Effects of inoculated Microcoleus vaginatus on the structure and function of biological soil crusts of desert

Abstract

Microcoleus vaginatus Gom., the dominant species in biological soil crusts (BSCs) in desert regions, plays a significant role in maintaining the BSC structure and function. The BSC quality is commonly assessed by the chlorophyll a content, thickness, and compressive strength. Here, we have studied the effect of different proportions of M. vaginatus, collected from the Gurbantunggut Desert in northwestern China, on the BSC structure and function under laboratory conditions. We found that when M. vaginatus was absent in the BSC, the BSC coverage, quantified by the percentage of BSC area to total land surface area, was low with a chlorophyll a content of 4.77× 10 −2 mg g −1 dry soil, a thickness of 0.86 mm, and a compressive strength of 12.21 Pa. By increasing the percentage of M. vaginatus in the BSC, the BSC coverage, chlorophyll a content, crust thickness, and compressive strength all significantly increased (P<0.01). The maximum chlorophyll a content (13.12 mg g −1 dry soil), the highest crust thickness, and the compressive strength (1.48 mm and 36.60 Pa, respectively) occurred when the percentage of inoculated M. vaginatus reached 80% with a complex network of filaments under scanning electron microscope. The BSC quality indicated by the above variables, however, declined when the BSC was composed of pure M. vaginatus (monoculture). In addition, we found that secretion of filaments and polymer, which stick sands together in the BSC, increased remarkably with the increase of the dominant species until the percentage of M. vaginatus reached 80%. Our results suggest that not only the dominant species but also the accompanying taxa are critical for maintaining the structure and functions of the BSC and thus the stability of the BSC ecosystems.

Response and resilience of soil biocrust bacterial communities to chronic physical disturbance in arid shrublands

“…Recent studies have provided evidence that, in addition to M. vaginatus, other bacteria play a role in early biocrust formation (Reddy and GarciaPichel, 2007;Wu et al, 2010;Zheng et al, 2011). The majority (74%) of Actinobacteria sequences identified in this study belong to the deepest branch of the phylum, the Rubrobacteridae, which are common in arid soils and on rock surfaces worldwide and are extremely resistant to desiccation and UV stress (Holmes et al, 2000;Rainey et al, 2005).…”

Mechanism of biocrusts boosting and utilizing non-rainfall water in Hobq Desert of China

“…But even in hyperarid environment, the special microhabitats with moist subsoil and abundant nucleation on the topsoil might not be as high as our zone. Nevertheless, the 0.08 mm threshold has been confirmed by Microcoleus vaginatus dominated biocrusts in Mu Us and Horqin sand land, Hobq, Ulan Buh and Hulun Buir desert (Zheng et al, 2011;Hu et al, 2012;Lan et al, 2014). It is the lowest value in inland aeolian sandy soil of China (250-400 mm annual precipitation).…”

“…This technology has been successfully applied in more than 40 km 2 desert region Liu et al, 2013;Lan et al, 2014;Zhao et al, 2016). The technology is also being largely attempted and further extended globally (Zheng et al, 2011;Liu et al, 2013;Wu et al, 2013b;Xiao et al, 2015;Chiquoine et al, 2016;Mallen-Cooper and Eldridge, 2016). The cyanobacterial-based inoculation technology (inoculation-based technology for short) was applied according to the following experimental flow: (1) suitable strains are selected; (2) a stable mass-cultivation system for growing the selected strains is optimized; (3) a proper culture-dispersal strategy is chosen and optimized; (4) proper techniques for habitat ameliorations were chosen (Liu et al, 2013;Rossi et al, 2017).…”

Nursing biocrusts: isolation, cultivation, and fitness test of indigenous cyanobacteria

“…submitted to a liquid‐culture based scale‐up approach, invariably had low yields or no growth at all, even if we used variations in incubation conditions that included light exposure, temperature, nutrient concentration, shaking intensity, or adding glass beads. This was surprising because mass growth of Microcoleus vaginatus has been reported in a greenhouse setting (Wang et al ; Zheng et al ), and in open‐raceway facilities (Chen et al ; Xie et al ; Lan et al , ), although no details on cultivation were given, nor any quality control of the final product usually reported (with the exception of Lan et al ), but also no reports on cultivation difficulties. In our experiment, all 32 Microcoleus spp.…”

“…Although significant advances have been achieved, a standard manual for the successful production of fit, high‐quality biocrust inoculum is a work in progress. Cultivation‐based production has been reported mostly for cyanobacteria (Buttars et al ; Chen et al ; Wang et al ; Zheng et al ; Lan et al ; Zhang et al ; Román et al ), yet technical detail required to cultivate the dominant biocrust cyanobacteria species under laboratory conditions is still needed. Although laboratory production of cultivated biocrust organisms is work intensive, it enables a stringent control of the composition of the inoculum produced.…”