Paleovegetation seesaw in Brazil since the Late Pleistocene: A multiproxy study of two biomes
Paleovegetation seesaw in Brazil since the Late Pleistocene: A multiproxy study of two biomes
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DOI：
10.1016/j.epsl.2021.116880
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发表时间：
2021-06
影响因子：
5.3
通讯作者：
V. Azevedo;N. Stríkis;V. Novello;Camila Leão Roland;F. Cruz;R. Santos;M. Vuille;Giselle Utida;Fábio Ramos Dias de Andrade;Hai Cheng;R. Edwards
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文献类型：
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作者：
V. Azevedo;N. Stríkis;V. Novello;Camila Leão Roland;F. Cruz;R. Santos;M. Vuille;Giselle Utida;Fábio Ramos Dias de Andrade;Hai Cheng;R. Edwards
巴西的古植被研究主要是基于花粉分析和湖泊和土壤记录中的地球化学指标。然而，这些记录在大陆上分布稀少，而且在大多数情况下，集中在全新世，提供了自末次盛冰期以来过去植被的一幅小图。长期以来，石笋一直被用作南美洲热带和亚热带地区古降水和季风活动的记录器，近年来，δ 13 C和87 Sr/86 Sr的联合应用也显示出记录植被和土壤变化的潜力。我们利用这一新方法确定了塞拉多古植被过渡和土壤发育的时期（巴西稀树草原）巴西中部的生物群系。我们的研究结果表明，一个连贯的过渡期，从稀疏的植被和较浅的土壤以上的洞穴密集的植被和较厚的土壤，因为最后一次冰消期约15万年BP。这一转变的时间是不同的多代理证据中发现的Caatinga（干林）生物群落，在巴西东北部，约4.2万年BP，在一段时期的古植被跷跷板模式之间的巴西中部和东北部地区。此外，大气pCO 2和温度的变化可能发挥了重要作用的古植被过渡在塞拉多地区，而降水与热带辐合带的古植被的主要调制器在卡廷加。
Paleovegetation studies in Brazil have been mostly based on pollen analysis and geochemical proxies in lacustrine and soil records. These records, however, are sparsely located in the continent and, in most of the cases, centered over the Holocene, giving a minor picture of past vegetation since the Last Glacial Maximum. Stalagmites have been long used as recorders of paleoprecipitation and monsoon activity over time in tropical and subtropical South America by using δ 18 O analyses, but recently they also showed the potential to record past vegetation and soil changes through the combined use of δ 13 C and 87 Sr/86 Sr. We utilize this new approach to determine the periods of paleovegetation transition and soil development in the Cerrado (Brazilian savanna) biome from central Brazil. Our results show a coherent period of transition from sparser vegetation and shallower soil above the cave to denser vegetation and thicker soil since the last deglaciation circa 15 ka BP. The timing of this transition is different from the multiproxy evidence found in the Caatinga (dry forest) biome, in northeastern Brazil, circa 4.2 ka BP, resulting in a period of paleovegetation seesaw pattern between central and northeastern regions of Brazil. Additionally, atmospheric pCO 2 and temperature variations may have played a major role on the paleovegetation transition in the Cerrado region whereas precipitation linked to the Intertropical Convergence Zone was the major modulator of paleovegetation in the Caatinga.