Apparent photosynthesis of terrestrial mosses: An indicator of population functional health

Terrestrial mosses dominate the ground in many vegetation types and most are long-lived perennials with highly complex canopies. Long-term population health continues through numerous wetting and drying cycles; however, extreme drought or extended wet periods may create conditions that cause some parts of the population to die or remain inactive. I examined apparent photosynthesis of fully hydrated populations of four terrestrial species of mosses occurring in leaf-free mesohabitats in temperate deciduous forests of eastern North America in order to explore photosynthetic variability of both popula-tions and species. There was high variability in rates of apparent photosynthesis among the popula-tions of mosses for all four species examined in this study. Despite this variability within species, all four species achieved similar mean rates of photosynthesis. Two years after relocation to nearly bare ground habitats, populations of three of the four species achieved similar apparent photosynthetic rates as natural popula-tions, and functioned in a similar manner.