Masters Thesis

Biomass quantification of live trees in a mixed evergreen forest using diameter-based allometric equations

Biomass quantification methods have become of increased interest recently due to the threat of climate change. Organizations such as the California Climate Action Registry (CCAR) have suggested the use of generalized biomass equations to quantify forest carbon stocks. However, studies have shown that biomass equation generalization can lead to inaccurate estimates of biomass of live trees. In this study, a mixed evergreen forest type in northwestern California was inventoried and total aboveground biomass was quantified using different types of biomass equations. A new model was developed to predict biomass of bay-laurel trees, which were found to be abundant at the study site. A total of 14 trees ranging from 7.6 – 61 cm dbh were destructively sampled. Biomass and dbh were log-linearized and fitted with ordinary least squares linear regression. The bay-laurel equation was used in conjunction with other biomass equations developed in similar geographic regions to quantify stand-level biomass at the study site, which was 292.3 Mg ha-1. This estimate was then compared to the estimate using the biomass quantification methods outlined by CCAR, which was 265.9 Mg ha-1. It was assumed that site and regional biomass equations are the standard method to predict biomass. When compared with the standard method, it was found that CCAR's equations differed significantly than the standard method and therefore did not accurately predict biomass at the study site.

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