Mpumalanga Biodiversity Conservation Plan Handbook - bgis-sanbi

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% untransformed land 100% 80% 60% 50% 19-28% 0% FIGURE 3.2: Classification of vegetation types into five ecosystem status categories based on % of natural habitat remaining. LEAST THREATENED VULNERABLE ENDANGERED: LOW ENDANGERED: HIGH CRITICALLY ENDANGERED FIGURE 3.3: The status of terrestrial ecosystems in Mpumalanga LT VU EN:L EN:H CR 100% of ecosystem intact CHAPTER 3 - MPUMALANGA’S ECOSYSTEMS If habitat loss continues, ecosystem functioning will be compromised Threshold for conserving ecosystem functioning A higher degree of ecosystem functioning lost - nearing CR status Point beyond which many species may be lost 15 ECOSYSTEMS
MPUMALANGA BIODIVERSITY CONSERVATION PLAN HANDBOOK Appendix 2 presents the statistical characteristics of each vegetation type in Mpumalanga: The names of the 68 vegetation types together with 16 their national biodiversity targets; The percentage of natural habitat remaining for each; Their ecosystem status; The proportion of the biodiversity target protected in formal protected areas; Their protection level category; The relevant biome and its percentage transformation. Note that a vegetation type can be well protected (i.e.100% of its biodiversity target included in formal protected areas) yet still be vulnerable or endangered if a large proportion of natural habitat in that vegetation type has been lost. 3.3 AQUATIC ECOSYSTEMS Aquatic ecosystems include both rivers and wetlands. These two are inter-related, with most wetlands feeding rivers, thereby extending and stabilising their varied and seasonal flows. Together they function as arteries for the lifeblood of our living landscapes and as kidneys that process much of the waste products of life – and of humanity. These functions are sensitive to disturbance and overload. Successful protection of aquatic biodiversity and water supplies is the foundation stone for sustainable development. Rivers and wetlands are South Africa’s most important ecosystems. Apart from the vital water they deliver they are also our most impacted and damaged ecosystems. Aquatic biodiversity has its own specifically aquatic characteristics but is strongly influenced by the terrestrial ecosystems within each catchment. Freshwater plants, animals and microorganisms act as useful indicators of the ecological health of aquatic ecosystems, which has the added benefit of reflecting aspects of the health of the entire catchment as well. Rivers and wetlands are controlled by three basic ‘drivers’ that define their health and ecological characteristics. It is the balance between these drivers that is important. Aquatic ecosystem drivers may be summarised as: Hydrological – the presence and the flow of water –– which will vary seasonally and after rainfall in terms M P U M A L A N G A of speed and volume of flow; Biodiversity Chemical and physical – water quality –– which is a measure of the dissolved chemicals, pollutants and sediment contained in and transported by the water; Geomorphological - the physical land surface – the types of rock, soil and the slope of the surfaces over which the water flows, both in uplands and in the water-courses of rivers and streams; this includes the plant cover that controls erosion. Changes in ecosystem health may be measured by changes in river biota, such as fish, aquatic insects and riverine vegetation. Health of a river system, including its wetlands, is usually good in pristine or well protected catchments. This is particularly true in headwater and upper level catchments. However, a section of river does not necessarily reflect the condition of the catchment it flows through. For example, the Olifants River flows through a protected part of its catchment in the Kruger National Park, but the health of the river has already been seriously compromised upstream. The management and use of water has the most obvious and direct effect on aquatic ecosystems. But their ecosystem status is equally dependent on the irreversible and widespread changes that take place on the land. Cultivation, hard surfacing and polluted return-flows from urban and irrigated land, place pressures on river systems that are permanent and increasingly costly to manage. These impacts affect everyone at the personal level and economically at the regional and national level. Disadvantaged communities are most vulnerable to these impacts. RIVER ECOSYSTEMS Rivers are much more than channels where rainfall runoff races away to the sea. They provide important ecological goods and services to the landscape and for human use. Providing and purifying water are the most obvious of these but there are many others such as providing fish, aquatic plants and animals and social goods and services. Headwaters, middle reaches and lowland stretches of rivers all perform different environmental functions and need to be managed differently. Mpumalanga has no coastline and no estuaries, but local river management is also required to provide water for downstream users in Swaziland and Mozambique. This responsibility is provided for by international agreements on shared water resources. Rivers are flow-driven linear systems, which means their biodiversity characteristics are difficult to represent and quantify spatially as we do for terrestrial ecosystems. (Terrestrial biodiversity is inter-connected like the strands in a complex fabric of many threads in many directions. Aquatic biodiversity is more like string, the threads are all bound together and are more vulnerable to an impact that might sever one or more of them, especially those that control the ecosystem drivers.) CONSERVATION PLAN HANDBOOK
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