Methods: C and N Addition Treatments

Three nutrient-amendment treatments were applied to all sites: addition of sugar (sucrose), sawdust, and nitrogen fertilizer (NH₄NO₃). The sugar and sawdust treatments were designed to increase the carbon:nitrogen ratio (C/N) of the forest floor to values typical of late successional communities (C/N = 50). The nitrogen fertilizer addition was designed to equal estimated yearly N mineralization in an attempt to double plant available nitrogen. Because the treatments were designed to make a specific change in factors that should alter nutrient availability of the research sites, each site required different levels of treatment addition (see Yarie and Van Cleve 1996). The sawdust and sugar treatments were applied once. The sawdust treatment was applied by hand and mixed with the surface organic layer during July and August of 1989. The sugar treatment was applied during May of 1990, prior tree growth. The fertilizer treatments are applied on a yearly basis in May prior to tree growth. We established a nontreated control plot at each replicated site.

Yarie, J. and K. Van Cleve. 1996. Effects of carbon, fertilizer, and drought on foliar chemistry of tree species in interior Alaska. Ecol. App. 6:815-827.