Title

Spatial variability of foliar nitrogen in the Adirondack Park, New York

Date of Award

8-2006

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Geography

Advisor(s)

Jane M. Read

Keywords

Foliar nitrogen, Adirondack Park, New York, Shade tolerance

Subject Categories

Forest Biology | Physical and Environmental Geography | Terrestrial and Aquatic Ecology

Abstract

This dissertation explores the relationship between the physical environment and the spatial pattern of the concentration of nitrogen in tree leaves, or foliar N. Maps of foliar N are of great interest due to relationships among foliar N, forest production, and N cycling. I propose that the spatial variability of foliar N is the outcome of a localized process involving species functional traits, the environment experienced by the species, and human' effect on that environment.

I obtained species-level and whole-canopy foliar N data from a diverse set of seventy-five forest plots within the Adirondack Park, New York. These plots contained a wide range of variation in foliar N and six factors hypothesized to control its spatial distribution (i.e. spatial controls): species composition, atmospheric N deposition, disturbance history, temperature, moisture availability, and bedrock geology. I also used a subset of the field data and imagery from the Hyperion hyperspectral sensor to predict whole-canopy foliar N with thirty-meter spatial resolution across two 185x7.7 km satellite images.

Analysis of the field and satellite foliar N datasets against descriptions of spatial controls obtained from field surveys and a geographic information system (GIS) revealed that species composition was the primary control on the spatial pattern of whole-canopy foliar N. In fact, inter-specific variation in the functional trait of mean foliar N accounted for 93% of the variation in the field whole-canopy foliar N data. The remaining intraspecific variability was related to all six hypothesized spatial controls, and especially to the anthropogenic controls of N deposition and disturbance history. Interestingly, the marked species differences in foliar N response to a single spatial control of N deposition, or to multiple spatial controls were strongly related to species' functional traits of leaf mass per area (LMA) and shade tolerance. In sum, I found the inter- and intra-specific sources of variability to explain 97% of the spatial variability in my field whole-canopy foliar N dataset. Given this evidence, I strongly suggest that maps of foliar N can be further developed as tools to discover fundamental ecological principles and indicate ecosystem response to environmental impacts.

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