ABSTRACT
PREMISE: The distribution and performance of bryophyte species vary with vertical gradients, as a result of changes in environmental factors, especially light. However, the morphological and physiological drivers of bryophyte distribution along forest vertical gradients are poorly understood. METHODS: For 18 species of mosses and liverworts distributed among three vertical microhabitats (ground, tree trunk, and branch, variance in 28 morphological and photosynthetic functional traits was comparatively analyzed among the microhabitats and bryophyte life-forms in a subtropical cloud forest in Ailao Mountain, Yunnan, southwestern China. Principal component analysis (PCA) was used to summarize trait differences among bryophyte species. RESULTS: In contrast to trunk and ground dwellers, branch dwellers tended to reduce light interception (smaller leaf and cell sizes, lower chlorophyll content), protect against damage from intense irradiation (higher ratios of carotenoids to chlorophyll), raise light energy use (higher photosynthetic capacity), and cope with lower environmental moisture (pendant life-forms, thicker cell walls). The PCA showed that ecological strategies of bryophytes in response to levels of irradiation were specialized in branch dwellers, although those of ground and trunk dwellers were less distinct. CONCLUSIONS: Environmental filtering shaped the combination of functional traits and the spatial distribution of bryophytes along the vertical gradients. Bryophyte species from the upper canopy of cloud forests show narrow variation in functional traits in high-light intensity, whereas species in the lower vertical strata associated with low-light intensity used contrasting, but more diverse ecological strategies.
Subject(s)
Bryophyta , Forests , China , Photosynthesis , Plant Leaves , TreesABSTRACT
Chlorophyll content in lichens is routinely used as an accurate indicator of lichen vigor, interspecific differences, and the effect of site-related environmental parameters. Traditional methods of chlorophyll extraction are destructive, time-consuming, expensive, and inoperable, especially when measuring large quantities of chlorophyll. However, non-destructive methods of measurement using portable chlorophyll meters are rarely used for lichens. Considering the characteristics of lichens such as rough blade surface and absence of chlorophyll b in cyanolichens, we compared the non-destructive methods with traditional methods and evaluated their applicability in studying lichen pigment content. Two instruments, SPAD-502 and CCM-300, were used to measure the pigment content of seven foliose lichen species. These pigment readings were compared with those determined using the dimethyl sulphoxide (DMSO) extraction method. Significant correlations were observed between SPAD/CCM values and pigments (chlorophyll and total carotenoids) extracted from chlorolichens, especially species with a smooth surface. The CCM-300 was more accurate in detecting the pigment content of foliose chlorolichens. However, both instruments showed certain limitations in the determination of pigment content in cyanolichens, especially gelatinous species. For example, CCM-300 often failed to give specific values for some cyanolichen samples, and both instruments showed low measurement accuracy for cyanolichens. Based on the high correlation observed between chlorophyll meter readings and pigments extracted from chlorolichens, equations obtained in this study enabled accurate prediction of pigment content in these lichens.
