Publication Date

8-2024

Date of Final Oral Examination (Defense)

6-7-2024

Type of Culminating Activity

Thesis

Degree Title

Master of Science in Biology

Department

Biological Sciences

Supervisory Committee Chair

Marie-Anne de Graaff, Ph.D.

Supervisory Committee Member

Marcelo Serpe, Ph.D.

Supervisory Committee Member

Leonora Bittleston, Ph.D.

Supervisory Committee Member

Deborah Page-Dumroese, Ph.D.

Abstract

Large areas of the sagebrush steppe are destroyed by wildfire, which catalyzes invasive species growth, increases soil nitrogen availability, reduces soil water retention, and disrupts soil symbiont-plant interactions. These changes in biogeochemical properties may explain why restoration success remains limited. Biochar is a soil amendment created from pyrolyzed plant biomass that may reduce soil N availability and increase water retention. Our study aims to evaluate whether changing soil properties using biochar may enhance the survival of sagebrush seedlings. We installed an experiment south of Boise, Idaho at a site that burned in 1983. Nursery-grown sagebrush seedlings were hand-planted in November 2021 and were amended with three biochar types that vary in particle size and chemical composition and a no biochar control. Biochar treatments were applied in two areas, one with partial recruitment of sagebrush near the boundary of the wildfire (hereafter: “recovering”) and one with no sagebrush recruitment further into the burned area (hereafter: “not recovered”). We analyzed planted seedling survival, biomass, and fitness as well as soil biogeochemical properties for two and a half years, to include three winters post-planting. The recovering zone exhibited greater seedling survival compared to the not recovered zone and was characterized by higher soil organic matter (SOM) and pH, and lower N. In general, biochar applications reduced plant growth as measured by the change in height and shoot volume over the duration of the experiment but increased the root-to-shoot ratio. Biochar only impacted survival after the third winter. Different biochar types did not consistently impact soil properties, and many of the biochar impacts were zone dependent. This highlights the differences in soil properties between the two zones that mediate the influence of biochar on plant-soil feedbacks. Overall, the recovering sagebrush zone aided in planted sagebrush survival. Biochar additions may have long-term impacts that contribute to sagebrush survival, but further research is needed to elucidate the specific mechanisms.

DOI

https://doi.org/10.18122/td.2312.boisestate

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