Graduation date: 1973Respiratory rates were measured, in situ, for the litter, the\ud soil, and the litter-soil subsystems of a Pseudotsuga menziesii forest\ud as a function of type of understory vegetation. The major objectives\ud were to demonstrate the utility of the litter layer as a distinct subsystem\ud of this forest ecosystem, to demonstrate the existence of\ud respiratory patterns in the litter subsystem related to type of understory\ud vegetation, to determine if moisture and/or temperature were\ud important factors in creating these patterns, and to generate an estimate\ud of annual rate of respiration of the litter subsystem of a\ud Pseudotsuga menziesii forest.\ud Six understory types (Holodiscus discolor, Acer circinatum,\ud Gaultheria shallon, Tsuga heterophylla, Castanopsis chrysophylla, and\ud Polystichum munitum) were sampled. All differences in annual respiratory\ud rates for all subsystems were significant at F₀[subscript .]₀₅, however the\ud range of differences between types in the respiratory rates of the litter\ud subsystems, normalized to a per gram of litter basis, were higher by\ud an average factor of six and exhibited a hierarchy of magnitudes different\ud from those of the unnormalized litter, the soil, or the litter-soil\ud subsystems. The litter subsystem was found to be a useful and meaningful\ud division of the forest ecosystem.\ud Due to suspected methodology related errors associated with\ud lateral movements of carbon dioxide into the sample areas from without,\ud the soil and the litter-soil measurements were probably in error,\ud possibly quite large. Error in absolute rate of respiration for the\ud litter subsystem is also suspected but probably to a smaller degree\ud and not affecting the hierarchy related to type.\ud The litter subsystems for two of the types were found to have\ud moisture contents different by a relatively large percentage from that\ud of the litter subsystems of the other types. It appeared, however,\ud that moisture difference was not the major cause of the hierarchy by\ud type of respiratory rates of the litter subsystem.. Temperature was\ud not a significant factor in the observed hierarchy. The annual respiration\ud yields based on the litter subsystem, as a probable result of the\ud specific methodology used, appeared to yield more reasonable estimates\ud for rates of decomposition of organic matter in a forest floor\ud than do previously published studies based on the litter-soil subsystem.\ud It appears that Pseudotsuga menziesii forests compared to other temperate\ud coniferous forests have a rapid turnover rate for organic matter\ud entering the litter subsystem
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