Post-fire Soil Health Assessment of the Grasslands and Woodlands in the Semi-arid Nebraska Sandhills

Authors

Stephanie M. Lugo, University of Nebraska-LincolnFollow

First Advisor

S. Carolina Córdova

Committee Members

Rhae Drijber, Tala Awada

Date of this Version

12-2025

Document Type

Thesis

Citation

A thesis presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the degree of Master of Science

Major: Agronomy

Under the supervision of Professor S. Carolina Córdova

Lincoln, Nebraska, December 2025

Comments

Copyright 2025, Stephanie M. Lugo. Used by permission

Abstract

Grasslands in the Nebraska Sandhills are shaped by natural wildfires, which help maintain the structure and function of native grasslands. In recent decades, afforestation with ponderosa pine and eastern redcedar has introduced new woodlands that altered the region’s fire dynamics and raised important questions about the effects of wildfire on different vegetation types. As wildfires become more frequent, understanding their impacts on soil health in grasslands and woodlands becomes increasingly important. This study examines the short-term effects of the 2022 Bovee Fire on physical, chemical, and biological soil properties in native grasslands and ponderosa pine and eastern redcedar afforested woodlands. Soil samples were collected at two depths (0–10 and 10–25 cm) across burned and unburned sites over five sampling times spanning 8 to 32 months post-fire. The objectives were to: (1) assess how vegetation type and fire affect soil physical properties, (2) evaluate changes in soil fertility and carbon fractions, (3) investigate microbial community composition and enzyme activities as indicators of soil biological function, and (4) integrate all these metrics into a comprehensive Soil Health Index (SHI). The results revealed that unburned grassland had the highest SHI scores, followed by pine, with the lowest scores in redcedar areas. Fire caused the most significant declines in soil health in grasslands and pine woodlands, while sandy soils with low organic matter were most vulnerable to post-fire impacts. These findings demonstrate that vegetation type, whether natural or hand-planted, plays a critical role in soil response to fire, underscoring the value of a soil health index for tracking ecosystem resilience and informing management in the Nebraska Sandhills.

Advisor: S. Carolina Córdova