NEWS
Lightning, biodiversity,
global change and Smarties in
the mountains – say what?
Paul Gordijn and Professor Tim O’Connor
Current Address: SAEON
Reprinted From: http://bit.ly/2OPhQDg
W
ith intrigue, researchers have
noted the co-occurrence of
grasslands and areas with fre-
quent lightning storms.
Lightning has played a key role in the
evolution of these grassland ecosys-
tems specifically, by influencing how of-
ten and when fires move through land-
scape.
Fire limits tree growth; without it, grass-
lands in tropical and subtropical regions
would transform into shrublands and
forest. Before humans became domi-
nant drivers in the grassland landscape,
fire regimes were driven by patterns in
lightning ignition. Although we may
predict that a lightning-driven fire re-
gime may be more variable than a rig-
orous anthropogenic or human-driven
management regime, the particulars of
historic lightning-driven fire regimes re-
main elusive.
What’s with the fascination in historic
fire regimes anyway?
Well, the reasoning goes that since
grassland flora and fauna have evolved
under these ‘natural’ fire regimes, if we
were able to reproduce a ‘natural’ re-
gime, ecosystems would flourish.
Perhaps we may expect optimal func-
tioning of ecosystems and maximal di-
versity in these grasslands? Maybe un-
der these regimes, grasslands would be
best suited to the extremes of climate
change associated with global change?
These are important questions to ask
under current global change pressures
and also realising that grasslands are
one of the most transformed biomes on
earth.
Drakensberg grasslands
Of southern African grasslands, Drak-
ensberg grasslands stand out for their
high levels of endemism and for being
a biodiversity hotspot (that is, the area
hosts numerous species and many of
them are found nowhere else), plus the
important ecosystem services they pro-
vide. Also, these grasslands are known
as the ‘water tower’ of southern Africa,
for from these mountains our great riv-
ers such as the Orange and uThugela
find their source.
In these grasslands, charcoal deposits
and palynological (i.e. ‘pollen archaeol-
ogy’) evidence from cores suggest that
with the arrival of farmers and pasto-
ralists, fire has intensified over the last
thousand years or so. In particular, fire
use may be expected to have become
more finely managed or rigorous over
the last century as settlement in the re-
gion increased.
The contrast of the presumed ‘natural’
fire regime versus the recent rigorous
fire regimes begs a question of the ef-
fect of different fire regimes on these
grasslands. If we were able to answer
this question we are on track to promot-
ing ecosystem functioning and biodi-
versity in the face of global change.
Cathedral Peak sentinel site
The SAEON Cathedral Peak research
platform provides a unique opportunity
to assess grassland vegetation change
over time in response to different fire
regimes or treatments. The platform is
a world-class research site with a long
history of research.
Importantly, the fire treatments at the
Cathedral Peak research catchments
have been running for over half a centu-
ry. The fire treatments include both fre-
quent (burnt every one to three years)
Figure 1: Lightning has played a key role in the evolution of our grassland ecosystems by influencing how often, when and
how fires move through the landscape (Photo: Sue Janse van Rensburg)
19
Grassroots
Vol 18
No 4
December 2018