Changes of Nutrients in Calcareous Soils in Pine Rocklands Due to Fire.

The South Florida’s Pine rockland is a fire-dependent habitat. So far, most researches have focused on studying restoration and regeneration of vegetation and animals following fire. The objective of this study is to evaluate impacts of described fire on availabilities of phosphorous (P) and other nutrients in the Pine rockland’s ecosystem. Four specific tasks were: (i) determining changes of macro-nutrients and micro-nutrients following the fire in field-burning condition; (ii) determining how burning temperatures and soil moistures influence on nutrients’ availabilities under controlled conditions of laboratory incubation; (iii) evaluating an availability of different forms of inorganic P following the fire by using MINTEQ software; and (iv) constructing a dynamic model for simulation and prediction of P concentration. The Long Pine Key in the Everglades National Park was chosen for collecting samples. In the field-burning experiment, eleven sampling campaigns were chosen for soil collection, including a pre-burn and post-burns (2 weeks, 1 month, 2, 3, 4, 6, 9, 12, 18, and 24 months). Geo-statistical methods such as Variogram and Kriging were used to analyze spatial and temporal variability of treatments by the sampling. The repeated measure design was applied for ANOVA analysis of treatments. The preliminary results showed that there were significant differences of pH, EC, TC, and TN following the fire (p < 0.05). The pH and EC increased in 2 weeks and went back to the pre-burn’s values in 9 months after the fire. The TC and TN also increase in 2 weeks, but they reached the lowest values (below pre-burn’s values) in 3 months following the fire. In the lab-incubation experiment, seven periods applied for the incubation consisted of 3 days, 2 weeks, 1, 2, 3, 4, and 6 months. The preliminary results showed that the burning temperatures and soil moistures had significant effects on pH (p < 0.05) and EC, TC, and TN (p < 0.001).