Page 23 - LandscapeSA Issue 108

ENVIRONmENTAl FEATuRE

scientists predict that a warmer, drier future climate may threaten the southern African savannahs may be compromised by the effects of CO fertilisation,
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high levels of fynbos species currently found in the Western Cape. which is likely to increase the growth rate of trees to the detriment of grasses.

immense ecological significance, because of water in deep soil layers to the detriment of
its great plant biodiversity. grasses.
Ongoing pollen research from high altitude The loss of open, grassy landscapes has
wetlands conducted by Dr Jemma Finch implications for grazers and other flora and
and Prof Trevor Hill from the University of fauna adapted to these environments and
Kwazulu-Natal has been used to reconstruct may be detrimental to wildlife tourism as
long-term vegetation dynamics and it will decrease game viewing potential.
associated climate change. “Their research According to Dr Quick, palaeo-ecological
indicates that grasslands found in the area, data such as pollen records can increase
which were traditionally viewed as secondary our understanding of ecological responses
features of the mountainous terrain, are to both natural and human-induced
actually an ancient primary vegetation type.” impacts and can help to design appropriate
restoration practices and stewardship While many allergenic trees such as planes,
Of particular interest in this region is the programmes. “Through this deep-time cypresses and oaks have been naturalised over
integration of pollen data with the more ecological lens we can see that grasslands are several hundred years, wind-born pollen from
traditional archaeological records that trace not degraded forms of landscapes. Therefore, the Morella or Waxberry tree was found in fossil
human occupation. Pollen records from we should carefully consider the implications pollen records of the south-western Cape and
the Drakensberg and surrounds reveal of planting trees and expanding forests as Namaqualand as far back as 66 million years ago.
that grasslands remained relatively stable these efforts may undermine the provision
over the past c. 5 000 years, whereas forests of valuable ecosystem goods and services nationwide pollen monitoring has only
were restricted in their distribution, likely associated with grasslands.” gained momentum in the last three years,
occupying fire protected valleys and kloofs having access to data over a longer period
as seen in the present day grassland-forest She says the study of both ancient and will help to predict long-term changes and
mosaic. present day pollen is essential as it will how it is likely to influence plant life and aero-
help to inform future climate models and allergens in the future.
Dr Quick says the long-term perspective conservation efforts.
provided by this pollen research highlights “The interest in pollen season trend studies
the conservation value of grasslands as The last 20 years of pollen monitoring in the increased during the 90s, when changing
an ancient and primary vegetation type Western Cape has provided crucial answers temperatures and shifting pollen season
dominating this important watershed. “As about the rate and extent to which climate parameters became more obvious. The
the climate continues to warm through change is occurring. changing climate alters the seasonality
the 21st century, there are concerns that and intensity of pollen seasons, as well
montane grassland species may be forced to Researchers have noticed fluctuations in as the distribution of allergenic plants.
respond by migrating upslope, altering the pollen seasons, which are starting earlier and Increasing CO concentrations and changes
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composition of these important grasslands, ending later than before. The above average in air pollution affect plant physiology and
and impacting species that may not be rainfall for the Cape in the past two years has allergenicity, which makes hayfever one
able to keep pace with the current rate of caused a surge in not only tree pollen levels, of the major health effects resulting from
environmental change”. but allergenic tree counts have been higher a changing climate. Pollen forecasting is
than the ten-year average. Since 2011, higher therefore becoming increasingly important
Analysing pollen in soil from southern grass pollen counts have also been recorded as doctors and allergists rely on the data to
African savannas shows varying changes in the month of October, which is when grass provide effective care to patients.
in rainfall and warmer periods that have pollen typically peaks in the Cape.
influenced vegetation changes in the last Information and photos supplied by Meropa
6 000 years. Scientists say these landscapes Prof Jonny Peter, Head of Allergology and Communications on behalf of the uCT Lung
might be compromised by the effects of CO 2 Clinical Immunology at the uCT lung Institute. For more information on Dr Quick’s
fertilisation, which will increase the growth Institute, who also leads the South African research visit https://accp.mandela.ac.za/
rate of trees, allowing more rapid access to Pollen Network (SAPNET), says while Palaeoecology-Lab.

Landscape SA • Issue 108 2021 21