Tropical Andean forest derives calcium and magnesium from Saharan dust

We quantified base metal deposition to Amazonian montane rain forest in Ecuador between May 1998 and April 2003 and assessed the response of the base metal budget of three forested microcatchments ( 8 - 13 ha). There was a strong interannual variation in deposition of Ca [ 4.4 - 29 kg ha(-1) a(-1)], Mg [ 1.6 - 12], and K [ 9.8 - 30]). High deposition changed the Ca and Mg budgets of the catchments from loss to retention, suggesting that the additionally available Ca and Mg was used by the ecosystem. Increased base metal deposition was related to dust outbursts of the Sahara and an Amazonian precipitation pattern with trans- regional dry spells allowing for dust transport to the Andes. The increased base metal deposition coincided with a strong La Nina event in 1999/ 2000.