Decomposition and nutrient dynamics of green and freshly fallen radiata pine ( Pinus radiata) needles

• Published in: Forest ecology and management 2003-07, Vol.179 (1), p.169-181
• Main Authors: Girisha, G.K., Condron, L.M., Clinton, P.W., Davis, M.R.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Chemical, physicochemical, biochemical and biological properties; conifer needles; Decomposition; forest litter; forest management; forest plantations; Freshly fallen needles; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Green needles; harvesting; lignin; lignocellulose; microorganisms; nitrogen content; nutrient content; Nutrient release; nutrients; Organic matter; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Pinus radiata; pruning; Soil science; Soil-plant relationships. Soil fertility; Soil-plant relationships. Soil fertility. Fertilization. Amendments
• ISSN: 0378-1127; 1872-7042
• DOI: 10.1016/S0378-1127(02)00518-2

Thinning and pruning operations in radiata pine ( Pinus radiata) plantation forests result in the addition of large amounts of green needles to the forest floor. The decomposition of green and freshly fallen radiata pine needles and the effects of adding green needles to freshly fallen needles were examined in a microcosm experiment. Green needles lost 72% of the original mass after 10 months, compared with 27% for freshly fallen needles. The corresponding mass losses for 1:1 ratios of green and freshly fallen needles were 55% when mixed and 53% when layered. Nutrient concentrations generally increased during decomposition while total amounts of nutrients decreased with time. Decomposition was primarily influenced by needle lignin and N content, and by the holocellulose to lignocellulose quotient (HLQ). The results of this study indicate that addition of green needles does not significantly affect the decomposition of freshly fallen needles. This outcome was attributed to substrate preference by decomposer microorganisms. It is, therefore, concluded that forest management practices (thinning, pruning and harvesting) which result in significant inputs of carbohydrates and nutrients in the form of green needles will have little impact on decomposition of existing forest floor materials.