You are here:
THE EFFECT OF NITROGEN OVER-ENRICHMENT ON SOME PLANT-SOIL RELATIONSHIPS AND MICROBIAL PROCESSES
Citation:
Wigand, C, R A. McKinney, J. Davis, B. Norwicki, AND P. M. Groffman. THE EFFECT OF NITROGEN OVER-ENRICHMENT ON SOME PLANT-SOIL RELATIONSHIPS AND MICROBIAL PROCESSES. Presented at 2002 ASA-CSSA-SSSA Annual Meetings, Uniting Sciences: Solutions for the Global Community, Indianapolis, IN, November 10-14, 2002.
Description:
Salt marshes of similar geomorphology and hydrology with varying watershed nitrogen loads were examined for differences in plant structure, soil characteristics, and
denitrification. We observed landward encroachment of the low marsh Spartina alterniflora, and the displacement of the high marsh dominant S. patens in the
marshes receiving the greatest nitrogen loads. Differences in the root morphology of the Spartina species appears to have consequences on soil characteristics and
microbial processes. S. alterniflora has a tap root system, in contrast, S. patens has a shallow turf-matrix with mycorrhizal roots. Along with the changes in the plant
species composition, there were noticeable differences in the soil characteristics including the bulk density, percent organic matter, percent sand, and the hardness of
the soil. S. patens root ergosterol was inversely related with both soil percent organic matter and the concentration of dissolved phosphate in discharge streams.
Denitrification enzyme activity in the high marshes along the gradient appeared to be significantly related to the estimated nitrogen loadings in a dry but not in a wet
year. At the most impacted sites, nitrogen fixation sometimes exceeded denitrification.