Effects of atmospheric CO<sub>2</sub> variability of the past 800 kyr on the biomes of southeast Africa
<p>Very little is known about the impact of atmospheric carbon dioxide pressure (<span class="inline-formula"><i>p</i>CO<sub>2</sub></span>) on the shaping of biomes. The development of <span class="inline-formula"><i>p</i&...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-06-01
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| Series: | Climate of the Past |
| Online Access: | https://www.clim-past.net/15/1083/2019/cp-15-1083-2019.pdf |
| Summary: | <p>Very little is known about the impact of atmospheric
carbon dioxide pressure (<span class="inline-formula"><i>p</i>CO<sub>2</sub></span>) on the shaping of biomes. The development
of <span class="inline-formula"><i>p</i>CO<sub>2</sub></span> throughout the Brunhes Chron may be considered a natural
experiment to elucidate relationships between vegetation and <span class="inline-formula"><i>p</i>CO<sub>2</sub></span>. While
the glacial periods show low to very low values (<span class="inline-formula">∼220</span> to
<span class="inline-formula">∼190</span> ppmv, respectively), the <span class="inline-formula"><i>p</i>CO<sub>2</sub></span> levels of the
interglacial periods vary from intermediate to relatively high
(<span class="inline-formula">∼250</span> to more than 270 ppmv, respectively). To study the influence
of <span class="inline-formula"><i>p</i>CO<sub>2</sub></span> on the Pleistocene development of SE African vegetation, we used
the pollen record of a marine core (MD96-2048) retrieved from Delagoa Bight
south of the Limpopo River mouth in combination with stable isotopes and
geochemical proxies. Applying endmember analysis, four pollen assemblages
could be distinguished representing different biomes: heathland, mountain
forest, shrubland and woodland. We find that the vegetation of the Limpopo
River catchment and the coastal region of southern Mozambique is
influenced not only by hydroclimate but also by temperature and atmospheric
<span class="inline-formula"><i>p</i>CO<sub>2</sub></span>. Our results suggest that the extension of mountain forest occurred
during those parts of the glacials when <span class="inline-formula"><i>p</i>CO<sub>2</sub></span> and temperatures were
moderate and that only during the colder periods when atmospheric
<span class="inline-formula"><i>p</i>CO<sub>2</sub></span> was low (less than 220 ppmv) open ericaceous vegetation including
C<span class="inline-formula"><sub>4</sub></span> sedges extended. The main development of woodlands in the area took place
after the Mid-Brunhes Event (<span class="inline-formula">∼430</span> ka) when interglacial
<span class="inline-formula"><i>p</i>CO<sub>2</sub></span> levels regularly rose over 270 ppmv.</p> |
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| ISSN: | 1814-9324 1814-9332 |