Factors controlling vegetation structure in peatland lakes-Two conceptual models of plant zonation

Two conceptual models of plant zonation in peatland lakes are given. The first represents vegetation on slightly sloping substrate (N<0.2) in shallow and relatively large lakes. The vegetation is not diverse (H' = 0.0+/-0.01). The frequency and biomass of the dominant (Sphagnum denticulatum) correlate positively with lake size, and negatively with depth and substrate slope. They are also correlated with water transparency and water color (r = -0.53), concentrations of total organic carbon (r = -0.43), Ca2+ (r = 0.40) and humic acids (r = -0.46), and redox potential (r = 0.44). The second model represents vegetation on steep peat walls (N>0.3) in deep, usually small lakes. Plants occur only on the upper part of the peat wall or form a multispecies curtain hanging from the lip of peat at the top. Species diversity in this scenario is higher (H' = 0.18+/-0.17). The curtains usually are composed of mosses such as Warnstorfia exannulata, S. cuspidatum and S. riparium, and vascular plants are rare. The frequency and biomass of bryophytes in this type of structure are related to substrate slope (r = 0.56), lake depth (r = 0.56), Ca2+ concentration (r = -0.69) and water color (r = -0.51). In both models, plant biomass is correlated with temperature (r = -0.78), irradiance (r = -0.64) and water oxygenation (r = -0.54). (C) 2011 Elsevier B.V. All rights reserved.