Effects of soil and mycorrhizae from native and invaded vegetation on a rare California forb

Abstract

Exotic annual grasses have invaded most California grasslands, but the degree of invasion varies, as do the mycorrhizal communities associated with different grasslands. When restoring species to grasslands, it is important to consider the role mycorrhizal fungi and soil environmental conditions can play in affecting restoration success. For edaphic endemics soil properties will also likely be an important factor dictating the growth of the target species. We investigated how the rare forb, Erodium macrophyllum, grows in three different soils with associated mycorrhizal inocula in full factorial design. Soil and inocula came from a grassland dominated with the native grass, Nassella pulchra, a grassland dominated with exotic grasses, and from a clay soil in which E. macrophyllum is currently found. We found that E. macrophyllum responded differentially to soil textural classes and inocula, but there were no interactions; growth was greatest in loamy soil from the invaded grassland and inoculum from the invaded grassland increased growth the most regardless of soil characteristics. When restoring E. macrophyllum to different areas, soil characteristics will likely have the greatest affect on growth, but inocula will likely increase growth also.