PARENT SESSION
Oral Session 15: Soil Ecology I: Mycorrhizal Communities.
Presiding: V Borowicz and X He
Monday, August 2, 8:00 AM to 11:30 AM, Meeting Room D 137.
Nitrogen deposition effects on ectomycorrhizal communities: A comparison between two soil types.
Huskins, Rebecca*,1, Tuininga, Amy1, Dighton, John2, Gray, Dennis2, Belton, Tom3, 1 Fordham University, Armonk, NY2 Rutgers University, New Brunswick, NJ3 NJ DEP, Trenton, NJ
ABSTRACT- An eastern to western transect through forests in northern New Jersey was identified to study N deposition effects over a five month period (May to October 2003). The effect of N deposition on soil chemistry and ectomycorrhizal community of pitch pine was studied by sampling from the field under mature pine trees at three sites in northern New Jersey (Palisades, Ringwood, High Point) and one reference site in southern New Jersey (Lebanon). The purpose of this study was to compare results from a similar study conducted the previous year on sandy soils in southern New Jersey to loamy soils in northern New Jersey. A greenhouse study was also conducted where differential rates of N applications (0, 8.75, 17.5, 35, 140 kg ha-1 equivalent) were made on intact soil cores in which pitch pine seedlings were grown in soils from these four sites. In the field there was increased extractable NH4-N in northern sites compared to the southern site in the spring, and increased NO3-N in the fall, but northern sites did not differ in soil extractable N, similar to a pattern seen among sites in southern New Jersey. Analysis of bulk precipitation showed increased NH4-N at the central site and a trend for increased NO3-N and NH4-N at the two most eastern sites closest to New York City. Ectomycorrhizal richness increased along the transect westward in northern New Jersey and was highest in the most nutrient deficient soil in the Lebanon reference site. This pattern was also reflected in the greenhouse study. Plants in Lebanon soils were smallest, yet had the highest ectomycorrhizal richness. This corresponds with the theory that increased N availability correlates to decreased mycorrhizal abundance and richness. There is less variability and means are more similar, however, across sites in northern New Jersey than those from southern New Jersey, possibly indicating increased sensitivity in oligotrophic, sandy soils of southern New Jersey.
Key words: nutrient, soil , nitrogen deposition, mycorrhiza