Influence of initial chemistry on decomposition of foliar litter in contrasting forest types in British Columbia

Abstract

We compare rates of decay of foliar litters of British Columbia tree species in two field studies, and assess which initial litter chemistry parameters best predict the decay rates. Nutrient concentrations, tannins, and carbon fractions (based on proximate analysis and nuclear magnetic resonance spectroscopy) were measured in fresh litter of 14 tree species in one experiment and seven species in a second experiment. Each study was replicated in a different site in order to assess the transferability of results. Broadleaf litters decayed faster than needle litters only during the first year; thereafter, they decayed slower. Lignin concentration was a good predictor of mass loss only during the first year and only in one of the two experiments, which may have resulted from all foliar litters having high lignin concentrations (>170 mg·kg–1). Litter chemistry effects on first-year decay were consistent and transferable among sites. None of the initial litter chemistry parameters were good predictors of mass remaining after 4 or 5 years, because mass loss of most litters was similar by this time. The convergence in mass losses of litters after 4–5 years despite initial differences indicates that decomposition estimates extrapolated from early rates or initial chemistry may not accurately predict long-term decay.