Evaluating the potential of nitrogen fixing of plants in the forest ecosystem by using natural 15N abundance method

The potential of nitrogen fixing of plants was evaluated by using the variation of nitrogen isotope component in leaves and stems of plants and in soil. It gives a feasible method to investigate the nitrogen fixing potential of wild plants from atmosphere in the forest ecosystem. Plant samples and soil were collected from Natural Protecting Area of Xiaowutai Mountain in Hebei Province. The contents of N and 15N in the legumes and other plants was obviously different from the value in soil. The δ 15N value in leaves and stems of non-legumes plants was obviously different from the value in soil. The δ 15N value of legumes was close to the value in the atmosphere (0 per mille). In the estimating of %Ndfa of nitrogen fixing plants in the forest ecosystem, the selection of non-nitrogen-fixing plants as reference is discussed. The chinese pine and a few non-legumes may have the potential of nitrogen fixing, because the δ 15N value is close to the δ 15N value in the atmosphere