MYRTLE CREEK — Two conservation groups are challenging a Bureau of Land Management timber sale east of Myrtle Creek that will test logging principles set down by two university professors. Portland-based Oregon Wild and Eugene-based Cascadia Wildlands claim the threatened northern spotted owl will be harmed by the 300-acre White Castle timber sale in BLM’s pilot project, about 20 miles east of Myrtle Creek. The groups have submitted an administrative challenge to the timber sale for review by the Interior Board of Land Appeals in Arlington, Va. Oregon Wild and Cascadia Wildlands join a Douglas County group, Myrtle Creek Rural …