The Effect of Prescribed Fires in Biotic and Abiotic Factors on South Region of Puerto Rico.

In the South Region of Puerto Rico (PR), “field fires” have become a great problem primarily during the dry season due to the low precipitation. In 2013, the Fire Department (FDPR) reported about 800 fire events impacting around 16,000 acres of the island. The heat and ash produced during a fire event can modify and affect soil nutrient cycling, as well as altering the soil microbial communities (SMC). For that reason, prescribed fires were performed by the FDPR to mimic the effect of a field fire in a hillside area located in Juana Díaz Agricultural Experiment Stations (AES) on October 2015 and March 2017 and in Lajas-AES on March 2017. The predominant soil present in Juana Díaz- AES study area is Yauco silty clay loam (Typic Calciustolls) and in Lajas-AES study are is Mariana gravelly clay loam (Typic Haplohumults). In both locations, a complete randomized block design with four treatments and four replications for a total of sixteen plots (6.1 by 12 m, having the longest part oriented with the slope of the hill) were established. The treatments used after burning were: positive control (burned plots (BP), no remediation), negative control (non-BP), mulching treatment (BP remediated with Leucaena spp. mulch), and surfactant treatment (BP remediated with IrrigAid^® Gold surfactant). Composite soil samples were collected from 0-15 cm soil depth to assess soil nutrients and SMC before prescribed burning (as a benchmark), three and six months after prescribed burning the experimental plots.