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Ant nest location, soil nutrients and nutrient uptake by ant-associated plants: does extrafloral nectar attract ant nests and thereby enhance plant nutrition?
|Title||Ant nest location, soil nutrients and nutrient uptake by ant-associated plants: does extrafloral nectar attract ant nests and thereby enhance plant nutrition?|
|Publication Type||Journal Article|
|Year of Publication||2010|
|Authors||Wagner, D, W. Nicklen, F|
|Journal||Journal of Ecology|
Summary1. As central place foragers, ants accumulate organic debris near their nests. Consequently, soilnutrient stocks are often enriched near the nest site. We investigated the hypothesis that plantderivedfood sources, such as extrafloral nectar (EFN), can encourage soil-dwelling ant colonies tonest near the plant, thereby inadvertently providing the plant with an additional source of mineralnutrients. The study focused on a population of Acacia constricta, a North American shrub bearingEFNs.2. Several lines of evidence supported the notion that food rewards drew ant nests close to A. constrictaplants. Firstly, ant species that visit EFNs nested significantly closer to A. constricta plantsthan would be expected by chance, whereas this was not the case for two ant species that do not visitEFNs. Secondly, A. constricta plants with an ant nest occurring naturally underneath the canopyhad greater foliar volume, more EFNs per leaf and more EFNs per cm of leaf rachis than plantslacking an ant nest under the canopy. Thirdly, experimental supplementation of the nectarresources on acacias led to the establishment of significantly more new nests near the plant, relativeto controls. However, nectar supplementation did not affect acacia seed production within the yearof the study.3. Soil from the nests of three, EFN-visiting ant species contained higher average stocks of mostmineral nutrients than nearby soils outside the influence of the nest.4. To test whether A. constricta can assimilate the nutrients in ant nests, we fed 15N-labelled foodto Dorymyrmex sp. (smithi complex) workers nesting near acacias. Twenty-four days later, theleaves of acacias with an experimentally fed ant colony under the canopy contained significantlyhigher 15N and %N than acacias without a nest under the canopy, indicating that acacias assimilatedand benefited fromnutrients derived fromants.5. Synthesis. The results indicate that nectar resources can attract the nests of some ant species, andthat plants may benefit from access to soil nutrients derived from ant nests. Our data support thehypothesis that EFNs may confer nutritive, as well as protective, benefits.