PARENT SESSION
Contributed Oral Session 135: Invasive Species: Plant - Soil Feedbacks; Invasion Success
Thursday, August 11, 1:30 PM - 5:00 PM, Meeting Room 518 A, Level 5, Palais des congrès de Montréal

Plant-microbial interactions within invasive and native plant communities grown under elevated CO₂.

Kao-Kniffin, Jenny^*,1, Balser, Teri¹, ¹ University of Wisconsin-Madison, Madison, WI

ABSTRACT- Invasive plants dominate many wetlands in North America, sometimes forming monocultures that span several thousand hectares in area. Many studies have shown that invasive plants affect nutrient cycling processes, but few studies have shown how soil microorganisms (the mediators of many important nutrient cycling processes) are impacted by such invasions. Furthermore, little is known about how rising global concentrations of CO₂ will affect plant-microbial interactions and nutrient cycling processes in wetlands dominated by invasive plants. In our study, we examined the effects of elevated CO₂ on plant growth and invasiveness, and on soil microbial community composition and function. We grew invasive and native wetland plants for four months in controlled greenhouses that received either 600 ppm or 365 ppm (ambient) CO₂. Within each of the six rooms (3 replicate rooms per CO₂ treatment), the plant communities were grown under high versus low nitrogen treatments that reflect actual levels found in agricultural runoff entering wetlands. At the end of the experiment, we collected soil samples for DOC and analysis of microbial community structure (lipid analysis). We also harvested the above- and belowground plant biomass and analyzed tissue C, N, and P. We found that the aboveground biomass of the invasive reed canary grass (Phalaris arundinacea L.) increased under elevated CO₂ and high N but there was no difference in the low N treatment. In contrast, the biomass of native grasses increased under elevated CO₂ and low N but did not differ under high N. We will discuss the results of the belowground biomass, soil microbial composition and abundance, and DOC analysis at the presentation.

Key words: reed canary grass, elevated CO₂, invasive species, microbial lipid analysis