Abstract Detail

Symbioses: Plant, Animal, and Microbe Interactions

Castillo, Buck Tanner [1], James, Timothy [2], Nave, Luke [2], Le Moine, Jim [2], Nadelhoffer, Knute [2].

Belowground Plant and Fungal Community response to accelerated forest succession.

Future climatic conditions are predicted to increase forest disturbances, which could alter productivity, biogeochemical cycles and successional trajectories. Understanding how soil processes, plant and fungal species composition, and nutrient cycles change during succession and in response to disturbances is essential for understanding the role of forests in a rapidly changing global environment. The Forest Accelerated Succession ExperimenT (FASET) at the University of Michigan Biological Station presents a unique opportunity to study changes in plant physiological responses and has the potential to show shifts in fungal community structure during secondary succession. FASET consists of a 33-ha treatment in which all mature primary successional trees of Populus tremuloides, P. grandidentata, and Betula paperifera were killed by stem-girdling in 2008. In this study I use molecular and biochemical techniques to link plant and fungal composition to alterations in nutrient cycling post disturbance. My study addresses the following question: How do root and fungal communities differ along a nitrogen availability gradient in a mid-successional mixed hardwood forest and following intermediate (non-stand replacing) disturbance? I address the following hypotheses: Given observed increases in root turnover in girdled stands and under higher N availability, root biomass will be progressively lower as N availability increases and in girdled plots. Furthermore, arbuscular mycorrhizae and saprotrophs will increase in their proportion of the soil fungal community in girdled stands and under higher N availability, while ectomycorrhizal proportions decline. I tested this set of hypotheses by examining root community composition of canopy dominant species and fungal communities along a naturally occurring N gradient in paired plots associated with FASET. Four years after the girdling treatment commenced overall fungal diversity, plant diversity, or root biomass does not differ between girdled and ungirdled stands. There is evidence of a shift in fungal functional groups, as there were significantly less EM fungi in girdled stands than in reference stands and a 7% increase in the proportion of saprotrophs. More research is needed into the direct mechanism for this decline in EM fungi, and what the shifts toward a more saprotrophic-dominated system mean for soil carbon storage and soil respiration rates.

1 - University of Michigan, Ecology and Evolutionary Biology, 830 North University Ave, Ann Arbor, MI, 48109, USA
2 - University of Michigan, Ecology and Evolutionary Biology, 830 North University Ave, Ecology and Evolutionary Biology, Ann Arbor, MI, 48109, United States

Keywords:
mycorrhizae
nitrogen
disturbance
Roots
succession.

Presentation Type: Oral Paper:Papers for Topics
Session: 51
Location: Salon 5/The Shaw Conference Centre
Date: Tuesday, July 28th, 2015
Time: 2:30 PM
Number: 51005
Abstract ID:1245
Candidate for Awards:None