Major
Environmental Science
Anticipated Graduation Year
2021
Access Type
Open Access
Abstract
As the most commonly-limiting nutrient in terrestrial ecosystems,
nitrogen plays a critical role in carbon sequestration and other
ecosystem services. However, it is notoriously difficult to measure
the availability of nitrogen in the forms that plants are able to take
up. We conducted a combined lab and greenhouse experiment to
determine the sampling sizes required to reliably measure plant
nitrogen availability in forest soils collected from two plots at The
Morton Arboretum, one angiosperm-dominated and the second
gymnosperm-dominated. We used two methods to measure plant
nitrogen availability in our forest soil samples: lab incubations and
phytometer growth. Lab incubations measure mineral nitrogen
concentration before and after a two-week incubation period to
determine net nitrogen mineralization. Phytometer growth indexes
nitrogen availability via height and biomass of seedlings grown in
the soil. Using 40 soil cores per plot, we will determine how
many samples are required to have an 80% chance of detecting
significant results between plots with a two-fold increase or
decrease in nitrogen availability. By determining minimum
sample sizes required, this pilot study will aid in the efficient
design of an upcoming larger study comparing soil nitrogen
availability across 18 plots at The Morton Arboretum.
Community Partners
The Morton Arboretum
Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.
Measuring plant nitrogen availability in forest soils with lab incubations and phytometer growth assays: a power analysis
As the most commonly-limiting nutrient in terrestrial ecosystems,
nitrogen plays a critical role in carbon sequestration and other
ecosystem services. However, it is notoriously difficult to measure
the availability of nitrogen in the forms that plants are able to take
up. We conducted a combined lab and greenhouse experiment to
determine the sampling sizes required to reliably measure plant
nitrogen availability in forest soils collected from two plots at The
Morton Arboretum, one angiosperm-dominated and the second
gymnosperm-dominated. We used two methods to measure plant
nitrogen availability in our forest soil samples: lab incubations and
phytometer growth. Lab incubations measure mineral nitrogen
concentration before and after a two-week incubation period to
determine net nitrogen mineralization. Phytometer growth indexes
nitrogen availability via height and biomass of seedlings grown in
the soil. Using 40 soil cores per plot, we will determine how
many samples are required to have an 80% chance of detecting
significant results between plots with a two-fold increase or
decrease in nitrogen availability. By determining minimum
sample sizes required, this pilot study will aid in the efficient
design of an upcoming larger study comparing soil nitrogen
availability across 18 plots at The Morton Arboretum.