Undergraduate Honors Theses

Thesis Defended

Spring 2019

Document Type

Thesis

Type of Thesis

Departmental Honors

Department

Environmental Studies

First Advisor

Dale Miller

Second Advisor

Katharine Suding

Third Advisor

Eve Hinckley

Abstract

Increased severity and duration of drought events in Colorado pose a threat to grassland systems. Utilizing plant traits to analyze community responses to environmental disturbance serves as an accurate mechanism in addressing climate change influences on grassland ecosystems. In this project, I aim to quantify the relationship between five plant traits and drought intensity over time, in order to see if plant traits can capture changes in community structure in response to drought. I calculated the mean value of traits at the community level as well as the amount of variation observed in those values, in order to analyze community trends and detect instances of environmental filtering. The effects of current annual drought and lagged annual drought showed significant relationships with certain traits. Current annual drought had a positive influence on final plant height (P=0.037) and lagged annual drought (t-1) had an adverse effect on root mass ratio (P=0.004) and a positive effect on root dry matter content (P=0.04). Current year drought also had a significant influence on the amount of variation in final plant height (P=0.002), and lagged annual drought had a significant influence on the amount of variation in root mass ratio values (P=0.02), suggesting a filtering effect of decreased investment in root traits after a non-drought year and the favoring of shorter plants during current drought years. The results of this experiment show that traits can be used to indicate changes in community composition. Root traits demonstrated to be the most sensitive to changes in drought. Future studies should continue to utilize traits to analyze interspecific variation in response to climate change, though my results imply the need for caution when using individual traits to quantify change at the community level. Trait values of dominant species have the potential to influence the mean value observed across the community, which highlights the need for attention to detail when utilizing traits to make inferences about the community.

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