Biological soil crust and disturbance controls on surface hydrology in a semi‐arid ecosystem

Abstract

Abstract. Biological soil crust communities (biocrusts) play an important role in surface hydrologic processes in dryland ecosystems and can be dramatically altered with soil surface disturbance. In this study, through a simulated rainfall experiment, we examined biocrust hydrologic responses to disturbance (trampling and scraping) at different developmental stages on sandy soils on the Colorado Plateau. Our results showed that all disturbance treatments of the early-successional light cyanobacterial biocrusts reduced runoff after 10 min of cumulative rainfall. Scraped and scraped + trampled treatments also reduced runoff after 30 min in the light biocrust when compared to the intact controls but runoff in the trampling treatments was not significantly reduced. Light biocrust sediment loss trended toward a decrease in total amount of sediment lost in all disturbance treatments but not significantly so. In contrast, trampling welldeveloped dark cyano-lichen biocrusts demonstrated an opposite response than the less-developed light biocrusts and increased runoff after 30 min of cumulative rainfall and in total sediment loss relative to intact controls. Scraping in dark crusts did not increase runoff, implying that soil aggregate structure was important to the infiltration process. Well-developed, intact dark biocrusts generally had lower runoff and sediment loss and highest aggregate stability, whereas the less-developed light biocrusts were highest in runoff and sediment loss after disturbance when compared to the controls. These results suggest the importance of maintaining the well-developed dark biocrusts, as they are beneficial for lowering runoff and reducing soil loss and redistribution on the landscape. These data also suggest that upslope patches of light biocrust may either support water transport to downslope vegetation patches or alternatively this runoff may place dark biocrust patches at risk of disruption and loss, given that light patches increase runoff and thus soil erosion potential.

Increased fire risk in Mojave and Sonoran shrublands due to exotic species and extreme rainfall events

“…The most significant effect of disturbance in arid areas is the destruction of microbiotic soil crusts (Faist et al. ), which in hot deserts has been shown to impede annual plant recruitment (Prasse and Bornkamm , Belnap et al. ).…”

Simulated climate change affects how biocrusts modulate water gains and desiccation dynamics after rainfall events

“…Nevertheless, this effect was modulated by rainfall intensity; despite its magnitude, if the intensity of a rainfall event was high, soil water gains turned to be lower than expected. Many studies have evaluated the effects of the amount and intensity of rainfall on infiltration and run‐off (e.g., Cantón et al, ; Chamizo, Cantón, Rodríguez‐Caballero, et al, ; Faist, Herrick, Belnap, Zee, & Barger, ; Kidron & Yair, ). Our results are similar to those of Chamizo, Cantón, Rodríguez‐Caballero, et al () and Kidron and Yair (), who observed that biocrust‐dominated soils had the ability to reduce run‐off when compared to bare ground soils under low intensity rainfall events.…”

“…However, when the intensity of the rainfall event was high, biocrusts lost their capacity to reduce run‐off. Faist et al () observed that under high intensity rainfalls, the capacity to reduce run‐off was dependent on the successional stage of the biocrusts, late successional biocrusts had the capacity to reduce run‐off, whereas early successional biocrust lost this capacity. Moreover, the higher the initial soil moisture, the lower the water gains after rainfall events.…”

Hydration status and diurnal trophic interactions shape microbial community function in desert biocrusts

“…Biocrust microbial activity produces extracellular organic exudates that alter the immediate environment by supporting a stable structure and altering the water retention and transport properties of the biocrusts (Mazor et al, 1996;Belnap and Lange, 2002;Belnap, 2003;Rodríguez-Caballero et al, 2015). The resulting modification of local hydrological processes, such as infiltration run-off and water storage (Chamizo et al, 2012), enhances the capability of other organisms to cope with water scarcity (Chamizo et al, 2016;Faist et al, 2017). Furthermore, this water-regulating function of biocrusts also protects the soil surface against wind and water erosion (Belnap and Gillette, 1998;Warren, 2001).…”