Natural restoration has better soil acid phosphatase kinetics than artificial plantations

Abstract

Soil acid phosphatase kinetics is important for clarifying phosphorus supply under different soil fertility conditions. However, little is known about the effects of the forest restoration type on the kinetics of soil acid phosphatase. Using a microplate fluorometric assay, we tested soil acid phosphatase kinetics and influencing factors in artificially restored native oriental oak (Quercus variabilis Bl.) plantations and introduced Japanese black pine (Pinus thunbergii Parl.) plantations and naturally restored secondary forests. Five, five, and six plots were randomly selected from each forest restoration type in Yimeng Mountain area in Northern China. Forest restoration type significantly influenced acid phosphatase kinetics. Acid phosphatase activity and acid phosphatase activity dissimilarity was higher in natural secondary forests than those in oriental oak plantations, which in turn were higher than those observed in black pine plantations. The difference between natural secondary forests and black pine plantations was significant. Moreover, the heterogeneity of soil acid phosphatase activity between the natural secondary forests and the two plantations was significantly higher than that between the two plantations. Forest restoration type did not significantly influence the potential maximum activity (V_max), half-saturation constant (K_m), or catalytic efficiency (V_max/K_m) of acid phosphatase. Ammonium nitrogen and available phosphorus content significantly influenced acid phosphatase kinetics, explaining 61.9% of the variation in acid phosphatase activity under different substrate concentrations in the three forest restoration types. V_max was positively influenced by available phosphorus content. The K_m value was positively influenced by total carbon content. Natural secondary forests showed better soil acid phosphatase kinetics than the native oriental oak plantations, which were better than those in the introduced black pine plantations, possibly due to the higher ammonium nitrogen and available phosphorus content. This study contributes novel insights into phosphorus supply under forest restoration types, ultimately providing theoretical bases for forest restoration in warm temperate areas.