Distinguishing the Forest Floors of Three Ecosystems

Forest floor classifications have been based on morphological properties which were perceived to reflect genesis. These classification systems have not been compatible with soil or ecological classifications, which may have limited their application to forest management. Three biogeocoenoses or ecosystem types near Port Hardy, British Columbia were selected for studying forest floor properties. The sites chosen represent xeric, mesic, and hygric positions along a hygrotopic gradient. The forest floor of each site was stratified into LF(01) and H(02) horizons. A stratified random sampling procedure was used to collect 15 samples within the horizon units of each site. Forty variables were measured or calculated for each sample. A two-way analysis of variance in conjunction with the Student-Newman-Keuls Range Test was used to determine which variables, on an individual basis, would distinguish the forest floors of each site, the LF and H horizons overall, and the individual forest floor horizons of each site. The forest floors of the three sites could be differentiated on the basis of total K, exchangeable Na displaced by 1N NH₄OAc, and the ratio of loss on ignition to total C (LOI/C). The LF and H horizons overall could be separated by total K, total Zn, exchangeable Ca and K displaced by 1N NH₄OAc, exchangeable K displaced by 1N NaCl, base saturation at pH 7.0, pH measured in water and 0.01M CaCl₂, LOI, the ratio of total Ca to total Mg, and the ratio of total Ca to total K. The forest floor horizons of all three sites could not be distinguished by use of single variables. Three stepwise discriminant analyses using nine, five, and two variables yielded classification accuracies of 94.4, 81.1, and 71.1%, respectively, for differentiating the forest floor horizons of all three sites. The multivariate analysis showed that the best combination of measurements for distinguishing the forest floor horizons of the individual sites are total N, total K, total P, LOI/C, and cation exchange capacity (CEC) estimated with 1N NaCl.