The impacts of soil freeze/thaw dynamics on soil water transfer and spring phenology in the Tibetan Plateau

• Published in: Arctic, Antarctic, and Alpine Research
• Main Authors: Huiru Jiang, Wenjiang Zhang, Yonghong Yi, Kun Yang, Guicai Li, Gengxu Wang
• Format: Article in Journal/Newspaper
• Language: English
• Published: Taylor & Francis Group 2018
• Subjects: freeze/thaw; permafrost; soil moisture; tibetan plateau; vegetation spring onset; Environmental sciences; GE1-350; Ecology; QH540-549.5; Antarctic and Alpine Research; Arctic
• Online Access: https://doi.org/10.1080/15230430.2018.1439155; https://doaj.org/article/72e91fb214704310a4bd6d13f54ebdfa

Climate warming has induced significant changes in permafrost and seasonally frozen ground (SFG) in the Tibetan Plateau, which have complex influences on local environments. A better understanding of the impacts of soil freeze/thaw (F/T) dynamics on soil water transfer and vegetation growth is important to explore related eco-hydrological influences. We investigated soil F/T dynamics and their impacts with in-situ and satellite-based observations. Our results showed the contrasting F/T dynamics between SFG and permafrost areas. In permafrost areas, soil froze downward from the ground surface and upward from the active layer bottom with a distinct freezing zero-curtain, and minimum soil moisture occurred in the intermediate layer, but the thawing process was unidirectional. However, the vertical F/T directions were contrary in SFG areas, where soil moisture generally increased with depth and the thawing zero-curtain was distinct. The spring onset showed a positive correlation with thaw onset in permafrost areas, but such a correlation was variable in SFG areas likely depending on soil-moisture level. Our results implied that the different soil-moisture patterns and the varying vegetation response might be related to the spatially contrasting F/T dynamics, which may have different impacts on soil water transfer, and further affect the zero-curtain and vegetation phenology.