scholarly journals Soil moisture and temperature dynamics in typical alpine ecosystems: a continuous multi-depth measurements-based analysis from the Qinghai-Tibet Plateau, China

2017 ◽  
Vol 49 (1) ◽  
pp. 194-209 ◽  
Author(s):  
Si-Yi Zhang ◽  
Xiao-Yan Li
Keyword(s):  
Soil Moisture ◽  
Soil Temperature ◽  
Climate Changes ◽  
Tibet Plateau ◽  
Qinghai Lake ◽  
Moisture Regime ◽  
Alpine Ecosystems ◽  
Alpine Regions ◽  
Qinghai Tibet Plateau ◽  
Soil Temperature And Moisture

Abstract Soil temperature and moisture are the key variables that control the overall effect of climate and topography on soil and vegetation in alpine regions. However, there has been little investigation of the potential soil temperature and moisture feedbacks on climate changes in different alpine ecosystems and their impact on vegetation change. Soil temperature and moisture at five depths were measured continuously at 10-min intervals in three typical ecosystems (Kobresia meadow (KMd), Achnatherum splendens steppe (ASSt), and Potentilla fruticosa shrub (PFSh)) of the Qinghai Lake watershed on the northeast Qinghai-Tibet Plateau, China. The findings of this study revealed that the KMd and PFSh sites had relatively low soil temperature and high soil moisture, whereas the ASSt site had relatively warm soil temperature and low soil moisture. The soil and vegetation characteristics had important effects on the infiltration process and soil moisture regime; about 47%, 87%, and 34% of the rainfall (minus interception) permeated to the soil in the KMd, PFSh, and ASSt sites, respectively. In the context of the warming climate, changes to soil moisture and temperature are likely to be the key reasons of the alpine meadow deterioration and the alpine shrub expansion in the alpine regions.

scholarly journals Thermal impacts of engineering activities on permafrost in different alpine ecosystems in Qinghai-Tibet Plateau, China

2016 ◽  
Author(s):  
Qingbai Wu ◽  
Zhongqiong Zhang ◽  
Siru Gao ◽  
Wei Ma
Keyword(s):  
Soil Temperature ◽  
Climate Warming ◽  
Tibet Plateau ◽  
Alpine Ecosystems ◽  
Railway Ballast ◽  
Alpine Meadows ◽  
Engineering Construction ◽  
Cooling Effects ◽  
Qinghai Tibet Plateau ◽  
Vegetation Layer

Abstract. Climate warming and engineering activities have various impacts on the thermal regime of permafrost in alpine ecosystems of the Qinghai–Tibet Plateau. Using recent observations of permafrost thermal regimes along the Qinghai–Tibet Highway and Railway, the change of such regimes beneath embankments constructed in alpine meadows and steppes are studied. The results show that alpine meadows on the Qinghai–Tibet Plateau can have a controlling role within engineering construction effects on permafrost beneath embankments. The artificial permafrost table (APT) beneath embankments is predominantly controlled by alpine ecosystems, but the change rate of APT is not closely related with those ecosystems; it is mainly related with cooling effects of railway ballast and heat absorption effects of asphalt pavement. Variation of soil temperature beneath embankments is independent of alpine ecosystems, but variation of mean annual soil temperature with depth is closely related to those ecosystems. The vegetation layer in alpine meadows can have an insulation role within engineering activity effects on permafrost beneath embankments. This insulation role is an advantage for alleviating permafrost temperature rise in the short term, but a disadvantage in the long term because of climate warming, suggesting that vegetation layer in alpine meadow should be removed upon initiating engineering construction.

The temperature and moisture regime of charcoal-enriched land use legacy soils

2020 ◽  
Author(s):  
Anna Schneider ◽  
Florian Hirsch ◽  
Alexander Bonhage ◽  
Alexandra Raab ◽  
Thomas Raab
Keyword(s):  
Thermal Conductivity ◽  
Land Use ◽  
Soil Moisture ◽  
Soil Temperature ◽  
Bulk Density ◽  
Forest Soils ◽  
Moisture Regime ◽  
Seasonal Temperature ◽  
Water Contents ◽  
Soil Temperature And Moisture

<p>The stratigraphy and properties of soils can be significantly altered by past land use, even in areas that have been continuously used for forestry. Soils on relict charcoal hearths (RCHs) are a widespread example of such a pedological legacy of past forest use. RCH soils occur in many forest areas and receive increasing attention as model sites to study long-term effects of soil amendment with biochars, however, their physical properties have hardly been studied. The objective of our study was to characterize the soil temperature and moisture regime of RCH soils through comparison to reference forest soils on sandy substrates in woodlands in Brandenburg, Germany. We combined laboratory analyses of bulk density, pore size distribution, thermal conductivity and saturated hydraulic conductivity with sensor-based monitoring of soil temperature, moisture contents and matric potentials. </p><p>The results of laboratory analysis reveal high soil organic matter (SOM) contents, a low bulk density and high porosity of the RCH substrates. Associated with this RCH specific soil structure, RCHs exhibit clearly lower thermal conductivity. However, the higher total porosity of RCH substrates does not necessarily imply higher water retention and plant-available water contents in the RCH soils than in the topsoil horizons of undisturbed forest soils.  The monitoring results reveal distinct differences between the temperature regimes of the RCH and reference profiles, with the RCH soil exhibiting higher daily and seasonal temperature variations within the topmost horizon, but lower variations in deeper parts of the profiles. Soil moisture monitoring shows higher water contents in RCH soils under relatively wet conditions and lower water contents under dry conditions, and increased spatial variation in soil moisture in RCH soils. Overall, the results show increased spatial and temporal variability of soil temperature and moisture on RCHs, which implies an increased variability in ecological site conditions in historic charcoal production areas.</p><p> </p>

scholarly journals Thermal impacts of engineering activities and vegetation layer on permafrost in different alpine ecosystems of the Qinghai–Tibet Plateau, China

2016 ◽  
Vol 10 (4) ◽  
pp. 1695-1706 ◽  
Author(s):  
Qingbai Wu ◽  
Zhongqiong Zhang ◽  
Siru Gao ◽  
Wei Ma
Keyword(s):  
Climate Change ◽  
Soil Temperature ◽  
Tibet Plateau ◽  
Alpine Ecosystems ◽  
Railway Ballast ◽  
Alpine Meadows ◽  
Engineering Construction ◽  
Cooling Effects ◽  
Qinghai Tibet Plateau ◽  
Vegetation Layer

Abstract. Climate warming and engineering activities have various impacts on the thermal regime of permafrost in alpine ecosystems of the Qinghai–Tibet Plateau. Using recent observations of permafrost thermal regimes along the Qinghai–Tibet highway and railway, the changes of such regimes beneath embankments constructed in alpine meadows and steppes are studied. The results show that alpine meadows on the Qinghai–Tibet Plateau can have a controlling role among engineering construction effects on permafrost beneath embankments. As before railway construction, the artificial permafrost table (APT) beneath embankments is not only affected by climate change and engineering activities but is also controlled by alpine ecosystems. However, the change rate of APT is not dependent on ecosystem type, which is predominantly affected by climate change and engineering activities. Instead, the rate is mainly related to cooling effects of railway ballast and heat absorption effects of asphalt pavement. No large difference between alpine and steppe can be identified regarding the variation of soil temperature beneath embankments, but this difference is readily identified in the variation of mean annual soil temperature with depth. The vegetation layer in alpine meadows has an insulation role among engineering activity effects on permafrost beneath embankments, but this insulation gradually disappears because the layer decays and compresses over time. On the whole, this layer is advantageous for alleviating permafrost temperature rise in the short term, but its effect gradually weakens in the long term.

scholarly journals Assessing the simulated soil thermal regime from Noah-MPLSM v1.1 for near-surface permafrost modeling on the Qinghai-Tibet Plateau

2020 ◽  
Author(s):  
Xiangfei Li ◽  
Tonghua Wu ◽  
Xiaodong Wu ◽  
Xiaofan Zhu ◽  
Guojie Hu ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Soil Temperature ◽  
Land Surface ◽  
Stomatal Resistance ◽  
Cold Season ◽  
Canopy Gap ◽  
Tibet Plateau ◽  
Surface Model ◽  
Near Surface ◽  
Qinghai Tibet Plateau

Abstract. Land surface models (LSMs) are effective tools for near-surface permafrost modeling. Extensive and rigorous model inter-comparison is of great importance before application due to the uncertainties in current LSMs. This study designed an ensemble of 6912 experiments to evaluate the Noah land surface model with multi-parameterization (Noah-MP) for soil temperature (ST) simulation, and investigate the sensitivity of parameterization schemes at a typical permafrost site on the Qinghai-Tibet Plateau. The results showed that Noah-MP generally underestimates ST, especially that during the cold season. In addition, the simulation uncertainty is greater in the cold season (October-April) and for the deep soil layers. ST is most sensitive to surface layer drag coefficient (SFC) while largely influenced by runoff and groundwater (RUN). By contrast, the influence of canopy stomatal resistance (CRS) and soil moisture factor for stomatal resistance (BTR) on ST is negligible. With limited impacts on ST simulation, vegetation model (VEG), canopy gap for radiation transfer (RAD) and snow/soil temperature time scheme (STC) are more influential on shallow ST, while super-cooled liquid water (FRZ), frozen soil permeability (INF) and lower boundary of soil temperature (TBOT) have greater impacts on deep ST. Furthermore, an optimal configuration of Noah-MP for permafrost modeling were extracted based on the connectivity between schemes, and they are: table leaf area index with calculated vegetation fraction, Jarvis scheme for CRS, Noah scheme for BTR, BATS model for RUN, Chen97 for SFC, zero canopy gap for RAD, variant freezing-point depression for FRZ, hydraulic parameters defined by soil moisture for INF, ST at 8 m for TBOT, and semi-implicit method for STC. The analysis of the model structural uncertainties and characteristics of each scheme would be constructive to a better understanding of the land surface processes on the QTP and further model improvements towards near-surface permafrost modeling using the LSMs.

scholarly journals Tillage systems and nutrient sources affecting soil cover, temperature and moisture in a clayey oxisol under corn

2010 ◽  
Vol 34 (6) ◽  
pp. 2011-2020 ◽  
Author(s):  
Milton da Veiga ◽  
Dalvan José Reinert ◽  
José Miguel Reichert
Keyword(s):  
Soil Temperature ◽  
Crop Residues ◽  
Soil Cover ◽  
Mineral Fertilizer ◽  
Growth Period ◽  
Moisture Regime ◽  
Tillage Systems ◽  
Area Index ◽  
Nutrient Sources ◽  
Soil Temperature And Moisture

Tillage affects soil physical properties, e.g., porosity, and leads to different amounts of mulch on the soil surface. Consequently, tillage is related to the soil temperature and moisture regime. Soil cover, temperature and moisture were measured under corn (Zea mays) in the tenth year of five tillage systems (NT = no-tillage; CP = chisel plow and single secondary disking; CT = primary and double secondary disking; CTb = CT with crop residues burned; and CTr = CT with crop residues removed). The tillage systems were combined with five nutrient sources (C = control; MF = mineral fertilizer; PL = poultry litter; CS = cattle slurry; and SS = swine slurry). Soil cover after sowing was greatest in NT (88 %), medium in CP (38 %) and lowest in CT treatments (< 10 %), but differences decreased after corn emergence. Soil temperature was related with soil cover, and significant differences among tillage were observed at the beginning of the growing season and at corn maturity. Differences in soil temperature and moisture in the surface layer of the tilled treatments were greater during the corn cycle than in untilled treatments, due to differences in intensity of soil mobilization and mulch remaining after soil management. Nutrient sources affected soil temperature and moisture in the most intense part of the corn growth period, and were related to the variation of the corn leaf area index among treatments

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