Abstract: The study on the carbon density, storage and distribution in a five-year birch forest on the forestland converted from farmland showed that in different organs of birch, carbon density ranged from 0.4519 to 0.5137 g C·g^-1, and decreased in the order of branch >trunk>leaf>root. The carbon density in floor was 0.3953 g C·g^-1, and that in soil was 0.0150 g C·g^-1 on average, being declined with soil depth. The total carbon storage in the birch forest ecosystem amounted to 127.9298 t C·hm^-2, of which, overstory stored 21.9282 t C·hm^-2, accounting for 17.14%, floor stored 0.3401 t C·hm^-2, accounting for 0.27%, and soil within the depth from 0 to 60 cm stored 105.6615 t C·hm^-2, accounting for 82.59% of the total. The carbon storage in different organs of birch was positively related to its biomass.Stem accumulated the highest biomass, and comprised 57.33% of carbon storage in overstory. The annual net productivity of birch trees was 8.9912 t C·hm^-2·a^-1, and the annual carbon storage was up to 4.4537 tC·hm^-2·a^-1. Compared with that before the conversion of farmland to forestland, the carbon storage of birch forest ecosystem on the converted forestland was increased by 15.4797 t C·hm^-2.

Key words: Medicinal woody plants Ecological protection, Environmental regulation