Different distribution patterns of woody species on a slope in relation to vertical root distribution and dynamics of soil moisture profiles

1999 ◽  
Vol 14 (2) ◽  
pp. 165-177 ◽  
Author(s):  
Nao Yanagisawa ◽  
Noboru Fujita
Keyword(s):  
Soil Moisture ◽  
Root Distribution ◽  
Woody Species ◽  
Distribution Patterns ◽  
Vertical Root Distribution ◽  
Moisture Profiles

scholarly journals An optimality-based model of the coupled soil moisture and root dynamics

2008 ◽  
Vol 12 (3) ◽  
pp. 913-932 ◽  
Author(s):  
S. J. Schymanski ◽  
M. Sivapalan ◽  
M. L. Roderick ◽  
J. Beringer ◽  
L. B. Hutley
Keyword(s):  
Soil Moisture ◽  
Water Uptake ◽  
Root Distribution ◽  
Root Respiration ◽  
Root Water Uptake ◽  
Dry Season ◽  
Soil Moisture Dynamics ◽  
Model Based ◽  
Vertical Root Distribution ◽  
Moisture Dynamics

Abstract. The main processes determining soil moisture dynamics are infiltration, percolation, evaporation and root water uptake. Modelling soil moisture dynamics therefore requires an interdisciplinary approach that links hydrological, atmospheric and biological processes. Previous approaches treat either root water uptake rates or root distributions and transpiration rates as given, and calculate the soil moisture dynamics based on the theory of flow in unsaturated media. The present study introduces a different approach to linking soil water and vegetation dynamics, based on vegetation optimality. Assuming that plants have evolved mechanisms that minimise costs related to the maintenance of the root system while meeting their demand for water, we develop a model that dynamically adjusts the vertical root distribution in the soil profile to meet this objective. The model was used to compute the soil moisture dynamics, root water uptake and fine root respiration in a tropical savanna over 12 months, and the results were compared with observations at the site and with a model based on a fixed root distribution. The optimality-based model reproduced the main features of the observations such as a shift of roots from the shallow soil in the wet season to the deeper soil in the dry season and substantial root water uptake during the dry season. At the same time, simulated fine root respiration rates never exceeded the upper envelope determined by the observed soil respiration. The model based on a fixed root distribution, in contrast, failed to explain the magnitude of water use during parts of the dry season and largely over-estimated root respiration rates. The observed surface soil moisture dynamics were also better reproduced by the optimality-based model than the model based on a prescribed root distribution. The optimality-based approach has the potential to reduce the number of unknowns in a model (e.g. the vertical root distribution), which makes it a valuable alternative to more empirically-based approaches, especially for simulating possible responses to environmental change.

scholarly journals An optimality-based model of the coupled soil moisture and root dynamics

2008 ◽  
Vol 5 (1) ◽  
pp. 51-94 ◽  
Author(s):  
S. J. Schymanski ◽  
M. Sivapalan ◽  
M. L. Roderick ◽  
J. Beringer ◽  
L. B. Hutley
Keyword(s):  
Soil Moisture ◽  
Water Uptake ◽  
Root Distribution ◽  
Root Respiration ◽  
Root Water Uptake ◽  
Dry Season ◽  
Soil Moisture Dynamics ◽  
Model Based ◽  
Vertical Root Distribution ◽  
Moisture Dynamics

Abstract. The main processes determining soil moisture dynamics are infiltration, percolation, evaporation and root water uptake. Modelling soil moisture dynamics therefore requires an interdisciplinary approach that links hydrological, atmospheric and biological processes. Previous approaches treat either root water uptake rates or root distributions and transpiration rates as given, and calculate the soil moisture dynamics based on the theory of flow in unsaturated media. The present study introduces a different approach to linking soil water and vegetation dynamics, based on vegetation optimality. Assuming that plants have evolved mechanisms that minimise costs related to the maintenance of the root system while meeting their demand for water, we develop a model that dynamically adjusts the vertical root distribution in the soil profile to meet this objective. The model was used to compute the soil moisture dynamics, root water uptake and fine root respiration in a tropical savanna over 12 months, and the results were compared with observations at the site and with a model based on a fixed root distribution. The optimality-based model reproduced the main features of the observations such as a shift of roots from the shallow soil in the wet season to the deeper soil in the dry season and substantial root water uptake during the dry season. At the same time, simulated fine root respiration rates never exceeded the upper envelope determined by the observed soil respiration. The model based on a fixed root distribution, in contrast, failed to explain the magnitude of water use during parts of the dry season and largely over-estimated root respiration rates. The observed surface soil moisture dynamics were also better reproduced by the optimality-based model than the model based on a prescribed root distribution. The optimality-based approach has the potential to reduce the number of unknowns in a model (e.g. the vertical root distribution), which makes it a valuable alternative to more empirically-based approaches, especially for simulating possible responses to environmental change.

Soil moisture profiles from multifrequency radar data at basin scale

Meccanica ◽  
1996 ◽  
Vol 31 (1) ◽  
pp. 59-72 ◽  
Author(s):  
O. Bolognani ◽  
M. Mancini ◽  
R. Rosso
Keyword(s):  
Soil Moisture ◽  
Radar Data ◽  
Basin Scale ◽  
Multifrequency Radar ◽  
Moisture Profiles

scholarly journals Root Response to Soil Water Status via Interaction of Crop Genotype and Environment

Agronomy ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 708
Author(s):  
Phanthasin Khanthavong ◽  
Shin Yabuta ◽  
Hidetoshi Asai ◽  
Md. Amzad Hossain ◽  
Isao Akagi ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Root Distribution ◽  
Water Status ◽  
Soil Layer ◽  
Shoot Biomass ◽  
Soil Conditions ◽  
Crop Adaptation ◽  
Soil Moisture Status ◽  
Root Distributions

Flooding and drought are major causes of reductions in crop productivity. Root distribution indicates crop adaptation to water stress. Therefore, we aimed to identify crop roots response based on root distribution under various soil conditions. The root distribution of four crops—maize, millet, sorghum, and rice—was evaluated under continuous soil waterlogging (CSW), moderate soil moisture (MSM), and gradual soil drying (GSD) conditions. Roots extended largely to the shallow soil layer in CSW and grew longer to the deeper soil layer in GSD in maize and sorghum. GSD tended to promote the root and shoot biomass across soil moisture status regardless of the crop species. The change of specific root density in rice and millet was small compared with maize and sorghum between different soil moisture statuses. Crop response in shoot and root biomass to various soil moisture status was highest in maize and lowest in rice among the tested crops as per the regression coefficient. Thus, we describe different root distributions associated with crop plasticity, which signify root spread changes, depending on soil water conditions in different crop genotypes as well as root distributions that vary depending on crop adaptation from anaerobic to aerobic conditions.

scholarly journals Rooting patterns of Rumex species under drained conditions

1987 ◽  
Vol 65 (8) ◽  
pp. 1638-1642 ◽  
Author(s):  
L. A. C. J. Voesenek ◽  
C. W. P. M. Blom
Keyword(s):  
Growth Rate ◽  
Root Distribution ◽  
Soil Layer ◽  
The Other ◽  
Rumex Acetosa ◽  
Soil System ◽  
Relative Growth ◽  
Soil Layers ◽  
Vertical Root Distribution ◽  
Rooting Patterns

Root development and architecture were studied in three Rumex species growing in a perforated soil system in the greenhouse. Distinct differences in vertical root distribution under drained conditions were found among the three species. Rumex acetosa and R. palustris had a relatively superficial root pattern, whereas in R. crispus much of the root growth was concentrated in lower soil layers. In the upper soil layer the relative growth rate of the roots of R. palustris was significantly larger than that of the other species. A relation between the characteristic rooting patterns under drained conditions and the Rumex zonation in the field is discussed.

scholarly journals Hydrological Analysis of Basin Behaviour from Soil Moisture Data

1988 ◽  
Vol 19 (1) ◽  
pp. 1-18 ◽  
Author(s):  
Lotta Andersson
Keyword(s):  
Soil Moisture ◽  
Root Distribution ◽  
Unsaturated Flow ◽  
Drainage Basin ◽  
Main Tool ◽  
Probe Field ◽  
Soil Moisture Dynamics ◽  
Soil Moisture Accounting ◽  
Forest Sites ◽  
Moisture Dynamics

Soil moisture dynamics in the Velen drainage basin (Sweden) were analyzed in order to assess the degree of and the reasons for spatial variation in basin behaviour. The main tool was a modified version of the soil moisture accounting routine in the conceptual runoff model HBV, optimized against neutron probe field data. Simulated soil moisture dynamics, interception and percolation rates agreed well with measurements and other calculations. Integration of simulated evapotranspiration from sites with different characteristics agreed well with water balance computations for the area. It was shown that unsaturated flow through macropores probably occurred after heavy rainstorms. During spring, evapotranspiration was limited to values below the potential (Penmans equation) even at times when no soil moisture deficit existed. Soil moisture differences between forest and grassland (including a deforested site) were, during summer, mainly attributed to differences in the root distribution with depth. The effect of interception on the total evapotranspiration rates was only significant during periods when transpiration demands were low. Soil moisture differences between forest sites were mainly attributed to topography but variations in soil characteristics and root distribution had to be considered, especially during dry periods.

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