dimorphum subsp. gratum which is currently listed as a Red data species. According to POSA (2009) its status is rare. dolerite sheets. This differs from the surrounding grasslands where less than 10% of the species are succulents. The second most important growth form is grasses (23%) followed by Karroid shrubs (12%). Perennial forbs makes up 10% of the total species list while annuals and geophytes represent almost the same percentage (9%). Shrubs (3%), sedges and ferns (2%) struggle to survive on these arid habitats and are not well represented. A number of species are endemic to this arid habitat. They are the succulents Anacampserus filamentosa, A. telephiastrum, Avonia ustulata, Crassula tetragona, Euphorbia catervifolia, Hereroa species, Othonna protecta, Rabiea species, Ruschia unidens, Stomatium braunsii, the geophytes Brachystelma dimorphum subsp. gratum, Strumaria tenella subsp. orientalis and the drought tollerant sedges Cyperus bellus and Mariscus indecorus (Annexure 1). It is only

Brachystelma dimorphum subsp. gratum which is currently listed as a Red data species. According to POSA (2009) its

#### **3.2. Species richness and diversity** status is rare.

Figure 3.

The percentages of the number of plant species present per growth form recorded on these rocky sheets are indicated on

Annuals 9%

Shrubs 2%

**Figure 2.** Typical appearance of the Bloemfontein Karroid shrubland vegetation type (Gh8). Succulents are limited to

Ferns 2%

Geophytes 9%

Succulents 30%

indicates the percentages of the number of plant species per growth form present on the dolerite sheets.

and ferns (2%) struggle to survive on these arid habitats and are not well represented.

**Figure 3.** The percentages of the number of plant species per growth form present on the dolerite sheets.

Grasses 23%

Karroid shrubs 12%

Perennial forbs 10%

Sedges 3%

shallow crevices in the dolerite sheets while the grasses and low shrubs occur on slightly deeper soil.

the Skoongesig stand with the Winburg and Kareefontein stands the lowest (Figure 4).

It is interesting to note that number of succulents (30%) is the highest out of a total of 111 plant species noted on these dolerite sheets. This differs from the surrounding grasslands where less than 10% of the species are succulents. The second most important growth form is grasses (23%) followed by Karroid shrubs (12%). Perennial forbs makes up 10% of the total species list while annuals and geophytes represent almost the same percentage (9%). Shrubs (3%), sedges

A number of species are endemic to this arid habitat. They are the succulents *Anacampserus filamentosa, A. telephiastrum, Avonia ustulata, Crassula tetragona, Euphorbia catervifolia, Hereroa* species*, Othonna protecta, Rabiea*  species*, Ruschia unidens, Stomatium braunsii*, the geophytes *Brachystelma dimorphum* subsp. *gratum*, *Strumaria tenella* subsp. *orientalis* and the drought tollerant sedges *Cyperus bellus* and *Mariscus indecorus* (Annexure 1). It is only *Brachystelma dimorphum* subsp. *gratum* which is currently listed as a Red data species. According to POSA (2009) its

The Bloemfontein stand of the Bloemfontein Karroid shrubland vegetation type (Gh8) has the highest species richness (81) with the Willem Pretorius Nature Reserve stand the second most namely 68 different species. That is followed by

Figure 3. A pie chart that

Figure 3.

334 Biodiversity - The Dynamic Balance of the Planet

status is rare.

**3.2 Species richness and diversity.** 

The Bloemfontein stand of the Bloemfontein Karroid Shrubland vegetation type (Gh8) has the highest species richness (81) with the Willem Pretorius Nature Reserve stand the second most namely 68 different species. That is followed by the Skoongesig stand with the Winburg and Kareefontein stands the lowest (Figure 4). **3.2. Species richness and diversity**  The Bloemfontein stand of the Bloemfontein Karroid shrubland vegetation type (Gh8) has the highest species richness (81) with the Willem Pretorius Nature Reserve stand the second most namely 68 different species. That is followed by the Skoongesig stand with the Winburg and Kareefontein stands the lowest (Figure 4).

Figure 4. Species richness of the different stands of the Bloemfontein karroid shrubland (Gh8). **Figure 4.** Species richness of the different stands of the Bloemfontein Karroid Shrubland (Gh8).

of the Bloemfontein Karroid shrubland vegetation type (Gh8) has the highest diversity followed by the Bloemfontein population (Figure 5). They are significantly different from the other three populations with the Kareefontein population the third most diverse. These results are confirmed in the Simpsons Index (Figure 6). According to the Shannon-Wiener Index (Smith & Wilson 1996) values the Willem Pretorius Nature Reserve population of the Bloemfontein Karroid Shrubland vegetation type (Gh8) has the highest diversity followed by the Bloemfontein population (Figure 5). They are signifi‐

According to the Shannon-Wiener Index (Smith & Wilson 1996) values the Willem Pretorius Nature Reserve population

cantly different from the other three populations with the Kareefontein population the third most diverse. These results are confirmed in the Simpsons Index (Figure 6).

The species diversity of a plant community refers to the different plant species and the relative abundance of each species. It is widely believed that the more diverse a community the more complex it is and the higher its production will be (Brower *et al.* 1990). Some ecologists also believe that the more diverse a community, the more stable it would be, but this assumption would not be true in all cases (Brower *et al.* 1990) for example a degraded community could have a high diversity of pioneer species, but would not be regarded as a mature or stable ecosystem. Thus the total species composition and ecological status of the species should be

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337

In the case of the Bloemfontein karroid shrubland (Gh8) the species comprises mostly of climax and secondary succesional species indicating the vegetation to be in a mature and stable

The Willem Pretorius Nature Reserve and Bloemfontein stands have the highest species richness and are also the two most diverse stands of this vegetation type (Figures 4 & 5). Not only are these two stands the largest in area size compared to the other three, but the Willem Pretorius stand occurs within the Willem Pretorius Nature Reserve which is a protected area that fall within the jurisdiction of the Free State Department of Economic, Tourism and Environmental Affairs (DETEA). Although the Bloemfontein stand has a higher species richness (81 species - figure 4) it is not as diverse as the Willem Pretorius Nature Reserve stand with 68 different species (Figures 5 & 6). The higher number of species of the Bloemfontein stand is most probably the result of the different habitats surrounding the area which have resulted in the presence of single individuals of different species. Both stands do however have

The Skoongesig and Winburg stands have the lowest diversity values (Figures 4 & 5). The Skoongesig stand however, has 35 different species compared to the 18 of the Winburg stand and the 17 of the Kareefontein stand. Both the Skoongesig and the Winburg stands are located in areas that are subjected to degradation. The Winburg stand is surrounded by local com‐ munities that utilise the whole area for grazing by domestic stock, while the N1 highway also passes through this vegetation type. The Skoongesig stand is also a small area that is sur‐ rounded by formal agricultural land with deep soil that has mostly been ploughed and the rest are grazed. Both these stands are small in size and are affected by surrounding human

In contrast the Kareefontein stand is very small with a low species richness (Figure 4) but a somewhat higher species diversity compared to the Winburg and Skoongesig stands (Figures 5 & 6). This stand is located within a private nature reserve with various game species utilising the vegetation. Whereas private game reserves are focused on tourism and hunting to ensure it to be economically viable compared to large provincial nature reserves, these reserves do many times have a higher number of animals stocked on their farms. Thus although protected it could be slightly more trampled than similar areas in larger nature reserves. Thus the higher diversity compared to the degraded stands is expected, but the lower species richness can be attributed to its small size in the private reserve as well as the effect of grazing by antelope.

a high biodiversity and species richness compared to the other stands.

associated impacts that has led to low diversity and isolation of these stands.

evaluated when interpreting species diversity indices.

condition.

Figure 5. Shannon-Wiener index values for the five stands of the Bloemfontein Karroid Shrubland vegetation. **Figure 5.** Shannon-Wiener index values for the five stands of the Bloemfontein Karroid Shrubland vegetation.

Figure 5. Shannon-Wiener index values for the five stands of the Bloemfontein Karroid Shrubland vegetation.

NR

p = 0.039. Based on the standardized residuals, Willem Pretorius Nature Reserve is over represented (+2.04) and the main contributor to the association. Figure 6. Simpson index values for the five stands of the Bloemfontein Karroid Shrubland vegetation. **Figure 6.** Simpson index values for the five stands of the Bloemfontein Karroid Shrubland vegetation.

succesional species indicating the vegetation to be in a mature and stable condition.

succesional species indicating the vegetation to be in a mature and stable condition.

The species diversity of a plant community refers to the different plant species and the relative abundance of each species. It is widely believed that the more diverse a community the more complex it is and the higher its production will be (Brower *et al.* 1990). Some ecologists also believe that the more diverse a community, the more stable it would be, but this assumption would not be true in all cases (Brower *et al.* 1990) for example a degraded community could have a high diversity of pioneer species, but would not be regarded as a mature or stable ecosystem. Thus the total species p = 0.039. Based on the standardized residuals, Willem Pretorius Nature Reserve is over represented (+2.04) and the main contributor to the association. The species diversity of a plant community refers to the different plant species and the relative abundance of each species. It is widely believed that the more diverse a community the more complex it is and the higher its production will There was a significant association between Shannon-Wiener Diversity Index values and areas surveyed X2(4)=10.06, p=0.039. Based on the standardized residuals, Willem Pretorius Nature Reserve is over represented (+2.04) and the main contributor to the association.

composition and ecological status of the species should be evaluated when interpreting species diversity indices.

In the case of the Bloemfontein karroid shrubland (Gh8) the species comprises mostly of climax and secondary

be (Brower *et al.* 1990). Some ecologists also believe that the more diverse a community, the more stable it would be, but this assumption would not be true in all cases (Brower *et al.* 1990) for example a degraded community could have a high diversity of pioneer species, but would not be regarded as a mature or stable ecosystem. Thus the total species composition and ecological status of the species should be evaluated when interpreting species diversity indices.

The Willem Pretorius Nature Reserve and Bloemfontein stands have the highest species richness and are also the two most diverse stands of this vegetation type (Figures 4 & 5). Not only are these two stands the largest in area size compared to the other three, but the Willem Pretorius stand occurs within the Willem Pretorius Nature Reserve which is a

The Willem Pretorius Nature Reserve and Bloemfontein stands have the highest species richness and are also the two most diverse stands of this vegetation type (Figures 4 & 5). Not only are these two stands the largest in area size compared to the other three, but the Willem Pretorius stand occurs within the Willem Pretorius Nature Reserve which is a

In the case of the Bloemfontein karroid shrubland (Gh8) the species comprises mostly of climax and secondary

There was a significant association between Shannon-Wiener Diversity Index values and areas surveyed X2(4) = 10.06,

There was a significant association between Shannon-Wiener Diversity Index values and areas surveyed X2(4) = 10.06,

The species diversity of a plant community refers to the different plant species and the relative abundance of each species. It is widely believed that the more diverse a community the more complex it is and the higher its production will be (Brower *et al.* 1990). Some ecologists also believe that the more diverse a community, the more stable it would be, but this assumption would not be true in all cases (Brower *et al.* 1990) for example a degraded community could have a high diversity of pioneer species, but would not be regarded as a mature or stable ecosystem. Thus the total species composition and ecological status of the species should be evaluated when interpreting species diversity indices.

cantly different from the other three populations with the Kareefontein population the third

**Shannon‐Wiener Index (H)**

**Shannon‐Wiener Index (H)**

5.51

5.51

0.83

0.83

Kareefontein Skoongesig

Kareefontein Skoongesig

0.00105791 0.000738769

Kareefontein Skoongesig

Kareefontein Skoongesig

0.00105791 0.000738769

0.47

0.47

Figure 5. Shannon-Wiener index values for the five stands of the Bloemfontein Karroid Shrubland vegetation.

**Figure 5.** Shannon-Wiener index values for the five stands of the Bloemfontein Karroid Shrubland vegetation. Figure 5. Shannon-Wiener index values for the five stands of the Bloemfontein Karroid Shrubland vegetation.

**Simpsons Index ‐ln (D)**

**Simpsons Index ‐ln (D)**

NR

NR

0.08353656

0.08353656

Figure 6. Simpson index values for the five stands of the Bloemfontein Karroid Shrubland vegetation.

Figure 6. Simpson index values for the five stands of the Bloemfontein Karroid Shrubland vegetation.

**Figure 6.** Simpson index values for the five stands of the Bloemfontein Karroid Shrubland vegetation.

Reserve is over represented (+2.04) and the main contributor to the association.

succesional species indicating the vegetation to be in a mature and stable condition.

succesional species indicating the vegetation to be in a mature and stable condition.

main contributor to the association.

main contributor to the association.

0.054806817

0.054806817

4.52

336 Biodiversity - The Dynamic Balance of the Planet

4.52

0.00 1.00 2.00 3.00 4.00 5.00 6.00

0.00 1.00 2.00 3.00 4.00 5.00 6.00

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09

There was a significant association between Shannon-Wiener Diversity Index values and areas surveyed X2(4) = 10.06, p = 0.039. Based on the standardized residuals, Willem Pretorius Nature Reserve is over represented (+2.04) and the

NR

NR

The species diversity of a plant community refers to the different plant species and the relative abundance of each species. It is widely believed that the more diverse a community the more complex it is and the higher its production will be (Brower *et al.* 1990). Some ecologists also believe that the more diverse a community, the more stable it would be, but this assumption would not be true in all cases (Brower *et al.* 1990) for example a degraded community could have a high diversity of pioneer species, but would not be regarded as a mature or stable ecosystem. Thus the total species composition and ecological status of the species should be evaluated when interpreting species diversity indices.

There was a significant association between Shannon-Wiener Diversity Index values and areas surveyed X2(4)=10.06, p=0.039. Based on the standardized residuals, Willem Pretorius Nature

The species diversity of a plant community refers to the different plant species and the relative abundance of each species. It is widely believed that the more diverse a community the more complex it is and the higher its production will be (Brower *et al.* 1990). Some ecologists also believe that the more diverse a community, the more stable it would be, but this assumption would not be true in all cases (Brower *et al.* 1990) for example a degraded community could have a high diversity of pioneer species, but would not be regarded as a mature or stable ecosystem. Thus the total species composition and ecological status of the species should be evaluated when interpreting species diversity indices.

There was a significant association between Shannon-Wiener Diversity Index values and areas surveyed X2(4) = 10.06, p = 0.039. Based on the standardized residuals, Willem Pretorius Nature Reserve is over represented (+2.04) and the

In the case of the Bloemfontein karroid shrubland (Gh8) the species comprises mostly of climax and secondary

The Willem Pretorius Nature Reserve and Bloemfontein stands have the highest species richness and are also the two most diverse stands of this vegetation type (Figures 4 & 5). Not only are these two stands the largest in area size compared to the other three, but the Willem Pretorius stand occurs within the Willem Pretorius Nature Reserve which is a

The Willem Pretorius Nature Reserve and Bloemfontein stands have the highest species richness and are also the two most diverse stands of this vegetation type (Figures 4 & 5). Not only are these two stands the largest in area size compared to the other three, but the Willem Pretorius stand occurs within the Willem Pretorius Nature Reserve which is a

In the case of the Bloemfontein karroid shrubland (Gh8) the species comprises mostly of climax and secondary

most diverse. These results are confirmed in the Simpsons Index (Figure 6).

0.53

0.53

Bloemfontein Winburg Willem Pretorius

Bloemfontein Winburg Willem Pretorius

0.00083301

Bloemfontein Winburg Willem Pretorius

Bloemfontein Winburg Willem Pretorius

0.00083301

In the case of the Bloemfontein karroid shrubland (Gh8) the species comprises mostly of climax and secondary succesional species indicating the vegetation to be in a mature and stable condition.

The Willem Pretorius Nature Reserve and Bloemfontein stands have the highest species richness and are also the two most diverse stands of this vegetation type (Figures 4 & 5). Not only are these two stands the largest in area size compared to the other three, but the Willem Pretorius stand occurs within the Willem Pretorius Nature Reserve which is a protected area that fall within the jurisdiction of the Free State Department of Economic, Tourism and Environmental Affairs (DETEA). Although the Bloemfontein stand has a higher species richness (81 species - figure 4) it is not as diverse as the Willem Pretorius Nature Reserve stand with 68 different species (Figures 5 & 6). The higher number of species of the Bloemfontein stand is most probably the result of the different habitats surrounding the area which have resulted in the presence of single individuals of different species. Both stands do however have a high biodiversity and species richness compared to the other stands.

The Skoongesig and Winburg stands have the lowest diversity values (Figures 4 & 5). The Skoongesig stand however, has 35 different species compared to the 18 of the Winburg stand and the 17 of the Kareefontein stand. Both the Skoongesig and the Winburg stands are located in areas that are subjected to degradation. The Winburg stand is surrounded by local com‐ munities that utilise the whole area for grazing by domestic stock, while the N1 highway also passes through this vegetation type. The Skoongesig stand is also a small area that is sur‐ rounded by formal agricultural land with deep soil that has mostly been ploughed and the rest are grazed. Both these stands are small in size and are affected by surrounding human associated impacts that has led to low diversity and isolation of these stands.

In contrast the Kareefontein stand is very small with a low species richness (Figure 4) but a somewhat higher species diversity compared to the Winburg and Skoongesig stands (Figures 5 & 6). This stand is located within a private nature reserve with various game species utilising the vegetation. Whereas private game reserves are focused on tourism and hunting to ensure it to be economically viable compared to large provincial nature reserves, these reserves do many times have a higher number of animals stocked on their farms. Thus although protected it could be slightly more trampled than similar areas in larger nature reserves. Thus the higher diversity compared to the degraded stands is expected, but the lower species richness can be attributed to its small size in the private reserve as well as the effect of grazing by antelope.

The diversity and species richness of the three smaller stands (Kareefontein, Skoongesig and Winburg) were significantly lower than those of the larger stands (Bloemfontein and Willem Pretorius Nature Reserve) (Figures 4, 5 & 6). Factors that could contribute to the lower species richness as discussed above include small size and degradation of the habitat and surrounding areas. The larger areas although also surrounded in same places by various human related activities and degraded areas seem to have a more stable species composition and higher diversity. Thus these areas are better adapted to withstand and survive any threat to their ecosystem. The impacts of fragmentation and human related activities has influenced the smaller and more isolated areas of this vegegtation type.

#### **3.3. Threats to the Bloemfontein Karroid Shrubland (Gh8) vegetation type**

To survive, humans need continuous access to clean water, air, food and shelter (Van As *et al.* 2012). This can only be assured if the environment is utilised and managed in a sustainable way. If the environment is managed and utilised in an unsustainable way both our renewable an non-renewable resources would become depleted that could cause total degradation of our ecosystems. That in turn could lead to the mass extinction of all organisms on earth including humans (Van As *et al.* 2012). One of the results of habitat exploitation and degradation is the fragmentation of habitats. Franklin *et al.* (2002) maintain habitat fragmentation to be a primary concern in conservation biology. The disruption of large sections of an ecosystem into smaller intact units, usually as a result of human activity is also referred to as fragmentation (Franklin *et al.* 2002). Humans are responsible for large scale habitat fragmentation due to pollution, urban development, agriculture, the introduction of alien species, forest plantations and especially mining activities (MacDonald 1989; Hogan 2013). Although not true in all cases it is generally regarded that the larger an area the more diverse and sustainable it will be. The general view is that the ecological effects of habitat destruction and fragmentation are negative (Franklin *et al.* 2002). From the results of this study the larger areas are more diverse and species rich, however the smaller areas contain certain species not present within the larger areas (Table 1 – Annexure 1).

(a)

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(b)

**Figure 7.** (a) Mining of the dolerite sheets of the Bloemfontein Karroid Shrubland vegetation type (Gh8) leads to total destruction and transformation of the area. (b) Mining of the dolerite hills of the Bloemfontein Karroid Shrubland veg‐

etation type (Gh8).

Due to the extensive dolerite layers associated with the Bloemfontein Karroid Shrubland they are frequently mined for road building material (Figure 7) while other areas are used for the development of houses. Most of these areas are left unrehabilitated causing further degrada‐ tion of the ecosystem. As a result these abandoned areas are either developed or left to become species poor transformed areas.

Another threat to the existence of this unique vegetation type is severe grazing of the area (Figure 8). Due to the sparse vegetation cover and shallow soil layers in some areas on rock sheets, overgrazing by domestic and other animals results in a reduction of the vegetation cover and the trampling of the shallow soil. High rainfall events therefore leads to erosion washing all the soil to the adjacent vegetation communities on the lower-lying valley bottom areas. This in turn leads to even lower vegetation cover and recruitment of plant species that leads to the exposed rock areas becoming larger with more pioneer species present.

Threats of Mining and Urbanisation on a Vulnerable Ecosystem in the Free State, South Africa http://dx.doi.org/10.5772/57589 339

The diversity and species richness of the three smaller stands (Kareefontein, Skoongesig and Winburg) were significantly lower than those of the larger stands (Bloemfontein and Willem Pretorius Nature Reserve) (Figures 4, 5 & 6). Factors that could contribute to the lower species richness as discussed above include small size and degradation of the habitat and surrounding areas. The larger areas although also surrounded in same places by various human related activities and degraded areas seem to have a more stable species composition and higher diversity. Thus these areas are better adapted to withstand and survive any threat to their ecosystem. The impacts of fragmentation and human related activities has influenced the

To survive, humans need continuous access to clean water, air, food and shelter (Van As *et al.* 2012). This can only be assured if the environment is utilised and managed in a sustainable way. If the environment is managed and utilised in an unsustainable way both our renewable an non-renewable resources would become depleted that could cause total degradation of our ecosystems. That in turn could lead to the mass extinction of all organisms on earth including humans (Van As *et al.* 2012). One of the results of habitat exploitation and degradation is the fragmentation of habitats. Franklin *et al.* (2002) maintain habitat fragmentation to be a primary concern in conservation biology. The disruption of large sections of an ecosystem into smaller intact units, usually as a result of human activity is also referred to as fragmentation (Franklin *et al.* 2002). Humans are responsible for large scale habitat fragmentation due to pollution, urban development, agriculture, the introduction of alien species, forest plantations and especially mining activities (MacDonald 1989; Hogan 2013). Although not true in all cases it is generally regarded that the larger an area the more diverse and sustainable it will be. The general view is that the ecological effects of habitat destruction and fragmentation are negative (Franklin *et al.* 2002). From the results of this study the larger areas are more diverse and species rich, however the smaller areas contain certain species not present within the larger areas

Due to the extensive dolerite layers associated with the Bloemfontein Karroid Shrubland they are frequently mined for road building material (Figure 7) while other areas are used for the development of houses. Most of these areas are left unrehabilitated causing further degrada‐ tion of the ecosystem. As a result these abandoned areas are either developed or left to become

Another threat to the existence of this unique vegetation type is severe grazing of the area (Figure 8). Due to the sparse vegetation cover and shallow soil layers in some areas on rock sheets, overgrazing by domestic and other animals results in a reduction of the vegetation cover and the trampling of the shallow soil. High rainfall events therefore leads to erosion washing all the soil to the adjacent vegetation communities on the lower-lying valley bottom areas. This in turn leads to even lower vegetation cover and recruitment of plant species that

leads to the exposed rock areas becoming larger with more pioneer species present.

smaller and more isolated areas of this vegegtation type.

338 Biodiversity - The Dynamic Balance of the Planet

(Table 1 – Annexure 1).

species poor transformed areas.

**3.3. Threats to the Bloemfontein Karroid Shrubland (Gh8) vegetation type**

(a)

**Figure 7.** (a) Mining of the dolerite sheets of the Bloemfontein Karroid Shrubland vegetation type (Gh8) leads to total destruction and transformation of the area. (b) Mining of the dolerite hills of the Bloemfontein Karroid Shrubland veg‐ etation type (Gh8).

The low vegetation structure and open rocky areas in-between the different plant species also leaves the impression that this vegetation type is generally degraded. As a result people often develop on these areas or use it for grazing without regard for the sensistivity ofthis ecosystem.

tion on this vegetation type is clearly illustrated by the lower species diversity of the isolated and overgrazed patches. The important role that large nature reserves and the conserva‐ tion of large sections of this vegetation type play in the conservation of the species diversity is also illustrated by the high species richness of the Bloemfontein and Willem Pretorius Nature Reserve stands. Although degraded and low in species diversity in some areas, these islands all are important and contribute to the larger community composition. Bond (1989) states that in some cases smaller islands of vegetation cover a wider area than a nature reserve. In such a case their combined species total could be greater than the smaller section conserved in a nature reserve. These smaller islands may also act as refugia for formerly widespread species even from the surrounding threatened ecosystems (Crawley 1997). The results from this study also indicate that the smaller stands contain plant species not present in the larger stands studied, thus their conservation and ecosystem value should

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It is important that these islands are conserved as natural communities to ensure contin‐ ued existence of these unique species assemblages and related ecosystem processes. If uncontrolled development of these areas are allowed it will not only lead to local destruc‐ tion of this sensitive ecosystem but also to further fragmentation that will lead to the total loss of this ecosystem and related plant species. Keddy (2007) states that the greater the loss of species and related ecosystem services, the more human survival is at risk. This chapter focused on the negative effect of humans on a unique vegetation type in the Free State Province of South Africa, however these negative effects is also applicable to other ecosystems in other parts of the world. It is important that nature conservation organisa‐ tions consider all aspects related to an ecosystem (structure, species assemblages, ecosys‐ tem processes and functions, fragmentation, condition of the ecosystem etc.) before decisions

The increasing amount of environmental research provides a better understanding of human impact on ecosystems. Further studies are needed to fully understand the extent and distribution of this vegetation type. Every taxon has a specific geographical range of distribution (Van Wyk & Smith 2001). Endemism is a scale related concept and the term "endemic" refers to a taxon that is geographically limited in its distribution, while "nearendemic" refers to a taxon that is marginally present elsewhere (Van Wyk & Smith 2001). For the purpose of this study these terms are applied to the Bloemfontein Karroid Shrub‐ land vegetation type (Gh8) (Mucina & Rutherford 2006). It is proposed that based on the data from this study, the Bloemfontein Karroid Shrubland vegetation type (Gh8) is regarded as an endemic vegetation unit within the Free State Province in need of a high conserva‐ tion status. In view of the fragmented nature of this vegetation type and the threats such as urbanisation, mining and overgrazing this vegetation unit as a whole must be listed a threatened ecosystem and no development or mining activity may be allowed unless detailed vegetation and ecosystem functioning studies have been conducted. Without a strict policy to protect these fragments, it would be difficult to control the destruction and

are made on whether development can be allowed or not.

the eventual loss of an unique vegetation type.

not be underestimated.

**Figure 8.** Degradation and reduction of vegetation cover of Bloemfontein Karroid Shrubland vegetation type (Gh8) as a result of overgrazing by domestic animals in the Winburg area..

### **4. Conclusion**

Changes in ecosystems throughout the world are done to increase the flow of energy to one species only namely humans. Human populations continue to increase at the expense of other species (Keddy 2007). Not only has that resulted in large scale destruction of habitats, but also in immeasurable loss of species and ecosystem functions.

The results of this study provide more information on the distribution as well as species composition of the Bloemfontein Karroid Shrubland (Gh8) as described in Mucina & Rutherford (2006). A number of plant species unique to this vegetation type occurs while one red data plant was also found to be present. The effect of degradation and fragmenta‐

tion on this vegetation type is clearly illustrated by the lower species diversity of the isolated and overgrazed patches. The important role that large nature reserves and the conserva‐ tion of large sections of this vegetation type play in the conservation of the species diversity is also illustrated by the high species richness of the Bloemfontein and Willem Pretorius Nature Reserve stands. Although degraded and low in species diversity in some areas, these islands all are important and contribute to the larger community composition. Bond (1989) states that in some cases smaller islands of vegetation cover a wider area than a nature reserve. In such a case their combined species total could be greater than the smaller section conserved in a nature reserve. These smaller islands may also act as refugia for formerly widespread species even from the surrounding threatened ecosystems (Crawley 1997). The results from this study also indicate that the smaller stands contain plant species not present in the larger stands studied, thus their conservation and ecosystem value should not be underestimated.

The low vegetation structure and open rocky areas in-between the different plant species also leaves the impression that this vegetation type is generally degraded. As a result people often develop on these areas or use it for grazing without regard for the sensistivity ofthis ecosystem.

**Figure 8.** Degradation and reduction of vegetation cover of Bloemfontein Karroid Shrubland vegetation type (Gh8) as

Changes in ecosystems throughout the world are done to increase the flow of energy to one species only namely humans. Human populations continue to increase at the expense of other species (Keddy 2007). Not only has that resulted in large scale destruction of

The results of this study provide more information on the distribution as well as species composition of the Bloemfontein Karroid Shrubland (Gh8) as described in Mucina & Rutherford (2006). A number of plant species unique to this vegetation type occurs while one red data plant was also found to be present. The effect of degradation and fragmenta‐

habitats, but also in immeasurable loss of species and ecosystem functions.

a result of overgrazing by domestic animals in the Winburg area..

340 Biodiversity - The Dynamic Balance of the Planet

**4. Conclusion**

It is important that these islands are conserved as natural communities to ensure contin‐ ued existence of these unique species assemblages and related ecosystem processes. If uncontrolled development of these areas are allowed it will not only lead to local destruc‐ tion of this sensitive ecosystem but also to further fragmentation that will lead to the total loss of this ecosystem and related plant species. Keddy (2007) states that the greater the loss of species and related ecosystem services, the more human survival is at risk. This chapter focused on the negative effect of humans on a unique vegetation type in the Free State Province of South Africa, however these negative effects is also applicable to other ecosystems in other parts of the world. It is important that nature conservation organisa‐ tions consider all aspects related to an ecosystem (structure, species assemblages, ecosys‐ tem processes and functions, fragmentation, condition of the ecosystem etc.) before decisions are made on whether development can be allowed or not.

The increasing amount of environmental research provides a better understanding of human impact on ecosystems. Further studies are needed to fully understand the extent and distribution of this vegetation type. Every taxon has a specific geographical range of distribution (Van Wyk & Smith 2001). Endemism is a scale related concept and the term "endemic" refers to a taxon that is geographically limited in its distribution, while "nearendemic" refers to a taxon that is marginally present elsewhere (Van Wyk & Smith 2001). For the purpose of this study these terms are applied to the Bloemfontein Karroid Shrub‐ land vegetation type (Gh8) (Mucina & Rutherford 2006). It is proposed that based on the data from this study, the Bloemfontein Karroid Shrubland vegetation type (Gh8) is regarded as an endemic vegetation unit within the Free State Province in need of a high conserva‐ tion status. In view of the fragmented nature of this vegetation type and the threats such as urbanisation, mining and overgrazing this vegetation unit as a whole must be listed a threatened ecosystem and no development or mining activity may be allowed unless detailed vegetation and ecosystem functioning studies have been conducted. Without a strict policy to protect these fragments, it would be difficult to control the destruction and the eventual loss of an unique vegetation type.
