Distribution characteristics of soil aggregate and its carbon and nitrogen in Pinus massoniana plantation with different development stages in central Guizhou province
[Objective]Investigate the effects of development stages on soil aggregate and its nutrient contents of Pinus massoniana plantation so as to provide a insights for the rational use of soil in P.massoniana plantation.[Method]Using the method of space instead of time,P.massoniana plantation at different development stages in central Guizhou province(young-aged forest→middle-aged forest→near-mature forest→mature forest→overripe forest)was selected as research material,and then based on the method of aggregate size fractionation,the composition,stability,carbon and nitrogen concentrations of soil aggregate and their correlation with each other were analyzed.[Result]1)The mass percentage of aggregate in the 0-80 cm soil layer at different development stages was as macroaggregate(45.57%-91.20%)＞microaggregate(7.24%-32.87%)＞slit-clay aggregate(1.09%-21.56%),the mass percentage of macroaggregate decreased with the deepening of the soil layer,while the microaggregate and slit-clay aggregate increased,the mass percentage of macroaggregate decreased in the later development stages,while the microaggregate and silt-clay aggregate was the opposite;2)The values of MWD and GMD in the 0-80 cm soil layers at different development stages were 0.57-1.04 and 0.30-0.92 mm,respectively,the MWD and GMD decreased significantly with deepening of the soil layer,there was no significant difference in MWD and GMD from young-aged to near-mature stage,which decreased significantly in mature stage and increased to some extent in overripe stage;3)The average contents of C and N in macroaggregate,microaggregate and silt-clay aggregate at different development stages were 18.47-32.61,1.20-1.98,21.99-38.42,1.12-1.80,14.49-29.39 and 0.94-2.45 g∙kg-1,respectively,the contents of C and N in each aggregate basically decreased with the deepening of soil layer,the contents of C and N in macroaggregate and micro-aggregate first increased and then decreased with forward development,while the contents of C in slit-clay aggregate decreased,N contents showed a fluctuating trend;4)The mass percentage of macroaggregate,C and N contents in each aggregate were positively correlated with MWD and GMD,there were significant positive correlation between C and N of the same aggregates,as well as C and C,C and N,N and N of different aggregates.[Conclusion]In the later development stages of P.massoniana plantation in central Guizhou province,the stability and the nutrients contents of soil aggregates decreased.
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