Abstract: Abstract: 【OBJECTIVE】It is recognized that cultivation strongly affects important ecosystem processes such as biomass accumulation, and thus changes cycles of C and nutrients in soils. However, changes of organic C, N and P distributions in different size fractions of the sandy soils after deforestation is insufficiently understood. 【METHOD】In this study, chemical forms and distribution of organic C, N, and P in different size of aggregates in a sandy Spodosols with three land uses in Florida were assessed. The three land uses were: (1) undisturbed natural forest, (2) 15-25 year citrus groves, and (3) 15-25 year vegetable farms. 【RESULTS】The organic C concentration in surface soils (0-15 cm) was significantly higher under natural forest (24.8 g kg-1) compared to the citrus groves (8.1 g kg-1) and vegetable farms (5.1 g kg-1). After deforestation, vegetable farms and citrus groves depleted soil organic C pool by 79% and 67%, and soil N by 64% and 31%. Soil C:N rations were lower in the agricultural soils (11-19) than that in the forest soils (25-37). The decrease of the particulate organic C (POM-C) was more significant than that of other organic C (non-particulate organic C). The proportions of POM-C in the total C were 69.1%, 41.0%, and 12.5%, respectively, for forest, citrus and vegetable soils. For forest soils, organic C and total N were mainly distributed in the > 0.5 mm and 0.25-0.5 mm aggregate fractions. For vegetable and citrus soils, organic C and total N were mainly distributed in the 0.25-0.5 mm and 0.053-0.125 mm aggregate fractions. Among the five aggregate fractions, total P was the highest in the >0.5 mm and <0.053 mm aggregate fractions. Phosphorus accumulated mainly as HCl-P in the agricultural soils, whereas NaOH-OP (organic P) and H2O-P was major P forms in the forest soils. 【CONCLUSION】The study indicated that the transformation of forest land to cultivated land could weaken the accumulation of C and N in sandy soils. The deforestation could affect greatly the forms of organic C, N and P, and their distribution in aggregate fractions of sandy soils.