Acacia cyclops is a widespread invader in Mediterranean-climate regions. However, although its naturalizationin the Mediterranean Basin dates back only a few years ago, and the invasion process has not beenstudied hitherto. We investigated seedlings recruitment strategy adopted by A. cyclops in a small island(Lampedusa, Italy) where its natural regeneration was strictly confined under mother plants canopy.Healthy plants (DCP), plants at incipient senescence (SCP) and dead plants (DP) were distinguishedaccording to vitality and canopy status. Living plants were also characterized in relation to leaf C andN isotope composition. Regeneration pattern (seedlings and saplings abundance) was related to themicroclimatic differences (soil temperature, air temperature and humidity, soil nutrients, light) observedbetween canopies and adjacent open areas, and among canopy types. Living canopies ensure milderconditions, reducing extreme values as well as fluctuations between night and day. However, beneathcanopies (DP, SCP and DCP) seedlings may benefit from significantly higher soil nutrients content thanin the outside, while light availability was much higher under DP. Saplings to seedlings ratio was foundto be around 12 under DP, while under SCP it was slightly higher than 1, and just less than 0.5 under DCP.Moreover, saplings growth was significantly higher under SCP and DP, suggesting a prominent role oflight in driving seedlings recruitment. Stable isotope analyses of C and N provided ecophysiologicalinformation in relation to changes in canopies structure. Thus, while seedling stage appears to be morenutrient-limited, subsequent sapling stage is much more light-limited. Although the species is not yetdisplaying an invasive spreading on the island, our study provides clear evidence that senescent canopiesare better facilitators than healthy in preserving the invasive potential of A. cyclops. This finding suggestssome best practices in order to gradually reduce the presence of the alien species within its pristinenuclei of introduction.
|Numero di pagine||8|
|Rivista||Forest Ecology and Management|
|Stato di pubblicazione||Published - 2014|
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