scholarly journals Using precipitation, vertical root distribution, and satellite-retrieved vegetation information to parameterize water stress in a Penman-Monteith approach to evapotranspiration modeling under Mediterranean climate

2017 ◽  
Vol 9 (1) ◽  
pp. 168-192 ◽  
Author(s):  
Yun Bai ◽  
Jiahua Zhang ◽  
Sha Zhang ◽  
Upama Ashish Koju ◽  
Fengmei Yao ◽  
...  
Keyword(s):  
Water Stress ◽  
Root Distribution ◽  
Mediterranean Climate ◽  
Vertical Root Distribution ◽  
Evapotranspiration Modeling

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 How to put plant root uptake into a soil water flow model

F1000Research ◽  
2016 ◽  
Vol 5 ◽  
pp. 43
Author(s):  
Xuejun Dong
Keyword(s):  
Water Stress ◽  
Soil Water ◽  
Water Uptake ◽  
Root Distribution ◽  
Plant Root ◽  
Root Water Uptake ◽  
Root Uptake ◽  
Water Dynamics ◽  
Rooting Depth ◽  
Plant Root Uptake

The need for improved crop water use efficiency calls for flexible modeling platforms to implement new ideas in plant root uptake and its regulation mechanisms. This paper documents the details of modifying a soil infiltration and redistribution model to include (a) dynamic root growth, (b) non-uniform root distribution and water uptake, (c) the effect of water stress on plant water uptake, and (d) soil evaporation. The paper also demonstrates strategies of using the modified model to simulate soil water dynamics and plant transpiration considering different sensitivity of plants to soil dryness and different mechanisms of root water uptake. In particular, the flexibility of simulating various degrees of compensated uptake (whereby plants tend to maintain potential transpiration under mild water stress) is emphasized. The paper also describes how to estimate unknown root distribution and rooting depth parameters by the use of a simulation-based searching method. The full documentation of the computer code will allow further applications and new development.

Belowground to aboveground biomass ratio and vertical root distribution responses of mature Pinus radiata stands to phosphorus fertilization at planting

2004 ◽  
Vol 34 (9) ◽  
pp. 1883-1894 ◽  
Author(s):  
Ayalsew Zerihun ◽  
Kelvin D Montagu
Keyword(s):  
Pinus Radiata ◽  
Aboveground Biomass ◽  
Root Distribution ◽  
Root Biomass ◽  
Phosphorus Fertilization ◽  
P Fertilization ◽  
Coarse Roots ◽  
Vertical Root Distribution ◽  
Allometric Relations ◽  
P Supply

We compared the belowground biomass (BGB)/aboveground biomass (AGB) ratio and the vertical root distribution of 40-year-old Pinus radiata D. Don fertilized with 0 or 90 kg P·ha–1 at planting. Root biomass was determined by a combination of coring (fine roots, ϕ < 2 mm; small roots, 2 ≤ ϕ < 15 mm) and excavation (coarse roots, ϕ ≥ 5 mm). Stand-level AGB and coarse root biomass (CRB) were estimated with the use of allometric relations. After 40 years, AGB and CRB of P-fertilized trees were 4.5 times those of unfertilized trees, indicating that CRB scaled isometrically with AGB independently of P supply. By contrast, P fertilization increased the fine and small root biomass (FSRB) pool by only 50%. As a result, the scaling of FSRB to AGB was dependent on P supply. The differential response of the FSRB to P fertilization caused the overall BGB/AGB ratio to decrease from 0.29 in control plots to 0.20 in P-fertilized plots. Phosphorus fertilization also altered the vertical distribution of fine root biomass (FRB). For example, the proportion of FRB in the top 15 cm increased from 41% to 52% with P fertilization. Collectively, the results showed that P added early in the growth phase had a persistent effect on the BGB/AGB ratio in P. radiata. This was primarily brought about by altered biomass partitioning to the nutrient-acquiring FSRB pool.

Root water uptake and profile soil water as affected by vertical root distribution

Plant Ecology ◽  
2006 ◽  
Vol 189 (1) ◽  
pp. 15-30 ◽  
Author(s):  
Gui-Rui Yu ◽  
Jie Zhuang ◽  
Keiichi Nakayama ◽  
Yan Jin
Keyword(s):  
Soil Water ◽  
Water Uptake ◽  
Root Distribution ◽  
Root Water Uptake ◽  
Vertical Root Distribution

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.

Root distribution of lychee trees growing in acid soils of subtropical Queensland

1990 ◽  
Vol 30 (5) ◽  
pp. 699 ◽  
Author(s):  
CM Menzel ◽  
RL Aitken ◽  
AW Dowling ◽  
DR Simpson
Keyword(s):  
Soil Properties ◽  
Root Distribution ◽  
Chemical Properties ◽  
Acid Soils ◽  
Sampling Technique ◽  
Exchange Capacity ◽  
Root Density ◽  
Rooting Depth ◽  
Ph Values ◽  
Vertical Root Distribution

A core sampling technique was used to investigate the vertical root distribution of 8-10-year-old lychee trees (Litchi chinensis cv. Tai So) growing on 5 acid soils in subtropical Queensland (lat. 27�s.). At each site, soil and roots were sampled at 10 cm depth intervals to 100 cm, the root density determined and a range of soil chemical and physical properties measured. Eighty percent of the feeder roots were located within the top 0-20 cm (1 site), 0 4 0 cm (2 sites) or 0-60 cm (2 sites). The depth of rooting was greatest in the fine textured soils, while the greatest total root density was recorded in the coarse textured soils. The data suggest that the placement of tensiometers for water scheduling needs to take into account the effective rooting depth of lychee because it may vary with soil type. At all sites, pH values were acidic (pH<6.0) and subsoil pH values were below 5.5, and exchangeable Ca decreased and exchangeable A1 increased with depth. Four of the 5 sites had subsoil with >30% Al saturation of the cation exchange capacity. Although root density (all sites) was correlated with a number of soil chemical properties, stepwise multiple linear regression showed that 62% of the variation in root density could be explained by a curvilinear function of depth. The intercorrelations between soil properties and the correlation of depth with some properties demonstrate the difficulties in separating the effects of depth per se from those of soil properties in reducing root growth.

scholarly journals Effects of Soil Type, Vertical Root Distribution and Precipitation on Grain Yield of Winter Wheat

2009 ◽  
Vol 12 (4) ◽  
pp. 503-513 ◽  
Author(s):  
Hirotake Itoh ◽  
Shigeki Hayashi ◽  
Takashi Nakajima ◽  
Tomohito Hayashi ◽  
Hozumi Yoshida ◽  
...  
Keyword(s):  
Winter Wheat ◽  
Grain Yield ◽  
Soil Type ◽  
Root Distribution ◽  
Vertical Root Distribution
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