High-Resolution Time Series of Vessel Density in Kenyan Mangrove Trees Reveal a Link with Climate

• Tropical trees are often excluded from dendrochronological investigations because of a lack of distinct growth ring boundaries, causing a gap in paleoclimate reconstructions from tropical regions. • The potential use of time series of vessel features (density, diameter, surface area and hydraulic conductivity) combined with spectral analysis as a proxy for environmental conditions in the mangrove Rhizophora mucronata was investigated. • Intra-annual differences in the vessel features revealed a trade-off between hydraulic efficiency (large vessels) during the rainy season and hydraulic safety (small, more numerous vessels) during the dry season. In addition to the earlywood-latewood variations, a semiannual signal was discovered in the vessel density and diameters after Fourier transformation. • The similarity in the Fourier spectra of the vessel features and the climate data, in particular mean relative humidity and precipitation, provides strong evidence for a climatic driving force for the intra-annual variability of the vessel features. The high-resolution approach used in this study, in combination with spectral analysis, may have great potential for the study of climate variability in tropical regions.