RECEPTIVENESS OF FOREST SOILS TO ECTOMYCORRHIZAL ASSOCIATION .1. CONCEPT AND METHOD AS APPLIED TO THE SYMBIOSIS BETWEEN LACCARIA BICOLOR (MAIRE) ORTON AND PINUS-PINASTER ART OR PSEUDOTSUGA-MENZIESII (MIRB) FRANCO

Soil receptiveness to a mycorrhizal association can be estimated by st andard bioassay from a dose-response relationship. The method was deve loped using the association Pinus pinaster or Pseudotsuga menziesii wi th Laccaria bicolor as a model and was successfully used to characteri ze the receptiveness of two forest soils. From a physical and chemical point of view, both soils were receptive to the Laccaria bicolor asso ciation. Our results show that microbial factors are very important in the receptiveness of soil to ectomycorrhizal association. Ectomycorrh izal development on seedlings at outplanting sites is discussed in rel ation to soil receptiveness and the ecological competence of selected strains.