Abstract
The specific bio-species and their spatial patterns play crucial roles in regulating eco-hydrologic process, which is significant for large-scale habitat promotion and vegetation restoration in many dry-land ecosystems. Such effects, however, are not yet fully studied. In this study, 12 micro-plots, each with size of 0.5 m in depth and 1 m in length, were constructed on a gentle grassy hill-slope with a mean gradient of 8° in a semiarid loess hilly area of China. Two major bio-crusts, including mosses and lichens, had been cultivated for two years prior to the field simulation experiments, while physical crusts and non-crusted bare soils were used for comparison. By using rainfall simulation method, four designed micro-patterns (i.e., upper bio-crust and lower bare soil, scattered bio-crust, upper bare soil and lower bio-crust, fully-covered bio-crust) to the soil hydrological response were analyzed. We found that soil surface bio-crusts were more efficient in improving soil structure, water holding capacity and runoff retention particularly at surface 10 cm layers, compared with physical soil crusts and non-crusted bare soils. We re-confirmed that mosses functioned better than lichens, partly due to their higher successional stage and deeper biomass accumulation. Physical crusts were least efficient in water conservation and erosion control, followed by non-crusted bare soils. More importantly, there were marked differences in the efficiency of the different spatial arrangements of bio-crusts in controlling runoff and sediment generation. Fully-covered bio-crust pattern provides the best option for soil loss reduction and runoff retention, while a combination of upper bio-crust and lower bare soil pattern is the least one. These findings are suggested to be significant for surface-cover protection, rainwater infiltration, runoff retention, and erosion control in water-restricted and degraded natural slopes.
Highlights
The deterioration of soil hydrological services, mainly including infiltration reduction and water erosion intensification, can aggravate the already-existing severe drought and landPLOS ONE | DOI:10.1371/journal.pone.0133565 July 24, 2015Soil Hydrological Response to biological soil crusts (BSCs) Micro-Patterns degradation in many dry-land regions, in the context of accelerated global warming [1,2,3,4,5]
PCs reduced soil porosity compared with BSCs, and soil buck density decreased in the decreasing order of mosses, lichens, non-crusted bare soil, and PCs
Significant difference of soil particle size distribution was observed between BSCs and PCs in most cases, while no significance was found between mosses and lichens, or between PCs and non-crusted bare soils
Summary
The deterioration of soil hydrological services, mainly including infiltration reduction and water erosion intensification, can aggravate the already-existing severe drought and landPLOS ONE | DOI:10.1371/journal.pone.0133565 July 24, 2015Soil Hydrological Response to BSCs Micro-Patterns degradation in many dry-land regions (e.g., the Mediterranean area and Loess Plateau in China), in the context of accelerated global warming [1,2,3,4,5]. Bio-crusts in the uppermost millimeters of the topsoil, known as "biological soil crusts (BSCs)", are common surface covers in many arid and semiarid environments [9,10]. These intertwined microorganisms mainly include mosses, lichens, green algae, micro-fungi, and other bacteria [11,12,13]. These spore species are an important and integral part of desert ecosystems, covering 40%-100% of the ground [14,15]. BSCs are recognized as crucial elements that directly connect biotic and abiotic ingredients in the arid and semiarid landscapes [17], being significant in soil carbon sequestration, slope stability, desertification prevention and plant recruitment [18,19]
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