There is growing evidence that species are able to coexist in communities through niche separation, and that consistent community structuring can take place at the biogeographical scale, as the same ...biotic interactions can determine species’ fate at large scales. In this study, we document niche differentiation at a larger scale within a specific plant community of softwater lakes in Western Europe. Five species were selected for their relative frequency and wide geographical distribution within the dataset that we collected. Their niches were modelled both from presence–absence data and from ordinal abundance data, using mixed regression techniques (generalized linear mixed models and proportional odds mixed models, respectively). The modelled realized niches differed among the species on the West-European scale, although strict separation was not shown and geographical coverage is not complete. Plant strategy characterization of the species supported the assumption that functional traits underpin the niche differentiation among the species through fitness trade-offs. Mechanistic experimental research at a range of spatial scales is needed to test the importance of different community structuring mechanisms at the biogeographical scale, such as biotic interactions and environmental filtering.
The saturated hydraulic conductivity (
K
s
) of the soil is one of the main soil physical properties. Indirect estimation of this parameter using pedo-transfer functions (PTFs) has received ...considerable attention. The Purpose of this study was to improve the estimation of
K
s
using fractal parameters of particle and micro-aggregate size distributions in smectitic soils. In this study 260 disturbed and undisturbed soil samples were collected from Guilan province, the north of Iran. The fractal model of
Bird and Perrier
was used to compute the fractal parameters of particle and micro-aggregate size distributions. The PTFs were developed by artificial neural networks (ANNs) ensemble to estimate
K
s
by using available soil data and fractal parameters. There were found significant correlations between
K
s
and fractal parameters of particles and microaggregates. Estimation of
K
s
was improved significantly by using fractal parameters of soil micro-aggregates as predictors. But using geometric mean and geometric standard deviation of particles diameter did not improve
K
s
estimations significantly. Using fractal parameters of particles and micro-aggregates simultaneously, had the most effect in the estimation of
K
s
. Generally, fractal parameters can be successfully used as input parameters to improve the estimation of
K
s
in the PTFs in smectitic soils. As a result, ANNs ensemble successfully correlated the fractal parameters of particles and micro-aggregates to
K
s
.
Management of groundwater resources is very important for economic development in arid and semi-arid lands. Unsaturated zone plays an important role in the fate of pollutants in the soil. Modeling of ...water flow in the vadose zone uses methods and techniques of soil physics. To describe and predict the behavior of water and solutes in unsaturated soil, knowledge of the soil hydraulic parameters is essential. The aim of this work is to evaluate the soil hydraulic parameters by direct and inverse methods from field measurements of cumulative infiltration and water contents. The inverse approach used here combined the numerical solution of the Richards equation two-dimensional with a Levenberg-Marquardt algorithm of optimization. Field experiments, using the disc infiltrometer, were conducted out in the Rmel area, sandy soil, in the Loukkos Basin located in northern Morocco. In this study, numerical and experimental results show that the simulated values are much closer to the measured values with a high correlation (
R
2
≈ 0.92, RMSE ≈ 0.146). Indicating that the model used here is efficient to estimate the soil hydraulic parameters by inverse modeling. Furthermore, the sensitivity analysis showed that the saturated conductivity (
K
s
) is sensitive to estimate with respect to other parameters.
Considering the model that the hydrothermal coupling moving rule of the seasonal frozen soil under freezing and thawing effect, a research was made that how deep we bury and the soil texture are to ...effect the rule of the diffusion and evaporation of water vapor. By monitoring the moisture content and temperature of the profile of the continuous freezing and thawing soil in region named Xiaotangshan mountain in Beijing and using the hydrothermal coupling moving model, the water transferring rule of clay and sandy loam in different depth that we buried was summarized. Many long-term field experiments showed that when frozen layer buried in a deep way was in a frozen state, the interactive movement of the water in the soil was not active and evaporated slowly. The average value of the water evaporation of clay was about 0.51 mm/day approximately and the situation of the sandy loam soil was 1.24 mm/day. By qualitative analyzing and observation, the less we buried (less than 0.8 m), the ice in the frozen soil layer got more. Besides, the density of the frozen soil layer went higher but the water barely diffused. On the contrary, with the increase of the depth, the diffusion went stronger and stronger due to the contact between the soil and the groundwater. In addition, according to the different soil texture detections, the diameter of soil particle has great influence on the diffusion of the water vapor in the soil. The diffusion rate of the water vapor in the sandy loam soil was twice than that of in clay. Other field water coupling experiments showed that, the soil moisture content was greater, soil freezing period density was larger, and soil water infiltration rate was zero. Soil evaporation was gradually decreased with the increasing of groundwater depth, and the size of soil particle would have a more obvious effect on soil water vapor diffusion and evaporation. Our research results can provide scientific basis for the buried area where contains groundwater to keep moisture in the winter and the resource content of the groundwater in Beijing and the locations in the same latitude of Beijing. This paper’s purpose was to research the law of water vapor diffusion and evaporation, with different soil texture and burial depth, so it can verify the coupled model of seasonal frozen soil water and heat migration.
—
Crop abandonment is a factor responsible for soil degradation in semi-arid regions. The effects of crop abandonment on soil restoration may depend on soil properties and climatic conditions of an ...area. In particular, soil hydraulic properties affect the vegetation recovery process. The objective of this study was to investigate the succession changes in water flow as a result of changes in soil hydraulic properties after crop abandonment under drought and non-drought conditions, and under water uptake by co-occurring perennial plants to clarify the observation that typical perennial grass species are seldom observed in abandoned fields. Soil hydraulic properties were measured in croplands which had been abandoned for different periods (2, 9, and 18 years ago) and in a grazed grassland site (control site). Hydrological processes in the soil profiles were simulated with soil hydraulic properties under drought and non-drought summer conditions with water uptake from perennial grass species. Suctioning the surface soils increased with the period of abandonment, with this trend being particularly obvious in a drought year. Soil water appears to be restricted in the later succession stage of abandoned fields and in grazed grassland for drought-tolerant plants. Dry soil and climate conditions are important factors determining the intrusion of the typical perennial grass,
Stipa krylovii
, into degraded abandoned fields. A water availability with low pressure (plant can use with low pressure) made difficult the intrusion of typical perennial grasses to abandoned cropland. This abiotic relation between soil hydraulic properties and climate conditions may play an important role for plant succession in abandoned cropland.
Simulation of heat transfer in soil under steady and unsteady situations requires reliable estimate of soil thermal conductivity (λ) at varying environmental conditions. In the current work several ...soil thermal conductivity predicting models including I) de Vries, II) Campbell, III) combined de Vries and Campbell and IV) de Vries-Nobre were evaluated for the four soils of coarse sand, sandy loam, loam and clay loam textured at varying in temperature and bulk density at low moisture range. Thermal conductivities measured by the cylindrical probe method served as the reference for models assessment. Results showed that approximately same thermal conductivities obtained by the five methods at low moisture range (θ ≤ 0.05 m
3
/m
3
). Also the de Vries and de Vries-Campbell models produced accurate than Campbell and de vries-Nobre models. The accuracy of the two models increased with soil compaction but decreased with temperature rise. Campbell model showed more reliability at higher (311.16 and 321.16 K) temperatures; but its accuracy declined with soil compaction in current work. It seems that assuming needle shape for the soil particles is far away from the reality whereas assuming spherical shapes may be more realistic and produced more satisfactory prediction of thermal conductivity. The compaction would alter particle arrangement and may increase the contact area of particles; and then make them behave more or less spherical shape.it seems thermal conductivity in solid particles increase via increasing in temperature. Since a modified mineral shape factor,
g
m
, was developed as a combination between sphere and needle according to geometric mean particle diameter as well as bulk density and temperature as modifying factors. This factor increased the accuracy of de Vries-Nobre model up to 10.37%. Regarding nonlinear regression model, moisture content, bulk density, temperature and quartz content demonstrated significant effect on soil thermal conductivity in our investigation.
Indonesian Coffee and Cocoa Research Institute (ICCRI) is a institution that Conducting research to obtain technological innovation in the field of cultivation and processing of coffee and cocoa ...products. ICCRI has an Experimental Garden and Office Area of 380 ha, consisting of arabica coffee experimental garden (KP Andungsari height of 100-1,200 m asl), robusta coffee and cocoa (KP Kaliwining and KP Sumberasin 45-550 m above sea level). The laboratory has an area of 2,365 m2 with equipment of 850 units. Consisting of Plant Breeding Laboratory, Soil Physics Laboratory, Soil Chemistry and Soil Biology, Tissue Culture Laboratory, Agricultural Mechanization Laboratory, Product Processing Laboratory, Quality Control Laboratory, Information Center and Training. The purpose of this research is to provide an overview of diversification by Indonesian Coffee and Cocoa Research Institute (ICCRI) to further develop coffee production business in Indonesia. Analysis data used in this study is discriptive analysis to describe holisticly and also SWOT analysis to discribe deeply strength weakness opportunity and threat to make strategy to improve the performance. The result of the research show that needed a diversification business conducted in the form of internal deverifikation by doing research to get a better quality coffee plant, quality and have high competitiveness at national and international level. The resulting coffee plant is also resistant to plant diseases, more fruiting, better fruit quality. Deverification is also carried out by performing aoutonomous fund with the establishment of Coffe and Cocoa science techno park which is also intended to disseminate the results and activities of ICCRI to the community.
In this study, two experiments (Experiment 1&2) were conducted to investigate the effects of chisel plowing on soil conditions and nitrogen absorption of maize (Zea mays L.) in upland fields ...converted from an andosol paddy field. In Experiment 1, two hybrids were planted under two tillage systems (rotary tilling and chisel plowing), and soil physics, soil chemistry and nitrogen absorption of maize were examined. In Experiment 2, the difference in fertilizer distribution between the two tillage systems was examined. In Experiment 1, the soil penetration resistance value at 0–5 cm depth was nearly the same in the two tilling systems, whereas, at 5–20 cm depth it was larger in the chisel plowing system, than in the rotary tilling system. In the chisel plowing system, the percentage of gas phase at 10 and 20 cm depth was lower and that of the solid phase was higher than in the rotary tilling system. Contents of nitrate nitrogen, exchangeable potassium and available phosphorus at the 6-leaf stage were higher in chisel plowing than in rotary tilling at a 0 –10 cm depth, whereas there were no significant differences between the two tillage systems at the maturity stage. There was no significant difference between the two tillage systems. In Experiment 2, more than 95% of fertilizer was distributed at 0–10 cm in the chisel plowing system, whereas in the rotary tilling system, the fertilizer distribution was almost uniform at 0–20 cm depth. It is concluded that, in the chisel plowing system, penetration resistance was high at 5–20 cm, and furthermore, fertilizer and soil nutrient were concentrated at 0–5 cm at the early growing stage. It is also concluded that chisel plowing allows farmers high-speed work while maintaining nitrogen absorption at the same level as in rotary tilling in an upland field converted from a paddy field.
This article reports on variation in infiltration rates of soil aggregates as a result of phenomenon known as air slaking. Air slaking is caused by the compression and subsequent escape of air ...captured inside soil aggregates during water saturation. Although it has been generally assumed that it occurs mostly when dry aggregates are rapidly wetted, the measurements used for this paper have proved that it takes place even if the wetting is gradual, not just immediate. It is a phenomenon that contributes to an infiltration variability of soils. In measuring the course of water flow through the soil, several small aggregates of five agricultural soils were exposed to distilled water at zero tension in order to characterize their hydraulic properties. Infiltration curves obtained for these aggregates demonstrate the effect of entrapped air on the increase and decrease of infiltration rates. The measurements were performed under various moisture conditions of the A-horizon aggregates using a simple device.
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