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University of Michigan Biological Station

The University of Michigan Biological Station (UMBS) was founded in 1909.

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Detrital Input and Removal Treatments - impacts on microbial communities and nutrient processes

Terrestrial
DIRT
nitrogen
litter addition
soil chemistry
Project Abstract: 
Soil ecosystems play a crucial role in global carbon cycling, yet the intricate relationships between detrital inputs, microbial communities, and nutrient processes remain poorly understood. Here, I propose to investigate how plant litter inputs (wood, leaf, root) and nutrient availability impact soil microbial communities and associated nutrient cycling in a mixed deciduous forest in Northern Michigan. Leveraging the Detrital Input and Removal Treatment (DIRT) project established at the University of Michigan Biological Station (UMBS), I will explore the long-term effects of nutrient manipulation on microbial composition, soil nitrogen and carbon cycling, and nutrient pools.Through a combination of DNA sequencing, net nitrogen mineralization assessments, soil enzyme analysis, and microbial biomass quantification, I aim to clarify the complex interactions between plant inputs, nutrients, and soil microbial communities. The findings of this project will contribute to a deeper understanding of soil ecosystem dynamics and detrital inputs' influence on microbial communities and their broader ecological significance.
Investigators: 
brendabh
Associates: 
klrand
Status of Research Project: 
Active
Years Active: 
2024
Research sites: 
UMBS DIRT Plots
Methods: 
The University of Michigan Biological Station (UMBS) is located in northern Michigan (45.56 N, -84.67W0) and is composed of northern hardwood forest (Gough 2020, Hardiman 2011). The Detrital Input and Removal Treatments (DIRT) experiment located at UMBS consist of plots with a gradient of nutrient inputs: no litter input (NL), no roots (NR), no input (NI)(no root, no litter), control (C), reference(REF), wood input (W), double liter(DL), double little & fertilizer (DLF) and fertilizer (F). DIRT has been running for 20 years, since then soil samples have been collected every 5 years from these plots and sampled for soil pH, total carbon and nitrogen,cation exchange capacity, acidity, base saturation and total SOM. We will resample these soil parameters this summer to stay consistent with the 5-year sampling interval. In addition, I will be sampling all of the plots for net nitrogen mineralization in situ using the “buried bag” method that consists of burying two ion exchange resins in nylon mesh bags, one at the bottom and another at the bottom of (Eno, 1960, Nadelhoffer et al., 1984) an inhibitor (PVC cylinder) around the bags to prevent plant root uptake of nitrogen (Nadelhoffer et al., 1984). The bags and inhibitor will be incubated for 30 days in order to measure nitrogen inputs and nitrogen leaching. The bags and inhibitor will be collected at the end of their incubation period and the ion exchange resin membranes along with the soil will be extracted for nitrogen at our lab on the Ann Arbor campus in the fall. I will collect mineral soil samples (0-10 cm depth; 2 cm diameter core) at peak growing season (mid-July) in each of the plots. I will immediately freeze these samples (-80 °C) and bring them back to Ann Arbor to analyze for ecologically relevant soil enzymes, microbial biomass, and send samples to the UM microbiome core for microbial DNA sequencing. I will also conduct a lab incubation to assess potential carbon mineralization of samples (Vourlitis & Zorba, 2006). Finally, I will also monitor soil moisture, soil temperature, and air temperature every 15 minutes using TMS-4 data loggers for the duration of that summer (Wild et al., 2019).