Brooke Propson, a PhD student at the University of Wisconsin, whom works in Zac Freedman’s lab (former Zak lab post-doc), studied the ecosystem response and recovery after the long-term elevated nitrogen treatment was stopped. There is also a natural gradient of ambient N deposition due to human activity at these sites, as well. The study showed that the C in the organic horizon that has previously accumulated from N-treatment has been lost with added deficits post-termination of the treatment with the exception of the northernmost site (least ambient N), showing a shift in mechanistic microbial activity. The mineral soil C still remained observable even after the 5-year termination of the treatment (though not significant). They concluded that most likely the sites are in a disturbed state and will most likely still exhibit higher levels of C storage overtime. The paper is out now and can be found here.
