Effects of atmospheric CO2 variability of the past 800 kyr on the biomes of southeast Africa
Effects of atmospheric CO2 variability of the past 800 kyr on the biomes of southeast Africa
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DOI：
10.5194/cp-15-1083-2019
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发表时间：
2019-06-19
影响因子：
4.3
通讯作者：
Castaneda, Isla S.
中科院分区：
文献类型：
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作者：
Dupont, Lydie M.;Caley, Thibaut;Castaneda, Isla S.
关于大气二氧化碳压力 (pCO(2)) 对生物群落形成的影响知之甚少。整个 Brunhes Chron 期间 pCO(2) 的发展可被视为阐明植被与 pCO(2) 之间关系的自然实验。虽然冰期显示出低至非常低的值（分别接近 220 至 190 ppmv），但间冰期的 pCO(2) 水平从中等到相对较高（分别接近 250 至超过 270 ppmv）。为了研究 pCO(2) 对东南部非洲植被更新世发育的影响，我们使用了从林波波河口以南的 Delagoa Bight 取回的海洋核心 (MD96-2048) 的花粉记录，并结合了稳定同位素和地球化学代理。应用端元分析，可以区分代表不同生物群落的四种花粉组合：石南地、山地森林、灌木丛和林地。我们发现林波波河流域和莫桑比克南部沿海地区的植被不仅受到水文气候的影响，而且还受到温度和大气pCO(2) 的影响。我们的结果表明，山地森林的扩张发生在pCO（2）和温度适中的冰川时期，并且只有在大气pCO（2）较低（低于220 ppmv）的较冷时期，包括C-4莎草在内的开放杜鹃花植被才会扩张。该地区林地的主要开发发生在Mid-Brunhes事件（大约430ka）之后，当时间冰期的pCO(2)水平定期上升超过270 ppmv。
Very little is known about the impact of atmospheric carbon dioxide pressure (pCO(2)) on the shaping of biomes. The development of pCO(2) throughout the Brunhes Chron may be considered a natural experiment to elucidate relationships between vegetation and pCO(2). While the glacial periods show low to very low values (similar to 220 to similar to 190 ppmv, respectively), the pCO(2) levels of the interglacial periods vary from intermediate to relatively high (similar to 250 to more than 270 ppmv, respectively). To study the influence of pCO(2) 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 pCO(2). Our results suggest that the extension of mountain forest occurred during those parts of the glacials when pCO(2) and temperatures were moderate and that only during the colder periods when atmospheric pCO(2) was low (less than 220 ppmv) open ericaceous vegetation including C-4 sedges extended. The main development of woodlands in the area took place after the Mid-Brunhes Event (similar to 430 ka) when interglacial pCO(2) levels regularly rose over 270 ppmv.