Does soil biota drive or hinder altitudinal expansion of invasive trees?

URCELAY, C, LONGO, S. & TECCO, P.

Ciudad de Buenos Aires

Simposio; 32 New Phytologist Symposium; 2013

New Phytologist trust

In addition to climate, biotic interactions might well limit tree recruitment and expansion along altitudinal gradients. Here we examined whether soil biota constrains the altitudinal expansion of invasive trees that do not occur at higher, albeit climatically suitable, altitudes in mountains from central Argentina (non-native range). Seedlings of three invasive trees -Ligustrum lucidum, Gleditsia triacanthos, and Pyracantha angustifolia- were grown in the greenhouse on soils originated at four altitudes, spanning the whole altitudinal range of the region (900, 1600, 2200, and 2700 masl). Three different soil biota treatments were nested within each altitudinal treatment: a) sterile soil, b) sterile soil + microorganisms excluding mycorrhizal fungi and c) sterile soil + microorganisms excluding mycorrhizal fungi + arbuscular mycorrhizal fungi. Responses to treatments were idiosyncratic. While Ligustrum and Pyracantha achieved lower biomass when growing on soils from higher altitudes they were not affected by soil biota. In contrast, Gleditsia was not affected by altitude per se but was positively affected by arbuscular mycorrhizal fungi, notably at higher altitudes. Our results suggest that biotic and abiotic properties of soils may drive or hinder altitudinal expansion of invasive trees depending on their identity.