Page 22 - LandscapeSA Issue 108

ENVIRONmENTAl FEATuRE
HOw ANCIENT pOllEN GRAINS
CAN pREDICT FuTuRE ClImATE
Dr Lynne Quick and her team extract sediment
from wetlands in order to analyse the pollen
grains that have accumulated over time. the age of the fossilised pollen. Knowing
“Knowing what types of
vegetation were growing
in an area allows us to
make inferences about
the climate at that time.
This is because plants
have bioclimatic niches,
which means they can
only live and thrive under
certain climatic and
environmental conditions.”
20 Landscape SA • Issue 108 2021
Ancient pollen grains found in sediment cores dating
back thousands of years are helping scientists to shed
light on the earth’s past and future climates. Pollen
analysis, also referred to as palynology, is the study
of the structure and formation of pollen grains and
spores, as well as their dispersal and preservation
under certain environmental conditions.
r Lynne Quick, a palynologist environmental conservation management
at Nelson Mandela University, initiatives.
is currently working on the
Ddevelopment of new paleo- Climate change threatens biomes
environmental records in Southern Africa. She says with future climate change,
significant shifts in vegetation distributions
She says pollen is distinct in two ways. It has are likely to occur, which may threaten the
a unique shape depending on what plant high levels of species richness and endemism
it comes from, and its outer layer is made found within some of South Africa’s unique
of sporopollenin, which is chemically very biomes.
stable and resistant to microbial decay. In
fact, it’s one of the most chemically inert These predictions are based on the outputs
organic compounds found on earth and is of bioclimatic models which require the use
known as the ‘diamond of the plant world’. of paleo-ecological data such as fossil pollen
Sporopollenin preserves pollen grains in records, to test the strength of the projections
ancient deposits and sediments when almost and validate the climate-vegetation
all other organic materials are reduced to hypotheses inherent within these models.
unrecognisable components.
Key regions of interest in South Africa include
“When pollen is blown into bodies of water the fynbos (Western and Eastern Cape),
and sinks, their walls remain intact, allowing Drakensberg (KzN), grassland (high central
them to remain preserved in sediment layers plateau and inland areas of KzN and the
at the bottom of lakes, oceans and wetlands. Eastern Cape) and savanna biomes (Free
Their unique shape enables us to identify State, North West and Gauteng).
what plant species were in abundance at
the time the sediment was deposited and Based on fossil pollen dating back 10 000 years,
through carbon dating, we can determine the Cape floral region was once abundant in
both fynbos and forest, indicating plenty of
what types of vegetation were growing in an rainfall and moisture, while future predictions
area allows us to make inferences about the suggest a much warmer and drier climate for
climate at that time. This is because plants the Western Cape.
have bioclimatic niches, which means they “It is expected that the extent of forest areas
can only live and thrive under certain climatic
and environmental conditions. Fossil pollen will be reduced to isolated patches where
leaves an important fingerprint that can help
conditions remain favourable, along with
us uncover how our climate has changed potential reductions in the extent of the
over millennia and what it may look like in the fynbos biome,” notes Dr Quick. “In addition to
the threat of climate change, ongoing habitat
future,” she explains.
There is a large body of work that covers transformations (as a result of agricultural,
coastal resort and urban development)
the reconstruction of landscapes and and the rapid spread of alien vegetation
environments using pollen evidence from makes the region particularly vulnerable to
thousands of years ago in different parts
significant reductions in biodiversity. To limit
of South Africa. Most of the data generated the impact, the conservation of the coastal
lowlands of the fynbos biome should be
by Dr Quick and other researchers
is incorporated into climate and prioritised.”
bioclimatic models as baselines for past The Drakensberg mountain range also has
vegetation changes, which can also aid in