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Interacting effects of atmospheric CO 2 enrichment and solar radiation on growth of the aquatic fern Azolla filiculoides
Author(s) -
Kempen Monique M. L.,
Smolders Alfons J. P.,
Bögemann Gerard M.,
Lamers Leon P. M.,
Roelofs Jan G. M.
Publication year - 2016
Publication title -
freshwater biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 156
eISSN - 1365-2427
pISSN - 0046-5070
DOI - 10.1111/fwb.12724
Subject(s) - azolla , photorespiration , fern , biomass (ecology) , botany , biology , temperate climate , photosynthesis , environmental science , ecology
SummaryAzolla spp. rank among the fastest growing plants in the world. Increased atmospheric CO 2 concentrations can be expected to have a strong impact on the biomass production of this fast growing floating fern, especially at northern latitudes. We investigated the growth of the northernmost occurring species, A. filiculoides , under past (Eocene), present and predicted future CO 2 levels. To study the interacting effects of temperature and solar radiation, we performed the atmospheric CO 2 fertilisation experiments in spring, summer and autumn. Azolla filiculoides grown at 1600 ppm CO 2 produced twice as much biomass as when grown at 400 ppm CO 2 in spring and autumn. However, high summer temperature and solar radiation seemed to significantly lower its maximum growth potential, presumably as a result of a metabolic shift as indicated by water loss. Nutrient availability became more important at higher atmospheric CO 2 concentration. In addition, high temperature and solar radiation affected the nitrogen concentrations in A. filiculoides , most likely by inducing photorespiration and photoinhibition. Our results indicate that temperate Azolla may become more productive in temperate regions as a result of rising atmospheric carbon dioxide concentrations. In addition, our results can help to explain the reported massive Azolla event in the Eocene.