封育与放牧对三江源区高寒草甸植物和土壤碳储量的影响

The response of carbon reserves of plants and soils to different grassland managements on alpine meadow of three headwater source regions

在三江源区选择不同封育年限的退化高寒草甸,测定其地上部分主要功能群(禾草类、杂类草、莎草类的总碳氮浓度)、植物根系和土壤碳浓度及储量的动态研究。结果表明:围栏封育主要功能群总碳浓度和碳氮比高于自由放牧草地;围栏封育地下根系碳浓度明显高于自由放牧草地;高寒草甸土壤有机碳储量最大,植物地上部分碳储量最小,植物根系碳储量居中。0～30cm深度土体单位面积有机碳储量由高到低依次为:围栏封育5年>围栏封育10年>自由放牧;封育5年和10年后,总碳储量较自由放牧草地提高了36.54%,24.61%;土壤有机碳分别增加了26.28%和24.28%;而封育5年和10年之间碳储量没有显著变化,说明围栏封育是高寒草甸固碳减排的有效措施之一。

Knowledge about carbon and nitrogen in plants and soils and response to fence and graze in alpine ecosystems is still rudimentary because of extremely geographic situation.The purpose of this study was to compare the difference among carbon concentration,and content of unit area and dynamics of above-and below-ground biomass,soil organic carbon and total nitrogen between fencing and grazing alpine meadow.The results showed that the total carbon and C：N ratio in the aboveground tissue were significantly higher in fenced and ungrazing grassland（FU） than those in free grazing grassland（FG）.In addition,the order of total carbon concentration of aboveground tissue of different function groups were not identical between them;The total carbon storage（TCS） per unit of aboveground tissue,roots and 0~30 cm soil layer increased after being fenced for 5 years from free grazing grassland（9 255.17 g/m2） to fenced and ungrazing grassland（1 2637.10 g/m2） by 26.79%.However there were no significant differences between fenced and ungrazing grasslands of 10 years and 5 years.Therefore fenced to exclude grazing by Tibetan sheep and yaks was an alternative approach to sequester C from the soil in alpine meadow systems.