1998. 8:11-18

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

Thomas R. Horton1, Thomas D. Bruns
Department of Microbial Biology, 111 Koshland Hall, University of California, Berkeley CA 94720, USA

Efren Cázares
Department of Forest Science, Oregon State University, Corvallis OR 97331, USA

1Present address: Department of Forest Science, Oregon State University, Corvallis OR 97331, USA
We followed the colonization frequency of ectomycorrhizal (EM), vesicular-arbuscular mycorrhizal (VAM), 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 observed from the third month after germination. EM fungi observed on the seedlings from the scrub site were limited to Rhizopogon subcaerulescens, R. ochraceorubens and Suillus pungens. Seedlings from the forest were colonized by a greater variety of EM fungi including Amanita spp., Russula brevipes and a member of the Cantharellaceae. VAM structures (vesicles, arbuscules or hyphal coils) were observed in the seedling root systems beginning 1 month after germination in the scrub site and 3 months after germination in 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 resident inoculum in the soils and did not disperse into the sites after the fire.

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