The water absorption capacity of 21 Sphagnum species

Sphagnum moss (peat moss) is the dominant land plant in peatlands, and it plays an essential role in peatland ecosystems because its remarkable water-holding capacity helps to conserve water resources and maintain the anoxic environment of peatlands. Sphagnum moss exhibits a super ability to absorb water. However, the water absorption capacity of different species and different parts of the same species is not well understood. In this study, we measured the short-term and saturated water absorption of 21 Sphagnum species from China. The results showed that the water absorption capacity of the investigated peat mosses was much higher than that of other bryophytes. Sphagnum imbricatum had the highest saturated water absorption capacity (about 44 times its dry weight), while the peat moss with the lowest saturated water absorption was Sphagnum flexuosum (about 19 times its dry weight). In addition, we determined the relative volume of hyalocysts of the spreading and pendent branch leaves of 18 Sphagnum species and further measured the water absorption capacity of the pendent branch, spreading branch, and stem of six of them. The results revealed that both pendent and spreading branches had strong water absorption capacity and were the primary water-absorbing parts of peat mosses. The water-absorbing capacity of different Sphagnum species was linearly related to the volume of hyalocysts. The results provide an essential scientific basis for selecting high-quality germplasm resources of peat moss.