Craig R. Allen
Date of this Version
Bevans, Rebecca. 2017. Plant diversity influences the structure and function of a restored prairie and its responses to added disturbances. MS Thesis, University of Nebraska.
As global warming, human conversion of natural landscapes to agricultural uses, and widespread biodiversity losses continue to alter the ecosystems we depend on, an understanding of the relationship between ecosystem structure, composition, and function is needed to maintain valuable ecosystem states and their associated functions. Research testing the limits of an ecosystem’s ability to maintain essential structure and functioning under disturbance conditions can aid in this goal.
In this study, I measured the relationship between plant diversity, community structure and functional traits, and their responses to added disturbances. I added disturbances representing those either caused or intensified by human activity to a prairie restoration planted at multiple levels of diversity and measured subsequent variation in ecosystem traits. My research scales up traditional 1mx1m-plot studies to test whether plant diversity can produce grassland ecosystems that are resilient to disturbances, as suggested by small-plot experiments.
Variation in ecosystem functional traits (including functional composition, nutrient cycling, invasion resistance, and plant growth strategy) was calculated using ANOVA, linear-mixed-effects regression models, post-hoc tests, and two-sample comparisons. Community structural variation was calculated via Bray-Curtis dissimilarity and PERMANOVA.
Vegetation structure and composition was more diverse in high-diversity plots, and ecosystem functional traits generally less variable in response to added disturbances. Invader counts were also lower in high-diversity plots. These patterns suggest that plant diversity can maintain ecosystem structure and function through disturbance events and limit biological invasion. Uncontrolled effects including weather and soil nutrient gradients also influenced vegetation structure and function. These effects were often more significant than diversity or disturbance treatments in structuring ecosystem traits.
Investing in biodiversity at the outset may aid the establishment of desired ecosystem states that are resilient to disturbance and help avoid costly invasive species management later on. However, system responses to disturbance are influenced by existing environmental conditions which should be accounted for when attempting to plan or conserve desired ecosystem states.
Advisor: Craig R. Allen