Distribution and phytosociological relations of two introduced plant species in an open sand grassland area in the Great Hungarian Plain
2002
Szigetvári, Cs
Two introduced plant species, <i>Cenchrus incertus</i> and <i>Ambrosia artemisiifolia</i> were studied in a 0.5 km<sup>2</sup> open sand area in the Kiskunság National Park. The site is covered by valuable semi-natural grassland and is bordered by dirt roads. The aim of the study was to assess the extent and pattern of the area occupied by the two species and to describe the composition of the vegetation invaded with more or less success. Populations of the two species were mapped. In each stand of <i>Cenchrus</i>, in fifty-three 4 m<sup>2</sup> quadrats aboveground plant cover, slope and exposition were documented. Both species concentrated on the roads. They – especially <i>Ambrosia</i> – were rare inside the intact part of the site, and were absent on abandoned roads. <i>Cenchrus</i> was found also in small patches not related to roads, in sites grazed with sheep. No colonization was detected from the road populations into adjacent intact natural vegetation. The analysis of the quadrats showed that <i>Cenchrus</i> cover was low where perennial or annual open sand grassland specialists dominated, and cryptogam cover was high. <i>Cenchrus</i> dominated quadrats on road or non-road sites were not discriminated from each other by cluster analysis. In non-road quadrats <i>Cenchrus</i> cover positively correlated with slope. <i>Ambrosia</i> was only present in quadrats taken on or near the roads. Aware of the life history traits of the species and of the vegetation dynamics of the target community it can be concluded that propagule transport, soil perturbation and disturbance of the native vegetation together enhance colonization and persistence of both species.
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