Investigations on the Grand Fir Mosaic Ecosystem of northern Idaho.

摘要

Secondary succession of conifers and shrubs is slow in some upper-slope forests in northern Idaho. Although several habitat types are involved, they are similar in many respects: invasion of cutover forests by pocket gophers, bracken fern, and western coneflower absence or reduced numbers of shrubs and seral conifers soil genesis topographic position and elevation range. Four studies are reported--each as a chapter intended for publication as a separate document.The allelopathic potential of western coneflower was studied using laboratory bioassay tests. Leachates reduced radicle lengths of conifer germinants. Volatile compounds delayed germination and reduced total germination of lodgepole pine seeds.Seed germination tests were conducted to determine if weeding bracken fern and western coneflower improved germination and survival of conifer seeds. Results were non-significant after 1 year. Weeding and testing should be continued for several years.Climatological monitoring of four habitats in and near the Grand Fir Mosaic showed that the Mosaic has good conditions for growing trees. Air temperatures were moderate, maximum surface temperatures did not often exceed 120The Grand Fir Mosaic Ecosystem is named for the most common conifer and the variety of sizes and shapes of openings in the forest canopy. A dichotomous key was developed to identify the Grand Fir Mosaic. It occurs on five habitat types--Abies grandis/Asarum caudatum, Abies grandis/Senecio triangularis, Thuja plicata/Asarum caudatum, Abies lasiocarpa/Streptopus amplexifolius, and Tsuga mertensiana/Streptopus amplexifolius. Elevations range from 4,200 to 6,000 feet. Within these elevations on the five habitat types, Actaea rubra and Synthyris platycarpa are indicator species for the Mosaic.Silvicultural recommendations are for minimal site disturbance, leaving woody debris, more partial cuttings, prompt planting of conifers, and protection of regeneration from pocket gophers.