Soil quality, function, and productivity potential are interrelated concepts that cover the range of soil properties and their associated ecological processes. Since the passage of the National Forest Management Act in 1976 (NFMA) and related legislation, management of National Forest lands must be done is such a way as to maintain their productive potential as demonstrated through implementation, effectiveness, and validation (research) monitoring. However, the concept of site productivity is not well defined, and the impacts of timber removal or fire on soil productive potential are not well understood or easily measured (Powers 2006). Two main factors make it difficult to define: (1) the variability in soil and climatic conditions across forest sites and (2) the length of time it takes for trees to reach a predictive age. If tree (or vegetative) growth is used as an indicator of productivity, it may take more than 20 years before the consequences of various management practices in many North American ecosystems can be evaluated (Morris and Miller 1994).