Effects of shading on demography and physiological changes of Tamarix chinensis: Outdoor and indoor respects

Background/Question/Methods

  Effects of environment factors on Tamarix chinensis L. (tamarisk) have been well documented in riparian and desert ecosystems, but relatively little is known about them in salt marsh ecosystem. In this study, we examined effects of shading to below 1-year seedlings in salt marsh, Youngjong Island, to know about their recruitment traits. We conducted outdoors and indoors experiments on demographic and physiological aspects. In outdoor experiments, we divided study site into riverside open area (RO) and riverside shade area (RS) to evaluate effects of shading on below 1-year seedling and surveyed demography and soil physical-chemical properties in each area (RO, RS). In indoor experiments, we made light gradient using rectangular shading net, 0-Layer (LO, full light), 1-Layer (L1, 78% shading), 2-Layer (L2, 92% shading), and measured growth and physiological factors to identify effects of shading gradient on below 1-year seedlings.

Results/Conclusions  

  Among soil properties, Na⁺ concentration of RO soil was over 4-folds higher than RS. Density of RS seedlings significantly lower than RO and after June 2011 seedlings all died in RS. Results of indoor experiments supported outdoor experiments. Growth and physiological factors, such as length, biomass, and total soluble carbohydrate contents were significantly decreased in shading treatment. Especially, total soluble carbohydrate contents of L0, L1, and L2 were 26.31 µg/g FW, 16.02 µg/g FW, and 8.99 µg/g FW, respectively. However, chlorophyll content did not significantly decrease in shading treatment (L0 vs. L1) and mortality of L2 seedlings steeply decreased but L1 did not comparing with L0. In many growth and physiological factors supported growth of tamarisk was disturbed by decreasing shading. These results suggest shading more negatively affected the length and survival of seedlings than other factors because tamarisk is halophyte. Therefore, tamarisk growth may be limited in shading areas. Such biological conditions have significant implications for successful recruitment, establishment, and early growth of tamarisk.