Spatial variability of soil properties in cypress domes surrounded by different land uses

Anthropogenic activities affect self-organization in wetlands, in turn affecting spatial patterns of soil properties such as pH, nutrient concentrations, and soil organic matter content. To better understand the effects of anthropogenic disturbance in wetlands, we examined soil patterns in wetlands subject to a gradient of human impact. Four cypress domes in north Florida representing reference/unmanaged, forest plantation, improved pasture, and urban land uses were sampled (n = 60 site(-1)) for soil pH, organic matter (OM), and total phosphorus (TP). Mean values varied significantly both within and among sites, with low pH, SOM, and TP at minimally impacted and plantation sites, and high values at pasture and urban sites. Within-site variability was large for SOM and TP in all sites (average coefficient of variation = 48% and 62%, respectively), and small for pH (average CV = 7%). Strong radial patterns for SOM and TP in minimally impacted and plantation sites were observed. In contrast, at pasture and urban sites linear/quadratic trends in pH were observed. We quantified spatial patterns by soil property for each site, observing significant structure (long range, low nugget:sill) for TP and SOM in minimally impacted and forest plantation sites. We infer a transition from endogenous to exogenous drivers with increasing anthropogenic influence. Our findings indicate that, for pH, a small number of samples (n < 3 for characterization within 10% of true mean) are needed, while more (n = 11-33) are needed for SOM and TP; sampling density requirements increase with the scale of spatial structure. Our results allow the definition of the necessary sampling intensity and design to achieve effective monitoring.