Submitted to: Canadian Journal of Forest Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/19/2006
Publication Date: 5/1/2007
Citation: Cline, E., Vinyard, B.T., Edmonds, R. 2007. Spatial Effects of Retention Trees on Mycorrhizas and Mycorrhizae and Biomass of Douglas-fir Seedlings.CanadianJournal of Forest Research 37:430-438. Interpretive Summary: In the Pacific Northwest wood is harvested by cutting forest trees and planting new tree seedlings in their place. In order to grow, the roots of the newly planted seedlings must be associated with certain helpful fungi that absorb nutrients from the soil and transport them to the seedlings. The helpful fungi come from mature trees that already have these fungi in their roots. This study examines the distance that seedlings should be planted from a mature tree in order to also obtain the helpful fungus. It was determined that the closer a seedling was planted to a mature tree the greater the number and kinds of helpful fungi that associate with the seedling roots. This research will be used by foresters to determine how close new seedlings should be planted to more mature trees in order to obtain the essential root-inhabiting fungi.
Technical Abstract: Retention forestry places seedlings in proximity to residual trees, exposing seedlings to additional sources of ectomycorrhizal fungus (EMF) inoculum. To investigate this, Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings were planted near (2-6 m) and far (16-30 m) from 44- to 72-year-old residual Douglas-fir trees in western Washington, USA. From 1998 through 2000, seedling shoot and root biomass was assessed and EMF taxa were identified using morphology and sequence analysis of internal transcribed spacer and large subunit ribosomal RNA genes. Seedlings near residual trees had significantly greater ectomycorrhizal (ECM) abundance (percent active ECM root tips), less necrotic root tips, and higher root to shoot biomass ratios. Seedlings near trees had a richness index of 4.1 EMF taxa per seedling and 42 total taxa compared to 3.5 taxa per seedling and 33 total taxa for seedlings far from trees. Proximity to residual trees may increase seedling ECM abundance and diversity.