Land–use change alters soil phosphorus fractions in tropical forests in southeastern Brazil
摘要
Land–use change in tropical regions alters essential nutrient cycling processes, especially phosphorus (P), an element that is often limiting in weathered soils. Understanding how these changes affect the dynamics of P fractions and cycling via litterfall is critical to ensuring the sustainability of forest ecosystems. This study aimed to evaluate the effects of land–use change on litterfall production and the distribution of P fractions in the soil in tropical forests in southeastern Brazil. The study was conducted in two different land–uses: (i) natural forest fragment; and (ii) Pinus caribaea plantation, located in southeastern Brazil. The physical and chemical characteristics of the soil, accumulated litterfall, nutritional composition of litterfall, physical fractionation of soil organic matter and P fractions in the 0–10, 10–20, and 20–40 cm depth layers were evaluated. Soil P fractions were significantly influenced by land–use. Greater Psol contents were observed in forest fragment areas, while greater PM3 and PoOH fraction values were found in the 20–40 cm layer in the Pinus caribaea plantation, suggesting greater immobilization and fixation of P in fast-growing environments. These results highlight the complexity of nutrient cycling in tropical soils and the influence of land–use on its availability. The effect of land–uses on soil C fractions (TOC, pOC, and MOC) was more pronounced at 20–40 cm depth, with higher values under Pinus caribaea. The litterfall accumulated was significantly greater in the Pinus caribaea plantation (46.0 Mg ha–1) compared to the forest fragment (8.3 Mg ha–1). In addition, the accumulation of N, P, Ca, and Mg in litterfall was, on average, 2.5 times greater in the plantation, indicating that the greater supply of needles contributes to accelerating nutrient cycling and favoring the maintenance of soil fertility in short rotations.