Effects of Arbuscular Mycorrhizal Fungi on the Vegetative Vigor of Ailanthus altissima (Mill.) Swingle Seedlings under Sustained Pot Limitation

In order to invade new ecosystems, invasive alien plants need to cope with differentmicrobial communities. Whilst the ability to avoid antagonists is well recognized, the opportunityto establish mutualistic associations is less known, even in widespread invasive species such asAilanthus altissima (Mill.) Swingle. We sought to evaluate whether the beneficial effects of arbuscularmycorrhizal fungi (AMF) on Ailanthus seedlings are maintained over time, under prolonged potlimitation. We compared three-month-, three-year- and four-year-old mycorrhizal seedlings grown innatural forest soil (NT) with seedlings grown in sterilized (ST) and non-mycorrhizal (NM) soils, in potsof 3.4 L (22 x 15 cm). Growth parameters and leaf traits were assessed, including carbon (13C) andnitrogen (15N) stable isotope compositions. NT seedlings showed relatively higher vigor in the earlystage but, subsequently, the benefits provided by AMF were lost. Interestingly, mycorrhizal seedlingsconsistently showed about 2‰ 13C enrichment, relatively to the other treatments. Negative linearrelationships between leaf 13C and N content were found. Higher photosynthesis rates and WUE arethe likely causes of the early enhanced growth in mycorrhizal seedlings. The symbiotic relationshipbetween AMF and Ailanthus could be driven by resource availability. Greater insights into suchaspects could provide an improved perspective on the ecological limits of Ailanthus