| It is perceived that cow-calf operations in south Florida can be a substantial source of phosphorus loading to Lake Okeechobee. Spatial and temporal information of cattle location within a pasture can be instrumental in estimating the deposition location of cattle fecal matter. To address this issue, cattle position data were analyzed and a simplified distribution model was developed. Cattle position data were acquired through GPS collars and a cattle distribution model was developed and incorporated into a regionally tested hydrological/water quality model, ACRU2000.; The GPS data were spatially and temporally analyzed to quantify the amount of time spent by cattle near shade and water locations. The analysis revealed the prominence of seasonal utilization of water troughs, ditches, and shade. Shade structures were utilized substantially during the warm seasons. Wetland utilization was similar across cool and warm periods but was variably distributed across times within periods. The analysis also revealed that there can be significant differences in an individual cow's behavior and utilization of water features.; The GPS analysis was instrumental in the identification of variables to be included in the cattle distribution model. This distribution model was added as an add-on module within the 14 Java-based object-oriented framework of the ACRU2000 modeling system. The algorithms are composed of attractants of cattle (shade, water, and forage) and their weighting factors. The algorithms were developed using the techniques of Habitat Suitability Index (HSI) and criteria weighting was developed using the Analytical Hierarchy Process. The HSI model was integrated with the current hydrology, nutrient, and vegetation modules within ACRU2000.; The HSI model was calibrated and verified on summer pastures of Buck Island Ranch, Lake Placid, FL. Model verification revealed that its performance was in good agreement with observed GPS data. Several Best Management Practice scenarios, designed to mimic fencing of selected pasture areas, revealed that the phosphorus release from senesced biomass may be a significant store amongst all other pools of phosphorus. The HSI model has enhanced the capability of ACRU2000 to represent the spatial variability and nutrient effects of cattle distribution within complex agro-ecosystems of south Florida. |
