Assemblages of species in plant communities are dynamic and likely to be more so under a changing climate. Community composition is governed by resource availability, climactic conditions, propagule pressure from the local species pool, and competitive interactions between individuals. Following disturbance, species that arrive and establish first often gain a competitive advantage relative to species that arrive later through preemption of resources such as space and light. This phenomenon, termed priority effects, is also manifest by the alteration of soil biota by early-arrivers. With the exception of certain allelopathic species, the influence soil legacy effects have on the establishment of species is often dubious. Furthermore, the interactions between plant colonists and soil conditioned by preceding plants may be altered in under conditions predicted by climate change scientists. To further our understanding of soil legacy effects given climate change, we established a growth chamber experiment to test the response of six old field species in the following treatments: presence or absence of soil microbes, conditioned by conspecific or heterospecific plants in warmed or ambient temperatures.
Results/Conclusions
The effects of soil legacy, temperature, and microbial inoculation varied among species and taxa. Temperature was the most important factor in determining grass and forb height with warmed individuals averaging 2.3 cm more growth than their ambient counterparts. Species such as Cichorium intybus performed better in microbially inoculated soils relative to the sterile treatment, with gains in average height of over 1.8 cm. At the taxa level, plants grown in soils conditioned by grasses outperformed those grown in soils conditioned by forbs by 3 cm. Plants that were grown in the soil of invasive species were 1.2 cm taller than plants grown in native soils. Soils that were conditioned by invasive species may represent a novel environment for native species, and thus avoid certain negative soil feedbacks that occur in soils of co-evolving species. These results suggest soil legacy effects can be determined by the identity and origin of both the previous occupant and the colonizer. It also suggests that the strength of the soil legacy effects has the potential to change substantially in a warming climate.