# Carbon and Nitrogen Pools and Fluxes in Adjacent Mature Norway Spruce and European Beech Forests
## 3 Results
### Carbon and Nitrogen Fluxes
#### 3.2.4 Nitrogen Fluxes  
The annual requirement of N to sustain ANPP (Nreq above) was calculated as 60 kg-ha\({}^{-1}\cdot\)year\({}^{-1}\) for the spruce stand and 127 kg-ha\({}^{-1}\cdot\)year\({}^{-1}\) for the beech stand. Based on allometric equations, higher annual uptake of N to support coarse root growth (Nreq coarse roots) was calculated for the spruce compared to the beech stand. Fine root growth, estimated as 14% of NPP ([PERSON] et al., 2015), required 28 kg-ha\({}^{-1}\cdot\)year\({}^{-1}\) of N in the spruce and 23 kg-ha\({}^{-1}\cdot\)year\({}^{-1}\) of N in the beech stand (Table 9).  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c c} \hline \hline  & **ANPP** & **ANPP** & **ANPP** & **ENPP** & & & & & & & **BNPP** & & & **BNPP** & & & \\  & **Wood** & **Foliage** & **Litter** & **Coarse** & **ANPP** & **TBCA** & **F\({}_{\text{s}}\)** & **R\({}_{\text{above}}\)** & **R\({}_{\text{root}}\)** & **R\({}_{\text{total}}\)** & **GPF** & **Fine** & **ENPP** & **ev/myc** & **NPP** & **WUE** \\  & & & & & **Root** & & & & & & & & & & & & \\ \hline  & & & & & & & & & & & & & & & & & \\ \multirow{4}{*}{Sprace stand} & \multirow{4}{*}{3495} & \multirow{4}{*}{230} & \multirow{4}{*}{1650} & \multirow{4}{*}{1382} & \multirow{4}{*}{5375} & \multirow{4}{*}{9600} & \multirow{4}{*}{9690} & \multirow{4}{*}{5160} & \multirow{4}{*}{5602} & \multirow{4}{*}{10,763} & \multirow{4}{*}{20,136} & \multirow{4}{*}{1335} & \multirow{4}{*}{1281} & \multirow{4}{*}{9373} & \multirow{4}{*}{2.6} \\  & & & & & & & & & & & & & & & & & \\ \cline{1-1}  & & & & & & & & & & & & & & & & \\ \hline \multirow{4}{*}{Bepech stand} & \multirow{4}{*}{2502} & \multirow{4}{*}{18} & \multirow{4}{*}{2882} & \multirow{4}{*}{370} & \multirow{4}{*}{5401} & \multirow{4}{*}{6579} & \multirow{4}{*}{9091} & \multirow{4}{*}{518  
Annual litterfall delivered on average 39 kg\(\cdot\)ha\({}^{-1}\cdot\)year\({}^{-1}\) of N to the forest floor in the spruce stand and 56 kg\(\cdot\)ha\({}^{-1}\cdot\)year\({}^{-1}\) of N in the beech stand (Table 8). Needlefall N consisted of 80% of total litterfall in the spruce stand, and leaf fall consisted of 73% of total litterfall in the beech stand. The average C/N ratio of litterfall was lower in spruce compared to beech (Table 8). Nitrogen requirements to build up foliage in the beech stand (116 kg\(\cdot\)ha\({}^{-1}\cdot\)year\({}^{-1}\)) were significantly higher than the annual litterfall N flux; thus, N translocated back to the tree (N\({}_{\text{trans}}\)) from foliage tissues accounted for 60 kg\(\cdot\)ha\({}^{-1}\cdot\)year\({}^{-1}\). In the spruce stand, only 5.7 kg\(\cdot\)ha\({}^{-1}\cdot\)year\({}^{-1}\) of N was translocated during senescence. Therefore, net N uptake was calculated as 71 kg\(\cdot\)ha\({}^{-1}\cdot\)year\({}^{-1}\) for both forest ecosystem types. Litterfall and throughfall N fluxes provided 57 kg\(\cdot\)ha\({}^{-1}\cdot\)year\({}^{-1}\) of N, which is 14 kg\(\cdot\)ha\({}^{-1}\cdot\)year\({}^{-1}\) less than the annual N needs calculated for the spruce stand. On the other hand, a roughly balanced N cycle was calculated for the beech forest (Table 9).