摘 要(英文)：Purpose Prescribed burning can alter nutrient availability to plants. Plant growth in tropical and subtropical forests is frequently phosphorus (P) limited. Soil P availability is influenced by a combination of multiple factors including soil chemical and biological properties. The aims of this study were to investigate the short-term effects of prescribed burning on soil P status and to evaluate the key drivers responsible for the variation in soil P fractions.Materials and methods Soil samples were collected at a
depth of 0–10 cm at two sites in a suburban native forest.One site (the burnt site) was burned on 11 August 2011. The other site (the control site) was not burned but served as a reference. Sampling was conducted at four times: before burning, 12 days after burning (T1), 1 week after T1 (T2),and 1 month after T2 (T3). Soil pH, P fractions, microbial biomass carbon (C) and P, and activities of acid and alkaline phosphatase were measured.Results and discussion Total P was relatively low at both sites compared with other subtropical forests. Microbial biomass P accounted for approximately 10 % of soil total P at the two sites, suggesting that the turnover of microbial biomass is critical for soil P availability. Soil properties at the control site remained unchanged over the time. Soil
organic forms of P at the burnt site were decreased by the prescribed burning, and the greatest reduction was found in
moderately labile organic P (e.g., NaOH-extractable fractions).
Soil inorganic forms of P, however, were not correspondingly
increased by the prescribed burning. Microbial biomass P was closely related to the shifts in P fractions.These effects were only detected immediately after the fire.Conclusions Microbial biomass could serve as a sink of P in P-impoverished soils and play an important role in soil P transformation. Our results indicate that microbial biomass is an important factor that governs P status after prescribed burning. The rapid recovery of microbial biomass P could
be beneficial to the P requirement for plant regrowth after
prescribed burning.
Short-term effects of prescribed burning on phosphorus availability in a suburban native forest of subtropical Australia