Root distribution of 12-year-old forests at rocky sites in southwestern Oregon: effects of rock physical properties

1994 ◽  
Vol 24 (9) ◽  
pp. 1791-1796 ◽  
Author(s):  
Maciej A. Zwieniecki ◽  
Michael Newton
Keyword(s):  
Bulk Density ◽  
Ponderosa Pine ◽  
Root Length ◽  
Root Length Density ◽  
Explanatory Power ◽  
Multiple Regression Model ◽  
Explanatory Variables ◽  
Forest Sites ◽  
Dense Stand ◽  
Pacific Madrone

Distribution of root length density (in terms of centimetres of fine and large roots per cubic centimetre of soil and bedrock) was analyzed at harsh forest sites supporting 12-year-old stands of pure whiteleaf manzanita (Arctostaphylosviscida Parry), pure ponderosa pine (Pinusponderosa Dougl. ex Laws.), or mixtures of Pacific madrone (Arbutusmenziesii Pursh) and Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) in southwest Oregon. On such sites, soil (usually <50 cm deep) dries below the wilting point of plants before the middle of the growing season. The bedrock contains enough water to support a dense stand of woody plants. The study shows that about one quarter to one third of the total root length is located in the rock layer. Stepwise procedures were applied to find the best fitting multiple-regression model for relating root length density to depth, bulk density of the soil and rock, and the space penetrable by roots (SPR). Linear expressions of SPR and depth were found to be the only significant explanatory variables. Bulk density had very limited explanatory power, reflecting the high general density of the bedrock containing the water but lower density of the fine material in minuscule fissures in which roots were found.

scholarly journals Effects of tillage on soil physical properties and root growth of maize in loam and clay in central China  

2013 ◽  
Vol 59 (No. 7) ◽  
pp. 295-302 ◽  
Author(s):  
B. Ji ◽  
Y. Zhao ◽  
X. Mu ◽  
K. Liu ◽  
C. Li
Keyword(s):  
Root Growth ◽  
Water Content ◽  
Bulk Density ◽  
Root Length ◽  
Root Length Density ◽  
Penetration Resistance ◽  
Soil Bulk Density ◽  
Conventional Tillage ◽  
Central China ◽  
Deep Tillage

Subsoil compaction can result in unfavourable soil physical conditions and hinder the root growth of maize. The effects of deep tillage and conventional tillage on soil physical properties and root growth of maize were studied during 2010&ndash;2011 at two sites (loam at Hebi and clay at Luohe) in central China. The results showed that soil penetration resistance, bulk density, water content and root length density were significantly affected by tillage, soil depth and year. Deep tillage had lower penetration resistance and lower soil bulk density, but higher soil water content than conventional tillage across years and depths. Averaged over the whole soil profile, deep tillage not only significantly decreased penetration resistance and soil bulk density, but significantly increased soil water content and root length density on loam, while deep tillage only significantly increased the root length density on clay. We conclude that deep tillage on the loam is more suitable for the root growth of summer maize.

scholarly journals CORN ROOT LENGTH DENSITY AND ROOT DIAMETER AS AFFECTED BY SOIL COMPACTION AND SOIL WATER CONTENT

Irriga ◽  
2007 ◽  
Vol 12 (1) ◽  
pp. 14-26 ◽  
Author(s):  
Charles Duruoha ◽  
Cassio Roberto Piffer ◽  
Paulo Arbex Silva
Keyword(s):  
Root Growth ◽  
Water Content ◽  
Bulk Density ◽  
Soil Water ◽  
Soil Water Content ◽  
Root Length ◽  
Soil Compaction ◽  
Root Length Density ◽  
Field Capacity ◽  
Root Diameter

CORN ROOT LENGTH DENSITY AND ROOT DIAMETER AS AFFECTED BY SOIL COMPACTION AND SOIL WATER CONTENT  Charles Duruoha1; Cassio Roberto Piffer2; Paulo Arbex Silva2(1) United States Department of Agriculture (USDA-ARS), National Soil Dynamics Laboratory, Auburn, AL - U.S.A, [email protected] (2) Universidade Estadual Paulista, Faculdade de Ciências Agronômicas, Departamento de Engenharia Rural, Botucatu, SP  1 ABSTRACT Negative effects of soil compaction have been recognized as one of the problems restricting the root system and consequently impairing yields, especially in the Southern Coastal Plain of the USA. Simulations of the root restricting layers in green house studies are necessary for the development of mechanism which alleviates soil compaction problems in these soils. The selection of three distinct bulk densities based on the standard proctor test is also an important factor to determine which bulk density restricts the root layer. The experiment was conducted to assess the root length density and root diameter of the corn (Zea mays L.) crop as a function of bulk density and water stress, characterized by the soil density (1.2; 1.4, and 1.6 g cm-3), and two levels of the water content, approximately (70 and 90% field capacity). The statistical design adopted was completely randomized design, with four replicates in a factorial pattern of (3 x 2). The PVC tubes were superimposed with an internal diameter of 20 cm with a height of 40 cm (the upper tube 20 cm, compacted and inferior tube 10 cm), the hardpan with different levels of soil compaction were located between 20 and 30 cm of the depth of the pot. Results showed that: the main effects of subsoil mechanical impedance were observed on the top layer indicating that the plants had to penetrate beyond the favorable soil conditions before root growth was affected from 3.16; 2.41 to 1.37 cm cm-3 (P<0.005). There was a significant difference at the hardpan layer for the two levels of water and 90% field capacity reduced the root growth from 0.91 to 0.60 cm cm-3 (P<0.005). The root length density and root diameter were affected by increasing soil bulk density from 1.2 to 1.6 g cm-3 which caused penetration resistance to increase to 1.4 MPa. Soil water content of 70% field capacity furnished better root growth in all the layers studied. The increase in root length density resulted in increased root volume. It can also be concluded that the effect of soil compaction impaired the root diameter mostly at the hardpan layer. Soil temperature had detrimental effect on the root growth mostly with higher bulk densities. KEYWORDS: Soil compaction, water, bulk density, soil strength, root growth.  DURUOHA, C.; PIFFER, C. R.; SILVA, P. A. COMPRIMENTO E DIÂMETRO RADICULAR DO MILHO, EM FUNÇÃO DA COMPACTAÇÃO E DO TEOR DE ÁGUA NO SOLO     2 RESUMO Os efeitos negativos da compactação do solo vêm sendo reconhecidos como um dos problemas que restringe o sistema radicular e conseqüentemente, impede a produção agrícola, especialmente no sudoeste dos Estados Unidos. Simulações de camadas de restrição de raízes, em casa de vegetação, são necessárias para desenvolver mecanismos que reduzam problemas de compactação dos solos. A seleção de três diferentes densidades de solo, baseadas no ensaio de Proctor é também um fator importante para determinar qual densidade restringe a penetração da raiz. O experimento foi conduzido para avaliar o comprimento e diâmetro radicular da cultura do milho (Zea mays L.), em função da densidade do solo e do estresse hídrico, caracterizado pelas densidades (1,2; 1,4 e 1,6 cm-3) e dois níveis de teor de água (70 e 90 % da capacidade de campo). O método estatístico utilizado foi inteiramente casualizado, com quatro repetições, em arranjo fatorial (3 x 2). Os vasos foram montados em tubos de PVC, com diâmetro interno de 20 cm, sobrepostos, totalizando 40 cm de altura (anel superior com 20 cm e anéis compactado e inferior com 10 cm), a camada com diferentes níveis de solo compactado foi instalada entre 20 e 30 cm de profundidade nos vasos. Os resultados indicaram, através da resistência mecânica que na camada superior as raízes conseguiram penetrar até onde havia condições favoráveis do solo, antes que o sistema radicular fosse afetado de 3,16; 2,41 e 1,37 cm cm-3 (P<0.005). Ocorreu diferença significativa na camada compactada para os dois níveis de teor de água, sendo que a 90 % da capacidade de campo houve uma redução do crescimento radicular de 0,91 para 0,60 cm cm-3 (P<0,005). O comprimento e o diâmetro radicular foram afetados pelo aumento da densidade do solo de 1,2 a 1,6 g cm-3, com resistência à penetração de 1.4 MPa. O teor de água de 70 % da capacidade de campo proporcionou maior comprimento radicular em todas as densidades estudadas.  O aumento no comprimento radicular resultou em maior volume radicular. Concluiu-se também que os efeitos da compactação do solo prejudicaram o diâmetro radicular, principalmente na camada compactada. A temperatura do solo afetou o crescimento radicular, principalmente nas camadas com densidade elevada. UNITERMOS: compactação do solo, teor de água, densidade do solo, resistência à penetração, crescimento radicular.

scholarly journals Correlating elements content in mosses collected in 2015 across Germany with spatially associated characteristics of sampling sites and their surroundings

2019 ◽  
Vol 31 (1) ◽  
Author(s):  
Stefan Nickel ◽  
Winfried Schröder
Keyword(s):  
Land Use ◽  
Population Density ◽  
Atmospheric Deposition ◽  
Vegetation Structure ◽  
Urban Areas ◽  
Explanatory Power ◽  
Spatial Density ◽  
Area Index ◽  
Explanatory Variables ◽  
Tree Layer

Abstract Background The aim of the study was a statistical evaluation of the statistical relevance of potentially explanatory variables (atmospheric deposition, meteorology, geology, soil, topography, sampling, vegetation structure, land-use density, population density, potential emission sources) correlated with the content of 12 heavy metals and nitrogen in mosses collected from 400 sites across Germany in 2015. Beyond correlation analysis, regression analysis was performed using two methods: random forest regression and multiple linear regression in connection with commonality analysis. Results The strongest predictor for the content of Cd, Cu, Ni, Pb, Zn and N in mosses was the sampled species. In 2015, the atmospheric deposition showed a lower predictive power compared to earlier campaigns. The mean precipitation (2013–2015) is a significant factor influencing the content of Cd, Pb and Zn in moss samples. Altitude (Cu, Hg and Ni) and slope (Cd) are the strongest topographical predictors. With regard to 14 vegetation structure measures studied, the distance to adjacent tree stands is the strongest predictor (Cd, Cu, Hg, Zn, N), followed by the tree layer height (Cd, Hg, Pb, N), the leaf area index (Cd, N, Zn), and finally the coverage of the tree layer (Ni, Cd, Hg). For forests, the spatial density in radii 100–300 km predominates as significant predictors for Cu, Hg, Ni and N. For the urban areas, there are element-specific different radii between 25 and 300 km (Cd, Cu, Ni, Pb, N) and for agricultural areas usually radii between 50 and 300 km, in which the respective land use is correlated with the element contents. The population density in the 50 and 100 km radius is a variable with high explanatory power for all elements except Hg and N. Conclusions For Europe-wide analyses, the population density and the proportion of different land-use classes up to 300 km around the moss sampling sites are recommended.

Sex-specifically responsive strategies to phosphorus availability combined with different soil nitrogen forms in dioecious Populus cathayana

2021 ◽  
Author(s):  
Xiucheng Liu ◽  
Yuting Wang ◽  
Shuangri Liu ◽  
Miao Liu
Keyword(s):  
Root Length ◽  
Root Length Density ◽  
Specific Root Length ◽  
P Uptake ◽  
Root Tip ◽  
P Availability ◽  
P Deficiency ◽  
Populus Cathayana ◽  
Leaf P ◽  
P Supply

Abstract Aims Phosphorus (P) availability and efficiency are especially important for plant growth and productivity. However, the sex-specific P acquisition and utilization strategies of dioecious plant species under different N forms are not clear. Methods This study investigated the responsive mechanisms of dioecious Populus cathayana females and males based on P uptake and allocation to soil P supply under N deficiency, nitrate (NO3 −) and ammonium (NH4 +) supply. Important Findings Females had a greater biomass, root length density (RLD), specific root length (SRL) and shoot P concentration than males under normal P availability with two N supplies. NH4 + supply led to higher total root length, RLD and SRL but lower root tip number than NO3 − supply under normal P supply. Under P deficiency, males showed a smaller root system but greater photosynthetic P availability and higher leaf P remobilization, exhibiting a better capacity to adaptation to P-deficiency than females. Under P deficiency, NO3 − supply increased leaf photosynthesis and PUE but reduced RLD and SRL in females while males had higher leaf P redistribution and photosynthetic PUE than NH4 + supply. Females had a better potentiality to cope with P deficiency under NO3 − supply than NH4 + supply; the contrary was true for males. These results suggest that females may devote to increase in P uptake and shoot P allocation under normal P availability, especially under NO3 − supply, while males adopt more efficient resource use and P remobilization to maximum their tolerance to P-deficiency.

scholarly journals The Impact of Work Characteristics on Social Distancing: Implications at the Time of COVID-19

2021 ◽  
Vol 18 (10) ◽  
pp. 5074
Author(s):  
Keisuke Kokubun ◽  
Yoshinori Yamakawa
Keyword(s):  
Information Processing ◽  
Multiple Regression ◽  
Explanatory Power ◽  
Work Conditions ◽  
Multiple Regression Model ◽  
Social Characteristics ◽  
Work Characteristics ◽  
Social Distancing ◽  
Using Data ◽  
The Impact

The coronavirus disease (COVID-19) continues to spread globally. While social distancing has attracted attention as a measure to prevent the spread of infection, some occupations find it difficult to implement. Therefore, this study aims to investigate the relationship between work characteristics and social distancing using data available on O*NET, an occupational information site. A total of eight factors were extracted by performing an exploratory factor analysis: work conditions, supervisory work, information processing, response to aggression, specialization, autonomy, interaction outside the organization, and interdependence. A multiple regression analysis showed that interdependence, response to aggression, and interaction outside the organization, which are categorized as ”social characteristics,” and information processing and specialization, which are categorized as “knowledge characteristics,” were associated with physical proximity. Furthermore, we added customer, which represents contact with the customer, and remote working, which represents a small amount of outdoor activity, to our multiple regression model, and confirmed that they increased the explanatory power of the model. This suggests that those who work under interdependence, face aggression, and engage in outside activities, and/or have frequent contact with customers, little interaction outside the organization, and little information processing will have the most difficulty in maintaining social distancing.

MBAR Models: A Test of ARIMAX Modelling

2011 ◽  
Vol 14 (02) ◽  
pp. 347-366
Author(s):  
Anastasia Maggina
Keyword(s):  
Loss Function ◽  
Stock Exchange ◽  
Explanatory Power ◽  
Accounting Earnings ◽  
Explanatory Variables ◽  
Minimum Value ◽  
Standard Models ◽  
Athens Stock Exchange ◽  
Squared Residuals ◽  
Earnings Change

The main purpose of this paper is to provide evidence on some of the standard models of accounting earnings and returns relations mainly collected through the literature. Standard models such as earnings level and earnings changes, among others, have been investigated in this study. Models that correspond better to the data drawn from the Athens Stock Exchange have been selected. Models I, II, V, VII and IX have statistically significant coefficients of explanatory variables. In addition, model II with the MSE (minimum value of squared residuals) loss function in ARIMAX (2,0,2) is prevalent. Models that include prior earnings in various forms using levels, changes in price and changes in earnings, change in price to beginning price, lagged parameters and differentiated price models have statistically significant explanatory power.

scholarly journals Root Phenotyping for Drought Tolerance: A Review

Agronomy ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 241 ◽  
Author(s):  
Allah Wasaya ◽  
Xiying Zhang ◽  
Qin Fang ◽  
Zongzheng Yan
Keyword(s):  
Drought Tolerance ◽  
Crop Yield ◽  
Root Length ◽  
Root Length Density ◽  
Canopy Temperature ◽  
Specific Root Length ◽  
Root Traits ◽  
Three Dimensions ◽  
Invasive Approach ◽  
Root Phenotyping

Plant roots play a significant role in plant growth by exploiting soil resources via the uptake of water and nutrients. Root traits such as fine root diameter, specific root length, specific root area, root angle, and root length density are considered useful traits for improving plant productivity under drought conditions. Therefore, understanding interactions between roots and their surrounding soil environment is important, which can be improved through root phenotyping. With the advancement in technologies, many tools have been developed for root phenotyping. Canopy temperature depression (CTD) has been considered a good technique for field phenotyping of crops under drought and is used to estimate crop yield as well as root traits in relation to drought tolerance. Both laboratory and field-based methods for phenotyping root traits have been developed including soil sampling, mini-rhizotron, rhizotrons, thermography and non-soil techniques. Recently, a non-invasive approach of X-ray computed tomography (CT) has provided a break-through to study the root architecture in three dimensions (3-D). This review summarizes methods for root phenotyping. On the basis of this review, it can be concluded that root traits are useful characters to be included in future breeding programs and for selecting better cultivars to increase crop yield under water-limited environments.

scholarly journals Simulation evidence on the properties of alternative measures of working capital accruals

2017 ◽  
Vol 25 (4) ◽  
pp. 378-394
Author(s):  
Javad Izadi Zadeh Darjezi ◽  
Homagni Choudhury ◽  
Alireza Nazarian
Keyword(s):  
Cash Flow ◽  
Estimation Error ◽  
Explanatory Power ◽  
Cash Flows ◽  
Working Capital ◽  
Accrual Quality ◽  
Content Type ◽  
Explanatory Variables ◽  
Study Results ◽  
The Uk

Purpose This paper aims to investigate the specification and power of tests based on the DD and modified DD model through the UK data between years 2000 and 2013, and make comparisons with tests using working capital accruals creating a measure of accruals quality as the standard deviation of the residuals value from firm-specific regressions base on working capital accruals on last, current and one-year-ahead cash flows from operations. Design/methodology/approach This study focuses both on the DD model and modified DD model to find out which of them can more accurately capture total working capital accrual estimation error and accrual quality. According to the DD model, the past, current and future net cash from operating activities as the three years’ operating cash inflows or outflows become omitted and correlated variables. In this study, the authors continue to document residuals from the DD and MDD models to demonstrate properties that are more consistent with behaviours of accruals estimation errors. Therefore, in this study, the authors are looking to compare the results from both the MDD and DD models and find which one of them is more effective in explaining the working capital accruals in the UK. Findings The authors find that adding additional explanatory variables may add additional explanatory power of variables to the DD model and extent to which accruals map into cash flow insights based on the UK data. This study is empirically well fitting with the internal workings of cash flows. As investors fixate only on the accounting earnings, they may fail to reflect fully on information contained within cash flow components and working capital accruals of current and future earnings. Originality/value The authors compare different equation to cover more items of working capital accruals. In addition, after examining earnings and accrual quality, the findings show that the average UK company behaviour was quite similar to the behaviour that was founded earlier for both models in the USA. Furthermore, this study results show that more volatility of sales, cash flow, accruals and earnings make a lower accrual quality. The results demonstrate that both models can capture the power to predict working capital accruals. Moreover, we find that adding additional explanatory variable of employee growth rate adds additional explanatory variables to DD model.

scholarly journals Shallow Substrates Support the Growth of Contrasting Plant Types Installed in Irrigated, Arid-Climate Green Roofs1

2017 ◽  
Vol 35 (4) ◽  
pp. 146-155
Author(s):  
Lauren Forrest ◽  
Rachel Gioannini ◽  
Dawn M. VanLeeuwen ◽  
Rolston St. Hilaire
Keyword(s):  
Root Length ◽  
Root Length Density ◽  
Dry Weight ◽  
Green Roofs ◽  
Greenhouse Experiment ◽  
Outdoor Environment ◽  
Arid Climate ◽  
Evaporative Demand ◽  
Design Factor ◽  
Substrate Depth

Abstract Extreme evaporative demand makes substrate depth a critical design factor in arid-climate green roofs. The objective of this study was to determine whether a shallow irrigated substrate could support the growth of hens and chicks (Sempervivum calcareum L.) and iceplant [Delosperma nubigenum (Hook.f.) L.Bolus] in an arid environment. First, an experiment was conducted in the greenhouse that established that plants survived in 10 cm (3.9 in), 15 cm (5.9 in), and 20 cm (7.9 in) substrate depths, which then lead to a second experiment in an outdoor environment. The substrate was heat-expanded clay:sand:worm castings (6:3:1, by volume) in a greenhouse experiment and heat-expanded clay:zeolite:worm castings (6:3:1, by volume) in an outdoor experiment. In the greenhouse experiment, deep root length density (RLD) was significantly greater in the 10 cm-deep (3.9 in) substrate, while outdoors, deep RLD was highest for plants grown in the 15 cm-deep (5.9 in) substrate. Outdoors, iceplant had significantly greater mean coverage and shoot dry weight than hens and chicks. Lack of significant differences in quality and coverage due to substrate depth, coupled with higher RLD in the 10 cm (3.9 in) and 15 cm (5.9 in) depths in both experiments provides evidence that shallow irrigated substrates support the growth of both taxa. Index words: iceplant, hens and chicks, plant coverage, root length density, quality, zeolite, heat expanded clay. Species used in this study: hens and chicks (Sempervivum calcareum L.); iceplant [Delosperma nubigenum (Hook.f.) L. Bolus].

scholarly journals Elevated carbon dioxide and temperature effects on rooting behaviour of grape cuttings

2021 ◽  
Vol 23 (3) ◽  
pp. 257-264
Author(s):  
SHRUTHI REDDY L ◽  
GOPALA KRISHNA REDDY A ◽  
VANAJA. M ◽  
MARUTHI. V. ◽  
VANAJA LATHA. K.
Keyword(s):  
Root Length ◽  
Root Length Density ◽  
Total Root Length ◽  
Thompson Seedless ◽  
Root Volume ◽  
Software Analysis ◽  
Root Parameters ◽  
Dry Biomass ◽  
Grape Varieties ◽  
The Impact

An experiment was laid out to study the impact of eCO2 (550ppm), eT (+3ºC) and their interaction (eCO2+eT) on rooting behaviour of cuttings of three grape varieties- Thompson Seedless, Bangalore Blue, and Dogridge in FATE and OTC facilities. Observations were recorded at 50 and 80 days after planting (DAP) and root growth data was recorded and analysed using WinRHIZO root scanner and its software. Analysis revealed that, among the selected grape varieties, Thompson Seedless cuttings has shown highest number of roots, root volume and dry biomass under eCO2 and eCO2+ eT conditions, while total root length and root length density were highest with Bangalore Blue. Under eT condition, Bangalore Blue showed highest number of roots, total root length and root length density, while root volume and dry biomass was highest with Thompson Seedless. The per se values of root parameters under all conditions and their response to eCO2 was lowest with Dogridge. Though eT condition reduced all the root parameters, their performance improved under eCO2+ eT indicating the presence of higher concentration of CO2 reduced the ill effects of high temperature. Overall, eCO2 and eCO2+eT conditions improved root parameters of grape varieties, while eT reduced them as compared to their performance under ambient condition and varietal variation is significant.

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