Ectomycorrhizal, vesicular-arbuscular and dark septate fungal colonization of bishop pine ( Pinus muricata ) seedlings in the first 5 months of growth after wildfire

Abstract

We followed the colonization frequency of ectomycorrhizal (EM), vesicular-arbuscular mycorrhi- zal (VAM), and dark septate (DS) fungi in 1- to 5- month-old bishop pine seedlings reestablishing after a wildfire. Seedlings were collected on a monthly basis at either a VAM-dominated chaparral scrub site or an EM-dominated forest site, both of which were burned. In both vegetation types, fully developed EM were ob- served from the third month after germination. EM fungi observed on the seedlings from the scrub site were limited to Rhizopogon subcaerulescens, R. ochra- ceorubens and Suillus pungens. Seedlings from the for- est were colonized by a greater variety of EM fungi in- cluding Amanita spp., Russula brevipes and a member of the Cantharellaceae. VAM structures (vesicles, ar- buscules or hyphal coils) were observed in the seedling root systems beginning 1 month after germination at the scrub site and 3 months after germination at the forest site. Seedlings from the scrub site consistently had more frequent VAM fungal colonization than those from the forest site through the fifth month after germination. DS fungi were observed in most seedlings from both the scrub and forest sites beginning in the first month post-germination. We propose that these fungi survived as a resident inoculum in the soils and did not disperse into the sites after the fire.