Variability in microhabitats prevalence in low lying peat polder ditches of the Netherlands

Small landscape elements such as ditches are an important remaining refuge for biodiversity in agricultural land especially in the Netherlands. By themselves ditches harbour steep gradients in environmental conditions creating a rich variety in microhabitat availability at the small scale. Regional variation in management and water quality could influence microhabitat variability among these ditches. Some 400 ditches in six major agricultural polder areas around Amsterdam were studied. Data were collected on ditch width, submerged or emergent plants, conductivity, bank height, slope and ditch depth. A principal component analysis using these variables showed observed variability and attributed to the ditch dimensions related to ditch maintenance carried out by the farmers and ditch water quality. Microhabitats prevalence such as percentage algal cover and emergent, vary greatly even in early spring. It was found that, there is a great variability between the ditches within the sampled agricultural polder areas.