Final Report - Center for Invasive Plant Management

DiscussionThe main objective of this study rvas to test whether seasonal changes in glomalin ti'actionsoccur o\,'er a growing season. ln a previous studv. glomalin had a long tumover time (up to 40years), much longer than the turnover time expected for AM hyphae (Rillig et al. 2001, Frieseand Aiien i llq l). ln a lab incr-rbation comparing glomalin and AMF extraradical hypiraedecomposition, glomalin concentrations only decreased by 250",ii over 150 days, while AMFextraradical hyphal length declined 6096 (Steinberg and Rillig 2003). Currently there is nointbrmation on tire seasonalitv of slomalin.lnConcentrations of the TG and IREEG glomalin fractions changed significantly throughtime, while the EEG and IRTG fi actions did not. This is the first report of seasonal changes ofpools. At this time, it is unclear how these operationally-elomalindetined glornalin pools differfrom each other in terms of biochemistry, function in soil, and age. or how the production ofglomalin is controlled (Ri[ig et al. 2001). fhe patterns of change in the TG and IREEGl5concentrations through time are generally dissimilar.Several fungal parameters fluctuated significantlv through time in the soil studied.External AM hyphal length changed significantly over the growing season, with a decrease inNovember. This decrease is sirnilar to the decrease noted in the IREEG fraction. Hyphal length20values measured in this study were fairly high, w-ith the highest hvphal length measured to be 82m g-1 soil in October. and an average hyphal length throughout the season of 50 m g'r soil. Ourhyphal length values were higher than hyphal lengths from several studies reported in Smith andGaninazi-Pearson (1988). It is not uncommon for hyphal lengths to vary considerably from12