For the effective control of an invasive species, gathering as much information as
possible on its ecology, establishment and persistence in the affected communities
is of utmost importance. We aimed to review the current distribution and characteristics
of Sporobolus cryptandrus (sand dropseed), an invasive C4 grass species of North American
origin recently discovered in Hungary. We aimed to provide information on (i) its
current distribution paying special attention to its invasion in Eurasia; (ii) the
characteristics of the invaded habitats in Central Europe; (iii) seed bank formation
and germination characteristics, crucial factors in early establishment; and (iv)
the effects of its increasing cover on vegetation composition. Finally, we aimed to
(v) point out further research directions that could enable us to understand the invasion
success of this potential invasive species. Field surveys uncovered large stands of
the species in Central and Eastern Hungary with most of the locations in the former,
especially in the Kiskunsag region. The species invaded disturbed stands of dry and
open sand grasslands, closed dune slack grasslands and it also penetrates natural
open sand grasslands from neighboring disturbed habitats. Increasing cover of Sporobolus
cryptandrus was associated with a decline in species richness and abundance of subordinate
species both in the vegetation and seed banks, but a low density of Sporobolus cryptandrus
can even have a weak positive effect on these characteristics. Viable seeds of Sporobolus
were detected from all soil layers (2.5 cm layers measured from the surface to 10
cm in depth), which indicates that the species is able to form a persistent seed bank
(1114 to 3077 seeds/m(2) with increasing scores towards higher abundance of the species
in vegetation). Germination of Sporobolus cryptandrus was negatively affected by both
litter cover and 1 cm deep soil burial. To sum up, Sporobolus cryptandrus can be considered
as a transformer invasive species, whose spread forms a high risk for dry sand and
steppe grasslands in Eurasia. We can conclude that for the effective suppression of
the species it is necessary: (i) to clarify the origin of the detected populations;
(ii) to assess its competitive ability including its potential allelopathic effects;
(iii) to assess its seed bank formation potential in habitats with different abiotic
conditions; and (iv) to assess the possibility of its suppression by natural enemies
and management techniques such as mowing or livestock grazing.
