What is the role of hair present in moss?
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Natural regeneration of many North American conifer species frequently occurs in association with the hair-cap mosses (Polytrichum spp.), common and widely distributed pioneer mosses of boreal and temperate coniferous forests. The role of Polytrichum mosses in the natural regeneration of white spruce (Picea glauca (Moench) Voss) was investigated through a comparative study of seedbed effects on seedling emergence, survival, morphology and the presence of competing vegetation. Intact monoliths of Polytrichum moss, mineral soil and undisturbed litter were collected from the forest floor of a mixed conifer stand in Central Ontario. Half of the litter seedbeds were later burned with a propane torch. Replicates of the four seedbeds (n = 24) were placed in a greenhouse and hand sown with white spruce seed. Percent effective seedling emergence was significantly higher on mineral soil than on the other three seedbeds but did not differ among moss, litter and burned litter. Seedling survival under a watering regime representative of the seedbed collection site did not differ among seedbeds. Survival of a short drought stress treatment, however, was significantly improved in mineral soil and moss as compared with the litter and burned litter seedbeds. Differential survival was related in part to the biomass of herbaceous and woody competition that developed from the seed bank and rhizomes present in the four seedbeds. Above- and below-ground biomass of competition on the litter and burned litter seedbeds were significantly higher and ten times that of mineral soil and moss seedbeds. This difference in biomass of competition was associated with lower average daily soil water potentials in the two litter seedbeds. Seedlings growing in mineral soil, and to a lesser extent burned litter, generally exhibited larger shoot, root and total dry mass and produced more robust shoots of higher mechanical strength (i.e. shoot dry mass/shoot length). Seedlings grown on moss were