Mpumalanga Biodiversity Conservation Plan Handbook - bgis-sanbi

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