Nutrient Limitation and Metrosideros Forest Dieback in Hawaii

Large numbers of Metrosideros polymorpha trees have died in the montane rain forest on the Island of Hawai'i, but previous research has failed to identify a principal cause. This paper describes an experiment that tests the hypothesis that nutrient deficiency is the principal cause of tree death and stand—level dieback. Treatments were fertilizing, stand thinning, and a combination of the two. No significant change in the mortality rate was caused by the treatments; however, stem diameter growth of surviving trees was found to be nutrient limited at all sites. We conclude that nutrient deficiency is not the principal cause of most Metrosideros dieback, but it may be a contributing factor.