Subjects: Geosciences >> Geography submitted time 2025-04-08 Cooperative journals: 《干旱区研究》
Abstract： This study focuses on Robinia pseudoacacia plantations of different stand ages (18, 22, 26, 30, 33, and 40 years) in the Caijiachuan watershed of Jixian County, located in the Loess Plateau region of western Shanxi Province. Using the Hedley phosphorus fractionation method, we investigated the distribution patterns of soil phosphorus fractions (H2O-P, NaHCO3-P, NaOH-P, D.HCl-P, C.HCl-P, Residual-P) in the 0-100 cm soil layer across different stand ages, clarified the variations in soil phosphorus fractions with stand age, and analyzed the effects of soil physicochemical on the variations. The results showed that: (1) the average total phosphorus (TP) content in the 0-100 cm soil depth of different stand ages followed this trend: 30 a (590.44 mg·kg-1) > 26 a (571.68 mg·kg-1) > 22 a (527.05 mg·kg-1) > 18 a (517.83 mg·kg-1) > 33 a (490.71 mg·kg-1) > 40 a (464.49 mg·kg-1). The proportions of phosphorus fractions in the soil were as follows: stable phosphorus > residual phosphorus > moderately active phosphorus > active phosphorus. (2) The contents of all phosphorus fractions initially increased and then decreased with stand age, reaching the highest levels in 30 a plantation. Both TP and phosphorus fractions decreased with increasing soil depth. (3) Redundancy analysis revealed that soil total nitrogen (TN) content and soil pH were the main factors influencing the variation in phosphorus fractions. During the early afforestation stages, soil phosphorus fractions in Robinia pseudoacacia plantations gradually accumulate, peaking at intermediate stand ages. As stand age increases, phosphorus limitation becomes more pronounced, resulting in a gradual decline of soil phosphorus fractions after reaching maturity. Therefore, from the perspective of phosphorus limitation, appropriate phosphorus fertilization at around 30 a can effectively mitigate phosphorus deficiency in the later stages of Robinia pseudoacacia plantations in the Loess Plateau region of western Shanxi Province.
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