Non-rainfall water sources in the topsoil and their changes during formation of man-made algal crusts at the eastern edge of Qubqi Desert, Inner Mongolia

In arid and semiarid areas, water uptake (non-rainfall water) serves as an important water source for plants, biological soil crusts, insects and small animals. In this study, a measurement program was undertaken to investigate water uptake and its changes during formation of man-made algal crusts in the Qubqi Desert. In the study region, water uptake from the atmosphere accounted for 25.07%-39.83% of the total water uptake, and was mainly taken up by a water vapor adsorption mechanism; the proportion of water uptake from the soil substrate was much higher (60.17%-74.93%). The formation of crusts promoted water uptake, but the increased uptake did not occur immediately after inoculation or crusts formation. The water taken up from the atmosphere increased significantly from day 15 after inoculation, and the soil water content was markedly enhanced from day 20 after inoculation. It is considered that the growth of algal filaments and their secretions were the main factors increasing the amount of water uptake and water content in the crusts, and these variables increased even during dry periods when some algae are likely to have died

Feasibility of cyanobacterial inoculation for biological soil crusts formation in desert area

Practical testing of the feasibility of cyanobacterial inoculation to speed up the recovery of biological soil crusts in the field was conducted in this experiment. Results showed that cyanobacterial and algal cover climbed up to 48.5% and a total of 14 cyanobacterial and algal species were identified at the termination of inoculation experiment; biological crusts' thickness, compressive and chlorophyll a content increased with inoculation time among 3 years; moss species appeared in the second year; cyanobacterial inoculation increased organic carbon and total nitrogen of the soil; total salt, calcium carbonate and electrical conductivity in the soil also increased after inoculation. Diverse vascular plant communities composed of 10 and 9 species are established by cyanobacterial inoculation on the windward and leeward surface of the dunes, respectively, after 3 years. The Simpson index for the above two communities are 0.842 and 0.852, while the Shannon-Weiner index are 2.097 and 2.053, respectively. In conclusion, we suggest that cyanobacterial inoculation would be a suitable and effective technique to recover biological soil crusts, and may further restore the ecological system. (C) 2008 Published by Elsevier Ltd.Practical testing of the feasibility of cyanobacterial inoculation to speed up the recovery of biological soil crusts in the field was conducted in this experiment. Results showed that cyanobacterial and algal cover climbed up to 48.5% and a total of 14 cyanobacterial and algal species were identified at the termination of inoculation experiment; biological crusts' thickness, compressive and chlorophyll a content increased with inoculation time among 3 years; moss species appeared in the second year; cyanobacterial inoculation increased organic carbon and total nitrogen of the soil; total salt, calcium carbonate and electrical conductivity in the soil also increased after inoculation. Diverse vascular plant communities composed of 10 and 9 species are established by cyanobacterial inoculation on the windward and leeward surface of the dunes, respectively, after 3 years. The Simpson index for the above two communities are 0.842 and 0.852, while the Shannon-Weiner index are 2.097 and 2.053, respectively. In conclusion, we suggest that cyanobacterial inoculation would be a suitable and effective technique to recover biological soil crusts, and may further restore the ecological system. (C) 2008 Published by Elsevier Ltd

Development of artificially induced biological soil crusts in fields and their effects on top soil

Biological soil crusts (BSCs) could improve severe environment ecological conditions by increasing soil moisture, soil nitrogen concentration, and so on. In order to control desertification and recover the destroyed soil fertility utilizing a new means using BSCs, the soil surface was artificially inoculated with Microcoleus vaginatus and Scytonema javanicum. Relationships between the development of the artificially induced biological soil crusts and the distribution and dynamic changes of nitrogen and phosphorus in the soil crusts have been analyzed. Crusts of different ages were investigated by measuring soil physical and chemical factors, such as moisture, pH, total and available N content, and total and available P, which were correlated with the depths of the crusts. This study found that the types of color, shape, and species components of the algal crusts increased with crust development. Soil moisture, total N, available N, and available P increased gradually with crust growth. Soil with crusts was wetter than the controlled naked sandy soil, and a significant correlation was observed between biomass and total nitrogen (r = 0.946, P = 0.015). Soil pH was lower than that of control. The scytonemin on the soil surface was exceptionally higher than the other pigments, and all the pigments were mainly distributed at the soil surface level. Though the crusts were mainly distributed on soil surface, the available P was mainly stored below the crust layer. Pearson correlation tests indicated that artificially inoculated biological crusts could improve soil fertility and micro-environment of the top soil: The development of artificially induced BSCs was very well, and this was favorable to inducing the following crust succession.Biological soil crusts (BSCs) could improve severe environment ecological conditions by increasing soil moisture, soil nitrogen concentration, and so on. In order to control desertification and recover the destroyed soil fertility utilizing a new means using BSCs, the soil surface was artificially inoculated with Microcoleus vaginatus and Scytonema javanicum. Relationships between the development of the artificially induced biological soil crusts and the distribution and dynamic changes of nitrogen and phosphorus in the soil crusts have been analyzed

Spatial heterogeneity of cyanobacteria-inoculated sand dunes significantly influences artificial biological soil crusts in the Hopq Desert (China).

Artificial biological soil crusts (ABSCs), formed by inoculating Microcoleus vaginatus Gom. and Scytonema javanicum Born. et Flah. onto the topsoil of desert dunes, proved to be effective tools for the stabilization of moving dunes and promotion of soil fertility. As dominant driving forces in arid habitats, the abiotic environmental conditions of undulating dunes produce a gradient of abiotic stresses on cyanobacteria. Cyanobacteria are considered pioneering phototrophs in early soil crust communities in deserts. In this study, the development of ABSCs under various environmental site conditions was investigated using 16S rRNA-based polymerase chain reaction, denaturing gradient gel electrophoresis (DGGE), and soil property measurements. After inoculation in 2002 and long-term development, patchy moss crusts were observed on the dunes. All of the available sequenced bands in the DGGE gels belonged to Oscillatoriales and Nostocales. The dominant Nostocales genus in the ABSCs was still Scytonema; however, more Oscillatoriales genera were identified, which belonged to Microcoleus and Phormidium. The cyanobacterial compositions of different slope types were significantly distinct (p < 0.05), particularly those from windward slopes. The crusts of the top-dune slopes were more heterogeneous. In addition, the soil physicochemical properties and richness indices of the windward slopes were significantly lower than those of the leeward and interdune slopes (p < 0.05). Compared with uninoculated control dunes, all of the inoculated dunes had far higher biodiversities

Effects of sand burial stress on the early developments of cyanobacterial crusts in the field

Sand burial is a noticeable environmental disturbance commonly experienced by various types of biological soil crusts (BSCs) composed of microorganisms. BSCs have been regarded as a feasible avenue to resist desertification in China. However, the cyanobacterial crusts, existing at early developmental stage of BSCs, are exceedingly susceptible to burial by sand. Therefore, a study campaign over 7-week was conducted in fields to evaluate the effects of sand burial (burial depth of 0, 0.5, 1, 3 and 5 cm) on the crusts in Hopq Desert, China. The results showed that sand burial imposed severe stress on the cyanobacteria crusts, such as the reduction of chlorophyll a, the restraint of scytonemin synthesis and the damage to PSII activity, as well as the decrease of total carbohydrate reserve. We discuss in this study possible mechanisms by which cyanobacterial crusts tolerate burial, and the positive role of rain in the recovery of cyanobacterial crusts from burial. It is necessary for the cyanobacterial crusts to allay burial disturbances in order to ensure their better contribution to desert reclamation. (C) 2011 Published by Elsevier Masson SAS.Sand burial is a noticeable environmental disturbance commonly experienced by various types of biological soil crusts (BSCs) composed of microorganisms. BSCs have been regarded as a feasible avenue to resist desertification in China. However, the cyanobacterial crusts, existing at early developmental stage of BSCs, are exceedingly susceptible to burial by sand. Therefore, a study campaign over 7-week was conducted in fields to evaluate the effects of sand burial (burial depth of 0, 0.5, 1, 3 and 5 cm) on the crusts in Hopq Desert, China. The results showed that sand burial imposed severe stress on the cyanobacteria crusts, such as the reduction of chlorophyll a, the restraint of scytonemin synthesis and the damage to PSII activity, as well as the decrease of total carbohydrate reserve. We discuss in this study possible mechanisms by which cyanobacterial crusts tolerate burial, and the positive role of rain in the recovery of cyanobacterial crusts from burial. It is necessary for the cyanobacterial crusts to allay burial disturbances in order to ensure their better contribution to desert reclamation. (C) 2011 Published by Elsevier Masson SAS