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Decomposition and nutrient release from four epiphytic lichen litters in sub-boreal spruce forests

Campbell, J., A.L. Fredeen and C.E. Prescott. 2010. Canadian Journal of Forest Research 40:1473-1484


Epiphytic lichens are highly abundant in many sub-boreal forests and may be important components of nutrient cycling. Decomposition of, and nutrient release from, two cyanolichens (with N2-fixing cyanobacterial partners) and two chlorolichens (with green-algal partners) were quantified to estimate N inputs from epiphytic lichen litter in late-seral forests. Initial decay rates were strongly correlated with initial %N; the high-N cyanolichen litters (Nephroma helveticum Ach. and Lobaria pulmonaria (L.) Hoffm.) lost 26% more mass than the lower-N chlorolichen litters (Alectoria sarmentosa (Ach.) Ach. and Platismatia glauca (L.) W.L.Culb. & C.F.Culb.) over the first 4 months. Morphological characteristics also influenced decay, as decomposition of the hair chlorolichen (A.sarmentosa) was similar to that of the foliose cyanolichens, despite an N concentration that was 87% lower. N was immediately released from cyanolichen litters and retained in chlorolichen litters. After 24months of decay, N concentrations remained highly divergent with 22-27 and 7-8mg N g-1 in cyanolichen and chlorolichen litter, respectively. Cyanolichen litter represents 0.1%-2.3% of the total aboveground litter biomass and 0.5%-11.5% of the total N input from aboveground litterfall. Decomposition of cyanolichen litter is estimated to release up to 2.1kg N ha-1 year-1 of newly fixed N that would otherwise be unavailable in mature sub-boreal forests.