Land use, geomorphology and climate as environmental determinants of emergent aquatic macrophytes in boreal catchments

We studied the distribution patterns of emergent aquatic macrophytes in relation to land use, geomorphology and climate variables throughout Finland, using data collected from 848 catchments. Our results confirmed previous findings on climatic factors as major determinants of macrophyte distribution, but also catchment land-use, especially drainage ditch intensity, appear to be significant. Drainage ditch intensity had equal or higher contribution to emergent aquatic macrophytes as compared with that of geomorphology variables. To our knowledge this is the first analysis to show that ditch intensity increases emergent aquatic macrophytes at the national level. Overall, our results demonstrate that neither overgrowth problems nor natural distribution patterns of emergent aquatic macrophytes can be understood without analyzing the joint effects of land use, climate and geomorphology.