3.5 Drivers of ecosystem change
3.5.2 Direct drivers of change
3.5.2.3 Climate change
traded medicinal plant species are threatened and this calls for urgent attention to achieve sustainability.
Hassan (2012) asserts that medicinal plants are important as they play a role in development of cultural traditions globally. In addition, medicinal plants are important as they contribute towards rehabilitation of degraded land through improving fertility of soils and control of erosion (Lambert et al., 2005). Furthermore, medicinal plants contribute towards the diversity of ecosystems.
Consequently, conservation of medicinal plants is critical to maintaining genetic and species diversity, cultural and traditional knowledge through research and documentation (Okigbo et al., 2008; SANBI, 2013). Okigbo et al. (2008) and Jain et al. (2012) suggest that there are various medicinal plant conservation strategies and they include practices that promote conservation within natural habitats and outside their natural habitats. A management strategy for conserving medicinal plants outside their natural habitats is known as ‘conservation through cultivation’ or ex-situ conservation (Okigbo et al., 2008; Jain et al., 2012). Jain et al. (2012) assert that ‘conservation through cultivation’ is used to safeguard and propagate species that are threatened in their natural habitats. More effective ecosystem management practices are needed especially those which consider the community needs for medicinal plants and those of conserving biodiversity. This study seeks to identify practices utilised in the GGEP in ecosystem management, which includes management of medicinal plants.
change affects the dispersal of species within a habitat and can affect species diversity within that habitat (Rosenzweig et al., 2007). According to Perrings (2010: 1), climate change
…is affecting species distributions and abundance, the timing of reproduction in animals and plants, animal and bird migration patterns, and the frequency and severity of pest and disease outbreaks. Species are moving from lower to higher elevations and from lower to higher latitudes. Species that are unable to move are at risk. At the same time, changes in the world’s biota from other causes are affecting the ability of ecosystems to adapt to climate change. The simplification of many ecosystems to make them more ‘useful’ to people reduces their flexibility. By eliminating species that are ‘redundant’ given current climatic conditions and current uses, we have reduced the capacity of many ecosystems to function if climatic conditions change.
Thus, the effects of climate change such as changing temperatures, precipitation, availability of pathogens and competition with invasive alien species, among others, negatively affect ecosystems (Cahill et al., 2012). Walther et al. (2009) and Perrings (2010) reiterate that increases in temperature that have been induced by climate change affect ecosystems by altering function, distribution, structure and composition of indigenous species. Climate change alters precipitation patterns, which in turn affects the availability of surface and ground water (IPCC, 2014). It affects seasons, intensity, and frequency of precipitation; and the same applies to temperatures (IPCC, 2014). Thus, a rise in temperature can cause harsh conditions for proliferation of certain species while the same effect may induce the proliferation of other species that require more sunlight to grow. Further, Walther et al.
(2009) assert that climate change can induce vulnerability of habitats to invasions by alien species, which can overtake and completely change the habitat’s biodiversity, and establish in the new habitat.
Extreme climatic events induced by climate change make it possible and easy for species to be transferred into new habitats where they can become invasive or even overtake the whole habitat (Walther et al., 2009).
Climate change predictions using 15 global circulation models reveal that by 2050 there will be transformation of biomes to varying degrees given different scenarios of low to high risk (Driver et al., 2012). SANBI (2013) states that climate change models reveal the changes that could occur under rising temperature and increased precipitation. Such changes may directly result from climate change or from efforts to adapt to climate change, an example of which is the recent campaign to turn to biofuels which lead to an increase in demand for agricultural land (Wilson et al., 2008; Bradley et al., 2012). According to Driver et al. (2012), South African ecosystems will adapt to changes in climate given that the critical aspects of biomes responsible for maintaining resilience are not compromised.
Some of the critical aspects of biomes that are important for climate change resilience include riparian
and coastal corridors, areas characterised by temperature, rainfall and altitudinal gradients, areas of high diversity and plant endemism, and refuge sites including south-facing slopes and kloofs (SANBI, 2013).
Resiliency and adaptation to climate change are important for survival of all species including humanity. Resilience is “defined not just according to how long it takes for the system to bounce back after a shock, but also how much disturbance it can take and remain within critical thresholds”
(Davoudi, 2012: 300). Thus, the concept of resilience hinges on a state of equilibrium to which an ecosystem will revert or progress to. According to Burns et al. (2006), resilience concerns the propensity of ecosystems to resist stress without being converted into inferior or different systems producing different services and governed by different processes. Thus, “resilience provides the capacity to absorb shocks while maintaining function; when change occurs, resilience provides the components for renewal and reorganisation” (Berkes et al., 2002, cited in Folke et al., 2002: 13).
Resilience is determined by diversity of genes, species, functional groups of species, and, processes within the system (Drever et al., 2006). Of these attributes, Thompson et al. (2009) assert that genetic diversity is the most important at various levels of species interaction. This is because it is the foundation upon which natural selection happens and it yields resilience of species within a given geographical location (Muller-Starck et al., 2005). Thus, genetic diversity regulates the ability of species within a given geographical location to counter change, resist change or even compete with other species for survival (Pease et al., 1989, Halpin, 1997, cited in Thompson et al., 2009: 14). In addition, ecosystems depend on genetic diversity within species to survive drastic environmental change such as that induced by climate change and development (Thompson et al., 2009). On the other hand, species diversity is important in producing long-term resilience in ecosystems as it determines processes important for genetic diversity and propagation of species (Thompson et al., 2009). For instance, the process of predation on herbivores ensures that consumption of primary producers is checked to maintain primary productivity within ecosystems (Thompson, 2011).
Folke et al. (2002), state that within the socio-ecological context, resilience is defined in terms of the ability of ecosystems to remain unchanged with respect to composition, structure, identity and function, in the face of pressure. Davoudi (2012) also defines resilience to include the amount of pressure or disturbance that a system can take without changing the existing state of equilibrium.
Therefore, resilience considers the extent to which pressure can be exerted on systems before changing the systems’ state of equilibrium. In addition, resilience can also imply the ability of ecosystems to continuously change but remain within the same state of equilibrium (Folke et al., 2010). This suggests that there are thresholds in ecosystems beyond which if pressure continues
mounting, the ecosystem changes the state of equilibrium (Figure 3.3 provides a graphical illustration of this concept) (Secretariat of the CBD, 2010).
Change in the state of biodiversity
Figure 3.3: Illustration of resilience (Adapted: Secretariat of the CBD, 2010: 72)
According to Plagányi et al. (2014), thresholds within systems resulting from changes in the condition of ecosystems and how they are organised continue to perturb managers. This is because it is unknown where the thresholds lie or when they are reached, only consequences of exceeding thresholds are visible (Secretariat of the CBD, 2010). Exceeding thresholds implies that ecosystems move into a new state of equilibrium, for instance, Figure 3.3 indicates that a move from the ‘safe operating space’ to the ‘changed state’ (Secretariat of the CBD, 2010). However, “once an ecosystem moves into a new state it can be very difficult, if not impossible, to return it to its former state”
(Secretariat of the CBD, 2010: 72). Therefore, “adaptive response to such changes, and planning for their occurrence, requires an understanding of the underlying drivers and system responses as well as appropriate monitoring” (Plagányi et al., 2014).
According to Folke et al. (2010), change can occur within a system and that change can enhance the ability of the system to be resilient at a larger scale. Within the socio-ecological context, self- organisation is an important attribute of resilience without which learning and preparedness for change would be impossible (Folke et al., 2006). Thus an ecosystem that can re-organise after
exposure to pressure provides an opportunity to study how ecosystems react to certain (amounts of) pressure. In this way, resilience can be viewed in terms of the ability for ecosystems to change thereby providing opportunities for learning, innovation and resolving socio-ecological challenges (Folke et al., 2010; IPCC, 2014).
Climate change exerts pressure on ecosystems through changing environmental temperatures and precipitation patterns which reduce or eliminate habitats suitable for species survival (Morit and Agudo, 2013). Morit and Agudo (2013) assert that archaeological records indicate that species survived previous climate changes while future climatic predictions indicate significant changes and reduction in the size and location of biomes which will affect species composition. This therefore renders resilience important for adapting to climate change. Biodiversity at a genetic and species level enhances resilience and knowledge developed from studying ecosystem resilience is important for developing natural resource management strategies (adaptive management) that enhance biodiversity and reduce human vulnerability (Burns et al., 2006: 381). According to the IPCC (2007), resilience is important mainly in regions where economies are dependent on primary production. This is because the ability of the natural environment to produce is compromised by the impact of climate change.
Therefore, there is need to enhance resilience through conservation of ecosystems and the diversity of species and genes within these ecosystems (IPCC, 2007). Andersson (2006) recommends the use of resilience theory in urban land-use planning and management to achieve sustainability within urban spaces.
Drivers et al. (2012) assert that current practice in climate change mitigation uses ecosystem resilience to enhance adaptive capacity of communities. The focus of climate change adaptation efforts is on socio-economic, structural and technological enhancement (Campbell et al., 2008; IPCC, 2014). However, it is increasingly accepted that the link between biodiversity and climate change should be incorporated into climate change adaptation planning (Thompson et al., 2009). Thus, the focus has shifted from technology-based adaptation to ecosystem-based adaptation by “maintaining and restoring ecological infrastructure, which frequently has the added benefit of creating jobs and contributing to livelihoods” (Drivers et al., 2012: 116). This therefore implies conserving natural ecosystems and rehabilitating degraded ecosystems to ensure that ecosystem function is not compromised (Drivers et al., 2012). Further,
…ecosystems-based adaptation focuses on managing, conserving, and restoring ecosystems to buffer humans from the impacts of climate change. It combines socio-economic benefits, climate change adaptation, and biodiversity and ecosystem conservation, contributing to all three of these outcomes simultaneously.
(Drivers et al., 2012: 117)
Figure 3.4: Concept of ecosystem-based adaptation Adapted: Drivers et al. (2012: 117)
According to Perez et al. (2010: 14), “ecosystem-based adaptation is an approach that builds resilience and reduces the vulnerability of local communities to climate change.” Figure 3.4 shows a representation of the concept of ecosystem-based adaptation. The three aspects (climate change adaptation, socio-economic benefits and, biodiversity and ecosystem conservation) depicted in Figure 3.4 can be prioritised to provide the most benefit to the target area or population (Drivers et al., 2012).
For instance, priorities in an urban environment would be to mitigate floods, through restricting ecosystem transformation in places such as estuaries, riparian corridors or coastal areas (IPCC, 2014).
Prioritisation can be achieved through “landscape-scale analysis including mapping and analysis of features at the local scale” (Drivers et al., 2012: 117). This is achieved through declaring Protected Areas, national reserves, and additional conservation zones, for instance through the D’MOSS in Durban. Thus, the GGEP is one of such areas earmarked for conservation using the D’MOSS to ensure ecosystems service supply and conservation of endangered species.