Degree Type

Dissertation

Date of Award

2020

Degree Name

Master of Science

Department

Natural Resource Ecology and Management

Major

Forestry

First Advisor

Miranda T Curzon

Abstract

As climate changes around the globe, forest ecosystem management must change as well. Future climate in north central Minnesota is expected to include higher seasonal temperatures, longer growing seasons, decreases in growing season precipitation and increases in frequency and severity of drought. Additionally, altered disturbance regimes, the introduction of exotic pests and pathogens, habitat fragmentation, and landscape homogenization have left forest stands vulnerable to undesirable state shifts in which an ecosystem transitions from a desirable state with high ecosystem productivity and service provision to a less desirable and less productive condition. The Adaptive Silviculture for Climate Change (ASCC) project was first established in a Pinus resinosa Ait. (red pine)-dominated forest, which is an economically and ecologically important forest type in the region in order to examine the impacts and effectiveness of three climate adaptation strategies (resistance, resilience, and transition) in an experimental, operational-scale setting. Designed around resisting the effects of climate change, resistance treatments aim to improve the health and defenses of forest stands, while resilience treatments were intended to create conditions that allow for change to occur but ensure an eventual return to a desired reference state. Transition treatments were designed to actively assist stands in transitioning to future climate and encouraging greater adaptive capacity within them. Using data collected during the fifth growing season since the site was treated, this study explores the short-term effects of adaptation strategies on biodiversity in the understory woody community as well as predicted future adaptability of historically P. resinosa-dominated forests based on the natural regeneration that has established up to five years post-treatment.

Field data, consisting largely of shrub and tree identification, density, and diameter measurements, were collected between May and August of 2019. Following field sampling, aboveground woody stem biomass estimates were calculated using species-specific allometric equations. The relative importance of each species was then calculated based on biomass estimates, stem densities, and frequency of observation across each stand, providing a measure of abundance which then enabled calculation of species biodiversity and future relative adaptability. Species diversity and richness of woody stems was highest within the resilience treatments and lowest within unharvested control treatments. Species richness of natural tree regeneration was also highest within the resilience treatments. Importance of Prunus serotina Ehrh (black cherry), a species considered better suited to anticipated future climate, was highest within transition treatments. An analysis of the community-weighted mean for future adaptability (based on published species adaptability scores) indicates that the change in adaptability of natural regeneration relative to untreated controls is greater within transition treatments than within resistance and resilience treatments. These results demonstrate early success in improving and increasing stand-scale species biodiversity and, potentially, future adaptability through silvicultural treatments. Silvicultural manipulation also shows promise for increasing the density and relative importance of individual species considered better suited for future climate. While these are only short-term results, they demonstrate the ability to influence ecosystem diversity and adaptability through harvest and provide insight to managing forests in a time of changing climatic conditions and uncertainty.

DOI

https://doi.org/10.31274/etd-20210114-161

Copyright Owner

Lewis Wiechmann

Language

en

File Format

application/pdf

File Size

68 pages

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