Influence of land use and rainfall variability on nutrient concentrations in Florida Lakes

Abstract

Xiong C, Hoyer MV. Influence of land use and rainfall variability on nutrient concentrations in Florida lakes. Lake Reserv Manage. 35:25–37.This research examined impacts of regional differences (total phosphorus zones [TP Zones]), land uses within watersheds (agriculture, urban, forest and wetland), and rainfall variability on nutrient concentrations (phosphorus and nitrogen) in Florida lakes (n = 87). Nutrient concentrations varied directly with TP Zones, which can be used as background nutrient concentrations within regions of Florida. After accounting for regional differences, lakes within watersheds with high percent agriculture tended to have higher nutrient concentrations, though relationships with nitrogen were strongest, suggesting different nutrient-transport mechanisms. Lakes within watersheds with high percent urban development showed no significant effect on nutrient concentrations, suggesting good nutrient management in urban areas. Lakes in watersheds dominated by forested land cover had low nitrogen concentration reflecting nutrient-buffering capabilities of forest stands. Lakes in watersheds with greater wetland coverage tended to have high nutrient concentrations, conflicting with previous studies and reflecting the complex nutrient-related processes that occur within wetlands. Cumulative rainfall deviations measured over a 20 yr period were significantly correlated (both positively and negatively) with nutrient concentrations within approximately 40% of the study lakes and the mechanisms driving these relations may overshadow impacts of land use within watersheds and changes in land use over time on lake nutrient concentrations. A thorough investigation of watershed land uses and relations between rainfall and limnological mechanisms must be considered before applying a nutrient management strategy to individual lakes.