不同经营年限对柑橘果园土壤有机碳及其组分的影响

土壤有机碳库是全球碳循环的重要组成部分，其积累和分解的变化直接影响全球的碳平衡。果园是我国重要的土地利用类型之一，果园面积占我国土地总面积的1.15%。因此，研究果园土壤有机碳库的演变规律，对于准确评估我国陆地生态系统的固碳潜力具有重要的科学意义。利用时空替代和物理、化学分组的方法比较研究不同经营年限对柑橘果园土壤有机碳库及其组分的影响，旨为果园土壤固碳增汇机理研究提供科学依据。利用时空替代法和物理化学分组的方法比较研究经营年限对柑橘果园土壤有机碳库及其组分的影响。结果表明：50年代柑橘果园0~20 cm和20~40 cm土层颗粒有机碳和轻组有机碳含量分别比80年代柑橘果园提高了9.6%和23.60%、2.57%和3.63%，其中对0~20 cm土层的影响显著高于20~40 cm，说明果园经营干扰对土壤活性有机碳的影响随着土层的加深而降低。50年代柑橘果园0~20 cm土层土壤有机碳含量比80年代果园提高27.2%，可溶性有机碳提高20.1%，微生物生物量碳提高5.3%；50年代柑橘园0~100 cm土层有机碳储量比80年代柑橘园提高30.3%，但50年代柑橘园的土壤颗粒有机碳、轻组有机碳、可溶性有机碳和微生物量碳占总有机碳的比率均低于80年代柑橘园，说明当种植年限超过30年后，随着种植年限增加，果园土壤有机碳质量存在退化的风险。

Effect of Different Cultivation Years on Soil Organic Carbon Pools in Citrus Orchards

Soil organic carbon is an important component of the global carbon cycle,and it has direct effects on the global carbon balance. Orchard is an important part of the landscape land, the area of which accounts for 1.15% of the total land area in China. To study the dynamic of soil organic carbon stock in orchard,would provide an important scientific basis to accurately evaluate carbon sequestration potential of terrestrial ecosystems. Effect of different cultivation years on soil stable organic carbon pools and fractions in Citrus orchard was investigated to elucidate the mechanism responsible for orchard soil carbon sequestration using the temporal-spatial substitution and physical and chemical fractionation methods. The results showed that the particle organic carbon content of 60’ citrus orchards in the 0~20 cm and 20~40 cm soil layers increased by 9.6% and 2.57% than those of 30’ citrus orchards, respectively, the light fraction organic carbon content increased by 23.6% and 3.63%, respectively. The variation of labile organic carbon in the 0~20 cm soil layer was significantly higher than that of the 20~40 cm soil layer. It indicated that the effect of orchard management on labile soil organic carbon decreased with the increase of soil layer depth. The results also showed that the 60＇ s citrus orchard compared with 30＇s citrus orchard citrus orchard, the content of organic carbon in the 0~20 cm soil layer increased by 27.%, dissolved organic carbon content increased by 20.1%, microbial biomass carbon content increased by 5.3%. Soil organic carbon storage of 60＇s citrus orchard in 0~100 cm soil layer increased 30.30% more than that of 30＇s citrus orchard. Compared with 30＇s citrus orchard, soil particulate organic carbon, light fraction organic carbon, dissolved organic carbon and microbial biomass carbon in the ratio of total organic carbon in 60＇s citrus orchard were all lower. It showed that more than 30 years after planting period, there is degradation risk of soil organic carbon quality with