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Alien and native plant life‐forms respond differently to human and climate pressures
Author(s) -
Marini Lorenzo,
Battisti Andrea,
Bona Enzo,
Federici Germano,
Martini Fabrizio,
Pautasso Marco,
Hulme Philip E.
Publication year - 2012
Publication title -
global ecology and biogeography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.164
H-Index - 152
eISSN - 1466-8238
pISSN - 1466-822X
DOI - 10.1111/j.1466-8238.2011.00702.x
Subject(s) - species richness , alien , propagule pressure , ecology , introduced species , population , propagule , range (aeronautics) , geography , arid , invasive species , native plant , biology , biological dispersal , demography , materials science , sociology , composite material , census
Aim To investigate whether differences in the elevational trend in native and alien species richness were dependent on climate or human pressures. Specifically we tested whether life‐form and/or alien/native status modifies the response of plant species richness to human population and temperature along: (1) a complete elevational gradient, and (2) within separate elevational bands that, by keeping temperature within a narrow range, elucidate the effects of human pressures more clearly. Location Two provinces ( c . 7507 km 2 ) on the southern border of the European Alps (Italy), subdivided into 240 contiguous sampling cells ( c . 35.7 km 2 ). Methods We used an extensive dataset on alien and native species richness across an elevation gradient (20–2900 m a.s.l.). Richness of natives and naturalized aliens were separately related to temperature, human population and Raunkiaer life‐form using general linear mixed models. Life‐form describes different plant strategies for survival during seasons with adverse cold/arid conditions. Results The relationship between species richness and temperature for natives was strongly dependent on life‐form, while aliens showed a consistent positive trend. Similar trends across alien and native life‐forms were found for the relationship between species richness and human population along the whole gradient and within separate elevational bands. Main conclusions The absence of life‐form‐dependent responses amongst aliens supports the hypothesis that the distribution of alien plant species richness was more related to propagule pressure and availability of novel niches created by human activities than to climatic filtering. While climate change will potentially contribute to relaxing species thermal constraints, the response of alien species to future warming will also be contingent on changes in anthropogenic pressures.