Nitrogen redistribution and seasonal trait fluctuation facilitate plant N conservation and ecosystem N retention

Low available soil nitrogen (N) limits plant productivity in alpine regions, and alpine plants thus resorb and reallocate N from senescing tissues to conserve this limited N during the nongrowing season. However, the destination and extent of N redistribution during plant senescence among above- and below-ground organs, let alone other processes of translocation outside of plants and into the soil components, remain poorly understood.
Utilizing the 15N stable isotope as a tracer, we quantified N redistribution among above- and below-ground plant organs and different soil components during senescence in an alpine meadow ecosystem, and explored the relationship between 15N among plant-soil N pools with seasonal fluctuations of plant functional traits.
We found a substantial depletion of 15N in fine roots (-40% ± 2.8%) and aboveground tissues (-51% ± 5.1%), and an enhanced 15N storage primarily in coarse roots (+79% ± 27%) and soil organic matter (+37% ± 10%) during plant senescence. In ..., , , # Nitrogen redistribution and seasonal trait fluctuation facilitate plant N conservation and ecosystem N retention

**Abstract**

1.  Low available soil nitrogen (N) limits plant productivity in alpine regions, and alpine plants thus resorb and reallocate N from senescing tissues to conserve this limited N during the nongrowing season. However, the destination and extent of N redistribution during plant senescence among above- and below-ground organs, let alone other processes of translocation outside of plants and into the soil components, remain poorly understood.

2.  Utilizing 15N stable isotope as a tracer, we quantified N redistribution among above- and below-ground plant organs and different soil components during senescence in an alpine meadow ecosystem, and explored the relationship between 15N partitioning among plant-soil N pools with seasonal fluctuations of plant functional traits.

3.  We found a substantial depletion of 15N in fine roots (-40% ± 2.8%) and aboveground ti...