黔中石漠化地区水土保持措施对土壤有机碳的影响

Effects of Different Soil and Water Conservation Measures on Soil Organic Carbon of Karst Rocky Desertification Region in Central Guizhou

土地石漠化是中国西南喀斯特地区的重大生态问题,石漠化治理引发土壤碳转变并对陆地碳循环产生影响。然而,石漠化地区水土保持措施对土壤有机碳的影响机制还不明确。选取典型石漠化区梯田嵌套鱼鳞坑(NL)、鱼鳞坑(FSP)、梯田(TR) 3种水土保持措施作为研究对象,以无任何水土保持措施的退耕还林地(CK)作为对照,研究不同水土保持措施土壤有机碳含量分布规律。结果表明:鱼鳞坑土壤有机碳含量分别是梯田嵌套鱼鳞坑和梯田的1.4,6.2倍,有机碳储量分别比梯田嵌套鱼鳞坑和梯田提高30.78%和444.44%,活性有机碳含量也显著大于其他2种水土保持措施,因此固碳效果最好。土壤有机碳储量与活性有机碳组分易氧化碳、可溶性碳、微生物量碳呈极显著相关(p<0.01),易氧化碳与可溶性碳、微生物量碳呈极显著相关(p<0.01),可溶性碳与微生物量碳呈显著相关(p<0.05),因此土壤活性有机碳组分能在一定程度上反映土壤质量变化情况。鱼鳞坑和梯田措施土壤全氮含量和碳氮比的增加会促进土壤有机碳固存。鱼鳞坑可作为石漠化地区生态恢复中优先考虑的治理措施。

Rocky desertification is an urgent ecological problem in karst areas of Southwest China. The control of rocky desertification leads to the transformation of soil carbon and has an impact on land carbon cycle. However, the effects mechanism of soil and water conservation measures on soil organic carbon in rocky desertification areas is not clear. Three soil and water conservation measures—Nested Ladder(NL), Fish Scale Pit(FSP) and Terrace(TR) in typical rocky desertification area were selected, and compared with natural slope(CK) to study the distribution law of soil organic carbon content. The results showed that the organic carbon content of FSP was 1.4 and 6.2 times higher than that of NL and TR respectively. The organic carbon storage in the 0—20 cm soil layer of the FSP was higher than that in NL and TR by 30.78%, 444.44% respectively. The soil active carbon content of FSP was also significantly higher than that of the other two water and soil conservation measures, so its carbon sequestration effect was the best. The storage of organic carbon was significantly positively correlated with the easily oxidized carbon, soluble carbon and microbial biomass carbon(p < 0.01), the easily oxidized carbon was significantly positively correlated with soluble carbon and microbial biomass carbon(p < 0.01), and the soluble carbon was significantly correlated with microbial biomass carbon(p < 0.05). The increase of carbon nitrogen ratio in FSP and NL would promote soil organic carbon sequestration. The study shows that FSP can be used as a priority control measure in the ecological restoration and construction of rocky desertification areas in the future.