The influence of flood duration on the surface soil properties and grazing management of karst wetlands (turloughs) in Ireland

摘要

Irish turloughs are hydrologically dynamic karst wetlands that are frequently used as marginal grazing land. We hypothesised that flood duration (FD) is a key driver of the spatial distribution of selected soil properties, and consequently turlough grazing practices. Six soil samples were collected during dry periods from eighteen turloughs between 2006 and 2008. Samples (n = 104) were analysed for pH, organic matter (OM) content, calcium carbonate content (CaCO3), sand/silt/clay content (INORG), total nitrogen (TN) and total phosphorus (TP). Data on flooding duration, flood frequency, grazing regime and vegetation type were collated for each soil sampling point. Multivariate and univariate statistical analyses were used to examine the relationships between soil properties, grazing regime and flooding variables. There was a positive association between CaCO3, FD and sedge-dominated communities, whereas INORG had a positive association with grazing and grassland. There was a strong positive association between TN, TP, OM and soil depth rather than FD, and OM was found to be an efficient predictor of TN. Extended FDs in ephemeral karst wetlands are likely to increase the extent and degree of calcium carbonate accumulation in soils, thus, reducing the grazing potential of land.