Apportioning above- and below-ground effects of moss biocrusts on soil detachment by overland flow in a subtropical climate

• Published in: Journal of mountain science Vol. 18; no. 10; pp. 2646 - 2655
• Main Authors: Zhang, Guan-hua, Yi, Liang, Ding, Wen-feng, Lei, Xu, Wang, Yi-ran, Sun, Bao-yang, Li, Jian-ming
• Format: Journal Article
• Language: English
• Published: Heidelberg Science Press 01.10.2021; Springer Nature B.V
• Subjects: Climate; Climate effects; Concretions; Crusts; Earth and Environmental Science; Earth Sciences; Ecological function; Ecology; Environment; Erosion resistance; Geography; Humid climates; Mosses; Original Article; Overland flow; Reduction; Soil erosion; Soil resistance; Surface runoff; Tissue; Three Gorges; Effect apportionment; Contribution rate; Soil detachment; Rill erodibility
• ISSN: 1672-6316; 1993-0321; 1008-2786
• DOI: 10.1007/s11629-021-6888-y

Biocrusts affect soil detachment through above-ground (top crust’s surface covering) and below-ground (sub-crust’s binding and bonding, B&B) effects, which might vary with biocrust development or coverage. However, these effects in humid climates are still unclear. This study was conducted to apportion and quantify the surface covering and B&B effects of moss biocrusts with five coverage levels (1%–20%, 20%–40%, 40%–60%, 60%–80%, and 80%–100%) on soil detachment by overland flow in a subtropical humid climate. Two treatments with one being intact moss crusts and one removing the above-ground moss tissues were designed for each coverage level, and bare soil was used as the baseline. The results indicated that soil detachment capacity ( D c ) and rill erodibility ( K r ) decreased with biocrust coverage. After removing the above-ground moss tissues, the impeding effect of biocrusts on soil detachment weakened, but still increasing soil erosion resistance relative to bare soil. For intact crust, D c was reduced by 50%–95% compared with bare soil, wherein 36%–55% and 14%–40% were attributed to the surface covering and B&B, respectively. The top crust contributed more than sub-crust to the soil detachment reduction, which were related to but not linear with biocrust coverage. When biocrust coverage reached mid-to-higher level (40%–100%), both top crust and sub-crust steadily contributed to soil detachment reduction with 60% and 40%, respectively. The findings advance a better understanding of the influencing mechanism of biocrusts on soil erosion in humid climates and highlight the importance of saving biocrusts as ecosystem functions.