Water and heat transport in boreal soils: Implications for soil response to climate change

Fan, Zeng; Neff, Jason C.; Harden, Jennifer W.; Zhang, Tingjun; Veldhuis, Hugo; Czimczik, C. I.; Winston, G.; O’Donnell, J. A.

doi:10.1016/j.scitotenv.2011.02.009

Cited by 21 publications

(12 citation statements)

References 44 publications

(54 reference statements)

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“…A shallower snow pack could result in lower soil moisture levels in spring. The dry soil has lower thermal conductivity, allowing surface energy to penetrate the soil less effectively, thereby lowering ALT (Fan et al, 2011). However, larger precipitation during the summer season can alleviate the soil dryness caused by the thinner SND.…”

Section: Variables Affecting To Alt Anomalymentioning

confidence: 99%

“…Hinkel et al (2001) found that the infiltration of melted snow water into soil layers caused rapid warming of the upper soil in spring. Soil moisture in the upper-soil layer during the thawing period has measurable impact on ALT, which increases significantly with increasing soil moisture content (Zhang and Stamnes, 1998;Fan et al, 2011). The deepened ALT likely thaws icerich permafrost near the permafrost table, forming a saturated surface and deforming the surface.…”

Section: Variables Affecting To Alt Anomalymentioning

confidence: 99%

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The influence of climate and hydrological variables on opposite anomaly in active-layer thickness between Eurasian and North American watersheds

et al. 2013

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Abstract. This study not only examined the spatiotemporal variations of active-layer thickness (ALT) in permafrost regions during 1948-2006 over the terrestrial Arctic regions experiencing climate changes, but also identified the associated drivers based on observational data and a simulation conducted by a land surface model (CHANGE). The focus on the ALT extends previous studies that have emphasized ground temperatures in permafrost regions. The Ob, Yenisey, Lena, Yukon, and Mackenzie watersheds are foci of the study. Time series of ALT in Eurasian watersheds showed generally increasing trends, while the increase in ALT in North American watersheds was not significant. However, ALT in the North American watersheds has been negatively anomalous since 1990 when the Arctic air temperature entered into a warming phase. The warming temperatures were not simply expressed to increases in ALT. Since 1990 when the warming increased, the forcing of the ALT by the higher annual thawing index (ATI) in the Mackenzie and Yukon basins has been offset by the combined effects of less insulation caused by thinner snow depth and drier soil during summer. In contrast, the increasing ATI together with thicker snow depth and higher summer soil moisture in the Lena contributed to the increase in ALT. The results imply that the soil thermal and moisture regimes formed in the prethaw season(s) provide memory that manifests itself during the summer. The different ALT anomalies between Eurasian and North American watersheds highlight increased importance of the variability of hydrological variables.

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Section: Variables Affecting To Alt Anomalymentioning

confidence: 99%

Section: Variables Affecting To Alt Anomalymentioning

confidence: 99%

The influence of climate and hydrological variables on opposite anomaly in active-layer thickness between Eurasian and North American watersheds

et al. 2013

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“…Indeed, water movement was substantially responsible for the larger total profile priming effects at the WD site. Furthermore, water movement can indirectly affect priming effects via impacts on soil thermal and water dynamics [51], which may be partially responsible for the differences in observed soil temperature and moisture between the WD and MWDp sites. At the WD site (with no underlying permafrost), the temperature and moisture content of deep soil layers are more favorable for microbial activity and thus priming effects (Figure 1).…”

Section: Discussionmentioning

confidence: 99%

Priming Effects in Boreal Black Spruce Forest Soils: Quantitative Evaluation and Sensitivity Analysis

et al. 2013

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Laboratory studies show that introduction of fresh and easily decomposable organic carbon (OC) into soil-water systems can stimulate the decomposition of soil OC (SOC) via priming effects in temperate forests, shrublands, grasslands, and agro-ecosystems. However, priming effects are still not well understood in the field setting for temperate ecosystems and virtually nothing is known about priming effects (e.g., existence, frequency, and magnitude) in boreal ecosystems. In this study, a coupled dissolved OC (DOC) transport and microbial biomass dynamics model was developed to simultaneously simulate co-occurring hydrological, physical, and biological processes and their interactions in soil pore-water systems. The developed model was then used to examine the importance of priming effects in two black spruce forest soils, with and without underlying permafrost. Our simulations showed that priming effects were strongly controlled by the frequency and intensity of DOC input, with greater priming effects associated with greater DOC inputs. Sensitivity analyses indicated that priming effects were most sensitive to variations in the quality of SOC, followed by variations in microbial biomass dynamics (i.e., microbial death and maintenance respiration), highlighting the urgent need to better discern these key parameters in future experiments and to consider these dynamics in existing ecosystem models. Water movement carries DOC to deep soil layers that have high SOC stocks in boreal soils. Thus, greater priming effects were predicted for the site with favorable water movement than for the site with limited water flow, suggesting that priming effects might be accelerated for sites where permafrost degradation leads to the formation of dry thermokarst.

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“…Soil columns in three experiments, especially saturated and saturated-unsaturated types, were seldom studied in the past because researchers mostly focused on arid areas with groundwater located far below the soil surface (Kane et al, 2001;Grifoll et al, 2005;Saito and Šimunek, 2009;Zeng et al, 2009;Fan et al, 2011;Kanzari et al, 2012). Figure 3 shows the moisture content observed at the 5 cm depth in the three experiments decreased with an increase in groundwater table depth.…”

Section: Capillary Water Rise Measurementsmentioning

confidence: 99%

Experimental study of the effect of shallow groundwater table on soil thermal properties

et al. 2015

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In plains areas with semi-arid climates, shallow groundwater is one of the important factors affecting soil thermal properties. In this study, soil temperature and water content were measured when groundwater tables reached 10 cm, 30 cm, and 60 cm depths (Experiment I, II, and III) by using sensors embedded at depths of 5 cm, 10 cm, 20 cm, and 30 cm for 5 days. Soil thermal properties were analyzed based on the experimental data using the simplified de Vries model. Results show that soil water content and temperature have fluctuations that coincide with the 24 h diurnal cycle, and the amplitude of these fluctuations decreased with the increase in groundwater table depth. The amplitude of soil water content at 5 cm depth decreased from 0.025 m 3 $m -3 in Experiment II to 0.01 m 3 $m -3 in Experiment III. Moreover, it should be noted that the soil temperature in Experiment III gradually went up with the lowest value increasing from 26.0°C to 28.8°C. By contrast, the trends were not evident in Experiments I and II. Results indicate that shallow groundwater has a "cooling" effect on soil in the capillary zone. In addition, calculated values of thermal conductivity and heat capacity declined with the increasing depth of the groundwater table, which is consistent with experimental results. The thermal conductivity was stable at a value of 2.3 W$cm -1 $K -1 in Experiment I. The average values of thermal conductivity at different soil depths in Experiment II were 1.82 W$cm -1 $K -1 , 2.15 W$cm -1 $K -1 , and 2.21 W$cm -1 $K -1 , which were always higher than that in Experiment III.

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Water and heat transport in boreal soils: Implications for soil response to climate change

Cited by 21 publications

References 44 publications

The influence of climate and hydrological variables on opposite anomaly in active-layer thickness between Eurasian and North American watersheds

The influence of climate and hydrological variables on opposite anomaly in active-layer thickness between Eurasian and North American watersheds

Priming Effects in Boreal Black Spruce Forest Soils: Quantitative Evaluation and Sensitivity Analysis

Experimental study of the effect of shallow groundwater table on soil thermal properties

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