Estimating soil organic carbon stocks in Mount Rainier National Park

Michelle Elizabeth Totman

The complex terrain and diverse climate of Mount Rainier National Park (MORA) make it a uniquely challenging location for conducting a park-wide soil organic carbon (SOC) survey. Remotely sensed climatic and topographic data were inputs for a landscape-wide statistical stratification technique employing principal components analysis and iso-cluster unsupervised classification methods. These techniques were combined with expert knowledge to divide the 957 km2 area of MORA into eight distinct classes. Soil pits and corresponding vegetative surveys were completed at a total of 33 sampling sites divided among these classes. Field and laboratory data were used in combination to distinguish taxonomic characteristics of the soils and their relationship with environmental variables and carbon storage. For the combination of Spodosols, Inceptisols, and Entisols sampled across the forested component of MORA, the average carbon concentration was 163 Mg C ha-1 in the mineral soil and 205 Mg C ha-1 for the total (organic and mineral) soil. Total ecosystem carbon (TEC) by class ranged from 168 to 1583 Mg C ha-1 . Class membership accounted for a significant proportion of SOC variance, as indicated by a gamma generalized linear model. The proportion of TEC represented by SOC vi also differed by class membership according to a beta regression model. The correlated variables of elevation and surface temperature were found to be the primary ecological factors influencing the spatial distribution of SOC, with soil mineralogy appearing to play an important role in its vertical distribution. Data from 99 micro-pits provided additional SOC data for the top 35 cm, improving precision and accuracy of estimates for the highly variable upper soil horizons. The establishment of benchmark sites, proximity to harvested National Forest land, and baseline data provided by this study all contribute to promoting future research related to carbon flux and the impact of forest management decisions on SOC. The results presented in this thesis expand current knowledge by providing unique insight into above- and below-ground carbon stores for a largely late-seral forest landscape in the Pacific Northwest, a standard to which the results of future studies can be compared.

Estimating soil organic carbon stocks in Mount Rainier National Park

Files and links (1)

Abstract

Metrics

Details