沙漠化过程中科尔沁沙地植物-土壤系统碳氮储量动态

研究了科尔沁沙地不同沙漠化阶段(潜在、轻度、中度、重度和严重沙漠化)植物-土壤系统的有机碳与氮储量,以揭示沙漠化对碳氮动态的影响.结果表明,从潜在沙漠化到轻度、中度、重度和严重沙漠化,生物量(地上与地下)有机碳储量分别下降26.4%、51.0%、79.0%和91.0%,生物量氮储量分别下降33.6%、66.9%、87.4%和93.2%;土壤有机碳储量分别下降52.2%、75.9%、87.0%和90.1%,土壤全氮储量分别下降43.5%、71.0%、81.3%和82.7%.植物-土壤系统的有机碳与氮储量大小为:潜在沙漠化(C:5 266 g·m^-2和N:534 g·m^-2)>轻度沙漠化(C:2 619 g·m^-2和N:303 g·m^-2>中度沙漠化(C:1368 g·m^-2和N:156 g·m^-2)>重度沙漠化(C:715 g·m-^-2和N:99 g·m^-2)>严重沙漠化(C:517 g·m^-2和N:91 g·m^-2).研究结果表明,生物量碳氮储量的衰减在沙漠化后期(从重度到严重)快于沙漠化初期(从潜在到轻度),而土壤碳氮储量的衰减在沙漠化初期快于沙漠化后期;沙漠化过程中土壤有机碳储量的衰减要快于全氮,而生物量氮储量的衰减在沙漠化初期快于碳,在后期则相反.

Dynamics of Carbon and Nitrogen Storages in Plant-Soil System During Desertification Process in Horqin Sandy Land

Organic carbon and nitrogen storages in plant-soil system were measured at different desertification stages(potential,light,moderate,severe,and most-severe) in Horqin sandy land.From potential desertification to light,moderate,severe,and most-severe desertification,total biomass(aboveground and belowground) carbon storages decrease by 26.4%,51.0%,79.0%,and 91.0%,respectively,while total biomass nitrogen storages decrease by 33.6%,66.9%,87.4%,and 93.2%,soil organic carbon storages by 52.2%,75.9%,87.0%,and 90.1%,and soil nitrogen storages by 43.5%,71.0%,81.3%,and 82.7%,respectively.The carbon and nitrogen storages in plant-soil system are in the order: potential(C:(5 266) g·m^-2 and N: 534 g·m^-2)>light(C:(2 619) g·m^-2 and N: 303 g·m^-2)>moderate(C:(1 368) g·m^-2 and N: 156 g·m^-2)>severe(C: 715 g·m^-2 and N: 99 g·m^-2)>most severe(C: 517 g·m^-2 and N: 91 g·m^-2).The biomass carbon and nitrogen storages decline more rapidly at later desertification stage(from severe to most-severe) than initial stage(from potential to light),while soil carbon and nitrogen decline more rapidly at initial stage.There is a greater proportional decline in soil carbon than in nitrogen during desertification process.The biomass nitrogen storages decline more rapidly than carbon at initial stage,however,the case is reverse at later stage.