Graduation Date

Fall 2016

Document Type

Dissertation/Thesis

Program

Master of Science degree with a major in Natural Resources, option Forestry, Watershed, & Wildland Sciences

First Committee Member Name

LUCY KERHOULAS

First Committee Member Email

LUCY.KERHOULAS@HUMBOLDT.EDU

First Committee Member Affililation

HSU Faculty or Staff

Second Committee Member Name

DEBORAH PAGE-DUMROESE

Second Committee Member Email

ddumroese@fs.fed.us

Second Committee Member Affililation

Community Member or Outside Professional

Third Committee Member Name

ROSEMARY SHERRIFF

Third Committee Member Email

ROSEMARY.SHERRIFF@HUMBOLDT.EDU

Third Committee Member Affililation

HSU Faculty or Staff

Abstract

Soil carbon (C) affects the active gases in the atmosphere, nutrient cycling, and diversity of flora and fauna. Soil organic matter (SOM) is partially comprised of C, and a widely-accepted ratio of 0.58 organic carbon (OC) to organic matter (OM) is used to measure soil C on a landscape scale. However, this ratio varies according to vegetation, depth, hydrology, and may lead to miscalculations of soil C and SOM estimates. Soil C and SOM are inherently complex and it is not completely understood which environmental factors have the most influence in their formation, which occurs on a time scale of decades to thousands of years. In order to accurately assess soil C and SOM on an appropriate time scale, baseline studies of inventory and investigations of relationships with environmental factors are needed.

Soils from two trenches at the L.W. Schatz Demonstration Tree Farm (LWSDTF) were sampled for SOM and SOC. The east trench was trench located at the toe slope in a position of accumulation and the west trench was located at the edge of a convex shoulder. This study investigated the amount of SOM and SOC currently present at LWSDTF using site specific OC:OM ratios, and analyzed the relationships between SOM and depth, bulk density, roots, and distance from tree bole.

I found a negative correlation of SOM with depth and bulk density, and a positive correlation between SOM and root abundance. I found large variability with SOC and SOM estimates with different sampling methods, and it is possible that the variability in SOM attributed to land use is smaller than the variability in SOM attributable to bulk density measurements. Soil organic matter increased with distance from tree bole, but this relationship is confounded by a forested setting and is not thought to accurately reflect ecological processes. The baseline inventory of SOM was 670 Mg OM ha-1 from east trench data and 490 Mg OM ha-1 from west trench data. The baseline inventory of SOC was 322 Mg C ha-1 from east trench data, and 200 Mg C ha-1 from west trench data using site specific ratios. These numbers represent a large potential C storage at the LWSDTF, and these findings may be used in future studies to inform future land management decisions.

Citation Style

APA

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