Tropical cloud forest canopy and subcanopy adapt to different light environments by regulating photosynthetic pigments

Abstract

The canopy and subcanopy of a Tropical Cloud Forest provide distinctly different light environments. Here, the amounts and ratios of photosynthetic pigments in leaves from a Cloud Forest canopy and subcanopy plants are compared. The pigments of forty canopy and subcanopy leaf samples are extracted using acetone and analyzed using a spectrophotometer. It is found that canopy and subcanopy plants possess equivalent means of concentrations of photosynthetic pigments per mass of leaf tissue (x = 0.21± 0.09 mg/g and 0.22 ± 0.11 mg/g, respectively). Therefore, plants from these two microhabitats invest the same quantity in major pigments for photosynthesis. However, the availability of light cause canopy plants to produce a higher concentration of photosynthetic pigments per area (x = 0.0079 ± 0.0026 mg/cm²) than subcanopy plants (x = 0.0059 ± 0.0019 mg/cm²). Based on the ratio of chlorophyll a to chlorophyll b, it appears that canopy plants (x =1.63 ± 0.57) use their photosynthetic pigments to maximize their rate of light processing. Subcanopy plants (x = 0.98 ± 0.26), in contrast, appear to maximize light absorption. Using the ratio of carotenoids to chlorophyll b, canopy plants (x = 1.24 ± 0.27) may be using carotenoids to prevent photoinhibition. Subcanopy plants, having a much lower carotenoids to chlorophyll b ratio (x = 0.97 ± 0.27), are possibly using carotenoids for further light absorption. El dosel y subdosel de un bosque nuboso tropical proporcionan ambientes de luz muy diferentes. En este caso, se comparan las cantidades y proporciones de los pigmentos fotosintéticos en hojas de un dosel del bosque nuboso y las plantas del subdosel.https://digitalcommons.usf.edu/tropical_ecology/1558/thumbnail.jp