Stem CO efflux of is reduced by chronic non-native insect herbivory.

Carbon dioxide efflux () from the base of K.D. Hill stems was quantified in four locations containing healthy populations and in one location with populations threatened by non-native insect herbivores in order to determine the influence of reduced plant health on . Minimal variation of occurred among the four locations with healthy plants, and ranged from 1.68 to 1.79 µmol·m·s. The threatened populations were on the island of Guam, where recent invasions of non-native insects have caused epidemic plant mortality, and the was 0.59 µmol·m·s. This is the first known report of for any cycad species, and the values for the unique pachycaulous stem form fit in the lower half of the range of published for woody trees. The results illuminate the potential for using to screen populations to identify the individual trees with the greatest likelihood of surviving conservation measures.