Survival and Growth of Pine Seedlings with Pisolithus Ectomycorrhizae after Two Years on Reforestation Sites in North Carolina and Florida

Abstract

Abstract Two-year field data indicated that ectomycorrhizae formed by Pisolithus tinctorius increase survival and growth of five southern pine species on routine reforestation sites. The seedlings with ectomycorrhizae of Pisolithus were grown earlier in nurseries using either mycelial or basidiospore inoculum to form the ectomycorrhizae. Control seedlings had ectomycorrhizae formed by fungi (mainly Thelephora terrestris ) that occurred naturally in the nurseries. Species that had significantly greater survival after two years with Pisolithus ectomycorrhizae than with natural nursery ectomycorrhizae were loblolly pine ( Pinus taeda L.) and eastern white pine (P. strobus L.) on one site and Virginia pine (P. virginiana Mill.) on two sites in North Carolina; and slash pine (P. elliottii Englem. var. elliottii) and sand pine (P. clausa var. immuginata Ward.) on two sites in Florida. A plot volume index (PVI) was developed for measurement of total growth response of seedlings. Significant increases in PVI due to Pisolithus ectomycorrhizae over natural ectomycorrhizae were observed; they varied from 25 percent for loblolly pine in North Carolina to 450 percent for sand pine in Florida and eastern white pine in North Carolina. On fertilized (90 kg/ha of N and P) plots in Florida, P. tinctorius did not increase the PVI over control slash pines, but this fungus increased PVI of seedlings by 175 percent on the nonfertilized plots. P. tinctorius persisted on roots of seedlings and produced many basidiocarps near seedlings of all pine species, especially on the poorer sites. Indigenous symbiotic fungi also formed significant quantities of ectomycorrhizae, particularly on the better sites. These results indicate that P. tinctorius ectomycorrhizae can persist and increase survival and growth of southern pines better than natural ectomycorrhizae on a variety of reforestation sites. FOREST SCI. 23:363-373.