A simple classification of soil types as habitats of biological soil crusts on the Colorado Plateau, USA

Abstract

Question: Can a simple soil classification method, accessible to non‐experts, be used to infer properties of the biological soil crust (BSC) communities such as species richness, evenness, and structure? Location: Grand Staircase‐Escalante National Monument, an arid region of the Colorado Plateau, USA. Methods: Biological soil crusts are highly functional soil surface communities of mosses, lichens and cyanobacteria that are vulnerable to soil surface disturbances such as grazing. We sampled BSC communities at 114 relatively undisturbed sites. We developed an eight‐tier BSC habitat classification based upon soil properties including texture, carbonate and gypsum content, and presence of shrinking‐swelling clays. We used simple structural equation models to determine how well this classification system predicted the evenness, richness, and community structure of BSC relative to elevation and annual precipitation. Results: We found that our habitat classification system explained at least 3.5 × more variance in BSC richness (R2= 0.57), evenness (R2= 0.59), and community structure (R2= 0.34) than annual precipitation and elevation combined. Gypsiferous soils, non‐calcareous sandy soils, and limestone‐derived soils were all very high in both species richness and evenness. Additionally, we found that gypsiferous soils were the most biologically unique group, harboring eight strong to excellent indicator species. Conclusions: Community properties of BSCs are overwhelmingly influenced by edaphic factors. These factors can be summarized efficiently by land managers and laypeople using a simple soil habitat classification, which will facilitate incorporation of BSCs into assessment and monitoring protocols and help prioritize conservation or restoration efforts.

Climate change and physical disturbance cause similar community shifts in biological soil crusts

“…These block effects suggest the existence of small-scale gradients in climate and disturbance impacts on biocrust communities. These gradients, possibly in soil nutrients or microclimate, may interact with interannual climatic variation such that areas prone to fluctuations in soil moisture or temperature may become more or less harsh for biocrust organisms over time (51)(52)(53). Environmental gradients can also affect the strength and direction of biotic interactions within these communities (47,54), highlighting the need to consider spatial and temporal influences on species responses in environmental change studies.…”

Development of bacterial communities in biological soil crusts along a revegetation chronosequence in the Tengger Desert, northwest China

“…It would be good to understand more of the factors that together influenced the composition and function of BSC bacteria in long-term revegetation, including BSCs, plants, soil biochemical properties and climate conditions, and the microorganisms that in turn have the positive influence on soil improvement (Li et al, 2007b(Li et al, , 2010. Many reports have interpreted correlations among soil properties and BSCs as an indicator that BSCs are drivers of soil fertility and development (Chamizo et al, 2012;Delgado-Baquerizo, 2013;Yu et al, 2014;Zhang et al, 2010); some have reported the opposite and suggest a direct influence of soil properties on BSC development (Belnap et al, 2014;Bowker et al, 2006a;Bowker and Belnap, 2008;Concostrina-Zubiri et al, 2013;Rivera-Aquilar et al, 2009;Root and McCune, 2012;Weber et al, 2016). These are important questions, and parsing out the interactions of BSCs and soil biogeochemical properties remains an important frontier in BSC research.…”

Controls on Distribution Patterns of Biological Soil Crusts at Micro- to Global Scales

“…Globally, the most significant soil properties influencing the ecoregional-scale cover and richness of biocrusts in dryland environments are soil texture, pH, and to a lesser extent, soil calcareousness (e.g., Rogers 1972;Eldridge and Tozer 1997;Ponzetti and McCune 2001;Eldridge 1996;Lalley et al 2006;Lobel et al 2006;Bowker and Belnap 2008;Root et al 2011;Ochoa-Hueso et al 2011). At smaller local, intra-site, or microscales, however, biocrust distribution and cover are tightly coupled to a relatively narrow range of soil physical and chemical properties, often in idiosyncratic ways.…”

“…Biocrust organisms have been shown to vary in abundance and richness among soils derived from different parent material (e.g., sandstone and shale bedrockderived soils on the Colorado Plateau in the western USA, Bowker et al 2006a; on igneous, sedimentary, and metamorphic bedrock-derived soils in the Mojave Desert, Belnap et al 2014) or in soils subjected to different levels of weathering (e.g., fluvisols, regosols, and calcisols in the Tehuacan Desert, Mexico; Rivera- Aguilar et al 2006). For example, filamentous cyanobacteria can flourish in sandy, poorly aggregated soils, which are less likely to support highly developed lichen and moss communities (Root and McCune 2012), whereas mosses and lichens are more likely to reach their strongest development on calcareous or gypsiferous soils (Bowker et al 2006b;Bowker and Belnap 2008;Martínez et al 2006).…”