Application of CCA for study on modern lake diatoms and environment in the Tibetan Plateau

Abstract

The relations between lake surface sediment diatoms and water environmental variables were revealed effectively by use of a new multivariate canonical correspondence analysis (CCA) based on 45 lakes in the Tibetan Plateau. Water depth, conductivity, Cl - , Mg 2+ , K + and pH, identified from 12 contemporary water environmental variables, can significantly and independently explain the diatom distributions ( p l 1=0.34, l 2=0.27) capture 16.1% of the variance in the species data, and account for 57.4% of the variance in diatom-environment relationship. The deletion of redundant environmental variables and unusual samples do not influence the explanation to diatom data. The final CCA result indicates that the water depth and the salinity are the two important environmental gradients and influence the diatom distribution in the plateau lakes. The water depth correlates with axis 1, while conductivity, Cl - , Mg 2+ and K + , indicating the direction of salinity changes, correlate with both of the first two axes. The definition of diatom-environment model may provide a basis for further quantitative inference on diatom-environment transfer function.