Root and mycorrhizal endophyte development in a chronosequence of restored tallgrass prairie

Abstract

SUMMARYThe relationships between root and mycorrhizal development were investigated at the community level for a chronosequence consisting of restored tallgrass prairie (including plots in the second, fifth, eighth and eleventh growing season) and a virgin prairie remnant. Fibrous ( 1 mm diameter) root length increased across the chronosequence, with the greatest length occurring in the prairie remnant. After an initial increase between the second and fifth growing seasons, the percentage of fibrous roots colonized by vesicular‐arbuscular mycorrhizal fungi declined. However, this decline did not truly reflect the mycorrhizal association in this system because the length of fibrous roots colonized by mycorrhizal fungi did not decrease after the fifth growing season but instead remained essentially constant throughout the remainder of the chronosequence. Evaluation of the data by fibrous root size classes indicated that increases in root length and colonized root length occurred largely in the smaller size class (< 0.2mm diameter); in contrast, percentage colonization and the density of intraradical fungal structures was greater in the larger size class (0.2–1 mm diameter). The importance of thoroughly evaluating responses of mycorrhizal fungi relative to host responses was demonstrated in a field situation.