The Decomposition of Nothofagus fusca Floral and Bark Litter
Degree GrantorUniversity of Canterbury
Degree NameMaster of Science
Nutrient cycles and budgets have been calculated for various ecosystems, but the impact of floral and bark litter decomposition on nutrient cycling has been little investigated. In this study, the characteristics and decomposition of floral and bark litter produced by Nothofagus fusca in the Lewis Pass Reserve, New Zealand, was investigated, using both field and laboratory studies. Nothofagus fusca floral litter production in 1999 was 734 ± 76 kg ha⁻¹. Floral production in 2000 was estimated to be approximately 1% of this mass, the considerable difference being due to mast flowering in 1999. The decay rate constant, k, for floral litter in the field was 0.94 ± 0.01, and mass loss after one year was estimated to be 61%. The input of nitrogen to the litter layer in Nothofagus fusca floral litter was 12 ± 1 kg ha⁻¹, and it was estimated that 65% of this nitrogen was released from the floral litter in the one year. Phosphorous input to the litter layer through Nothofagus fusca floral litter in 1999 was 0.8 ± 0.1 kg ha⁻¹, of which 69% was released in one year. It was estimated that in 1999 nitrogen and phosphorous inputs to the litter layer through Nothofagus fusca floral litter were 117% and 73% respectively of that through foliar litter. Four types of Nothofagus fusca bark were identified and further differences between bark types were confirmed by chemical analysis. Inner bark contained less nitrogen than outer bark, and was slower to decompose in microcosms, contradicting the findings of other research. Annual nitrogen and phosphorous inputs through the production of all types of Nothofagus fusca bark litter was estimated to be 1.0 kg ha⁻¹ and 0.2 kg ha⁻¹ respectively, although confidence in these values was low. Significant proportions of the nitrogen and phosphorous content in bark were water soluble. Field and laboratory experiments indicated net nitrogen immobilisation occurred in all bark litter types after one year in the field, while net release of phosphorous occurred after one year.