Plant diversity changes associated to <i>Gunnera tinctoria</i> invasion in Irish grasslands

2017-06-20T00:03:55Z (GMT) by Cristina Armstrong Javier Atalah
<p>In this study we have assessed and quantify the impacts of the invasive species <i>Gunnera tinctoria</i> on vegetation biodiversity at three different habitats, namely grasslands, riparian and coastal cliffs. Habitat selection was based on the extent and dominance of <i>G. tinctoria</i> invasion, e.g. grasslands and riparian habitats. Coastal cliffs were chosen as they are one of the few habitats which have little to no human influences. We hypothesized that alpha and beta vegetation diversity will be significantly reduced at all habitat types, irrespective if the habitats are highly disturbed, human influenced or semi-natural. Additionally, we hypothesized that changes in plant assemblage structure and composition will be associated to the invasion of <i>G. tinctoria</i>.</p><p>Plant assemblages were sampled in July 2009 at twelve sites in three different habitats (grassland, coastal cliff and waterways), differing in the invasion status by the <i>Gunnera tinctoria</i>, in Achill Island, Co. Mayo, West Ireland. </p><p>Within each habitat two locations were selected and within each location one invaded and one non-invaded site were sampled. The two locations in the grassland habitat were Dooega (53° 57.2’ N, 9°57.9’ W) and Sraheens (53° 57.2’ N, 9°57.9’ W), the two locations in the coastal cliff habitat were Dooega and Keel, and in the waterways the two sampled locations were Ashleam and Dooega River.</p><p> </p><p>In each habitat, invaded and non-invaded sites were chosen so that they were geographically interspersed. When possible, sites were chosen randomly from a larger pool of candidate sites and based on monitoring programme in the area. At each site, an area of 100 x 100 m was randomly selected were 4 replicated 1 m<sup>2</sup> quadrats were sampled. Percentage cover was estimated using the point-intercept method with a quadrat of 1 m<sup>2</sup> and 144 intersection points. Most conspicuous taxa were identified to species level, while others were grouped into functional-form groups. The intersection data was then transformed into percentage cover. Plants present in the quadrat not recorded by this method were given a cover of 1%. In the case of multi-strata growth, total percentage cover exceeded 100%.</p>