 For example, on poorly drained sites on ridge or upper slope positions, large areas of rosebay rhododendron, particularly at the high elevations, have recently died out presumably due to the "Phytophthora" fungus, or due to recent prolonged periods of below-average precipitation.Yet, rosebay rhododendron now occupies sites that historically were free of evergreen understory.There are still important questions to be answered regarding this species to completely understand its role in forest understories.