Relationship Between Soil Organic Carbon And Soil Productivity At Plot Scale In Hilly Red Soil Region

Global climate change and its impact is one of the most serious environmentalproblems （that human faces in current days）. As the largest organic carbon reservoirin the Earth’s surface, soil carbon pool plays an important role in the global carboncycle. Land use can cause a series of changes such as soil nutrients, moisture, surfacerunoff and erosion, and biogeochemical cycles (etc.), and cause the changes of soilcarbon storage. Therefore, studying the relationship between soil carbon and herbbiomass (represents soil productivity) is of great theoretical and practical significancefor discussing the essence of degradation on soil productivity so as to adopt properecological and environmental protection measures.To explore the reasons for decrease in soil productivity in the hilly red soil regionof Southern China, based on the long-term monitoring soil erosion, the studyinvestigated the effect of different land use (wasteland, pinewood, grassland) ondistribution of soil properties, soil organic carbon content in different sized particlesand soil active organic carbon and its relationship to herb biomass. The results are asfollows:(1) SOC (soil organic carbon), organic carbon content in different sized soilparticles and active organic carbon are the key factors for impacting herb biomass.SOC is not the decisive factor for herb biomass on wasteland slope, however, it playsa critical role in herb biomass on pinewood slope and grassland slope. Organic carbonin sand has considerable impact on herb biomass on the slope mainly coved withherbs (wasteland and grassland). DOC, ROC, MBC are key factors affected herbbiomass in wasteland slope, pine forest slope, grassland slope respectively.(2) The effect of land uses on soil properties, organic carbon in different sizedsoil particles and active organic carbon is more obvious. Different land uses havedifferent effect on soil properties, and the variability of soil properties is larger;Organic carbon in different sized soil particles performance for grassland＞pineforest＞wasteland, and the proportion of organic carbon in different sized soil particles may not be relevant to land uses and slope positions; ROC and MBC areexpressed as largest in grassland, and it is consistent for pineforest and wasteland,while DOC is shown as grassland＞pineforest＞wasteland.