The interception effect of heavy metals in different types of Chinese fir plantations

The aim of this research is to investigate the interception effect of heavy metals, such as zinc (Zn), copper (Cu), lead (Pb), arsenic (As), and cadmium (Cd) in different ages of Chinese fir plantations. The study was conducted in 21-year-old (CF21, near mature stand) and 29-year-old (CF29, old stand) pure Chinese fir forest stands (CF) as well as a mixed coniferous and broad-leaved forest stand (MF) in Huitong from November 2016 to October 2017. The study results revealed the variation ranges of interception of Cu, Zn, Cd, As, and Pb by the research forest stands were respectively, 3.436-36.778 mg·m^-2·month^-1, 7.458-98.763 mg·m^-2·month^-1, 0.003-0.608 mg·m^-2·month^-1, 0.094-4.471 mg·m^-2·month^-1, and 1.251-23.141 mg·m^-2·month^-1. Compared with the different ages of CF, the average monthly interception of Cu, Zn, Cd, As, and Pb in CF21 were respectively, higher 6.0%, - 3.3%, 59.0%, 1.4%, and 3.4% than those in CF29. However, seasonal changes of that in CF of different ages were those in CF21 > in CF29 in summer and autumn, and those in CF21 < in CF29 in winter and spring. Compared in different forest types, the average monthly interception of Cu, Zn, Cd, As, and Pb in MF was respectively, higher 20.2%, 5.8%, 185.2%, 2.6%, and 12.3% than those in CF. Furthermore, the seasonal flux of heavy metal retention in the forest ecosystems was higher during winter and spring than in summer and in autumn. This study provided an important information regarding the dynamics of heavy metal interception in forest ecosystems.