退耕还林地桦木林生态系统碳素密度、贮量与空间分布

Carbon density,storage and distribution in birch forest ecosystem on the forestland converted from farmland

对退耕还林5年生的桦木林生物量、碳素密度、碳贮量及其空间分布进行测定。结果表明，桦木各器官的碳素密度在0．4519～0．5137gC·g^-1，排列顺序为枝〉干〉叶〉根颈〉粗根〉中根〉细根；死地被物层的碳素含量为0．3953gC·g^-1，土壤平均碳素密度为0．0150gC·g^-1，随土层深度的增加，各层次土壤碳素密度呈逐渐减少的趋势；桦木林生态系统总的碳贮量为127．9298tC·hm^-2，其中乔木层为21．9282tC·hm^-2，占整个生态系统的17．14％，死地被物为0．3401tC·hm^-2，占0．27％，林地土壤（0～60cm）为105．6615tC·hm^-2，占82．59％；桦木各器官的碳贮量与其生物量成正比例的关系，树干的生物量最大，其碳贮量也最大，占乔木层碳贮量的57．33％；5年生桦木林年净生产力为8．9912t·hm^-2·a^-1，有机碳年固定量为4．4537tC·hm^-2·a^-1。较之退耕前，桦木林生态系统碳贮量增加15．4797t·hm^-2。

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 a- mounted 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 t C · 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.