Effects of freeze-thaw cycles on soil macropores and its implications on formation of hummocks in alpine meadows in the Qinghai Lake watershed, northeastern Qinghai-Tibet Plateau

Gao, Zhou; Hu, Xia; Li, Xiaoyan; Li, Zong-Chao

doi:10.1007/s11368-020-02765-2

Cited by 27 publications

(12 citation statements)

References 55 publications

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“…Microtopography can also be initiated through abiotic processes, such as freeze–thaw cycles (Ogata, 2005; Smith et al, 2012; Tsuyuzaki, 2006), bedrock outcropping (Wetzel, 2002), and preferential sediment delivery and accretion (Werner & Zedler, 2002). For example, in high‐latitude and alpine regions, microtopography may arise from differential responses of soil macropores to soil moisture variability during freeze–thaw events, with a higher soil water content being associated with hummock formation (Gao et al, 2020). Additionally, vegetated islands can develop on small bedrock or mineral soil outcrops, or even on “pop‐up” islands of floating peat freed from the soil surface (Wetzel, 2002).…”

Section: Initiation and Reinforcement Of Microtopographymentioning

confidence: 99%

“…Soil mass can include mineral and organic matter. GPP refers to gross primary production responses of soil macropores to soil moisture variability during freeze-thaw events, with a higher soil water content being associated with hummock formation (Gao et al, 2020). Additionally, vegetated islands can develop on small bedrock or mineral soil outcrops, or even on "pop-up" islands of floating peat freed from the soil surface (Wetzel, 2002).…”

Section: Initiationmentioning

confidence: 99%

“…A common feature in wetlands globally is microtopography, the vertical variation in the soil surface occurring at centimeter to meter scales. Microtopography has been described in fens (Sullivan, Arens, Chimner, & Welker, 2008), peat bogs (Malmer & Wallén, 1999; Nungesser, 2003), arctic and alpine tundra ecosystems (Biasi et al, 2005; Gao, Hu, Li, & Li, 2020), forested swamps (Bledsoe & Shear, 2000), tidal freshwater swamps (Casey & Ewel, 2006; Duberstein, Krauss, Conner, Bridges, & Shelburne, 2013), freshwater marshes (van de Koppel & Crain, 2006; Watts, Cohen, Heffernan, & Osborne, 2010), and coastal marshes (Fogel, Crain, & Bertness, 2004; Posey, Alphin, Meyer, & Johnson, 2003; Stribling, Cornwell, & Glahn, 2007; Figure 1).…”

Section: Introductionmentioning

confidence: 99%

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A little relief: Ecological functions and autogenesis of wetland microtopography

et al. 2020

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Microtopography, or the small‐scale variation in ground surface height (10−1–100 m) over short (100–102 m) spatial scales, is a ubiquitous feature of wetlands globally. This variation in elevation, characterized by local high (“hummocks”) and low (“hollows”) patches, is more structured than what is observed in uplands, and is intertwined with concordantly structured spatiotemporal variability in hydrologic regimes and associated ecological processes. The importance of microtopography in wetlands is manifold, with critical influence on local hydrological, biogeochemical, and biological processes. Further, the creation and maintenance of wetland microtopography is a balance between activation processes (i.e., those that induce random elevation variation) and autogenic reinforcement processes (i.e., those that provide the feedbacks necessary for the persistence of microtopography). While there are many mechanisms that create vertical structure (e.g., tree falls, accumulation of roots and soil organic matter, and sediment deposition), they all yield a similar core feedback to enhance and sustain microtopographic structure. Finally, microtopography contributes to spatial patterning that confers emergent ecosystem‐scale functions such as hydrologic storage and flows, carbon cycling, organism dispersal, and biodiversity. There is an ongoing need to study the origins and implications of this fine‐scale variation in elevation, as well as the utility of including microtopography in model predictions and ecological restoration efforts. This article is categorized under: Water and Life > Conservation, Management, and Awareness

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Section: Initiation and Reinforcement Of Microtopographymentioning

confidence: 99%

Section: Initiationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A little relief: Ecological functions and autogenesis of wetland microtopography

et al. 2020

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“…However, knowledge gaps still exist about how FTCs affect soil pore structure in the QTP. Freeze-thaw cycles, an extremely complex soil-surface process in cold regions, has great impacts on soil structure, such as reducing the size of soil aggregates (Starkloff et al, 2017;Zhang et al, 2016), changing soil porosity and bulk density (Gao et al, 2020;Starkloff et al, 2017;Zhao et al, 2020), and affecting the capacity of soil water holding and conductivity (Ishikawa et al, 2016). Some studies have indicated that FTCs could lead to a decrease in soil porosity (Chamberlain & Gow, 1979;Tang & Yan, 2015).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the impact of freeze–thaw cycles on the soil pore structure of alpine meadows using X‐ray computed tomography

Zhao

et al. 2021

Soil Science Soc of Amer J

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Freeze-thaw cycle (FTC) is an extremely complex soil surface process in cold regions, and quantifying the changes in soil pore structure during successive FTCs remains challenging. This study investigated response of soil pore structure to FTCs and revealed the underlying influence on soil water infiltration through an FTC simulation experiment (0, 1, 3, 5, and 10 cycles) and computed tomography (CT) scanning of undisturbed soil cores in an alpine meadow. One FTC involved soil freezing at −10˚C for 12 h, followed by thawing at 20˚C for 12 h. The results showed that CT-measured soil porosity presented a variation trend of increase-decrease during successive FTCs. With increasing number of FTCs, soil porosity first increased and then decreased in the 0-to-75-mm soil layer, decreased after five FTCs in the 75to-150-mm soil layer, and gradually decreased in the 150-to-280-mm soil layer. Pore structures of different soil layers responded differently to FTCs, which was attributed to soil texture. The connectivity of soil pores and soil water infiltration rate decreased considerably after 10 FTCs. Therefore, FTCs changed soil pore structure of the alpine meadow, which was not conducive for soil water infiltration to deep soil layers.

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“…The Tibetan Plateau is characterized by low temperatures, dryness, ultraviolet radiation, freeze and thaw cycles and a short growing season, and the alpine grassland on the plateau is one of the most sensitive and vulnerable ecosystems to regional climate change and human activities (Xu et al, 2010). The soil structures under alpine vegetation can differ from those in nonalpine areas that contain fewer rock fragments (Gao et al, 2020); alpine grassland soil exhibits obvious stony characteristics, and the soil macropore size is different from that in non-alpine areas (Wang et al, 2011;Qin et al, 2015). Therefore, the vegetation in alpine areas grows under unique soil conditions and harsh climate conditions.…”

Section: Introductionmentioning

confidence: 99%

Soil Macropores Affect the Plant Biomass of Alpine Grassland on the Northeastern Tibetan Plateau

et al. 2021

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Macropores are an important part of soil structure. However, in alpine regions, the effects of soil macropores on soil properties and vegetation growth are not clear. We used the X-ray computed tomography (CT) method to obtain 3D images and visualize the distribution and morphology of soil macropores. By combining principal component analysis (PCA) and stepwise regression methods, we studied the relationships between soil macropores and both soil properties and vegetation growth in three types of grassland [alpine degraded steppe (ADS), alpine typical steppe (ATS), and alpine meadow steppe (AMS)] on the Tibetan Plateau. More tubular and continuous macropores occurred in the soil profiles of the AMS and ATS than in that of the ADS. In addition, the AMS soil had the highest macropore number (925 ± 189), while the ADS soil had the lowest macropore number (537 ± 137). PCA and correlation analysis suggested that macroporosity (MP) has significant positive correlations with the contents of soil organic matter, total nitrogen (TN), available phosphorus (AP) and total phosphorus (TP) (p < 0.05). The two parameters with the greatest influence on aboveground and belowground biomass were the shape factor (p < 0.05) and MP (p < 0.05), respectively. However, there was no significant correlation between plant diversity and soil macropores. We conclude that the irregularity of soil macropores restricts the growth space of roots and causes plants to sacrifice the accumulation of aboveground biomass for that of roots to find suitable sites for nutrient and water absorption.

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Effects of freeze-thaw cycles on soil macropores and its implications on formation of hummocks in alpine meadows in the Qinghai Lake watershed, northeastern Qinghai-Tibet Plateau

Cited by 27 publications

References 55 publications

A little relief: Ecological functions and autogenesis of wetland microtopography

A little relief: Ecological functions and autogenesis of wetland microtopography

Evaluation of the impact of freeze–thaw cycles on the soil pore structure of alpine meadows using X‐ray computed tomography

Soil Macropores Affect the Plant Biomass of Alpine Grassland on the Northeastern Tibetan Plateau

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