Hydrological and vegetation shifts in the Wallacean region of central Indonesia since the Last Glacial Maximum
Hydrological and vegetation shifts in the Wallacean region of central Indonesia since the Last Glacial Maximum
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DOI：
10.1016/j.quascirev.2016.12.006
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发表时间：
2017-02
影响因子：
4
通讯作者：
S. Wicaksono;J. Russell;A. Holbourn;W. Kuhnt
中科院分区：
文献类型：
--
作者：
S. Wicaksono;J. Russell;A. Holbourn;W. Kuhnt
降水是印尼气候的最重要的变量，但在该地区过去和未来的水文气候动力学有很大的不确定性。这项研究探讨了过去26,000年来Wallacea的植被和降雨以及大气环流的相关变化，Wallacea是印度尼西亚中部的一个地理区域，夹在Sunda和Sahul大陆架之间，以其异常高的雨林生物多样性而闻名。我们使用陆地植物生物标志物从曼达湾，西苏拉威西岛附近的沉积岩芯中检索，重建Wallacean植被和气候的变化，因为末次冰期最大（LGM）。在末次盛冰期曼达尔湾记录的富叶蜡碳同位素（δ 13 Cwax）值，以及其他区域植被记录，记录了草原扩张，暗示了区域干旱，可能更具季节性的冰川气候。末次盛冰期曼达尔湾的叶蜡氘同位素（δDwax）值减少，附近站点的降水同位素组成重建较低，表明澳大利亚-亚洲夏季季风环流增强，热带辐合带的平均位置南移，这可能是由于南半球夏季日照强烈和北方大冰盖的存在。在末次盛冰期和末次冰消期，Mandar湾δ 13 Cwax与δ Dwax呈反相关，而在全新世大部分时间内，二者呈正相关，表明该地区降雨同位素组成受时变控制。巽他大陆架的淹没事件，特别是在9.4和11.1万年前的爪哇海和Karimata海峡的开放可能提供了新的水分来源的区域对流和/或影响水分来源的轨迹，提供触发大气环流的变化和控制降水同位素组成从末次盛冰期到全新世。
Precipitation is the most important variable of Indonesian climate, yet there are substantial uncertainties about past and future hydroclimate dynamics over the region. This study explores vegetation and rainfall and associated changes in atmospheric circulation during the past 26,000 years in Wallacea, a biogeographical area in central Indonesia, wedged between the Sunda and Sahul shelves and known for its exceptionally high rainforest biodiversity. We use terrestrial plant biomarkers from sediment cores retrieved from Mandar Bay, off west Sulawesi, to reconstruct changes in Wallacean vegetation and climate since the Last Glacial Maximum (LGM). Enriched leaf wax carbon isotope (δ13Cwax) values recorded in Mandar Bay during the LGM, together with other regional vegetation records, document grassland expansion, implying a regionally dry, and possibly more seasonal, glacial climate. Depleted leaf wax deuterium isotope (δDwax) values in Mandar Bay during the LGM, and low reconstructed precipitation isotope compositions from nearby sites, reveal an intensified Austral-Asian summer monsoon circulation and a southward shift of the mean position of the Intertropical Convergence Zone, likely due to strong southern hemisphere summer insolation and the presence of large northern hemisphere ice sheets. Mandar Bay δ13Cwaxwas anti-correlated with δDwaxduring the LGM and the last deglaciation, but was positively correlated during most of the Holocene, indicating time-varying controls on the isotopic composition of rainfall in this region. The inundation event of the Sunda Shelf and in particular the opening of the Java Sea and Karimata Strait between 9.4 and 11.1 thousand years ago might have provided new moisture sources for regional convection and/or influenced moisture source trajectories, providing the trigger for shifts in atmospheric circulation and the controls on precipitation isotope compositions from the LGM to the Holocene.