Plant nitrogen demand decouples net mineralization and nitrification in disturbed forests

Nitrification is a key process in the global nitrogen cycle, indicative of both soil nitrogen availability and potential for nitrogen losses that cause environmental degradation. Heterotrophic soil microbes and plants compete with nitrifiers for ammonium, thereby influencing the fraction of mineralized nitrogen converted to nitrate. Microbially available carbon constrains heterotrophic nitrogen demand and therefore regulates the coupling of net nitrogen mineralization and nitrification rates. Whether soil carbon availability remains a central control on the coupling of these processes in disturbed ecosystems with reduced plant nitrogen demand remains relatively unexplored. Using a series of partially disturbed forests that vary in aboveground biomass and soil carbon availability, we test the relative influence of plant and heterotrophic nitrogen demand on the relationship between net nitrogen mineralization and nitrification. We analyzed differences between harvested and unharvested sta..., Study area 
We conducted our work at Yale-Myers Forest, a mixed hardwood, second-growth forest in the northeastern USA (41° 57' N, 72°07’ W). Yale-Myers Forest is an actively managed research and demonstration forest with annual timber harvests that can be used to study changes over time since harvest through a chronosequence approach. We selected 15 oak-hardwood stands with similar silvicultural treatments that were harvested from 1994 through 2016 as well as five unharvested controls that had comparable characteristics to the harvested stands and hence were all eligible for the same silvicultural treatment. Each of the 15 harvested stands were managed to promote the regeneration of shade-intolerant tree species, such as oaks (Quercus spp.), through the creation of large canopy openings interspersed with legacy overstory trees at a spacing of 35 – 80 m.
Sampling design
To capture within-site variation in microbially available C and aboveground plant biomass, we stratified our samp..., , # Plant nitrogen demand decouples net mineralization and nitrification in disturbed forests

[https://doi.org/10.5061/dryad.j9kd51cpg](https://doi.org/10.5061/dryad.j9kd51cpg)

## Description of the data and file structure

This data was collected to assess the effects of changes in aboveground biomass and soil carbon availability following partial forest disturbances from timber harvesting on the coupling of net nitrogen mineralization and nitrification rates. We used a stratified random sampling design to capture variation in stand age, legacy structure, soil type, and topography in a second-growth, oak-hardwood forest in the northeastern U.S. We used this data to compare the coupling of net nitrogen mineralization and nitrification in 15 harvested stands managed to promote tree regeneration (*n* = 144 plots) and five unharvested controls (*n* = 48 plots) and over time since harvest in the harvested stands only (*n* = 144). Using the data from the harvested stands (n = 144), we also a...,