Dendrochronological Study of Manilkara Huberi (Ducke) A. Chev. (SAPOTACEAE) in a Upland Forest of Central Amazonia using High-Frequency Densitometry

This study evaluated the correlation of climatic variables with the chronology of a tree species, Manilkara huberi (Ducke) A. Chev. (Sapotaceae), from a upland forest in Central Amazonia. Samples were taken from a forest management area and analyzed using a dendrochronological technique, high-frequency densitometry. Instrumental climate data in the Amazon are insufficient to describe the natural variability of rainfall regimes and their association with major ocean–atmosphere interaction events. A dendroclimatic signal was found for Manilkara huberi, which forms annual growth rings as a consequence of the seasonality of rainfall. The annual growth rings of this species are indicated by an alternation of fiber and parenchyma with a band of distinct fibers marking its boundary and are macroscopically difficult to detect. In order to produce a reliable marker of the rings for Manilkara huberi, the technique of high-frequency densitometry was applied, an innovative method of measuring density variations in relation to the wood surface, in high resolution, using the dielectric properties of the wood. The indexed chronology showed a significant correlation with precipitation data from the study region, as well as with sea surface temperature anomalies from the Tropical North Atlantic and traditional El Niño regions. Close congruence was also found with Berlage's (1931) chronology in Java, Indonesia, for the period between 1725 and 1929, despite a distance of more than 18,000 km between the two study regions. This can be explained by teleconnections between the two precipitation regimes, regional and ENOS, and also indicates the potential of dendrochronology, specifically high-frequency densitometry, as a powerful tool for obtaining information about past climatic conditions in the tropics using the annual growth rings of tree species.