Climate and CO2 effects on the vegetation of southern tropical Africa over the last 37,000 years
Climate and CO2 effects on the vegetation of southern tropical Africa over the last 37,000 years
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DOI：
10.1016/j.epsl.2014.06.043
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发表时间：
2014-10
影响因子：
5.3
通讯作者：
V. Khon;Yiming V. Wang;U. Krebs-Kanzow;J. Kaplan;R. Schneider;B. Schneider
中科院分区：
文献类型：
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作者：
V. Khon;Yiming V. Wang;U. Krebs-Kanzow;J. Kaplan;R. Schneider;B. Schneider
热带南部非洲稀树草原植被以C4草原和C3林地共同优势为特征。热带稀树草原植被在干旱和半干旱气候中的长期变化通常被认为主要是对降水和大气二氧化碳浓度的敏感。然而，热带植被对温度的敏感性通常被认为是次要的或可以忽略不计的，特别是在古生物研究中，因为很难恢复热带地区的陆地温度。在这项研究中，我们使用陆地植被模型BIOME4，该模型是由基尔气候模型(KCM)对全新世的气候模拟和最近冰期的气候重建所强制的，以了解过去37,000年来热带南部非洲重建的植被变化。我们把重点放在这两个时期，因为赞比西河河口附近的海洋沉积岩芯的植被重建不能仅用降水和大气CO2的变化来解释。对于全新世，我们使用KCM重建的大气CO2浓度以及全新世早期和中期(9.5和6ka BP)模拟的空间和季节气候模式进行BIOME4模拟。对于冰期，我们根据重建的31、28和21ka BP的温度、降水和二氧化碳分析了理想化的实验。我们的研究表明，在考虑温度变化的情况下，全新世和冰川植被覆盖的模拟与重建的C4：C3比值都表现出很好的一致性。而降水和温度共同控制着全新世C4/C3比，大气CO2和温度变化是控制冰期植被变化的主要因素。在我们的模拟中，温度随降水和大气二氧化碳的变化与过去37,000年来在赞比西河流域观测到的植被的演变相一致。因此，在模拟过去或未来的气候时，应考虑温度变化对热带稀树草原植被的影响。
The savanna vegetation of southern tropical Africa is characterized by co-dominance of C 4 grasslands and C 3 woodlands. Long-term variations in the tropical savanna vegetation in arid and semi-arid climates are commonly considered to be primarily sensitive to precipitation and atmospheric CO 2 concentrations. The sensitivity of tropical vegetation to temperature, however, is often considered as secondary or negligible, particularly in paleostudies due to difficulties of reconstructing terrestrial temperature in the tropics. In this study, we use the terrestrial vegetation model BIOME4, which was forced by climate simulations from the Kiel Climate Model (KCM) for the Holocene and by climate reconstructions for the most recent glacial period to understand reconstructed vegetation changes in southern tropical Africa of the past 37,000 yr. We focus on these two periods because vegetation reconstructions from a marine sediment core near the Zambezi River mouth cannot be explained by precipitation changes and changes of atmospheric CO 2 alone. For the Holocene, we force BIOME4 simulations with reconstructed atmospheric CO 2 concentrations, and spatial and seasonal climate patterns from the early-and mid-Holocene (9.5 and 6 ka BP) simulations with the KCM. For the glacial period, we analyze idealized experiments based upon reconstructed temperature, precipitation and CO 2 at 31, 28 and 21 ka BP. Our study shows that both Holocene and glacial simulations of vegetation cover exhibit good agreement with reconstructed C 4: C 3 ratios when temperature changes are taken into account. While both precipitation and temperature control the C 4: C 3 ratio during the Holocene atmospheric CO 2 and temperature variations are major factors controlling vegetation changes during the glacial period. In our simulations, variations in temperature along with precipitation and atmospheric CO 2 reconcile the evolution of vegetation observed in the Zambezi catchment during the last 37,000 yr. In consequence, the effect of temperature variations on tropical savanna vegetation should be taken into account with respect to modeling past or future climates.