Litter decomposition : experimental tests of concepts for predicting interactions between climate and letter quality /
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| Other Authors: | , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1988.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy |
| Abstract: | A mechanistically based decomposition model is developed by integrated rate methodology (IRM) to test concepts for predicting interactions between climate and litterfall quality in control of decomposition processes. The model is divided into four subsystems, one each for sugars, holocellulose, lignin, and recalcitrant substances. These four chemical groups decay by different processes. Climatic factors include temperature and precipitation, and litterfall quality factors include lignin, nitrogen and phosphorus. These factors determine six functional indices which control the transition rates of the model. The functional relationships for these indices are established from published experimental results. The model has been evaluated using a one-year study of needle decomposition by the litterbag method in five 17-23 year-old Pinus taeda plantations. The data from two sites with extreme characteristic in litterfall quality and precipitation have been used to estimate weighting parameters in the model. The results of the simulations have been compared with the data from the remaining sites. After one year of decay, the mass loss of needle litterfall showed wide variation among study sites, ranging from 24 to 44%. During this period, 60 to 87% of sugar mass and 19 to 41% of holocellulose mass were lost, but lignin varied from a slight increase to a decline of 22 to 32% from its original mass. For N and P, the amounts remained relatively constant. The predictions of the model compare favorably to actual data on total litterfall mass, holocellulose, and lignin decomposition but not on sugar decomposition. By generalizing the interactions among control factors, the model can achieve reasonable predictions of litterfall mass loss over a broad area with various climates and litter qualities, as well as identify the critical factors for controlling the decomposition rate at any one site. The model identified the lack of concepts and understanding of the processes controlling the synthesis and degradation of recalcitrant substances. More detailed basic research on this important component of the decomposition process is needed. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Forestry." |
| Physical Description: | xiv, 150 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references (leaves 119-136). |