Climate change is causing species with previously disparate ranges to come in contact. A key challenge in ecology is to predict the consequences of climate change caused species reshuffling. Experiments aimed at addressing this issue have focused on competition, but other interactions, like plant-microbe interactions, are less studied. In this glass house study, we test the effects of novel, low elevation microbial communities interacting with alpine restricted grasses from the West Elk Mountains, CO, USA. We compared the effects of microbes from within and below the elevation range of focal alpine plants from three replicate mountains on the production and traits of three grass species (Poa alpina, Festuca brachyphylla, Elymus scribneri). Traits include specific leaf area (SLA), height, and root to shoot ratio. Inocula was added to make up 10% of pot volume and was either live or autoclave sterilized. The factorial design resulted in 36 treatment combinations (2 elevations x 3 mountains x 2 inocula treatments x 3 species) replicated 10 times (360 pots). We used linear mixed effects models to compare treatment effects on biomass and traits of the plants, with greenhouse block and mountain as random effects.
Results/Conclusions
Results suggest that plants in sterilized soil inocula had higher biomass compared to live inocula, and live soil from the plant’s home range decreased biomass to a greater extent than the novel soil microbial communities. The depressed growth in home range soils may reflect heavier species-specific pathogens found in the home range soils. Though traits didn’t respond to the elevation of the microbes, they were altered by inocula sterilization. SLA was lower in sterilized inocula for all three species, which suggests that microbes lead the plants’ leaves to become more resource acquisitive. Height responded in a species-specific manner (e.g. P. alpina taller in live, while E. scribneri was taller in sterile soils). All three species invested more in roots with sterile inocula (higher root-shoot ratio), suggesting that soil microbes altered plant organ tissue investment strategies. Overall, the experiment suggests that these alpine grasses may initially benefit from the upward migration of microbial communities. Future work should manipulate plant-microbe interactions in situ to gain a better understanding of how the environment can alter these important relationships.