摘要
干旱和半干旱地区生物结皮的普遍发育显著改变了表层土壤的结构与养分富集特征,但其对土壤养分迁移和淋失的影响目前尚不明确。本研究针对黄土高原风沙土和黄绵土上发育的藓类生物结皮,以Ca^2+和Cl^-为示踪离子开展溶质穿透试验,对有无生物结皮层及其覆盖下不同深度土壤的溶质运移特征进行了研究。结果表明:在0~5 cm土层,生物结皮覆盖延缓了风沙土和黄绵土的溶质穿透过程,其Cl^-的穿透时间比无结皮延长了3.83(风沙土)和2.09倍(黄绵土),而Ca^2+则分别延长了2.50和2.73倍。生物结皮覆盖条件下,表层0~5 cm土壤溶质完全穿透所对应的孔隙体积数比下层5~10 cm土壤更高,且其穿透历时更长;其中,Cl^-的穿透时间分别增加了67.3%(风沙土)和51.8%(黄绵土),Ca^2+的穿透时间分别增加了8.0%和33.7%。生物结皮覆盖降低了土壤孔隙水流速(37.5%~70.2%);除风沙土的5~10 cm土层外,生物结皮使溶质弥散系数提高了1.73~6.29倍,使溶质弥散度提高了2.77~20.95倍。置换液完全穿透土壤后,风沙土和黄绵土的生物结皮层Ca^2+含量显著高于无结皮,其分别比无结皮高4.14和2.58倍。研究证实,生物结皮覆盖能够提高表层土壤对养分的吸附与固持能力,从而减少土壤表聚养分的深层渗漏和流失,对干旱和半干旱地区退化土壤的肥力提升与植被恢复具有重要意义。
Biological soil crusts(BSCs)greatly change surface soil structure and nutrient enrichment processes in arid and semiarid regions.However,their impacts on solute transport characteristics and nutrient loss are still not clear.In this study,the solute(Cl^-and Ca^2+)transport experiments were conducted on soils covered by moss-dominated BSCs and uncrusted soil on sandy and loessal soils on the Loess Plateau,respectively.We analyzed the solute transport characteristics of the BSCs covered soil and uncrusted soil in different soil depths(0-5 cm and 5-10 cm).The BSCs mulching generated delay effects on the solute breakthrough process of 0-5 cm soils.The breakthrough time of Cl^-in the BSCs covered soil was 3.83(sandy soil)and 2.09 times(loessal soil)longer than that in the uncrusted soil.The breakthrough time of Ca^2+in the BSCs covered soil was 2.50 and 2.73 times longer than that in the uncrusted soil.Due to the strong influence of BSCs mulching,the pore volume number of the complete solute breakthrough at 0-5 cm depth was higher than that at 5-10 cm depth in the BSCs covered soils.The breakthrough time of Cl^-at 0-5 cm depth was increased by 67.3%(sandy soil)and 51.8%(loessal soil)by the BSCs as compared with that at 5-10 cm depth.The breakthrough time of Ca^2+at 0-5 cm depth was increased by 8.0%and 33.7%by the BSCs.The BSCs reduced soil pore water flow velocity by 37.5%-70.2%compared with the uncrusted soil.Except for the sandy soil at 5-10 cm depth,the BSCs increased the solute dispersion coefficient by 1.73-6.29 times and the degree of dispersion by 2.77-20.95 times compared with the uncrusted soils.After the complete breakthrough of solute,the content of Ca^2+in the BSCs layer(0-2 cm)was 4.14 and 2.58 times higher than that in the uncrusted sandy and loessal soils,respectively.In conclusion,our results indicated that BSCs could reduce the deep percolation and loss of nutrients accumulated in surface soil through improving their solute adsorption and retention abilities,which is of great significance for the improvement of soil fertility and vegetation restoration on degraded land in arid and semiarid regions.
作者
王芳芳
肖波
孙福海
李胜龙
WANG Fang-fang;XIAO Bo;SUN Fu-hai;LI Sheng-long(College of Land Science and Technology,China Agricultural University,Beijing 100193,China;Key Laboratory of Arable Land Conservation in North China,Ministry of Agriculture and Rural Affairs,Beijing 100193,China;State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau,Institute of Soil and Water Conservation,Chinese Academy of Sciences,Yangling 712100,Shaanxi,China)
出处
《应用生态学报》
CAS
CSCD
北大核心
2020年第10期3404-3412,共9页
Chinese Journal of Applied Ecology
基金
国家自然科学基金项目(41671221)
中国科学院“西部引进人才”项目(2019)资助。
