三工河流域5种荒漠群落土壤有机碳动态

Soil organic carbon dynamics of five desert communities in Sangong River basin

土壤有机碳是土壤质量和健康的重要指标,其来源是根系和凋落物,了解土壤有机碳的分布格局及土壤有机碳密度、储量与细根、凋落物的关系,是深入理解荒漠生态系统碳循环过程的关键.以新疆三工河流域的骆驼刺(Alhagi sparsifolia)、沙枣(Elaeagnus angustifolia)、多枝柽柳(Tamarix ramosissima)、芦苇(Phragmites australis)、梭梭(Haloxylon ammodendron)等5种荒漠群落为研究对象,采用连续土钻取样法和土柱法,研究土壤有机碳的密度、储量和细根、凋落物对土壤有机碳的补充.结果表明,随着土层深度的增加,5个群落的土壤有机碳含量均呈逐渐降低的趋势,最大值均出现在0-5 cm土层;5个群落的土壤有机碳密度和0-100 cm土壤有机碳储量分别为3.19 kg/m^2、306.87g/m^2,土壤有机碳的总储量为5.13×10^5 t.5个群落的凋落物年产量为10.10-79.78 g/m^2,通过分解每年补充的土壤有机碳为0.44-9.53 g/m^2,占土壤有机碳储量的0.21%-3.94%. 5个群落的细根周转速率为1.41-1.98次/年,通过分解每年补充的土壤有机碳为6.31-44.12 g/m^2,占土壤有机碳储量的2.25%-20.90%,是凋落物贡献的2.09-2.58倍.可见,细根和凋落物对土壤有机碳库的积累起关键作用,细根较凋落物对土壤有机碳的贡献更大.

Soil organic carbon generated from plant root and litter is an important indicator of soil quality and soil health.The aims of this study were to understand the distribution pattern of soil organic carbon and the relationship of soil organic carbon between fine roots and plant litters from five desert communities in the Sangong River basin of China.The soil drill sampling method and sequential soil coring were used to investigate the distribution pattern of soil organic carbon and the effects of fine roots and litters on soil organic carbon in Alhagi sparsifolia,Elaeagnus angustifolia,Tamarix ramosissima,Phramites australis,and Haloxylon ammodendron communities.Results showed that soil organic carbon content decreased with soil depth,and the maximum values in all five communities appeared at a depth of 0-5 cm in the soil layer.The soil organic carbon density and stock at a depth of 0-100 cm for the five communities were 3.19 kg/m^2 and 306.87 g/m^2,respectively,and the total soil organic carbon storage was 5.13×10^5 tons.The annual litter production in the five communities was 10.10-79.78 g/m^2.The annual replenishment of soil organic carbon through litter decomposition was 0.44-9.53 g/m^2,accounting for 0.21%-3.94%of the soil organic carbon stock.The fine root turnover rate of the five communities was 1.41-1.98 times/yr,and soil organic carbon replenishment via decomposition was 6.31-44.12 g/m^2,accounting for 2.25%-20.90%of the stock,which is 2.09-2.58 times more than litter contribution.This shows that fine roots and litters play a key role in the accumulation of soil organic carbon stock,and fine roots contribute more to this carbon than litter.