Semester

Summer

Date of Graduation

2019

Document Type

Thesis

Degree Type

MS

College

Davis College of Agriculture, Natural Resources and Design

Department

Division of Forestry and Natural Resources

Committee Chair

Kirsten Stephan

Committee Co-Chair

William Peterjohn

Committee Member

William Peterjohn

Committee Member

Mary Beth Adams

Abstract

Although the herb layer represents less than 1% of the biomass of temperate forests, this layer may contain up to 90% of the plant species in the forest and can contribute up to 20% of the foliar litter, thus playing an essential role in forest biodiversity and nutrient cycling. The objectives of this study were to investigate the differences in cover, species richness, Shannon-Wiener diversity, and evenness of herb layer plants a) under tree species associated with contrasting soil nitrogen levels and b) in watersheds that vary in nitrogen deposition, stand age, and watershed aspect at the Fernow Experimental Forest in West Virginia. In the watersheds evaluated, overstory tree species, N deposition level, stand age, and other environmental factors influenced herb layer characteristics. This study demonstrated 1) a sugar maple effect, i.e. sugar maple having a positive effect on understory cover, at intermediate levels of soil fertility in reference watersheds and in an N-fertilized watershed by improving the nutrient microenvironment for herb layer plants, 2) that long-term N enrichment can reduce ecosystem biodiversity by favoring nitrophilic species, and 3) that herb layer characteristics can be influenced by stand age, with more recent disturbance being reflected in higher herb layer abundance and diversity. This study justifies further examination of tree-herb layer interactions for a wider range of tree species, N-deposition levels, and stand ages in future studies in order to inform adaptive forest management in the light of climate change and other continuing anthropogenic influences.

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