Document: LAU-3-32-17

The effects of soil moisture and mycorrhiza on two species of goldenrod.

YOUNG, L.M.*, A.V.WHIPPLE and W.G.ABRAHAMSON

Bucknell University, Lewisburg, PA, U.S.A. ¹

Abstract:
One way in which two species can coexist over time is to diverge in their resource requirements. Differentiation in soil moisture requirements and in symbiotic associations with mycorrhiza are two ways in which plant species can reduce competition with each other and therefore coexist. The goldenrods Solidago altissima and Solidago gigantea co-occur throughout much of their overlapping ranges. Field observations suggest S. gigantea is found in sites with greater soil moisture than S. altissima. To determine whether soil moisture and mycorrhiza influence the ability of these species to coexist, we conducted a greenhouse experiment. Plants of both species were grown in field soil that was either sterile or inoculated with mycorrhiza infected roots from the field. One of three soil moisture levels was maintained for all of the plants. Both species had greater above-ground performance when inoculated with mycorrhiza. Solidago gigantea did not produce as much above ground biomass in greater soil moisture, but produced more rhizome than S. altissima under these conditions. There was also more rhizome produced by S. gigantea in the presence of mycorrhiza suggesting it will be favored in conditions where potential mycorrhizal colonization is greater. The greater rhizome growth by S. gigantea in greater soil moisture supports our observation that this species grows in wetter areas. Our results suggest these two underground interactions of mycorrhiza and water availability play a role in these goldenrods' ability to coexist.

Keywords: Goldenrod, Mycorrhiza, Soil Moisture

This abstract is being presented at: 3:30 PM in session:
WATER RELATIONS