The gas exchange of Carex species from eutrophic wetlands and its dependence on microclimatic and soil wetness conditions

Sedges of the genus Carex (Cyperaceae) are often the dominant species in wetland vegetation in the temperate zones nearly all over the world. Knowledge of gas exchange and stomata behaviour of sedges is significant for understanding the exchange of water vapour and carbon dioxide between wetlands and the atmosphere. The gas exchange of four Carer species from eutrophic wetlands was studied in an experimental site of the Botanical Garden Dusseldorf (Germany). Transpiration (E) and net-assimilation (A), leaf conductances (g) and microclimatic parameters were measured porometrically during two vegetation periods. Patterns of dependence of leaf gas exchange on microclimatic conditions were worked out for the different species and culture regimes. The sedges differ in stomatal sensitivity to changing air humidity and therefore in regulation of transpirational water loss. The importance of these species-specific differences in modelling and upscaling water vapour, carbon dioxide and trace gas fluxes are pointed out. (C) 1998 Elsevier Science Ltd. Air rights reserved.