库布齐沙漠东部不同生物结皮发育阶段土壤温室气体通量

以流动沙地为对照,采用时空替代法分析库布齐沙漠东部固定沙地上不同发育阶段生物结皮藻类结皮和地衣结皮土壤温室气体通量特征及其与环境因子之间的关系,研究生物结皮发育对荒漠土壤温室气体通量的影响.结果表明: 荒漠土壤CO₂排放通量大小为地衣结皮(128.5 mg·m^-2·h^-1)>藻结皮(70.2 mg·m^-2·h^-1)>流动沙地(48.2 mg·m^-2·h^-1),CH₄吸收通量大小为地衣结皮(30.4 μg·m^-2·h^-1)>藻结皮(21.2 μg·m^-2·h^-1)>流动沙地(18.2 μg·m^-2·h^-1),N₂O排放通量大小为地衣结皮(6.6 μg·m^-2·h^-1)>藻结皮(5.4 μg·m^-2·h^-1)>流动沙地(2.5 μg·m^-2·h^-1).CO₂排放具有明显的季节变化,生长季显著大于非生长季;CH₄和N₂O季节变化差异不显著,前者生长季吸收大于非生长季,后者非生长季排放大于生长季.土壤有机碳和全氮含量、土壤微生物数量均是影响温室气体通量的重要因素,环境水热因子是影响土壤CO₂排放的关键因子,但CH₄和N₂O通量对水热因子的变化不敏感.随着植被恢复和生物结皮发育,荒漠土壤温室气体累积通量的不断增大导致其百年尺度的全球增温潜势亦显著提高,依次为地衣结皮(1135.7 g CO₂-e·m^-2·a^-1)>藻结皮(626.5 g CO₂-e·m^-2·a^-1) >流动沙地(422.7 g CO₂-e·m^-2·a^-1).

Greenhouse gas fluxes at different growth stages of biological soil crusts in eastern Hobq desert,China

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).