Species-based classification reveals spatial processes of phytoplankton meta-communities better than functional group approaches: a case study from three freshwater lake regions in China

Phytoplankton communities respond rapidly to environmental selection at a given locality, and they are also shaped by spatial processes at certain scales. The extracted effect of environmental selection and spatial processes may vary if different classification approaches are applied to phytoplankton and the spatial scales. In this study, summer phytoplankton of 43 lakes from three major lake regions in China were investigated and phytoplankton were classified with three approaches: taxonomy of species, habitat template-based functional groups, and morphology-based functional groups. Within a single lake region, the pattern of phytoplankton meta-community was significantly explained by environmental but not by spatial variables. In a larger scale covering all the three lake regions, both environmental and spatial variables explained the variance of the phytoplankton community, but the spatial variables were detected only by classification with species, and only the environmental variables were detected with phytoplankton functional groups. This study revealed that although vegetative populations of different species sorted into the same functional group have common response to environmental changes, their dispersal abilities, mechanisms, and strategies might differ markedly and therefore the species-specific approach cannot be disregarded when studying phytoplankton patterns at spatial scales.