Indonesian vegetation response to changes in rainfall seasonality over the past 25,000 years
Indonesian vegetation response to changes in rainfall seasonality over the past 25,000 years
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DOI：
10.1038/ngeo2182
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发表时间：
2014-07-01
影响因子：
18.3
通讯作者：
Linsley, Braddock K.
中科院分区：
文献类型：
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作者：
Dubois, Nathalie;Oppo, Delia W.;Linsley, Braddock K.
在过去的25000年中，印度-太平洋暖池区对气候强迫的水文响应在空间上发生了变化（1-5）。例如，推断爪哇和婆罗洲在末次盛冰期结束后的一段时间内较为干燥，而澳大利亚西北部则较为湿润(4)。植被对这些过去降雨变化的响应没有得到很好的约束。通过对整个印度洋-太平洋暖池的30个表层海洋沉积物样本的分析，我们证明了今天维管植物脂肪酸的稳定同位素组成（δ (13)CFA）反映了区域植被组成。这反过来又受到与旱季水压力一致的降雨季节性的控制(6)。在婆罗洲东北部近海沉积物岩心中应用这一代用物，我们发现末次盛冰期和全新世的植被覆盖范围大致相似，这表明尽管冰川条件普遍较为干燥，但没有明显的旱季。相比之下，三角洲（13）CFA和来自松巴海岸外一个岩心的花粉数据表明，在最近的冰期，C-4草本植物的数量增加，这意味着旱季干旱和水分胁迫加剧。全新世植被趋势也与对旱季水分胁迫的响应一致。因此，我们得出结论，热带季风区的植被容易受到降雨季节性增强引起的水资源压力增加的影响，正如过去几十年所发生的那样(8)。
The hydrologic response to climate forcing in the Indo-Pacific warm pool region has varied spatially over the past 25,000 years(1-5). For example, drier conditions are inferred on Java and Borneo for the period following the end of the Last Glacial Maximum, whereas wetter conditions are reconstructed for northwest Australia(4). The response of vegetation to these past rainfall variations is poorly constrained. Using a suite of 30 surface marine sediment samples from throughout the Indo-Pacific warm pool, we demonstrate that today the stable isotopic composition of vascular plant fatty acids (delta(13)CFA) reflects the regional vegetation composition. This in turn is controlled by the seasonality of rainfall consistent with dry season water stress(6). Applying this proxy in a sediment core from offshore northeast Borneo, we show broadly similar vegetation cover during the Last Glacial Maximum and the Holocene, suggesting that, despite generally drier glacial conditions(1,7), there was no pronounced dry season. In contrast, delta(13)CFA and pollen data from a core off the coast of Sumba indicate an expansion of C-4 herbs during the most recent glaciation, implying enhanced aridity and water stress during the dry season. Holocene vegetation trends are also consistent with a response to dry season water stress. We therefore conclude that vegetation in tropical monsoon regions is susceptible to increases in water stress arising from an enhanced seasonality of rainfall, as has occurred(8) in past decades.