Structural features of Polytrichum formosum Hedw. populations along a habitat sequence of cutover restoration in the eastern Tibetan Plateau

In order to detect the effects of forest harvesting on bryophyte populations, structural parameters (frequency, coverage, density, height, and biomass) of Polytrichum formosum Hedw. populations in the eastern Tibetan Plateau were investigated on four cutover habitats which had been harvested by clear‐cut in 1998, 1997, 1994 and 1990, representing restoration histories of 4, 5, 8, and 12 years, and on nearby primary spruce forest. Vascular plant coverage including shrubs, herbs and litter was estimated as well. It was found that the moss was not recorded in the nearby primary spruce forest but occurred on all clear‐cut habitats. The frequency index, coverage, average height, shoot density and biomass on all cutovers was 23.8±10.3% (±SD), 1.8±2.5%, 105.5±53.3 mm, 1,358.9±1,744.1 shoot/m2 and 7.3±12.5 g/m2, respectively. The moss population on clear‐cut habitat was an invading pioneer moss, and the structural parameters showed large‐scale variability, agreeing with the initial hypothesis that deforestation promoted the establishment of the moss, which prefers light, on clear‐cut habitats. Of all structural parameters, only the average height increased across clear‐cut habitats along the restoration sequence. The relationships between the structural parameters and vascular coverage indicated the moss only occurred patchily on clear‐cut habitats. The population occurrence potentially depended on shrub coverage, and the development was crucially controlled by herb coverage. The results suggested that the present structure of P. formosum populations on the clear‐cut habitats was the result of environmental degradation resulting from forest clear‐cut logging, population biology and reproductive strategies.