NEWS
and infrequent burn regimes (burnt eve-
ry five to eight years).
We sampled an historic grass spe-
cies monitoring project in the research
catchments. We were confident that
after at least two decades of fire treat-
ments, an impact on grass communities
would be clear (Gordijn et al., 2018). To
our surprise, the influence of the fire re-
gime on vegetation was only evident af-
ter more than half a century of fire treat-
ments. This is a very interesting find,
specifically in the face of global change.
Comparison with other nearby savanna
ecosystems highlights these grasslands’
unique resistance. In nearby savannas,
within a decade, vegetation compo-
sition has changed dramatically, with
bush encroachment.
What about changes in trends in spe-
cies abundance across all the fire
treatments?
If global change was driving some of
these, we may expect to find a few grass
species to win and others to lose across
the fire treatments?
Well, over more than three decades, the
largest change observed across the fire
treatments was less than six percent.
This is a really small change and illus-
trates the ‘resistance’ of these grass-
lands to global climate change (at least
so far).
Next round, little Jordan the sweet-
tooth gets hold of the Smartie box.
With eagerness Jordan hands out the
Smarties until the box is empty and eve-
ryone’s hands are filled with differently
coloured Smarties. Jordan’s preference
for different colours (and her bias for
who should receive these) has affected
who has what colours. So now even
though everyone can say, ‘what a lot I
got’ - everyone has a different set of col-
oured Smarties.
The forest patches are like the first
round where everyone only had a few
differently coloured Smarties due to
Dad’s diligence, also in this process
no one ended up with a unique set of
Smartie colours. In contrast, grassland
species assemblages are like Jordan’s
eager dishing out of Smarties – every-
one had many different colours (or spe-
cies), plus, Jordan’s colour bias led to
everyone having unique sets or assem-
blages of species.
In our grassland study, fire acted simi-
larly to Jordan’s preferences for colours.
That is, after more than half a century
of different fire treatment applications,
we found that the legacy of these treat-
ments was important in shaping unique
species assemblages. So, although
these grasslands species assemblages
So, the grasses may be ‘resistant’ to
change, but what about the other flow-
ering plants in the grass layer that make
up 78 percent of the species richness of
the area?
The answer to this question is not clear-
cut - some comparisons with the work of
other ecologists on the isolated indige-
nous forest patches in the Drakensberg
are useful (Adie et al., 2017). These for-
est patches are restricted to the cooler
slopes or aspects of this montane envi-
ronment and to areas protected from
fire (for example, rivers, cliffs and rocky
outcrops).
‘Life is like a box of Smarties’
Since we’re thinking about forests, we’ll
take a lead from the movie Forrest
Gump, ‘Life is like a box of Smarties’.
Imagine a box of Smarties being shared
out in a family where each different col-
our Smartie represents a different spe-
cies. Now, Dad shares out a strict three
Smarties to each family member paying
no attention to who gets what colour,
being distracted by the Soccer finals.
In this round, everyone’s small hand-
ful only represents a small subset of all
the different colours in the Smartie box.
Grassroots
Vol 18
No 4
mediate fire regimes. This provides fur-
ther evidence that grassland flora is well
adapted to a variable fire regime.
Does this mean that we should stop
burning our grasslands and let light-
ning do the job?
The short answer is no, because we can-
not impose a ‘natural’ fire regime on a
human-dominated landscape - this has
been tried before. What are the take
homes then for managing our grass-
lands in the face of global change?
Well, yes, these grasslands appear to be
resistant to rapid changes under global
change and variable fire regimes. How-
ever, in the long term we would need to
promote a variable fire regime over the
landscape to maintain diversity.
Apart from influencing fire regimes, hu-
mans have also altered grazing regimes
and are transforming the ‘natural’ func-
tioning of these grasslands that are im-
portant reservoirs of biodiversity which
provide our dams with clean water. So,
what about the impacts of different
grazing practices and other land uses
(associated with different types of land
tenure or ownership) around Cathedral
Peak?
That’s for another time and another box
of chocolates. For now, we appreciate
the sheer biodiversity and associated
clean water provided from the uKhahl-
amba Drakensberg mountains and, im-
portantly, our collective responsibility in
retaining the observed resistance, for
our own good. SAEON’s responsibility
in the future is to continue observation
programmes in these grasslands and
evaluate response strategies to project-
ed change.
Acknowledgements
Figure 2: Grassland fauna and flora
have evolved under ‘natural’ fire re-
gimes (Photo: Paul Gordijn)
were initially resistant to fire, over a long
time period variation in the fire regime
influenced the uniqueness of species
assemblages over the landscape.
So how does this relate to interest in
historic, variable lightning-driven fire
regimes?
Well, this relation between unique spe-
cies assemblages and variation in the
fire regime is something that one would
expect if species were adapted to a var-
iable fire regime. This fits well with the
hypothesis that the historic fire regime
was variable, as one may expect a light-
ning-driven fire regime to be.
What’s more is that the highest number
of species was found in areas with inter-
December 2018
SAEON's Grasslands-Forests-Wetlands
Node would like to thank its host or-
ganisation, Ezemvelo KwaZulu-Natal
Wildlife, for allowing node scientists to
do this research in the Drakensberg and
for providing excellent support.
Further reading
•
•
Adie, H., Kotze, D.J. and Lawes,
M.J. 2017. Small fire refugia in the
grassy matrix and the persistence
of Afrotemperate forest in the Drak-
ensberg mountains. Scientific Re-
ports 7, 1-10.
Gordijn, P.J., Everson T.M. and
O’Connor, T.G. 2018. Resistance of
Drakensberg grasslands to com-
positional change depends on the
influence of fire-return interval and
grassland structure on richness and
spatial turnover. Perspectives in
Plant Ecology, Evolution and Sys-
tematics 34, 22-36.
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