The biodiversity could be influenced by your trap method conditions such as plant hosts etc. Here some papers that discussed about it. To address this, it may worth it to directly analyses your soil samples using independent culture methods to get an idea the dominant taxa in your sample and compare it with the trap method. However, it depends on your objectives.

1.Redecker, D., Hijri, I., & Wiemken, A. (2003). Molecular identification of arbuscular mycorrhizal fungi in roots: perspectives and problems. Folia Geobotanica, 38(2), 113-124.

https://link.springer.com/content/pdf/10.1007%2FBF02803144.pdf

2.Jansa, J., Mozafar, A., Anken, T., Ruh, R., Sanders, I., & Frossard, E. (2002). Diversity and structure of AMF communities as affected by tillage in a temperate soil. Mycorrhiza, 12(5), 225-234.

https://link.springer.com/content/pdf/10.1007%2Fs00572-002-0163-z.pdf

Dear Nelly

Allium porrum is a good host in order to reproduce AM fungi. The subject is not that Allium porrum is going to change the diversity of that fungi in soil exactly, or at least says in that form, technically speaking. The problem is that a trap culture is going to reproduce species that may be were not sporulated in the field at the moment of sampling and then, probably you will find other new species not reported in your initial survey. In that sense, A porrum will modify the initial spores diversity in soil, but only seeing in that way

The use of Allium porrum will host a variety of mycorrhizal species. If you want to optimize a divergence of mycorrhizal species take a perennial mixed grass herb swath and then harvest some soil. Make a mix with vermiculite and perlite. Use 1:1:1 soil, vermiculite and perlite by volume. Plant seeds of Allium porrum, maize, clover and sunflower. All of these are good hosts for a wide variety of mycorrhizae. Let the plants be propagated for 3 to 5 months and then determine the sporangium numbers and varieties. The soil can be used as propagation media to produce mycorrhizal inoculated transplants.