|Title||Nitrogen oligotrophication in northern hardwood forests|
|Publication Type||Journal Article|
|Year of Publication||2018|
|Authors||Groffman, PM, Driscoll, CT, Durán, J, Campbell, JL, Christenson, LM, Fahey, TJ, Fisk, MC, Fuss, C, Likens, GE, Lovett, GM, Rustad, LE, Templer, PH|
|Pagination||1 - 17|
|ISBN Number||0168-2563, 1573-515X|
While much research over the past 30 years has focused on the deleterious effects of excess N on forests and associated aquatic ecosystems, recent declines in atmospheric N deposition and unexplained declines in N export from these ecosystems have raised new concerns about N oligotrophication, limitations of forest productivity, and the capacity for forests to respond dynamically to disturbance and environmental change. Here we show multiple data streams from long-term ecological research at the Hubbard Brook Experimental Forest in New Hampshire, USA suggesting that N oligotrophication in forest soils is driven by increased carbon flow from the atmosphere through soils that stimulates microbial immobilization of N and decreases available N for plants. Decreased available N in soils can result in increased N resorption by trees, which reduces litterfall N input to soils, further limiting available N supply and leading to further declines in soil N availability. Moreover, N oligotrophication has been likely exacerbated by changes in climate that increase the length of the growing season and decrease production of available N by mineralization during both winter and spring. These results suggest a need to re-evaluate the nature and extent of N cycling in temperate forests and assess how changing conditions will influence forest ecosystem response to multiple, dynamic stresses of global environmental change.