Date of Award

Spring 1996

Project Type

Dissertation

Program or Major

Natural Resources

Degree Name

Doctor of Philosophy

First Advisor

James Hornbeck

Abstract

Red oak (Quercus rubra L.) and white pine (Pinus strobus L.) forests on sandy soils of the northeastern U.S. may have been depleted of nutrient cations by acid precipitation and intensive land use. Foliar Ca in oak was 5257 mg Ca kg$\sp{-1}$ matter, or over 3 times the amount of Ca in white pine foliage. Red oak also has more Mg, K, and N than white pine. Foliar Al concentration for white pine, 132 mg Al kg$\sp{-1}$ dry matter, is twice that of red oak foliage. Foliar Ca and N are correlated with basal area increment. Foliar Ca:Al ratios and Mg levels in pine foliage suggest a risk to tree health. In the organic horizons of both oak and pine forests, bases occupied 80% of the exchange sites. However, in the mineral horizons, Al occupied 96% of the exchange sites. These data indicate that both forest types are susceptible to nutrient imbalances and deficiencies that result from atmospheric deposition and harvest.

A microwave oven was used to digest standard reference materials for foliage and organic and mineral soils. We achieved recovery rates for total Al, Ca, Fe, K, Mg, Mn, and P from mineral soils of 87% to 114% with CV's of less than 10%. Recovery rates greater than 90% were achieved for Ca, K, Mg, Mn, and P for Pine foliage. Total nitrogen recovery was 99.3% (CV 9.2%) for B horizon soils. Hyperspectral analysis techniques have proven useful for determining cellulose, lignin, and nitrogen in foliar material. These same techniques may be able to predict other foliar element concentrations thereby reducing the need for acid digestion of foliar material. Near infrared reflectance spectroscopy (NIRS) was evaluated for its effectiveness at predicting Al, Ca, Fe, K, Mg, Mn and P concentrations in white pine (Pinus strobus L.) and red oak (Quercus rubra L.) foliage. A near infrared spectrophotometer was used to scan dried, ground foliage samples. Predictions were satisfactory for Al, Ca, K, and Mg, producing CVs ranging from 14 (Mg) to 28% (Al) and explained variance ranging from 78% for Mg to 97% for Ca.

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