Chin J Plan Ecolo ›› 2017, Vol. 41 ›› Issue (9): 985-994.DOI: 10.17521/cjpe.2017.0005

• Research Articles • Previous Articles     Next Articles

Empirical relationship between specific leaf area and thermal dissipation of Phragmites australis in salt marshes of Qinwangchuan

Qun LI, Cheng-Zhang ZHAO*(), Lian-Chun ZHAO, Jian-Liang WANG, Wei-Tao ZHANG, Wen-Xiu YAO   

  1. College of Geography and Environmental Science, Northwest Normal University, Research Center of Wetland Resources Protection and Industrial Development Engineering of Gansu Province, Lanzhou 730070, China
  • Received:2017-01-07 Revised:2017-07-09 Online:2017-09-10 Published:2017-10-23
  • Contact: Cheng-Zhang ZHAO

Abstract:

Aims The correlation between specific leaf area (SLA) and thermal dissipation reflects not only the accumulation and dissipation of plant photosynthesis, but also plants’ adaptation to their habitats and changing environment. The objective of this study is to examine the correlation between SLA and thermal dissipation of reed (Phragmites australis) under different soil moisture conditions and salt contents.Methods Our study site was located in the National Wetland Park in Qinwangchuan, Gansu Province, China. Our sampling site extends from the edge to the central of a salt marsh where the reed was the single dominant species. The study site was divided into three zones based on the distance from the water. Within each zone, six 2 m × 2 m sampling plots were randomly located to select six reed individuals in each plot (total = 18). Vegetation height, aboveground biomass, soil moisture, and soil electrical conductivity (EC) were measured, with the six reed individuals taken to the laboratory to measure leaf thickness. Leaf net photosynthetic rate (Pn), transpiration rate (Tr), and other parameters of the reeds were also measured in each plot prior to harvesting. Quantitative measures of chlorophyll fluorescence were taken after 30-min dark adaptation. Quadrat survey method was used to model the empirical relationship between the transpiration rate and leaf characteristics.Important findings Vegetation height and aboveground biomass increased with soil moisture content, but EC and photosynthetically active radiation decreased. Leaf area, Tr and Pn increased along the gradient, leaf thickness showed decreasing, but the increasing trend of SLA switched to a decreasing trend, while leaf dry mass presented an opposite trend. From plot I to III, the quantum yield of regulated energy dissipation (Y(NPQ)) and non-photochemical quenching decreased, the actual photochemical efficiency of PSII and photochemical quenching increased, and quantum yield of non-regulated energy dissipation increased before decreasing. There appeared a highly significant negative correlation (p < 0.01) between SLA and Y(NPQ) at plot I and III, and a less significant negative correlation (p < 0.05) at plot II. Along the soil moisture gradient, reed seemed using light effectively by changing leaf thermal dissipation through adjusting their leaf size and SLA—A potential self-protection mechanism in light of adapting the habitat.

Key words: specific leaf area, thermal dissipation, the quantum yield of regulated energy dissipation, Phragmites australis, Qinwangchuan, salt marshes