the establishment of the mycelial network that another plant of a different species can utilize for mineral uptake. This implies that arbuscular mycorrhizae are able to balance below-ground intra–and interspecific plant interactions. Since Glomeromycota fungi live inside plant roots, they can be influenced substantially by their plant host and in return affect plant communities as well. Plants can allocate up to 30% of their photosynthate carbon to AM fungi and in return AM fungi can acquire up to 80% of plant phosphorus and nitrogen. The diversity of AM fungal communities has been positively linked to plant diversity, plant productivity and herbivory. Arbuscular mycorrhizal fungi can be influenced by small scale interactions with the local plant community. For example, the plant neighborhood around a focal plant can alter AM fungal communities as can the order of plant establishment within sites. AM fungi and plant invasion During invasions of plant species, the AM fungal community and biomass can be drastically altered. In the majority of cases AM fungal biomass and diversity decrease with invasions. However, some mycotrophic plant species may actually increase AM fungal diversity during invasion. The mycorrhizal status of invasive plant species often varies between regions. For example, in the United Kingdom and central Europe recently invasive plants are more frequently obligately mycorrhizal than expected, while invasive plants in California were found to be less frequently mycorrhizal than expected. Interactions between AM fungi and other plant symbionts All symbionts within a plant host interact, often in unpredictable ways. A 2010 meta-analysis indicated that plants colonized by both AM fungi and vertically transmitted endophytes often are larger than plants independently colonized by these symbionts. However, this relationship is context-dependent as AM fungi can interact synergistically with fungal endophytes inhabiting the leaves of their host plant, or antagonistically. Similar ranges of interactions can occur between AM fungi and ectomycorrhizal fungi and dark septate endophytes. Response to environmental gradients Arbuscular mycorrhizal fungi vary across many environmental gradients. Their tolerance to freezing and drying is known to shift between AM fungal taxa. AM fungi become less prevalent and diverse at higher soil nutrient and moisture concentrations, presumably because both plants allocate less carbon to AM fungi and AM fungi reallocate their resources to intraradical hyphae in these environmental conditions. Over the long term, these environmental conditions can even create local adaptation between plant hosts, AM fungi and the local soil nutrient concentrations. AM composition