In this study, nitrogen fluxes or flows in litterfall, nitrogen stocks and available nitrogen in soils of two plots representing evergreen broadleaf and Bulgarian fir forests were assessed. Both plots are in good quality sites and for this reason, the litterfall quantities and nitrogen fluxes were relatively high. The woody litterfall flux of nitrogen was significantly higher in the fir forest than in the evergreen broadleaf one. The total nitrogen stock was higher in the soil under the fir forest. However, the percentage of the available nitrogen (ammonium + nitrates) was significantly higher in the upper 20 cm soil layer of the evergreen broadleaf forest in spite of the higher average C/N ratios in the foliar litterfall of the broadleaf forest and insignificant difference of the C/N ratios in all soil layers of the two ecosystems. The microclimatic conditions (higher soil temperatures in the evergreen broadleaf forest) is probable possible cause for this difference. The available nitrogen in the soils and its retranslocation from senescing leaves cover the nitrogen requirements of trees. It is hypothesized that trees may also take up nitrogen from deeper soil layers.

在这项研究中，评估了代表常绿阔叶林和保加利亚冷杉林的两个地块的凋落物的氮通量或流量、氮库和土壤中的有效氮。两个地块都处于优质地点，因此，凋落物数量和氮通量相对较高。冷杉林的木质凋落物氮通量显着高于常绿阔叶林。冷杉林下土壤中的总氮储量较高。然而，尽管阔叶林凋落物的平均 C/N 比较高，但常绿阔叶林上部 20 cm 土层的有效氮（铵 + 硝酸盐）百分比显着较高，且差异不显着。两个生态系统所有土壤层的 C/N 比。小气候条件（常绿阔叶林土壤温度较高）可能是造成这种差异的原因。土壤中的有效氮及其从衰老叶片中的再转移满足了树木对氮的需求。据推测，树木也可能从更深的土壤层吸收氮。