4.3 Study area
4.3.4 Ecosystems
Ecosystem degradation is a global trend owing to increasing natural resource consumption needs (MEA, 2005; Secretariat of the CBD, 2010). The MEA (2005) and Managi (2013) highlight some of the threats to ecosystems globally most of which are human-induced and include land-use change, population growth, unsustainable natural resource harvest, alien species invasion, governance and climate change, among others. Land-use change has been the main instigator of the drastic ecosystem conversion in the GGEP in the past 50 years (D’MOSS, undated).
The GGEP is a diverse open space consisting of various ecosystems and species of varying importance (GGEP, undated). It is comprised of four ecosystems including grassland, forest, cliffs and, wetlands and rivers (EPCPD, 2010a). Biodiversity existing within the GGEP ecosystem is important for the services they provide to the GGEP community and the wider community of Durban (EPCPD, 2011). The services include provisioning such as building materials, regulatory such as climate regulation, cultural such as recreation, and supporting services such as soil formation (DEAT, 2006; EPCPD, 2011). Figure 4.3 provides an overview of the ecosystems within the GGEP open space.
Figure 4.3: The GGEP open space ecosystems (Adapted: GGEP management files, undated)
Figure 4.3 shows the various ecosystems in the GGEP and the developed or suburban areas. The forest ecosystem is highlighted in green while the woodland is in red. Further, the grassland and the wetland ecosystems are highlighted in amber and blue, respectively. The remaining areas within the GGEP boundary (the areas bound within the red line) show the developed or suburban area.
4.3.4.1 Grassland ecosystem
The grassland type found in the GGEP open space is known as the KwaZulu-Natal sandstone sourveld (GGEP, undated). It is unique grassland characterised by acidic sandy soils formed by the weathering of sandstone rocks (GGEP, undated). The sandstone sourveld grasslands of the GGEP are unique to the coastal areas of KwaZulu-Natal where majority of this ecosystem has been transformed. This phenomenon reflects the state of the sandstone sourveld grasslands throughout the country where it is estimated that over 68% is transformed (GGEP, 2011: 14). Only 0.2% of this ecosystem falls under Protected Areas (GGEP, 2011: 14). Consequently, the SANBI declared the ecosystem ‘endangered’ while Ezemvelo KwaZulu-Natal declared it ‘critically endangered’ (GGEP, 2011). The grasslands support a
range of plant and animal life including birds, insects, small mammals, and a variety of grasses and flowering plants (GGEP, 2011). Some of the species in the grassland include striped caco (Cacosternum striatum) and spotted shovel-nosed frog (Hemisus guttatus). Figure 4.4 shows part of the KwaZulu-Natal sandstone sourveld.
Figure 4.4: GGEP open space sandstone sourveld grassland (Adapted: GGEP Management files, undated)
The sandstone sourveld is a biodiverse grassland and its biodiversity is revealed in spring after flowers blossom and pollinators are abundant; a scenario which invites many predators and small insects (GGEP, undated). One of the important factors that influence this phenomena and which is responsible for the health of the grassland is fire. Fire is responsible for clearing off old dry grass to give way to new life; it also prevents invasion of non-herbaceous plants and by doing so, it maintains the whole life system of grasslands (EPCPD, 2010a). The main threats to the remaining part of this ecosystem include bush invasion, soil erosion, alien plant invasion and irregular fire regimes (EPCPD, 2010a). Being an endangered ecosystem, it is important that this ecosystem is conserved through introduction of sustainable management practices.
4.3.4.2 Scarp forest
The type of forest in the GGEP open space is known as scarp (as shown in Figure 4.5). This kind of forest usually occurs on rugged terrain, mountainous and coastal areas which are protected from fire (GGEP, undated). In the study area, the scarp forest is diverse in plant and animal species (D’MOSS, 2010). Some species found in the GGEP scarp forest are particularly unique to the scarp forest, some of which include:
ruby-footed giant millipede (Doratogonus rubipodus), spotted ground-thrush (Zoothera guttata) and kloof frog (Natalobatrachus bonebergi) (GGEP, undated).
Figure 4.5: Scarp forest of the GGEP open space (Adapted: GGEP management files, undated) The scarp forest is an endangered ecosystem and 20% (GGEP, undated) is protected by the National
Forest Act of 1998 (D’MOSS, 2010). In addition, the GGEP open space is home to many animals and plant species some of which are unique to this place while others are simply endangered (EPCPD, 2010a).
For instance, the African crown eagle whose populations are decreasing, nests in the scarp forest; the ruby-footed giant black millipede (Doratogonus rubipodus) is only found in the GGEP open space and Kranztkloof nature reserves; the spotted ground thrush (Zoothera guttata) lives only in the Eastern Cape forests and KwaZulu-Natal scarp forest; and the kloof frog (Natalobatrachus bonebergi) lives in streams of scarp forests (EPCPD, 2010a; GGEP, 2011). Scarp forests are also rich in variety of animal and plant species ranging from insects, small mammals to birds (GGEP, 2011).
The major threat to the scarp forest ecosystem is unsustainable resource extraction practices, especially for medicinal purposes, which makes the forest susceptible to invasion by alien species (GGEP, undated).
Due to lack of knowledge on sustainable harvesting on the part of the harvesters, their practices are usually detrimental to the health of the plants and animals (GGEP, undated). This further disturbs the structure of the forest by opening up the canopy to sunlight which immediately results in proliferation of the understory (GGEP, undated). With presence of invasive alien species in the understory, the understory gets taken over by alien species which then threaten the survival of the poorly managed indigenous species. The importance of the structure of the scarp forest cannot be understated because it is critical to maintenance of indigenous species and the forest itself (GGEP, undated: 10).
4.3.4.3 Rivers and wetlands
The GGEP is a well-drained open space which is endowed with rivers and streams as well as many smaller drainage systems which all drain into the main rivers (GGEP, undated: 11). Rivers and wetlands make up 4.3% of the GGEP and occupy about 10 hectares of the total GGEP manageable area (GGEP, 2011: 16). The two main rivers in the GGEP are the Giba and Umhlatuzana rivers which both run through the GGEP open space. In addition to the rivers are smaller drainage systems like streams. Further, the rivers in the GGEP open space are replenished by seepage as well as ground water (GGEP, undated). The GGEP open space is also endowed with pools and waterfalls on the upper Umhlatuzana River (as shown in Figure 4.6).
Figure 4.6: Pools and waterfalls characteristic of the upper Umhlatuzana river (Adapted: GGEP Management files, undated)
The GGEP open space wetlands are an important feature as they are rich in animal and plant species.
They are important for the entire open space as they provide water and shelter to terrestrial animals as well as a habitat for hygrophilous plants (such as sedges and reeds) and animals (GGEP, undated; GGEP, 2011). In addition, the wetlands are rich in insects and frogs of which some were discovered in the Giba Gorge. It must be emphasised that the GGEP open space is home to more than 20 frog species and this is almost a quarter of all recorded species in South Africa (GGEP, undated). However, the rivers and wetland ecosystems are not without challenges to their health and sustainability. The major environmental threats include pollution, erosion and alien species invasion (GGEP, 2011).
4.3.4.4 Cliffs
Cliffs are special features as they occur in almost all ecosystems except rivers and wetlands (GGEP, 2011). The sandstone sourveld cliffs of the GGEP are very rich in animal and plant life, despite their harsh environmental conditions (GGEP, undated). In order to live in harsh conditions, animal and plant
species have had to adapt to surviving on rocky terrain which has very little water and nutrients. One such plant species is the blood lily (Gladiolus cruentus), a very rare species mainly occurring in Durban which has been declared ‘critically endangered’ by the SANBI (GGEP, undated). Figure 4.7 shows some plants that grow on cliffs, one of which is the red flowering plant called blood lily (Gladiolus cruentus).
Figure 4.7: Cliff Ecosystem with the blood lily (Gladiolus cruentus) (Adapted: GGEP management files) In addition to plant species, cliffs provide a home to many animal and bird species. Some of the animal species such as rock hyrax (Procavia capensis) find the cliffs a refuge against predators while others such as lanner falcons (Falco biarmicus) inhabit the cliffs seasonally (GGEP, undated: 12). However, the health of cliff ecosystems is threatened by illegal harvesting of ornamental plants, erosion and dumping of waste from the adjacent residential areas (GGEP, 2011). Proper management of these threats is critical to conserving the plant and animal species of cliff ecosystems.