Responses of Microalgal-Microbial Biomass and Enzyme Activities of Biological Soil Crusts to Moisture and Inoculated Microcoleus vaginatus Gradients
2013-09-29
Biological soil crusts (BSCs) are organic complexes composed of biotic components including cyanobacteria, green algae, lichens and mosses, fungi, and other bacteria mixed with soil particles. BSCs reduce soil erosion, increase organic content of sand, are capable of nitrogen fixation, and can either promote or retard growth of vascular plants. BSCs also excrete beneficial extracellular substances, which retain soil moisture and can reduce salinity stress.
Microcoleus vaginatus Gom. is the pioneer organism and dominant species of algal crusts and serves critical roles in their early formation. During algal crusts formation, polysaccharide sheath material from M. vaginatus winds throughout soil surfaces and binds soil particles together. Sheaths and filaments will absorb water when wet and swell to cover soil surfaces more extensively, which in turn greatly improves soil crust efficacy.
Gurbantunggut Desert is the largest fixed and semi-fixed desert in China with an area of 48,800 km2. There are abundant BSCs on sand surfaces throughout the Gurbantunggut Desert, which grow primarily during wet, cool periods when dew, fog and occasional rainfall provide sufficient moisture for species to form soil crusts.
The objectives of this work were to investigate the change of microbial-microalgal biomass with different moisture and inoculated M. vaginatus dosage treatment and investigate the enzymatic activities along moisture and inoculated M. vaginatus gradients.
Four inoculum dosages of M. vaginatus (0.5, 1, 3, and 7 g/m-2) were inoculated across a sand surface and subjected to five moisture treatments (0, 1, 2, 3, and 4 L/m-2). Microalgal biomass, microbial biomass, and enzyme activities (invertase, alkaline phosphatase, and urease) were subsequently determined. In general, microalgal biomass, microbial biomass composed of carbon and nitrogen, as well as alkaline phosphatase and urease activity were increased by increasing inoculum dosages and moisture, whereas invertase activity decreased with higher moisture content. Combination of 7 g/m-2 inoculum and 2 or 3 L/m-2 moisture was recommended for M. vaginatus to recover BSCs. Significant positive correlations were observed between microalgal biomass, microbial biomass, C:N ratios, and enzyme activities. Increasing microalgal biomass can act as an energy source for microbial activity, while the growth of cyanobacteria and microorganisms provides substrates for enzymatic activities.
Results from the study allows better understanding of the conditions for M. vaginatus forming BSCs and offers guidance for successful recovery of BSCs in the field. The result was published in Arid Land Research and Management in July 2013.
Microcoleus vaginatus Gom. is the pioneer organism and dominant species of algal crusts and serves critical roles in their early formation. During algal crusts formation, polysaccharide sheath material from M. vaginatus winds throughout soil surfaces and binds soil particles together. Sheaths and filaments will absorb water when wet and swell to cover soil surfaces more extensively, which in turn greatly improves soil crust efficacy.
Gurbantunggut Desert is the largest fixed and semi-fixed desert in China with an area of 48,800 km2. There are abundant BSCs on sand surfaces throughout the Gurbantunggut Desert, which grow primarily during wet, cool periods when dew, fog and occasional rainfall provide sufficient moisture for species to form soil crusts.
The objectives of this work were to investigate the change of microbial-microalgal biomass with different moisture and inoculated M. vaginatus dosage treatment and investigate the enzymatic activities along moisture and inoculated M. vaginatus gradients.
Four inoculum dosages of M. vaginatus (0.5, 1, 3, and 7 g/m-2) were inoculated across a sand surface and subjected to five moisture treatments (0, 1, 2, 3, and 4 L/m-2). Microalgal biomass, microbial biomass, and enzyme activities (invertase, alkaline phosphatase, and urease) were subsequently determined. In general, microalgal biomass, microbial biomass composed of carbon and nitrogen, as well as alkaline phosphatase and urease activity were increased by increasing inoculum dosages and moisture, whereas invertase activity decreased with higher moisture content. Combination of 7 g/m-2 inoculum and 2 or 3 L/m-2 moisture was recommended for M. vaginatus to recover BSCs. Significant positive correlations were observed between microalgal biomass, microbial biomass, C:N ratios, and enzyme activities. Increasing microalgal biomass can act as an energy source for microbial activity, while the growth of cyanobacteria and microorganisms provides substrates for enzymatic activities.
Results from the study allows better understanding of the conditions for M. vaginatus forming BSCs and offers guidance for successful recovery of BSCs in the field. The result was published in Arid Land Research and Management in July 2013.