Graduation Year

2024

Graduation Month

December

Document Type

Thesis

Degree Name

Bachelor of Science

School or Department

Forestry and Conservation

Major

Environmental Science and Sustainability

Faculty Mentor Department

Forestry and Conservation, College of

Faculty Mentor

Akasha Faist

Keywords

secondary succession, timber harvest, vegetation, understory, functional groups

Subject Categories

Environmental Sciences | Forest Sciences | Plant Sciences

Abstract

Timber harvest, as a necessary and common global practice, can significantly affect the ecosystems being harvested through opening the canopy, disturbing the understory, and resetting successional trajectories. This study examined how timber harvest influenced understory plant functional group dominance, understory species richness, and understory species dominance along a 40-year, or older, harvest timeline across two forest types (mesic and xeric) in Northwestern Montana, U.S.A. In our two forest types, vegetation sampling was completed at 208 sites with 1,040 quadrats across six timber-harvest timelines. Harvest timelines varied from the most recent at 1-5 years post-harvest to over 40 years as the oldest, in addition to unharvested forests being sampled as well to serve as reference sites. Forest types consisted of two systems, mesic (wet systems) and xeric (dry systems). For all variables tested, forest type had no significant effect on our understory metrics. Timber harvest timelines had no significant effect on plant functional group dominance, however, some functional group cover was found to be significantly different from other groups. In our system, shrubs were the dominant functional group in the early time-since-harvest, 1-10 years post-harvest, then in 11-20 years were second to perennial grasses, and returned as the dominant group 21-over 40 years post-harvest. Species richness was significantly affected by timber harvest timelines with a steady increase 1-10 years post-harvest, a peak at 11-20 years, and a decline 21-over 40 years. While the specific dominant species differed across forest types, species present in corresponding harvest timelines had highly similar successional preferences. These findings can provide important, system-specific information for restoration managers seeking to target specific successional stages or recreate specific successional trajectories in our study area.

Honors College Research Project

1

GLI Capstone Project

no

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© Copyright 2024 Reese A. Poindexter, Trevor Weeks, Chad Bishop, and Akasha Faist