Soil Inorganic Phosphorus Fractions of Remnant Native and Plantation Forests in Foshan Region

Abstract:

Soil phosphorous (P) availability is always thought to be a limiting factor for ecosystem primary productivity in the highly weathered tropical and subtropical areas, but our knowledge about soil P availability in tropical and subtropical forests is still poor, particularly in remnant native forests and frequently disturbed plantation forests in the urban and suburban areas. The soils at 0-3 cm and 3-23 cm mineral depths from 14 forest patches in Foshan region (seven native forest patches and seven plantation forest patches) were collected, and pH in water and concentrations of organic carbon (C), total nitrogen (N), total P, Bray-1 Pi and sequential extractable inorganic P fractions to estimate soil P availability were determined. The results showed that Fe-Pi and reductant soluble inorganic P were major inorganic P fractions at the study forest patches. Most of the selected soil nutrient measures did not differ significantly between forest types in both soil layers. The concentrations of Al-Pi, Bray 1-Pi and total Pi in the 0-3 cm mineral soil layer and Ca-Pi in the 3-23 cm mineral soil layer were significantly lower at the plantation forest patches than those at native forest patches. Concentrations of organic C, total N, total P and all P fractions were significantly higher in 0-3 cm mineral soil layer than those in the 3-23 cm mineral soil layer for both forest types. Correlation analysis indicated that soil organic matter concentration was significantly and positively correlated with soil concentrations of all inorganic P fractions except Ca-Pi. Fourteen selected forest patches could be divided into three groups according soil P availability by Cluster analysis. Generally, the plantation forest patches were lower in soil P availability compared to native forest patches. These could help us for understanding the soil nutrient status and strengthen nutrient management at remnant forest patches in the urban and suburban areas.

Key words:Inorganic phosphorus fractions;Remnant forest;Phosphorus availability;Foshan region