A Tsugaheterophylla – Piceasitchensis ecosystem of coastal Oregon: decomposition and nutrient balances of fallen logs

Abstract

Weight loss and changes in N, P, Ca, Mg, K, and Na content were determined for fallen Tsugaheterophylla (Raf.) Sarg. logs in a 121-year-old Tsugaheterophylla – Piceasitchensis (Bong) Carr. stand on the central Oregon coast. Log ages ranged from 2 to 38 years.Weights of fallen logs decreased in a roughly negative logarithmic pattern; after 38 years the average log had lost 34.5% of its original weight.Nitrogen, calcium, and magnesium contents of logs increased for about the first 20 years and declined thereafter. Phosphorus and potassium contents decreased steadily with age. Sodium content increased with age. Except for calcium, nutrient input to log surfaces by litterfall and throughfall was greater than any increases in nutrient content.