Seasonal variations in leaf and branch trace elements and the influence of a 3-yr 100% rainfall exclusion on Pinus massoniana Lamb

Background Trace elements are essential for the growth and survival of plants, and their concentrations and distributions in plants are effective reflections of ecological adaptation strategies. However, this aspect has seldom been addressed. Method Changes in the leaf and branch trace elements of Pinus massoniana Lamb, induced by seasonal dynamics and in response to a 3-yr 100% rainfall exclusion, were evaluated. Results The results showed that the concentrations of Fe, Cu, Zn, Cd, Ni and Cr in leaves of P. massoniana in the control group had high seasonal resolution. There were three groups according to their patterns over the growing season: (1) nutrient elements (Cu, Zn, Ni and Cd), which continuously decreased in concentration during the growing season, with the highest concentration in spring and the lowest in autumn; (2) accumulating element (Cr), which increased in concentration from spring to autumn; and (3) indifferent element (Fe), which increased in concentration from spring to summer and decreased in concentration from summer to autumn. The concentrations of trace elements in leaves and branches showed no significant differences with mild drought stress, except for Fe and Cr in leaves and Cr in branches, which significantly increased ( p < 0.05) under the result of self-selection under mild drought stress. Therefore, the resultant seasonal and drought effects on trace element cycling in P. massoniana could provide theoretical support to respond to future climate change.