Forest-site relationships within an outbreak of lodgepole needle miner in central Oregon.

Abstract

The distribution of an outbreak population of lodgepole needle miner, Coleotechnites near milleri (Busck), in central Oregon was studied in relation to forest stand and site characteristics. The outbreak occurred primarily in topographic basins where lodgepole pine, Pinus contorta Douglas, grows in pure stands and is the topo-edaphic climax species. Tree defoliation was not continuous but was interrupted by uninfested stands in basin drainage systems and on well-drained slopes. The transition from infested to uninfested stands was usually marked by changes in topography, soils, tree stocking, and plant communities. Needle miners were virtually absent on sites characterized by high seasonal water tables, deeply developed soil profiles, and dense tree stocking. Similarly, populations usually declined abruptly on well-drained slopes where lodgepole pine was sera1 or was growing in mixed stands with ponderosa pine, Pinus ponderosa Laws. In general, Pinus contorta / Purshia tridentata communities were severely infested, but adjacent Pinus contorta / Purshia tridentata- Arctostaphylos patula and Pinus contorta / Arctostaphylos uva-ursi communities were relatively free of attack. Degree of infestation is apparently influenced by a combination of environmental and tree physiological factors that vary significantly under different forest-site conditions.

Citation

Mason, Richard R.; Tigner, Timothy C. 1972. Forest-site relationships within an outbreak of lodgepole needle miner in central Oregon. Res. Pap. PNW-RP-146. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 23 p