Papers by Sascha Reth
Modern lysimeter facilities in connection with meteorological stations allow monitoring and evalu... more Modern lysimeter facilities in connection with meteorological stations allow monitoring and evaluation of mutual basic components of the environment, such as water, air, soil and vegetation. Water is the most important component of the ecosystem and the component which connects all the other components. Therefore, we need to know the basic distribution and water balance in the different components of the environment to be able to interpret some processes in nature. Rainfall, which is the primary source of vital processes in the soil, is formed in the air. The amount of precipitation that gets into the soil and into the groundwater is affected by weather conditions. Primary distribution of rainwater is divided between infiltration, surface runoff, transpiration and evapotranspiration. The amount of water infiltrated into the soil and then evaporated by solar activity or activities of plants can be identified primarily by monitoring changes in weight. For this monitoring we use weighable lysimeter. This equipment with the monolith size of surface area 1 m 2 and the depth of 1.5 m is able to follow online updates of weight of the 2 ton body with an accuracy of 100 g. When we add to quantification of leakages through the bottom layer, we obtain a comprehensive record of rainfall at the time in the natural environment of the individual components. The obtained data can be further interpreted in terms of the needs of hydrology, agriculture, and environmental studies, and according to the purpose and objectives for which we want to use them.
In Europe, about 2,500 lysimeters are installed. They were
originally built for investigations of... more In Europe, about 2,500 lysimeters are installed. They were
originally built for investigations of the hydrological cycle,
pesticide degradation, and nutrient fluxes (e.g., Winton and
Weber, 1996). Present research areas of lysimeter studies
include biological processes, such as root development of
plants and enzyme activities (e.g., Dizer et al., 2002; Schloter
et al., 2005), which are often closely related to soil structure.
At present, data on soil structure can be estimated by transferring
the information of the surrounding soil to the lysimeter at
the beginning of an experiment. After long-term experimentation,
there was a lack of knowledge on the transformations and
evolution of the lysimeter soil. Formermethods (e.g., Keese and
Knappe, 1996; Godlinski et al., 2004), which removed the soil
manually from the lysimeter vessel or which forced the soil out
of the casing by applying large pressure, were dissatisfying
because the soil structurewas largely disturbed.
A new technique, the Lysimeter Soil Retriever tool (LSR) (Reth
et al., 2006), was developed to retrieve the soil out of lysimeter
vessels with minimal disturbance of soil structure. This technique
also makes the sampling of lysimeter soil more time-efficient
and reproducible. The method can be applied to a range of
lysimeter sizes from0.5 to 2m2 and up to 2mdeep.
Generally research fields of lysimeter studies scheduled as long term experiments. In the course ... more Generally research fields of lysimeter studies scheduled as long term experiments. In the course of the studies, the lysimeters act more or less as a " black box ". Usually the soil material is identified and analyzed at the beginning of the experiments, but there is also a strong need to analyze the soil without disturbance of the soil structure after the experiments in order to obtain information about spatial and structural changes within the soil profile. The new technique of the Lysimeter Soil Retriever (Reth et al. 2006; 2007; Seyfarth and Reth 2008) for the first time enables studies on the heterogeneous migration of percolating water, and changes of soil structure as well as soil organic matter (SOM) and biomass distribution, as well as the distribution of mycorrhiza and microbes in different depths on intact soil profiles. The main target by using the LSR is the preparation of an intact soil monolith from the field lysimeter and the immediate dissection into slices to enable a direct sampling of its soil environment at several depths. Distribution and composition of SOM, pF-values, soil porosity, as well as degradation of PAH were only a few parameters, which are determined at the different soil depths. In this presentation we give some examples for the different application of the LSR and the advantage for the experiments:
In Europe more than 2,500 lysimeters operated by research institutes and industry (Lanthaler 2005... more In Europe more than 2,500 lysimeters operated by research institutes and industry (Lanthaler 2005). Originally lysimeters were built for investigations of soil water and solutes, nutrient leaching and pesticide degradation (see e.g. Winton and Weber 1996). Currently lysimeters additionally used as a tool for investigations on biological processes, and structural changes of plants, including root distribution, and enzyme activities etc. (see e.g. Dizer et al. 2002; Schloter et al. 2005).
To quantify the effects of soil temperature (Tsoil), and relative soil water content (RSWC) on so... more To quantify the effects of soil temperature (Tsoil), and relative soil water content (RSWC) on soil respiration we
measured CO2 soil efflux with a closed dynamic chamber in situ in the field and from soil cores in a controlled
climate chamber experiment. Additionally we analysed the effect of soil acidity and fine root mass in the field. The
analysis was performed on three meadow, two bare fallow and one forest sites. The influence of soil temperature on
CO2 emissions was highly significant with all land-use types, except for one field campaign with continuous rain.
Where soil temperature had a significant influence, the percentage of variance explained by soil temperature varied
from site to site from 13–46% in the field and 35–66% in the climate chamber. Changes of soil moisture influenced
only the CO2 efflux on meadow soils in field and climate chamber (14–34% explained variance), whereas on the
bare soil and the forest soil there was no visible effect. The spatial variation of soil CO2 emission in the field
correlated significantly with the soil pH and fine root mass, explaining up to 24% and 31% of the variability.
A non-linear regression model was developed to describe soil CO2 efflux as a function of soil temperature, soil
moisture, pH-value and root mass. With the model we could explain 60% of the variability in soil CO2 emission
of all individual field chamber measurements. Through the model analysis we highlight the temporal influence
of rain events. The model overestimated the observed fluxes during and within four hours of the last rain event.
Conversely, after more than 72 h without rain the model underestimated the fluxes. Between four and 72 h after
rainfall, the regression model of soil CO2 emission explained up to 91% of the variance.
Plant and Soil, 2005
To quantify the effects of soil temperature (T soil ), and relative soil water content (RSWC) on ... more To quantify the effects of soil temperature (T soil ), and relative soil water content (RSWC) on soil N 2 O emission we measured N 2 O soil efflux with a closed dynamic chamber in situ in the field and from soil cores in a controlled climate chamber experiment. Additionally we analysed the effect of soil acidity, ammonium, and nitrate concentration in the field. The analysis was performed on three meadows, two bare soils and in one forest. We identified soil water content, soil temperature, soil nitrogen content, and pH as the main parameters influencing soil N 2 O emission. The response of N 2 O emission to soil temperature and relative soil water content was analysed for the field and climate chamber measurements. A non-linear regression model (DenNit) was developed for the field data to describe soil N 2 O efflux as a function of soil temperature, soil moisture, pH value, and ammonium and nitrate concentration. The model could explain 81% of the variability in soil N 2 O emission of all individual field measurements, except for data with short-term soil water changes, namely during and up to 2 h after rain stopped. We validated the model with an independent dataset. For this additional meadow site 73% of the flux variation could be explained with the model.
Conference Presentations by Sascha Reth
Lysimeters are an important way of determining the water balance for ecosystems using water balan... more Lysimeters are an important way of determining the water balance for ecosystems using water balance parameters. In addition to the quantity, it is also possible to investigate the quality of soil and seepage water. Soil monoliths of defined dimensions are taken from their natural environment and given defined boundary conditions. In combination with corresponding measurement technology, it is possible to investigate the function and mode of action of ecosystems in this way. The results can be transferred from small to large scales and are amongst other things a good method to determine the evapotranspiration of a defined area (typically 1-2 m²), of the water and solute transport in a defined volume (typically 1-5 m³) and the degradation and conversion of substances under weathering influences. Due to the possibility of long term outdoor investigations under real location conditions, statements may be made using lysimeter tests on the water balance of certain climate scenarios, for example. Other possibilities are the comparison of several similar lysimeters in areas with different weathering conditions or the comparison of different soil types or different vegetation with the same weather over a longer time period. These investigations provide the foundation for many models to estimate the effect of climatic change, the spread of contamination in the soil or the success of re-conditioning measures. Typical areas of use for lysimeters are agricultural land locations, forest locations, landfills and post-mining landscapes as well as areas with existing waste deposits in need of recultivation. The combination of several lysimeters is recommended for statistically verified statements.
Anthropogenic environmental changes threaten
biodiversity as well as interactions between trophic... more Anthropogenic environmental changes threaten
biodiversity as well as interactions between trophic
levels and consequently alter ecosystem functions. A
new experimental research platform, the „iDiv Ecotron“,
was developed to investigate the mechanisms underlying
the relationship between biodiversity and ecosystem
functioning by manipulating biodiversity at multiple
trophic levels. This vertical biodiversity manipulation
more realistically mimics biodiversity changes in natural
ecosystems and will thus shed light on mechanisms
and consequences of species loss for the functioning of
terrestrial ecosystems. The iDiv Ecotron comprises 24
identical experimental units, called „EcoUnits“, each
of which may be separated into four compartments, allowing
for the study of up to 96 isolated ecosystems. The
iDiv Ecotron can be used to investigate abovegroundbelowground
interactions among different plant and
animal species, microorganisms, and abiotic factors
and to measure element and energy flows under nearnatural
conditions using non-invasive methods under
controlled environmental conditions. Here we present
the scientific background and technical possibilities of
the iDiv Ecotron.
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Papers by Sascha Reth
originally built for investigations of the hydrological cycle,
pesticide degradation, and nutrient fluxes (e.g., Winton and
Weber, 1996). Present research areas of lysimeter studies
include biological processes, such as root development of
plants and enzyme activities (e.g., Dizer et al., 2002; Schloter
et al., 2005), which are often closely related to soil structure.
At present, data on soil structure can be estimated by transferring
the information of the surrounding soil to the lysimeter at
the beginning of an experiment. After long-term experimentation,
there was a lack of knowledge on the transformations and
evolution of the lysimeter soil. Formermethods (e.g., Keese and
Knappe, 1996; Godlinski et al., 2004), which removed the soil
manually from the lysimeter vessel or which forced the soil out
of the casing by applying large pressure, were dissatisfying
because the soil structurewas largely disturbed.
A new technique, the Lysimeter Soil Retriever tool (LSR) (Reth
et al., 2006), was developed to retrieve the soil out of lysimeter
vessels with minimal disturbance of soil structure. This technique
also makes the sampling of lysimeter soil more time-efficient
and reproducible. The method can be applied to a range of
lysimeter sizes from0.5 to 2m2 and up to 2mdeep.
measured CO2 soil efflux with a closed dynamic chamber in situ in the field and from soil cores in a controlled
climate chamber experiment. Additionally we analysed the effect of soil acidity and fine root mass in the field. The
analysis was performed on three meadow, two bare fallow and one forest sites. The influence of soil temperature on
CO2 emissions was highly significant with all land-use types, except for one field campaign with continuous rain.
Where soil temperature had a significant influence, the percentage of variance explained by soil temperature varied
from site to site from 13–46% in the field and 35–66% in the climate chamber. Changes of soil moisture influenced
only the CO2 efflux on meadow soils in field and climate chamber (14–34% explained variance), whereas on the
bare soil and the forest soil there was no visible effect. The spatial variation of soil CO2 emission in the field
correlated significantly with the soil pH and fine root mass, explaining up to 24% and 31% of the variability.
A non-linear regression model was developed to describe soil CO2 efflux as a function of soil temperature, soil
moisture, pH-value and root mass. With the model we could explain 60% of the variability in soil CO2 emission
of all individual field chamber measurements. Through the model analysis we highlight the temporal influence
of rain events. The model overestimated the observed fluxes during and within four hours of the last rain event.
Conversely, after more than 72 h without rain the model underestimated the fluxes. Between four and 72 h after
rainfall, the regression model of soil CO2 emission explained up to 91% of the variance.
Conference Presentations by Sascha Reth
biodiversity as well as interactions between trophic
levels and consequently alter ecosystem functions. A
new experimental research platform, the „iDiv Ecotron“,
was developed to investigate the mechanisms underlying
the relationship between biodiversity and ecosystem
functioning by manipulating biodiversity at multiple
trophic levels. This vertical biodiversity manipulation
more realistically mimics biodiversity changes in natural
ecosystems and will thus shed light on mechanisms
and consequences of species loss for the functioning of
terrestrial ecosystems. The iDiv Ecotron comprises 24
identical experimental units, called „EcoUnits“, each
of which may be separated into four compartments, allowing
for the study of up to 96 isolated ecosystems. The
iDiv Ecotron can be used to investigate abovegroundbelowground
interactions among different plant and
animal species, microorganisms, and abiotic factors
and to measure element and energy flows under nearnatural
conditions using non-invasive methods under
controlled environmental conditions. Here we present
the scientific background and technical possibilities of
the iDiv Ecotron.
originally built for investigations of the hydrological cycle,
pesticide degradation, and nutrient fluxes (e.g., Winton and
Weber, 1996). Present research areas of lysimeter studies
include biological processes, such as root development of
plants and enzyme activities (e.g., Dizer et al., 2002; Schloter
et al., 2005), which are often closely related to soil structure.
At present, data on soil structure can be estimated by transferring
the information of the surrounding soil to the lysimeter at
the beginning of an experiment. After long-term experimentation,
there was a lack of knowledge on the transformations and
evolution of the lysimeter soil. Formermethods (e.g., Keese and
Knappe, 1996; Godlinski et al., 2004), which removed the soil
manually from the lysimeter vessel or which forced the soil out
of the casing by applying large pressure, were dissatisfying
because the soil structurewas largely disturbed.
A new technique, the Lysimeter Soil Retriever tool (LSR) (Reth
et al., 2006), was developed to retrieve the soil out of lysimeter
vessels with minimal disturbance of soil structure. This technique
also makes the sampling of lysimeter soil more time-efficient
and reproducible. The method can be applied to a range of
lysimeter sizes from0.5 to 2m2 and up to 2mdeep.
measured CO2 soil efflux with a closed dynamic chamber in situ in the field and from soil cores in a controlled
climate chamber experiment. Additionally we analysed the effect of soil acidity and fine root mass in the field. The
analysis was performed on three meadow, two bare fallow and one forest sites. The influence of soil temperature on
CO2 emissions was highly significant with all land-use types, except for one field campaign with continuous rain.
Where soil temperature had a significant influence, the percentage of variance explained by soil temperature varied
from site to site from 13–46% in the field and 35–66% in the climate chamber. Changes of soil moisture influenced
only the CO2 efflux on meadow soils in field and climate chamber (14–34% explained variance), whereas on the
bare soil and the forest soil there was no visible effect. The spatial variation of soil CO2 emission in the field
correlated significantly with the soil pH and fine root mass, explaining up to 24% and 31% of the variability.
A non-linear regression model was developed to describe soil CO2 efflux as a function of soil temperature, soil
moisture, pH-value and root mass. With the model we could explain 60% of the variability in soil CO2 emission
of all individual field chamber measurements. Through the model analysis we highlight the temporal influence
of rain events. The model overestimated the observed fluxes during and within four hours of the last rain event.
Conversely, after more than 72 h without rain the model underestimated the fluxes. Between four and 72 h after
rainfall, the regression model of soil CO2 emission explained up to 91% of the variance.
biodiversity as well as interactions between trophic
levels and consequently alter ecosystem functions. A
new experimental research platform, the „iDiv Ecotron“,
was developed to investigate the mechanisms underlying
the relationship between biodiversity and ecosystem
functioning by manipulating biodiversity at multiple
trophic levels. This vertical biodiversity manipulation
more realistically mimics biodiversity changes in natural
ecosystems and will thus shed light on mechanisms
and consequences of species loss for the functioning of
terrestrial ecosystems. The iDiv Ecotron comprises 24
identical experimental units, called „EcoUnits“, each
of which may be separated into four compartments, allowing
for the study of up to 96 isolated ecosystems. The
iDiv Ecotron can be used to investigate abovegroundbelowground
interactions among different plant and
animal species, microorganisms, and abiotic factors
and to measure element and energy flows under nearnatural
conditions using non-invasive methods under
controlled environmental conditions. Here we present
the scientific background and technical possibilities of
the iDiv Ecotron.