Spatial distribution of biological soil crusts on the slope of the Chinese Loess Plateau based on canonical correspondence analysis

Abstract

Biological soil crusts (BSCs) are a living ground cover widely distributed in arid and semi-arid regions, and providing important ecological functions in arid and semi-arid ecosystems. An understanding of the spatial distribution patterns of BSCs is foundational for the scientific management of this resource. In this study, a typical slope was selected from a small watershed, Liudaogou, in the wind-water erosion crisscross region of the Loess Plateau in northwest China. The spatial distribution characteristics of BSCs and associated influencing factors were investigated at the slope scale via a comprehensive survey and statistical analysis using GS+ and CANOCO statistical software. The results showed that the distribution of BSCs was clearly spatially differentiated, with the majority of BSCs widely and continuously distributed in sandy areas at a mean coverage of greater than 30%. Sporadic distribution of BSCs was observed in loess areas mainly at the edges of slopes with a mean coverage of generally less than 20%. The thickness and shear strength of the BSCs did not present significant spatial variation, indicating that these two BSC indices were primarily associated with the age and developmental stage of the BSC which was relatively constant throughout the study area. A canonical correspondence analysis revealed that the spatial distribution of BSCs was closely correlated with soil type, vegetation, surface soil moisture content, slope and aspect. Among these factors, soil type had the most significant impact on BSC distribution and explained 20% of the spatial variation of BSCs. The vegetation community type and topographic wetness index were the secondary influencing factors, and sagebrush (Artemisia desertorum) shrubland and aspen (Populus simonii) woodland provided the most ideal growth environments for BSCs. Other factors such as slope, aspect and solar radiation also affected BSC distribution to a certain degree. Overall, BSCs were clearly selective for topography, soil type and vegetation community and preferentially grew in humid areas with psammophytic plant communities.

Measurements and ecological implications of non‐rainfall water in desert ecosystems—A review

“…Although some of the habitats obtained similar amounts, large differences in the dew duration took place, explaining in turn the variable species composition and biomass of the lithobionts at these habitats (Kappen et al, 1980;Kidron, 2000a;Kidron et al, 2011). Interestingly, wetness duration was also found to explain biocrust biomass and species composition, However, in the case of soil biocrusts, this wetness duration results from rain, as shown for the Negev (Kidron, Vonshak, & Abeliovich, 2009;Kidron, Vonshak, Dor, Barinova, & Abeliovich, 2010) and for the Chinese Loess Plateau (Bu et al, 2016).…”

Analysis of the contributions of human factors and natural factors affecting the vegetation pattern in coastal wetlands

“…Canonical correlation analysis (CCA) is a sorting method based on a single-peak model that combines correspondence analysis and multivariate regression analysis in the sorting process (Ter Braak 1986;Li et al 2017) and is thus capable of presenting the quadrats, the study object and the sorting results for the environmental factors on the same plot (Bu et al 2016). In this paper, because the study object is a type variable, we added three virtual variables and converted the four vegetation types to quantitative variables.…”

Bryophyte-dominated biological soil crusts mitigate soil erosion in an early successional Chinese subtropical forest

“…Slope was the most prominent of those factors, causing a considerable decline in biocrust cover with increasing slope. This finding was explained by their decreasing ability to fix themselves on the soil surface at high slope angles and thus their tendency to erode from the soil surface when large surface water flows occur during rainfall events (Chamizo et al, 2013;Bu et al, 2016). Thus, the surface-protecting effect of biocrusts decreases at steep plantation sites and during heavy monsoon rainfall events, which frequently occur in the broader research area in Jiangxi Province, PR China (Yang et al, 2013;Goebes et al, 2015).…”

“…Biocrust cover varies across spatial scales (from centimetres to kilometres), and it could be shown that it depends not only on the surrounding vascular vegetation cover but also on soils, geomorphology, and (micro-)topography or terrain (Evans and Johansen, 1999;Ullmann and Büdel, 2003;Kidron et al, 2009;Bowker et al, 2016) in arid, semi-arid, temperate and boreal environments. Different biocrust distributions have been related to elevation and terrain-influenced microclimatic gradients (Kutiel et al, 1998), different geomorphic zones (Eldridge, 1999), varying aspects (George et al, 2000 and soil types (Bu et al, 2016). We assume that this is also true for mesic subtropical forest environments.…”

“…We assume that this is also true for mesic subtropical forest environments. To our knowledge, investigations of the influence of small-scale (centimetres to metres) topographic variations in biocrust development are rare, and further studies will help to understand the role of these small-scale factors (Garcia-Pichel and Belnap, 2003;Bu et al, 2016;Bowker et al, 2016). Furthermore, as the development of biocrusts is characterised by a high complexity and spatial heterogeneity with many microclimatic and micro-environmental factors, it is of great significance to conduct comparative studies on the spatial distribution of biocrusts (Bu et al, 2013).…”