**6. Conclusion**

Moist grasslands feature strongly in all vegetation studies done on the MCP, and are termed "hygrophilous grasslands". Various studies [9, 34, 35, 36] detail 'high water-table grassland' communities termed 'hygrophilous grasslands', which corresponds loosely to both The PL and IDD systems. All the above studies noted dominant occurrence of *Ischaemum fascicula‐ tum*, which was not found abundantly in the PL System. The water table of the PL System (> 3 m deep) is in most areas not as high as the hygrophilous grassland communities described by the above authors. The absence of *I. fasciculatum* from the PL System might thus be a result of the variable hydrological regime. This argument is supported by Matthews [33] who states

There is therefore a large overlap between the terrestrial zones and the wetter zones of the PL and IDD Systems (e.g. *Sorghastrum stipoides*, which occurs in high abundances and in Com‐ munity 5 and sub community 8.2). The terrestrial zones of the PL System (sub community 5.1) are similar to the wet and seasonal zones of both the PL and IDD system (sub community 8.2), and not so much similar to the terrestrial zones of the IDD System (sub community 5.2). This is because the transition between the zones of the open PL System is much more gradual than

As a result of the hydrological regime and gradual zone transition, the zones of the PL System are difficult to delineate with certainty, and display a lot of species overlap. Still there is a strong division between the 'wet' zones and the terrestrial zones of the PL System. Zones 1 and 2 occur together as the 'Sandy Organic Grasslands' (sub community 8.2), and Zones 3 and 4 occur as the 'Terrestrial Sandy Grassland' (sub community 5.1). *Cyperus natalensis* occurred in most of the zones in the PL System, as well as in some IDD communities. *Centella asiatica* occurred abundantly in the wet zones of the PL and IDD Systems, but not at all in the terrestrial zones. These two species together seem to be indicative of some signs of 'wetland' conditions

One of the biggest threats to seasonally wet, event-driven, rainwater-dependent, hygrophilous grasslands such as the PL System is a drop in the water table [9, 36]. This is mostly caused by afforestation, and can already be seen as the numerous informal plots of *Eucalyptus* trees (Figure 10 d). These hygrophilous grasslands are an essential and important part of the wetland catchment area of the Kosi Bay lake system and Lake Sibaya, and are also responsible for the recharge of the lower lying wetland areas such as the Muzi Swamp to the west and the numerous swamp forests occurring in the drainage lines to the east of the PL System [9, 17]. The drop of the water table over the past 20 years have had a significant effect on the PL System, and might explain the floristic and hydrological differences that exist between this system and

Subsistence agriculture also poses a threat to the wetlands of the PL System (Figure 10 a). These gardens make use of the organic rich and moist soil in the wettest portions of the wetlands. No drainage lines are usually necessary, as the PL System is not permanently wet. Because it is mainly a sedge and grassland system, the vegetation removal to make space for crops is minimal. The effect of the gardens are thus less severe in this system, but a lot of the soil organic

that *I. fasciculatum* is a species which reflects periods of inundation.

that of the closed and sharply demarcated IDD System.

290 Biodiversity - The Dynamic Balance of the Planet

on sandy substrates (they were absent in the clay systems).

the other described hygrophilous grasslands on the MCP.

carbon still goes lost during the agriculture practices.

The results from this study indicate clear differences between the different wetland systems in terms of plant communities and species richness.

The clay systems (PP and DP) have three distinct zones:


The DP System has more vegetation zones than only three, but they cluster with the hydro‐ logical zones set out above.

The sandy and organic wetlands (including the duplex MS System) are characterized by more than three vegetation zones, which can be grouped into a permanently and seasonally wet, and a terrestrial hydrological zone:


Few of the communities, sub-communities and variants in this study are floristically associated with other vegetation communities described in the literature, probably due to the detailed scale of this wetland study. Although some vegetation studies have been conducted on the MCP, few have focused on wetlands specifically.

The statement by Matthews [31]: '…the important determinants of vegetation communities (are) the interconnected effects of water table (moisture), soil type and topography ….' is supported by this study. Although the specific type of wetland systems add to the various vegetation assemblages found, it does not account for all the differences encountered between vegetation communities. The main difference between vegetation compositions can be accounted for by the substrate type. In the ordination following the removal of the clay substrate type, the main division made was based on substrate (organic versus sand) and hydrological regime (a terrestrial group, and a combined seasonally and permanently wet group (Figure 8)). Although it is unclear at this stage which of these two factors is the main divisive factor, it is deemed unnecessary to investigate in detail as it is known that hydrological regime and organic content of soils are interlinked.

The specific type of system from which a relevé originates is the final classification factor. In certain instances the whole system is characterized by a specific substrate (such as the DP and PP systems), in which case it can be said that their vegetation types are limited to that specific system. The rest of the wetlands on the MCP occur on a predominantly sandy substrate, and species assemblages will therefore not be limited or exclusive to a specific wetland system (also the reason why the sandy IDD and PL systems are more associated with each other than with the somewhat duplex MS System). Vegetation composition of a specific wetland zone can therefore be influenced and driven on two levels:

It is thought that the wetlands on the MCP are currently under stress as a result of drought and intensified forestation and agricultural practices on the MCP. These wetlands, especially the Upland Wetland (PL) System which act as a recharge area for the whole MCP [17], are extremely sensitive ecosystems. In the unprotected areas these wetlands are currently being exploited on a large scale for its goods and services (Figure 10). Human population increases are putting a demand on these resources which cannot be sustained. The Tonga community is dependent on the wetlands on the MCP. However, the current rate of uncontrolled utiliza‐ tion, with the added stress of the *Eucalyptus* plantations, could eventually cause these sensitive wetlands to become totally degraded with resultant loss of plant species and ecosystem

The Ecology and Species Richness of the Different Plant Communities Within Selected…

http://dx.doi.org/10.5772/58219

293

1 Applied Behavioural Ecology and Ecosystem Research Unit, University of South Africa,

2 Department of Soil, Crop, and Climate Sciences, University of the Free State, Republic of

[1] South African National Biodiversity Institute, 2010, *Further Development of a Proposed National Wetland Classification System for South Africa*, The Freshwater Consulting

[2] Grundling, A.T., 2009, 'Annexure A of Project Proposal', Agriculture Research Coun‐ cil – Institute for Soil, Climate and Water, Water Research Commission Project

[3] Moll, E.J., 1980, 'Terrestrial plant ecology', in M. N. Bruton & K. H. Cooper (eds.), *Studies on the Ecology of Maputaland,* Rhodes University Press and the Natal Branch of

[4] Moll, E.J., 1978, 'The vegetation of Maputaland-a preliminary report of the plant communities and their present and future conservation status', *Trees in South Africa,*

the Wildlife Society of Southern Africa, Rhodes University.

and C.W. Van Huyssteen2

functioning.

**Author details**

Republic of South Africa

Group (FCG), Pretoria.

K5/1923.

29, 31-58.

, L.R. Brown1\*, G.J. Bredenkamp1

\*Address all correspondence to: lrbrown@unisa.ac.za

M.L. Pretorius1

South Africa

**References**


Plant species assemblages (communities) and species richness are therefore characteristic for the different wetland zones. However, zone delineation using vegetation composition varies between the different wetland systems in terms of amount and types of zones present, and should be evaluated according to the specific system in question. Not only can the different plant assemblages be used for the successful identification of the different zones within certain wetland types on the MCP, but all could be related to environmental conditions in the field.

**Figure 10.** Examples of wetland degradation on the MCP with a) cultivation in wetlands in the PL System; b) slash and burn and subsequent cultivation in the swamp forests; c) a destructed wetland now known as a 'fossil garden'; and d) one of numerous *Eucalyptus* plantations in a wetland on the MCP.

It is thought that the wetlands on the MCP are currently under stress as a result of drought and intensified forestation and agricultural practices on the MCP. These wetlands, especially the Upland Wetland (PL) System which act as a recharge area for the whole MCP [17], are extremely sensitive ecosystems. In the unprotected areas these wetlands are currently being exploited on a large scale for its goods and services (Figure 10). Human population increases are putting a demand on these resources which cannot be sustained. The Tonga community is dependent on the wetlands on the MCP. However, the current rate of uncontrolled utiliza‐ tion, with the added stress of the *Eucalyptus* plantations, could eventually cause these sensitive wetlands to become totally degraded with resultant loss of plant species and ecosystem functioning.
