Mycorrhizal Phenology Under Altered Snowmelt Timing
Authors
Hannah B. Shulman1* (hshulman@utk.edu), Patrick O. Sorensen2, Olivia Vought3, Peter Falb3, David W. Inouye4, Aimee T. Classen3, Stephanie N. Kivlin1
Institutions
1University of Tennessee, Knoxville, TN; 2Climate and Ecosystems Division, Lawrence Berkeley National Laboratory, Berkeley, CA; 3University of Michigan, Ann Arbor, MI; 4University of Maryland, College Park, MD
Abstract
The warmer and drier conditions created by climate change shift plant phenologies through altered environmental cues, potentially creating novel organismal interactions between plants and mycorrhizal fungal partners. The symbiosis between plants and arbuscular mycorrhizal (AM) fungi is fundamental for plant access to labile nutrients. During the early spring in alpine ecosystems, snowmelt creates a flush of soil resources (water, nitrogen, and phosphorus), which AM fungi provide to the plant host in exchange for photosynthate carbon (C). This snowmelt date is advancing as the climate warms, which researchers hypothesized would result in asynchrony of plant-mycorrhizal fungal nutrient cycling. The team advanced the snowmelt date by 10 days in a Colorado subalpine meadow using shade cloth. Throughout the following growing period (May to September), the team tracked new root and hyphal growth with ingrowth cores and composition of the soil microbiome with amplicon sequencing (loci: ITS – general fungi, SSU – AMF). Researchers coupled this to simultaneous measures of mineral and microbial biomass nitrogen. Shotgun metagenomic sequencing was also used to track the genetic inventory of microbial biogeochemical functions, revealing significant temporal variation of bacterial nitrogen cycling genes. The team found that the standing stock of AM hyphae was highest under snowpack in early May, steadily decreasing throughout the growing period. Snowmelt treatment did not impact this metric of AM growth but did decrease hyphal density of saprotrophic fungi during the senescence period in mid-September. The team will detail how altered snowmelt impacted the synchrony of root and fungal growth and the resulting impact on AM community composition, soil nitrogen availability, and microbial nitrogen cycling.