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摘要
The vegetation profile and the photosynthetic efficiency, oxidative damage, and stomatal conductance in the evergreen dwarf shrub Calluna vulgaris (L.). Hull was analyzed in a Mediterranean ecosystem characterized by intense geothermal activity. Among the higher plants present in the area, this species appears to be the sole to possess the ability to grow near the geothermal sources. The hot fluid springs strongly alter the environment in their proximity: the emitted water vapor, CO2, H2S, CH4, H3BO3, SO42-, and NH4+ partly condensate and precipitate to the soil, thus leading to its extreme acidification and nutrient depletion. Furthermore, the temperature starts to rise sharply just a few centimeters under the soil surface. Under this multiple stress, the individuals of C. vulgaris growing within a few meters from the springs showed lower photosystem II efficiency, higher oxidative damage to the biomembranes, and lower stomatal conductance than the individuals growing farther away. Drought and high air temperatures occurring in summer exacerbate these harsh conditions, but only the plants closer to the springs did undergo an acute, yet transient crisis, as shown by the analyzed parameters. These results suggest that the main factors of stress are related to the physical and chemical features of the soil, while the adverse climate conditions apparently are of secondary importance. The possible role of reduced stomatal conductivity in enhancing the resistance of C. vulgaris to this hostile environment is discussed.
- 出版日期2015-10
