Composition of photosynthetic organisms and diurnal changes of photosynthetic efficiency in algae and moss crusts

Abstract

AbstractsAims In Dalateqi region of Inner Mongolia (at eastern edge of Qubqi Desert), man-made algae crusts were constructed with two filamentous cyanobacteria. Two to three years later, the algae crusts began to succeed to moss crusts under some microterrain conditions. In order to characterize the community structure and compare the photosynthetic characteristics in different successional stages of biological soil crusts (BSCs). Methods This paper studied composition of photosynthetic organisms and diurnal changes of photosynthetic efficiency, with microscopic observation and chlorophyll fluorescence monitoring techniques. Results Compared with the early successional algae crusts, later moss crusts had a higher photosynthetic efficiency, which was closely related with the different community structure of photosynthetic organisms. Further, moss crusts had a higher total photosynthetic biomass, although the algal biomass decreased along the successional sequence. Similar to higher vascular plants, a midday depression of photosynthetic efficiency was detected in BSCs, although the depression extents were different in different successional stages. Analysis demonstrated the depression was mainly caused by non-stomata limitations, and photosynthetically active radiation (PAR) was a significant influencing factor in the down-regulation of photosynthetic efficiency. Conclusions We conclude, cyanobacterial inoculation effectively promotes the formation, development and seccession of BSCs. Furthermore, the later successional BSCs have a better photosynthetic performance and thus are expected to play a more effective role in desertification control.

Artificially Accelerating the Reversal of Desertification: Cyanobacterial Inoculation Facilitates the Succession of Vegetation Communities

“…Crust organisms also promoted the conversion of sand into soil by increasing soil nutrients and improving topsoil texture. 6,18 In addition, the increased dust deposition on crust surface also could increase soil organic matters and nutrients. 27 Succession of Vascular Vegetation Communities.…”

“…In our experimental region, with cyanobacterial inoculation, cyanobacterial crusts formed quickly and in some micoenvironments gradually succeeded to moss crusts 2−3 years later. 17,18 In the survey of Wang et al, 19 it was found the diverse vegetation communities (17 species of vascular plants in total) were established on the different sides of dunes after 3 years of cyanobacterial inoculation. However, the mechanisms of formation, development, succession of BSCs, revegetation of vascular plants, and succession of vegetation communities after cyanobacterial inoculation are still unknown.…”

Analysis of environmental factors determining development and succession in biological soil crusts

“…In Dalate Banner region, after inoculating the two filamentous cyanobacteria, cyanobacterial crusts formed quickly and gradually succeed to moss crusts on the shady side of dunes 2-3 years later (Lan et al, 2012b). With the development and succession from cyanobacterial crusts to moss crusts, moss coverage gradually increased, photosynthetic biomass and microbial CFU also increased significantly (P b 0.05), while cyanobacterial and algal biomass decreased (P b 0.05; Fig.…”

“…Based on our previous observations, in Shapotou region (at the southeast edge of Tengger Desert) BSCs generally succeed from cyanobacterial crusts to lichen and moss crusts along a pathway of "cyanobacterial crusts, cyanobacteriallichen crusts, lichen crusts, lichen-moss crusts and moss crusts" (Lan et al, 2012a(Lan et al, , 2013. However in Dalate Banner region (mainly in Jiefangtan; at the eastern edge of Qubqi Desert), BSCs directly succeed from cyanobacterial crusts to moss crusts (Lan et al, 2012b(Lan et al, , 2014. As a whole, three different successional stages including cyanobacterial, lichen and moss crusts are found in Shapotou region, while only cyanobacterial and moss crusts appear in Dalate Banner region.…”

“…More than 7 years elapsed since the cyanobacterial inoculation, the environment in this restored region had been much improved at this experimental time, and the established BSCs (more than 80% in coverage) included cyanobacterial (60-70%; dominated by M. vaginatus) and moss crusts (20-30%; dominated by Didymodon sp. ; Xie et al, 2007;Rao et al, 2009;Lan et al, 2012b).…”