Biodiversity in the Knersvlakte 25.09.2014
From
Olivia Helmcke, Natnael Tzeggai,
Sarita Makekella, Nadine Koeppe
Biodiversity in the Knersvlakte
Our study area was in Ratelgat which is located in the Knersvlakte. The Knersvlakte is
characterised by a gently undulated landscape and is streaked by numerous quartz veins. The
study area is dominated by leaf succulent dwarf shrubs and very rich in plant species among
which leaf succulent Aizoaceae and Asteracae.
We choose this area to look at which plot size the species variety does not increase anymore.
At this point we distinguish between quartz and non-quartz.
Our Methods
The Study area which is located in the west side of South Africa is called Ratelgat it is more or
less 300km in the north of Cape Town (average annual rainfall ~ 159 mm).
First we searched for different habitats, quartz and non-quartz. Quartz fields are mainly
dominated by Argyroderma and Monilaria. Mostly the non-quartz fields were shrubby. In the
next step we mark out the plot with the 50m measuring tape and the 100m measuring tape so
we got a 1000 square meter plot with 20 x 50 meters. In this plot we made smaller plots like the
0,1m x 0,1m plot. After this we named the whole plot. For each size of the plot we wrote down
the occurrence of species. If we did not know the name of the plants, we took photos of them
and gave them working names, so that we can identify them after the field work. And at the end
of working in one plot we took soil samples from it.
Graph number 1: “Plot sizes”
Our results
Total amount of species in mosaic areas 40 35 Total amount of species 30 25 ATBT 20 Beautytown 15 Shrubby Mosaic 10 5 0 0,01 1 11,0889 100 1000 Plot size in square meters 1089 Graph number 2: “Total amount of species in mosaic areas”
The graph ”Total amount of species in mosaic areas” shows the total amount of species in
relation to the plot size in square meters. The graph includes three individual curves.
The first curve is named “ATBT” and is shown in blue. The species increases steadily with the
rising size of the plot and stands out from the other two curves at 1000 square meters, where
the amount of species reaches the highest point with 35 different types of plants. Afterwards the
curve decreases to an amount of 29 species in the plot size of 1089 square meters.
The second curve, which describes the second plot, is named “Beautytown” and is shown in
red. The curve increases flat until 100 square meters, where it starts to rise sharply until 1000
square meters, where the highest point with 24 species is reached. Subsequently the curve
decreases to an amount of 18 species.
The third and last curve is shown in green and is named “Shrubby Mosaic”. The curve rises
evenly up to the highest point of 28 types of plants in a plot of 1089 square meters.
Total amount of species in quarz areas 45 40 Total amount of species 35 30 25 SONN 20 Quarz island 15 Monilaria Quarz 10 5 0 0,01 1 11,0889 100 1000 1089 Plot size in square meters Graph number 3: “Total amount of species in quartz areas”
The graph” Total amount of species in quartz areas” shows the total amount of species in
relation to the plot size in square meters. The graph includes three individual curves.
The first curve is named “SONN” and is shown in blue. The curve rises slightly and stagnates
between one and 11,0889 square meters with seven species. Afterwards the curve increases
and reaches the highest point at 1000 square meters with 28 different types of plants. To 1089
square meters the curve decrease flat to 25 species.
The second curve is named “Quarz Island” and is shown in red. The curve rises steadily up to
25 species in 1000 square meters. Subsequently the curve decreases to 24 plants in a plot of
1089 square meters.
The third curve is named “Monilaria Quarz” and is shown in green. Up to 100 square meters the
curve rises steadily to 14 species in the plot. Up to 1000 square meters the curve increases
sharply to 39 different types of plants and reaches the highest point in the graph. Subsequently
the curve increases to 33 species in the plot of 1089 square meters.
Our conclusion
Our task was to look for different types of plant species on different types of soils. Our aim was
to find out if the number of species increases or if the number stagnates with the size of the plot.
To get the results, we worked on quartz and non-quartz (mosaic) fields.
We found out, that some types of plants can be found on both types of soils. For example the
Didelta carnosa, Artriplex lindleyi and different types of the Drosanthemum family.
On all quartz fields we found especially the Senecio arenarius, the Caulipsolon rapaceum and
the Argyroderma fissum. The difference within the quartz fields is the existence of Monilaria
persiformis, which cannot be found on every quartz field, but if it exists, it dominates the field.
On the mosaic fields we always found the Tripteris sinuata, the Mesem nodiflorum and the
Galenia sarcophylla. It was conspicuous, that on the mosaic fields where a lot more shrubs than
on the quartz fields.
To sum up, the more the plot grows, the more species can be found. When the plot reaches the
size of 1000 square meters, the number of species is on the highest point. When you compare
the 20 x 50 meter plot with the 33 x 33 meter plot you can see that the 20 x 50 plot includes the
most different species. A reason for that can be that with the 20 x 50 plot we reached more
different habitats, which include more other species. You can determine that the number of
different types of plants stops increasing in a bigger area. This means that no more species can
be found.
Graph number 4: “Didelta carnosa”
Graph number 5: “Argyroderma delaetii”