Comparisons of photosynthesis-related traits among understory lichens, mosses and vascular plant leaves in a high-elevation subalpine forest

Abstract

AbstractMany mosses and lichens thrive in high-elevation subalpine forests and even become dominant species on the forest floor. Although they play an irreplaceable ecological role in the forest, less is known about their eco-physiological status, and how their photosynthesis-related functional traits differ from those of co-occurring vascular plants. We determined the carbon, nitrogen and phosphorus concentrations and stoichiometric ratios, tissue mass per area, chlorophyll concentrations and photosynthetic light–response curves of three lichens, three mosses and four vascular plants in a subalpine forest in the eastern Tibetan Plateau of China. Trait values were compared among and within each group. The lichens possessed a higher nitrogen concentration than that of mosses. In addition, the two poikilohydric groups exhibited lower concentrations of nitrogen, phosphorus and chlorophyll, light-saturated assimilation rates and photosynthetic nutrient use efficiencies, and higher light compensation points than those of vascular plant leaves. Furthermore, variations in photosynthesis-related traits for lichen species reflect their different adaptation strategies to their corresponding environments. In contrast, the differences were weak among the three forest-floor mosses and the three herb species. These results demonstrate that the high abundance of understory lichens and mosses in the high-elevation subalpine forest cannot be explained by the photosynthesis-related traits.