关键词: 生物结皮, 荒漠生态系统, 温室气体, 植被恢复, 全球增温潜势

Abstract: We analyzed greenhouse gas fluxes at the different growth stages of algae and lichen crusts in fixed sand with mobile dune as control in the eastern Hobq Desert, China, using the spatio-temporal substitution method. We explored the correlation of these fluxes with environmental factors and with biological soil crust growth. The results showed that variation of CO₂ fluxes followed the order: lichen crust (128.5 mg·m^-2·h^-1) > algae crust (70.2 mg·m^-2·h^-1) > mobile dune (48.2 mg·m^-2·h^-1). CH₄ absorption rates were in the following order: lichen crust (30.4 μg·m^-2·h^-1) > algae crust (21.2 μg·m^-2·h^-1) > mobile dune (18.2 μg·m^-2·h^-1). The N₂O fluxes were in the following order: lichen crust (6.6 μg·m^-2·h^-1) > algae crust (5.4 μg·m^-2·h^-1) > mobile dune (2.5 μg·m^-2·h^-1). CO₂ emission had obvious seasonal variation, with higher emission in the growing season. CH₄ and N₂O fluxes had no seaonal variation. CH₄ absorption mainly occurred in the growing season and N₂O emission mainly occurred in non-growing season. Contents of soil total nitrogen and organic carbon and the abundance of microorganisms were important factors affecting greenhouse gas fluxes. Hydrothermic factors were important for soil CO₂ emission, but not for CH₄ and N₂O fluxes. The cumulative greenhouse gas emissions were gradually increased with vegetation restoration and the development of biological soil crust. The global warming potential increased following an order: lichen crust (1135.7 g CO₂-e·m^-2·a^-1) > algae crust (626.5 g CO₂-e·m^-2·a^-1) > mobile dune (422.7 g CO₂-e·m^-2·a^-1).

Key words: biological soil crust, vegetation restoration, greenhouse gas, global warming potential, desert ecosystem