Department or Program

Geology

Abstract

Accelerated soil erosion is one of the greatest threats to soil health and function, making it imperative to understand the impact of deforestation on erosional processes for sustainable soil management. This research occurred in the Hubbard Brook Experimental Forest (HBEF), to evaluate soil erosion in the whole-tree harvested watershed (W5) through the application of 239+240Pu as soil erosion tracers. Additionally, this study investigates the suitability of 239+240Pu isotopes as soil erosion tracers in a Northern Hardwood Forest under the influence of lateral podzolization, a sub-surficial process characterized by the lateral downslope movement of water, Fe, Al, and organic matter. Samples were collected from four hillslope positions throughout the watershed: the E, Bhs, Typical, and Bh Podzols moving downslope from the summit to the toeslope. Based on a comparison of plutonium inventory between watersheds 3 (reference) and 5 (study) we calculate average soil redistribution rates of -6.80 t/ha/yr in the Typical Podzol (erosion) and 2.06 t/ha/yr in the Bh Podzol (deposition). Qualitative soil disturbance data reflected in the correlation of δ13C and total organic carbon (TOC) confirms these results with relatively low R2 values displayed in the Typical (R2=0.40) and Bh (R2=0.50) Podzols compared to values displayed in the E (R2=0.75) and Bhs (R2=0.68) Podzols. Plutonium data throughout both watersheds generally indicates a typical exponential decrease with depth, though the Typical Podzol is not influenced by lateral podzolization and displays reduced inventory at depth. Due to this difference in plutonium depth profile between soils formed by lateral podzolization and those not, we find that plutonium is slightly mobilized through the subsurface. The mobilization of 239+240Pu is not significant enough to undermine the application of these soil erosion tracers in environments influenced by lateral podzolization. The significance of this study lies in its contribution to (1) understanding soil redistribution processes in relation to deforestation, and (2) the suitability of 239+240Pu isotopes as effective erosion tracers in environments influenced by lateral podzolization. By demonstrating that the mobilization of these isotopes is not significant enough to compromise their application, this study offers a reliable method for assessing soil erosion in similar environments. This knowledge is crucial for the development of sustainable soil management practices aimed at mitigating the negative effects of deforestation and soil degradation.

Level of Access

Restricted: Embargoed [Open Access After Expiration]

First Advisor

Raquel Castro

Date of Graduation

5-2023

Degree Name

Bachelor of Arts

Number of Pages

53

Components of Thesis

1 Pdf file

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Embargoed

Available to all on Tuesday, April 18, 2028

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