Precipitation as the main driver of the radial growth of Cupressus lusitanica (Mill.) at Wondo Genet, Ethiopia.
There is a wide range of literature on the failure of tropical trees to form clearly visible annual growth rings, especially where there is an extended rainy season. Most southern parts of Ethiopia have a bimodal rainfall distribution with varying degrees of distinction between rainy seasons. We measured the ring-widths of Cupressus lusitanica which is the second most important plantation species in Ethiopia and has not been utilised in many other dendrochronological studies. Cross-dating of 30 radii ensured that the trees were absolutely-dated and that its growth rings were annual. The association with climate was investigated over the 30 years meteorological records from Wondo Genet in Ethiopia. The standardized ring-width index was significantly correlated (r=0.59; p<0.05) with the amount of precipitation. Even though the distribution of precipitation was not clearly unimodal, this study demonstrates that exotic species growing in far from optimal dendrochronological conditions still have the potential for dendrochronological studies by forming clearly visible annual growth rings.