Understory vegetation-environment relationships of lichen-rich forests in north-central British Columbia.

I examined the environmental relationships of feathermosses, vascular plants, and mat-forming lichens in lodgepole pine forests. Seventy-two mature forest plots were surveyed using microhabitat-scale sampling for functional group abundance, canopy characteristics, nutrient availability, soil texture, topography, relative humidity and air temperature. Feathermosses positively associate with canopy closure, afternoon shade, nitrogen or base-cation availability, duff thickness, fine soil texture, and water-receiving positions. Lichens positively associate with total irradiance, aluminum:calcium availability, water-shedding positions, and base-cation or nitrogen deficiency. Vascular plants have higher within-group variability, but positively associate with direct irradiance, afternoon shade, canopy heterogeneity, duff thickness, nutrient availability, alkalinity, and fine soil texture. Lichen patches are characterized by lower atmospheric moisture than vascular plant or feathermoss patches, but microclimate is more strongly associated with macroclimate and soil than canopy or understory vegetation. Competition among functional groups probably occurs but is unimportant environmental filtering and initial floristics are more likely mechanism of niche partitioning. --P.i.