ABSTRACT
Aim Alien plant invasion is prominent in the Hawaiian Islands. There are many
factors involved in invader success. To date, there is a general lack of information
about one of them, which we aim to study here: the terpene emission capacity of
both Hawaiian native and alien plants.
Location Oahu (Hawaii).
Methods We screened 35 alien and 35 native dominant plant species on Oahu
Island for monoterpene emissions. The emission rates were measured from fieldgrown
plants under standardized conditions of temperature and quantum flux
density in the laboratory.
Results The emission rates of total terpenes ranged from 0 mg g-1 h-1 to
55 mg g-1 h-1, and altogether 15 different terpenes were emitted in detectable
amounts by the overall set of species. A phylogenetic signal was observed for total
terpene emissions. Total terpene emission rates were higher in aliens than in native
species (12.8 2.0 vs. 7.6 1.9 mg g-1 h-1, respectively).
Main conclusions The greater terpene emission capacity may confer protection
against multiple stresses and may partly account for the success of the invasive
species, and may make invasive species more competitive in response to new global
change-driven combined stresses. These results are consistent with aliens coming
from very diverse ecosystems with generally higher biotic and abiotic stress pressures,
and having higher nutrient concentrations. On the contrary, these results are
not consistent with the ‘excess carbon’ hypotheses. These results indicate changes in
vegetation terpene emissions brought about by alien plant invasions.
Keywords
Alien species, a-pinene,Hawaiian Islands, monoterpenes, nitrogen, phosphorus