Seed bank of Littorella uniflora (L.) Asch. in the Czech Republic, Central Europe: does burial depth and sediment type influence seed germination?

Abstract

Littorella uniflora (Plantaginaceae) is a scarce and declining aquatic plant in Europe. Its population has been strongly reduced by changes in fishpond management (eutrophication) in the Czech Republic since the 1950s. We studied its seed bank in both recent (n = 8) and historical localities (the last found from 1972 to 2000; n = 10) and tested the effects of sediment type and burial depth on seed germination using extracted seeds from two recent populations. The seeds were found in 60% of the historical localities, mostly in low densities (≤6 seeds per 3.75 l of sediment), and also in 100% of the recent localities in various densities (8–1390 seeds per 3.75 l of sediment); however, low germination rates (0–13.3%) were estimated. The seeds germinated best on wet filter paper, followed by nutrient-rich fishpond sediment, but poorly on sand mixed with different substrates. Burial depth significantly affected seed germination. The seeds germinated only on the soil surface and at the depth of 1 cm but no seed germinated at the depth of 3 and 5 cm. Besides low water transparency, both high rate of sediment accumulation and the absence of summer drainage may endanger L. uniflora populations in fishponds.