TY - JOUR
T1 - Moss-biocrusts strongly decrease soil surface albedo, altering land-surface energy balance in a dryland ecosystem
AU - Xiao, Bo
AU - Bowker, Matthew A.
N1 - Funding Information:
This study was funded by the National Natural Science Foundation of China (No. 41671221 ), the China Scholarship Council (No. 201906355019 ), and the “Light of West China” Program of the Chinese Academy of Sciences (No. 2019 ). The authors are grateful to the Shenmu Experimental Station of Soil Erosion and Environment, CAS & MOE for its logistical support. Dr. Matthew A. Bowker was supported by the National Science Foundation Dimensions of Biodiversity Program (No. 1638966 ).
Funding Information:
This study was funded by the National Natural Science Foundation of China (No. 41671221), the China Scholarship Council (No. 201906355019), and the ?Light of West China? Program of the Chinese Academy of Sciences (No. 2019). The authors are grateful to the Shenmu Experimental Station of Soil Erosion and Environment, CAS & MOE for its logistical support. Dr. Matthew A. Bowker was supported by the National Science Foundation Dimensions of Biodiversity Program (No. 1638966).
Publisher Copyright:
© 2020 Elsevier B.V.
PY - 2020/11/1
Y1 - 2020/11/1
N2 - Land surface albedo measures the degree to which the sun's radiation is absorbed or reflected, and thus can be highly influential in global climate trends, local weather phenomena, and biological processes. As an extensive living cover in drylands, biocrusts cover substantial land surface but their potential influences on surface albedo and energy balance are underdocumented, and its temporal dynamic is virtually unknown. We continuously measured the surface albedo, land-surface energy balance, temperature and moisture of moss-biocrust covered soil and bare soil for two years, and measured the surface color and roughness of the two land cover types. Our results showed that the surface albedo of the biocrusts was 43.4% lower than that of the bare soil, due to the increased darkness (43.7%) and roughness (90.4%) together with increased moisture (20.7%) of the biocrust layer. Through time, the albedo of the biocrusts were negatively and linearly related with surface soil temperature or moisture, which resulted in lower albedo in summer and higher albedo in other seasons. As a result of decreased albedo, biocrusts decreased outgoing short-wave radiation by 44.8% in comparison to the bare soil, and consequently they increased net short-wave radiation by 11.4% and net all-wave solar radiation by 22.9% However, the increased energy absorption by the biocrusts did not consistently increase soil temperature; instead, soil temperature increased by up to 9.3 °C under dry conditions but decreased by as much as 11.4 °C under wet conditions, resulting in a net cooling. This indicates that the temperature regimes of the biocrust-covered soil were not determined only by albedo, but also by modification of soil thermal properties by biocrusts. Because biocrusts are highly responsive to land use, it appears that altered albedo and energy balance may be one of the ways in which human activity can impact climate and weather.
AB - Land surface albedo measures the degree to which the sun's radiation is absorbed or reflected, and thus can be highly influential in global climate trends, local weather phenomena, and biological processes. As an extensive living cover in drylands, biocrusts cover substantial land surface but their potential influences on surface albedo and energy balance are underdocumented, and its temporal dynamic is virtually unknown. We continuously measured the surface albedo, land-surface energy balance, temperature and moisture of moss-biocrust covered soil and bare soil for two years, and measured the surface color and roughness of the two land cover types. Our results showed that the surface albedo of the biocrusts was 43.4% lower than that of the bare soil, due to the increased darkness (43.7%) and roughness (90.4%) together with increased moisture (20.7%) of the biocrust layer. Through time, the albedo of the biocrusts were negatively and linearly related with surface soil temperature or moisture, which resulted in lower albedo in summer and higher albedo in other seasons. As a result of decreased albedo, biocrusts decreased outgoing short-wave radiation by 44.8% in comparison to the bare soil, and consequently they increased net short-wave radiation by 11.4% and net all-wave solar radiation by 22.9% However, the increased energy absorption by the biocrusts did not consistently increase soil temperature; instead, soil temperature increased by up to 9.3 °C under dry conditions but decreased by as much as 11.4 °C under wet conditions, resulting in a net cooling. This indicates that the temperature regimes of the biocrust-covered soil were not determined only by albedo, but also by modification of soil thermal properties by biocrusts. Because biocrusts are highly responsive to land use, it appears that altered albedo and energy balance may be one of the ways in which human activity can impact climate and weather.
KW - Biological soil crust
KW - Chinese Loess Plateau
KW - Microbiotic crust
KW - Soil reflectance
KW - Soil temperature
KW - Solar radiation balance
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U2 - 10.1016/j.scitotenv.2020.140425
DO - 10.1016/j.scitotenv.2020.140425
M3 - Article
C2 - 32615433
AN - SCOPUS:85086900895
SN - 0048-9697
VL - 741
JO - Science of the Total Environment
JF - Science of the Total Environment
M1 - 140425
ER -