Ecophysiological response of dune species to experimental burial under field and controlled conditions

Field, greenhouse, and growth chamber experiments were conducted to determine the effects of different burial treatments on photosynthesis (carbon dioxide exchange rate), chlorophyll-a fluorescence, leaf area, biomass, leaf thickness, total chlorophyll content and chlorophyll a/b ratio of ten sand dune species: Agropyron psammophilum, Cakile edentula, Cirsium pitcheri, Corispermum hyssopifolium, Elymus canadensis, Oenothera biennis, Panicum virgatum, Strophostyles helvola, Tusilago farfara, and Xanthium strumarium. Although there were significant differences between species, all of them exhibited stimulation in growth following burial in sand. Generally, buried plants of these species showed an increase in biomass, photosynthetic efficiency, and chlorophyll-a fluorescence because of higher energy content in their roots, rhizomes, and underground stems. The main reasons for the stimulation in growth were an increase in leaf area, leaf thickness, and root biomass. The total chlorophyll content of leaves of buried plants of A. psammophilum, E. canadensis, and P. virgatum was higher than controls, but there were no significant differences for Cirsium pitcheri, O. biennis, and S. helvola. The similarities and differences exhibited by the test species in their responses to burial would be ecologically adaptive to survive the harsh environmental conditions of foredunes. All species showed a clear compensatory response following recovery from the burial episode and surpassed control by enhancing the vital physiological, morphological and growth functions.