黄土高原不同人工林型微生物残体碳对土壤有机碳组分的积累贡献及影响因素

为探究不同人工林型微生物残体碳(Microbial necromass carbon, MNC)对土壤有机碳组分的积累贡献及影响因素,在黄土高原选取刺槐林、山杏林、油松林为研究对象,分析了三种人工林0-60 cm土层真菌残体碳(Fungal necromass carbon, FNC)、细菌残体碳(Bacterial necromass carbon, BNC)、MNC对颗粒态有机碳(Particulate organic carbon, POC)和矿物结合态有机碳(Mineral-associated organic carbon, MAOC)的积累贡献及其影响因素。结果表明:(1)三种人工林POC、MAOC中FNC、BNC、MNC含量均随土层深度的增加而降低;(2)刺槐林和山杏林MNC对MAOC的积累贡献(60.9%,52.0%)高于POC(33.5%,49.5%),其中FNC对MAOC的积累贡献分别是BNC的4.4和2.5倍,油松林在0-10 cm土层MNC对POC的积累贡献(73.8%)高于MAOC(48.2%),其中FNC对POC的积累贡献是BNC的3.5倍,而在10-60 cm土层MNC对MAOC的积累贡献(30.9%)高于POC(24.4%),其中FNC对MAOC的积累贡献是BNC的3.4倍;(3)总有机碳和全氮含量与MNC/POC、MNC/MAOC呈显著正相关关系(P ＜ 0.05),黏粒含量与MNC/MAOC呈显著正相关关系(P ＜ 0.05),pH值、砂粒含量与MNC/MAOC呈显著负相关关系(P ＜ 0.05)。说明黄土高原三种人工林0-60 cm土层MNC主要贡献MAOC的积累,油松林0-10cm土层除外,且与细菌残体碳相比,真菌残体碳在土壤有机碳组分积累中的贡献更大,土壤总有机碳、全氮、黏粒、砂粒含量、pH值是影响该区不同人工林型微生物残体碳贡献土壤有机碳组分积累的主要因素。

Contributions of microbial necromass carbon to soil organic carbon fractions accumulation and influencing factors under different artificial forest types on the Loess Plateau

To explore contributions of microbial necromass carbon (MNC) to soil organic carbon (SOC) fractions under different artificial forest types, Robinia pseudoacacia, Armeniaca sibirica, and Pinus tabuliformis plantations on the Loess Plateau were selected as the study objectives. Then contributions of fungal necromass carbon (FNC), bacterial necromass carbon (BNC), and MNC to particulate organic carbon (POC) and mineral-associated organic carbon (MAOC) at 0—60 cm soil layers as well as its influencing factors under three artificial forest types were analyzed. Results showed that (1) contents of BNC, FNC, and MNC in POC and MAOC degraded with increasing of the soil layer depth under three types of artificial forest. (2) Contributions of MNC to MAOC accumulation under Robinia pseudoacacia and Armeniaca sibirica plantations were 60.9% and 52.0%, which were higher than that of POC (33.5% and 49.5%). The contributions of FNC to MAOC accumulation were 4.4 and 2.5 times that of BNC. For the Pinus tabuliformis plantation, contribution of MNC to POC accumulation at 0—10 cm soil layer was 73.8%, which was higher than that of MAOC (48.2%). And contribution of FNC to POC accumulation was 3.5 times that of BNC. However, at 10—60 cm soil layer, contribution of MNC to MAOC accumulation was 30.9%, which was higher than that of POC (24.4%). And contribution of FNC to MAOC accumulation was 3.4 times that of BNC. (3) There existed significantly positive correlations between SOC, total nitrogen contents and MNC/POC, MNC/MAOC (P ＜ 0.05). Clay content was positively correlated with MNC/MAOC significantly (P ＜ 0.05). However, pH value and sand content were negatively correlated with MNC/MAOC significantly (P ＜ 0.05). These results suggested that on the Loess Plateau, MNC at 0—60 cm soil layers mainly contributed to MAOC accumulation under three types of plantations, except for that in Pinus tabuliformis plantation at 0—10 cm soil layer. Compared to BNC, contribution of FNC to SOC fractions accumulation was higher. Contents of SOC, total nitrogen, clay, and sand as well as pH value were the major factors to affect contributions of MNC to SOC fractions accumulation.