Environ Exp Biol (2017) 15: 113–126

Adaptation strategies of rare plant species to heterogeneous soil conditions on a coast of a lagoon lake as revealed by analysis of mycorrhizal symbiosis and mineral constituent dynamics

Abstract

Soil chemical heterogeneity in sea-affected wetlands and its effect on mineral nutrition is a seldom studied aspect in ecophysiology of wild plants. The aim of the present study was to analyze seasonal changes in concentration of different mineral nutrients in leaves of several salt marsh species (Aster tripolium, Glaux maritima, Plantago maritima, Trifolium fragiferum, Triglochin maritima) in comparison to changes of plant-available nutrients in soil, with emphasis on mycorrhizal symbiosis. Extreme heterogeneity was noted for soil mineral nutrient concentrations, varying both spatially and temporiarily. A pronounced correlation between the concentrations of different soil mineral nutrients was observed. Early season flooding at the end of May coincided with a peak of summary precipitation and high sea level, and eventually resulted in significant increase in soil salinity in June. Peaks of Na and Cl accumulation in plant leaves in June were clearly related to the corresponding peak of soil concentrations of the respective ions. Seasonal trends of soil mineral concentrations were compared with respective leaf mineral concentration dynamics of the five species studied within the season. In general, a trend of leaf N concentration folowed that for soil N content. Minimum intensity and frequency of mycorrhizal symbiosis in July corresponded to the peak of soil salinity in June for roots of A. tripolium, G. maritima, P. maritima, and, possibly, T. fragiferum. Mycorrhizal symbiosis of G. maritima was the most sensitive to these conditions, with the intensity close to zero in July and August. Both intensity and frequency of mycorrhizal symbiosis in roots of T. maritima was highest in July, with significant decrease in August and September. The presence of arbuscules was evident in roots of all species, but with different intensity at different time points. The results of this study support the hypothesis that wild plants native to habitats with heterogeneous soil conditions have developed effective physiological adaptations allowing to grow normally and reproduce within a wide range of mineral concentration, as well as drastic changes in soil salinity.