Degree Name

Master of Science (MS)

Semester of Degree Completion

2015

Thesis Director

Scott J. Meiners

Abstract

In functional ecology, traits that capture aspects of plant performance are used to understand how organisms interact with their environment. Leaf nutrients are an example of a functional trait that directly links to plant metabolic processes and therefore may describe plant assemblage dynamics. Multivariate leaf nutrient analyses may be used with other functional traits to understand ecological strategies because they are a direct measure of leaf metabolic processes and can describe nuances in plant allocation patterns. In this thesis, I explored (1) whether a suite of leaf nutrients (carbon, nitrogen, phosphorus, potassium, calcium, and magnesium) was related to plant growth form (forb, graminoid, or woody plant), species origin (native or exotic), or invasiveness (invasive or non-invasive), (2) how these nutrients were associated across species and whether these relationships were different among species' groups, and (3) how leaf nutrients related to Westoby's leaf-height-seed (LHS) scheme and to a successional gradient.

Healthy, mature leaves were taken from 122 species across a wide range of growth forms in a mesic continental community of successional fields and young and old-growth oak-hickory forests in New Jersey, USA. Multivariate analyses of leaf nutrients by growth form, origin, and invasiveness were conducted, as well as correlations of leaf nutrients by growth form and with specific leaf area (SLA), maximum height, seed mass, and peak successional year. The primary factor in variation of leaf nutrient patterns was growth form. Forbs had the strongest nutrient associations and had greater levels of leaf macronutrients compared with woody and graminoid species, which had higher amounts of foliar carbon. After distinguishing leaf nutrient allocation strategy by growth form, there were minimal relationships between leaf nutrients and plant origin and invasiveness. SLA and seed mass, but not height or peak successional year, were correlated with leaf nutrients of some growth forms.

In community level studies, comparisons should be made by plant growth form or analyses will yield spurious results. While the focus of the literature thus far has been on carbon and nitrogen, understanding the relationships with other leaf nutrients will help describe the nuances of tradeoffs in plant growth strategies. This understanding will inform restoration ecology of successional communities.

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