Effects of clonality on heavy metal tolerance of clonal ferns

Background/Question/Methods: As an environmental friendly and cost-effective technique, phytoremediation (i.e. an ecological restoration technique using plant hyperaccumulator to remove pollutants from environments, e.g. soil, water and atmosphere), becomes more and more popular. Although there are many researches focused on the phytoremediation of toxic heavy metals, the researches about clonal plants, especially clonal ferns were so limited. We carried out two experiments on heavy metal tolerance of two common clonal ferns, Bolbitis heteroclita which is a terrestrial fern in tropical seasonal rainforests and Nephrolepis auriculata which is an epiphytic fern on the border trees along avenues. One experiment was to survey the tolerance of Pb and Zn of single ramets, while the other was to test the effects of clonal integration on the Pb and Zn tolerance of pairs of ramets.

Results/Conclusions: The first one showed that the toxic damages were increased with the concentration of heavy metal and increased from one heavy metal to two metals on both ferns. The second one showed that physiological integration minimized the damages of heavy metals and mediated the tolerance of Pb and Zn of ramets. Our findings clarified that the stresses of single heavy metal on ferns can hardly represent those of multiple heavy metals in the simulated greenhouse studies. Furthermore, we first verified that clonal integration had played an important role in the heavy metal tolerance of ferns. This may imply that the ecological adaptation and strategy of ferns relates to the clonal growth in the long history.