Arbuscular mycorrhizal fungi (AMF) are suggested to be important for invasions by many exotic plants. However, it is not yet known how associations between AMF and invasive plant populations change in mountains ranges and how changed associations affect further expansion of different populations in new habitats. We conducted a field survey to detect AMF colonization rate of the invasive Galinsoga quadriradiata along an elevational gradient ranging from 223 to 1947 masl in the Qinling and Bashan Mountains, China. Additionally, a greenhouse experiment was conducted to compare plant growth performance among five elevational populations. In the field, total plant mass and seed production, as well as root AMF colonization rate, significantly decreased with elevation. When populations were grown in a novel soil environment in the greenhouse, the high-altitude populations achieved higher seed and total mass at lower AMF colonization rate than the low-altitude populations. Moreover, high AMF association was related to high intraspecific competition within low-altitude populations and limited seed production. Our results revealed that the associations between AMF and G. quadriradiata decrease with altitude in mountain ranges, and this may indicate that differentiation of association between AMF and elevational populations occurs during range expansion of G. quadriradiata. The results of the greenhouse experiment suggest that the high-altitude populations are more aggressive than the low-altitude populations in a non-stressful environment.

丛枝菌根真菌（AMF）被认为对许多外来植物的入侵很重要。但是，尚不清楚AMF和入侵植物种群之间的关联如何在山脉中改变，以及改变后的关联如何影响新栖息地中不同种群的进一步扩展。我们进行了实地调查，以检测侵入性Galinsoga quadriradiata的AMF定植率沿秦岭和巴山山脉的海拔梯度范围为223至1947 masl。此外，还进行了温室试验，以比较五个海拔种群的植物生长性能。在田间，总植物质量和种子产量以及根部AMF定殖率随海拔升高而显着下降。当种群在温室中的新型土壤环境中生长时，与低海拔种群相比，高海拔种群在较低的AMF繁殖率下获得了更高的种子和总质量。此外，高AMF关联与低海拔种群中的种内竞争较高以及种子产量有限有关。我们的研究结果表明，AMF和G.quadriradiata之间的关联随着海拔高度的降低，这可能表明AMF和海拔种群之间的关联性分化发生在G.quadriradiata的范围扩展过程中。温室实验的结果表明，在非压力环境中，高海拔人群比低海拔人群更具侵略性。