ISHS Acta Horticulturae 494: II International Symposium on Chestnut
DYNAMICS OF LEAF LITTER STRUCTURAL COMPOUNDS IN C. SATIVA AND P. PINASTER FOREST ECOSYSTEMS DURING THE DECOMPOSITION PROCESS: INTERACTIONS WITH SOIL ORGANIC MATTER AND NUTRIENT RELEASE |
| Authors: | A. Martins, S. Azevedo, L. Carvalho |
| Keywords: | Organic matter, forest ecosystems, litterfall, decay rate, nutrient cycling |
| Abstract:
The quality of organic matter in forest ecosystems plays a very important role in nutrient cycling and availability, soil properties and pedogenesis. The quality of organic matter is highly dependent on the nature of leaf litter, as expressed by the relative amounts of the constituent chemical structural compounds, on which the leaf litter decomposition process to a large extent depends. Therefore, the decay rate and the relative amounts of non polar extractable compounds (fats and waxes), alcohol and water soluble compounds (resins, tannins and simple sugars), acid soluble compounds (cellulose and hemicellulose) and Klason lignin, in leaf litter in stands of Pinus pinaster (Ayton) and Castanea sativa (Miller), were studied. The results indicate a clear difference between the two species in the composition of leaf litter and in the decay rate. C. sativa leaves have larger amounts of relatively easily decomposed compounds (alcohol/water soluble compounds and hemicellulose); P. pinaster needles have higher proportions of difficult-to-decompose compounds (fats & waxes, Klason lignin and cellulose). The higher amounts of the first group of compounds, seem to stimulate the litterfall decomposition process, which is shown by a higher decrease of lignin in C. sativa after 200 days of the onset of decomposition. Thus, the annual decay rate (k) is much higher in C. sativa leaves, negatively related to C/N and lignin/N ratios and positively related to the EC/lignin ratio. The P. pinaster species produced low quality litterfall leading to low organic matter and nutrient rates in the forest floor, when compared to C. sativa. | |
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