Experimental Studies on the Natural Restoration and the Artificial Culture of the Moss Crusts on Fixed Dunes in the Tengger Desert, China

Abstract

Soil microbiotic crusts cover extensive portions of the arid and semiarid regions of the world and play an important ecological role. Moss is one of the major components in the crusts. The reproduction and establishment of the mosses are crucial to the formation of moss crusts. Bryum argenteum is the dominant species of moss crusts in the Shapotou region (104?57 2E, 37?27 2N) of the Tengger Desert. In search for the characteristics of natural reproduction and establishment of the mosses, 10 quadrates (10?10 cm for each) were obtained by removing the moss crusts in different positions of fixed dunes. These 10 quadrates were observed for 3 years depending on the species  components and coverage. Meanwhile, in the third year, two quadrates (1?1 m for each) were set up in a crustabsent area and two different experiments of the asexual reproduction (broadcast planting and offshoots) were conducted, respectively. The reproductive process was observed under the microscope, and the morphological indicators of the new individuals were measured. The results were compared with the ones from indoor experiments using the same methods. All the results showed the following: (1) 70% of the quadrates (i.e., 7 of the 10 quadrates) were recovered within 3 4 years; thus, the quick recovery might be due to the dispersal and reproduction of the fragments of stems and leaves of B. argenteum; (2) as for the two quadrates in the artificial reproduction test, the new plants occupied the uncovered space of the quadrates in 1 month, and there were two main reproduction approaches, one of which was that the stems continually branched and produced young plants, and the other was that the young plants and the fragments of the stems and leaves repeatedly and extensively reproduced protonema, which finally developed into a large number of new plants; (3) the reproductive characteristics were identical, though the protonema in the field was more robust and had more branches than the ones indoors.