Rt. Myers et al., Landscape-level patterns of microbial community composition and substrate use in upland forest ecosystems, SOIL SCI SO, 65(2), 2001, pp. 359-367
The composition and diversity of biotic communities are controlled by the a
vailability of growth-limiting resources. Resource availability for microbi
al populations in soil is controlled by the amount and types of organic com
pounds entering soil from plant litter, Because plant communities differ in
the amount and type of substrates entering soil, we reasoned that the comp
osition and function of soil microbial communities should differ with the d
ominant vegetation. We tested this idea by studying two sugar maple (Acer s
accharum Marsh.)dominated and one oak (Quercus spp,)-dominated forest ecosy
stems in northern Lower Michigan that differ in rates of soil N cycling. We
used phospholipid fatty acid (PLFA) analysis to gain insight into microbia
l community composition, and we used a subset of Biolog GN substrates found
in root exudate to assess the metabolic capabilities soil microbial commun
ities, Although microbial biomass did not differ among ecosystems, principa
l components analysis of bacterial, actinomycetal, and fungal PLFAs clearly
separated the microbial communities of the three ecosystems. Similarly, pr
incipal components analysis separated microbial communities by differences
in growth on carbohydrates, organic acids, and amino acids. Discrimination
among microbial communities in the three ecosystems by PLFAs and substrate
use occurred in spring, summer, and fall, but the individual PLFAs and subs
trates contributing to discrimination changed during the growing season. Ou
r results indicate that floristically and edaphically distinct forest ecosy
stems also differ in microbial community composition and substrate use, Thi
s pattern was consistent across the growing season and repeatedly occurred
across relatively large land areas.