Wet season precipitation during the past century reconstructed from tree-rings of a tropical dry forest in Southern Ecuador

- The first dendroclimatic study in a dry forest of southern Ecuador was conducted.
- 103 years of precipitation were reconstructed on the basis of tree-ring width analysis.
- B. graveolens and M. tinctoria were identified as potential species for climate reconstruction.
- Tree growth was highly linked to the central Pacific precipitation and SST patterns.
- Strong El-Niño and droughts were clearly registered in the reconstructed precipitation.

This study investigates the dendroclimatic potential of tree species in a tropical dry forest in southern Ecuador. From 10 selected tree species, Bursera graveolens and Maclura tinctoria exhibited distinct annual and cross-datable tree-rings. It was possible to synchronize individual tree-ring series and to establish two tree-ring chronologies of 203 and 87 years length, respectively. The characteristic ENSO frequency band is reflected in wavelet power spectra of both chronologies. Both species show a strong correlation between ring width and precipitation of the wet season (January-May). Strong El Niño events (1972, 1983 and 1998) lead to strong growth responses in the tree-ring chronologies, whereas 'normal' ENSO events do not trigger long-lasting growth responses. The first ring-width based wet-season precipitation reconstruction for the past 103 years was developed. Statistical and spatial correlation analysis verified the skills of the reconstructed precipitation which captures a great part of the Rainfall Index over the land area of Ecuador and the equatorial Pacific. Furthermore, teleconnections with central Pacific precipitation and SST patterns were found.

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