Description: Despite its great ecological importance, the main factors governing tree cover in tropical savannas as well as savanna-forest boundaries are still largely unknown. Here we address this issue by investigating marine sediment records of long-chain n-alkane stable carbon (δ13Cwax) and hydrogen (δDwax) isotopes from a core collected off eastern tropical South America spanning the last ca. 45 thousand years. While δ13Cwax is a proxy for the main photosynthetic pathway of terrestrial vegetation, tracking the relative proportion of C3 (mainly trees) versus C4 (mainly grasses) plants, δDwax is a proxy for continental precipitation, tracking the intensity of rainfall. The investigated core was collected off the mouth of the São Francisco River drainage basin, a tropical savanna-dominated region with dry austral autumn, winter and spring. On top of millennial-scale changes, driven by anomalies in the amount of precipitation associated with Heinrich Stadials, we identify a marked obliquity control over the expansion and contraction of tree and grass cover. During periods of maximum (minimum) obliquity, trees (grasses) reached maximum coverage. We suggest that maximum (minimum) obliquity decreased (increased) the length of the dry season allowing (hampering) the expansion of tree-dominated vegetation. Periods of maximum obliquity induced an anomalous heating (cooling) of the summer (winter) hemisphere that in combination with a delayed response of the climate system slightly increased autumn precipitation over the São Francisco River drainage basin, through a shift of the Intertropical Convergence Zone towards or further into the anomalously heated hemisphere. We found that atmospheric CO2 concentration has only a secondary effect on tree cover. Our results underline the importance of the dry season length as a governing factor in the long-term control of tree cover in tropical landscapes.

Description: Fractional abunances of isoprenoid GDGTs calculated from the peak areas detected for the molecule peaks in the HPLC chromatograms. These data are an addition to the already archived TEX86 and UK'37 data in core-top sediments from off Indonesia (doi:10.1594/PANGAEA.823057).

Description: The data set contains lipid biomarker and bulk organic matter data from two sediment cores in the Shaban Deep, in the northern Red Sea. One core is deposited in the hypersaline brine (GeoB7805-1 2) and the other core (GeoB7807-2) is deposited outside the brine. The data set compares the lipid biomarker signals in the two deposition settings. For both cores the data set contains total organic carbon data, total nitrogen data, bulk organic matter carbon and hydrogen isotope data, long-chain n-alkane concentrations, alkenone concentrations, long- and short-chain fatty acid concentrations, long-chain n-alkane and long-chain fatty acid average chain length and carbon preference index data, UK37 data, stable carbon and hydrogen isotope data for long-chain n-alkanes, alkenones, and long- and short chain fatty acids.

Description: This data set includes δ¹³C of bulk OC and Fatty acids in two nearshore sediment cores collected by the piston corer from coastal South China Sea. These data could help us to constrain the anthropogenic perturbations of different terrestrial OC export to the coastal ocean.