Accumulated soil seed bank of the invasive sand dropseed ( Sporobolus
cryptandrus ) poses a challenge for its suppression.
Abstract
Global warming, elevated atmospheric CO 2
concentrations, and increased likeliness of extreme drought and
wildfires in many regions will likely favour C4 grass species. We
explored the effect of the encroachment of an invasive perennial C4
grass, Sporobolus cryptandrus on the composition of soil seed
banks in dry sand grasslands in Central Europe. In five mass-locality
sites of the species we assessed the composition and vertical
segmentation of the soil seed bank in twelve 1-m 2
plots along an increasing cover of the invasive species. We found that
the seed bank diversity and density decrease with the increasing
sampling depth; the decrease of density is affected by the increasing
Sporobolus cover. Neither the diversity nor the seed bank density
of other species were affected by increasing Sporobolus cover
but, affected by the sampling site. Most of the studied seed bank
characteristics were affected by the sampling depth, but none of them
were affected by the increasing cover of Sporobolus. Increasing
cover of Sporobolus in the vegetation was associated with an
increasing proportion of Sporobolus seeds in the seed bank, and
we found viable seeds of the species in the soil even in plots with no
Sporobolus cover. Given that a decrease in the precipitation of
the summer months and an increase in the frequency of droughts is
projected in this region, we expect that the accumulated massive seed
bank of Sporobolus will facilitate the further rapid spread of
the species.