the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 13 Oct 2025
Technical note: Lys-clim, a combination of lysimeters and an atmospheric conditions simulator to study biogeochemical processes in the shallow critical zone
Abstract. Studying the Critical Zone (CZ), i.e. the outermost envelope of Earth, and its bio-geochemical processes requires an interdisciplinary approach. The deployment of critical zone observatories has led to significant scientific advances but does not offer the possibility of comparing treatments or apprehending different climatic scenarios. Conversely, mesocosm studies are often discipline-specific and can be limited in scope. Here, we propose a complementary approach that relies on the combination of 15 lysimeters and a climate chamber. The lysimeters have been equipped to allow for a detailed monitoring of the water flow, which connects most biogeochemical processes in the critical zone. This monitoring relies on scales, tipping buckets, soil moisture sensors and a facilitated high frequency sampling of discharge water. Besides, in-situ continuous gas analysis is enabled by a 45-channel manifold. The climate simulator is a 81 m3 isolated chamber that enables regulation of temperature; atmospheric CO2; relative humidity; quantity and quality of irrigation water and quantity and quality of light. We evaluate the design in terms of its ability to assess the interactions between CZ processes. The main advantages of this set-up are as follows: it allows for the simulation of future climates or extreme events; it enables replication and the application of different treatments, facilitating the isolation of processes and the assessment of anthropogenic impacts; and it provides automated data acquisition.
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Status: open (until 04 Mar 2026)
- RC1: 'Comment on egusphere-2025-4243', Anonymous Referee #1, 21 Nov 2025 reply
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RC2: 'Comment on egusphere-2025-4243', Kevin Bishop, 28 Jan 2026
reply
This paper presents an innovative mesocosm approach to simulating changes in the crucial zone with an emphasis on climatic factors. The paper is well-written and appropriately detailed in the presentation. As such it provides the critical zone community with a useful overview of this infrastructure.
Major concern:
I lack information on the possibility for researchers to make use of this facility. Is there a possibility for the scientific community to make use of this infrastructure? Or is the presentation more an inspiration for others to try to create their own mesocosm since the one presented in this manuscript is not going to be accessible for testing new ideas from people not already involved in this in this particular mesocosm.
Minor comments
Figure 5: There is platueau in cumulated discharge, and a gap in conductivity data between hours 10-25 from start of the drainage. Please explain if this is an experimental artefact or a feature of the planned experiment.
Line 264. Please consider adding “or downslope changes along a soil catena” after the workds “... vadose zone, such as preferential flow”
Citation: https://doi.org/10.5194/egusphere-2025-4243-RC2
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This paper presents a new research facility that combines fifteen small lysimeters (surface area of 0.1 m², depth of 72 cm) within one climate chamber. This allows the lysimeters, including growing plants, to be operated under identical climatic conditions. The paper describes the technical design, instrumentation, and modus operandi of the system. The paper also presents test data on temperature, air humidity, PPFD, and the spectral composition of light provided by the LED lighting system. The lysimeters can be semi-automatically irrigated; soil pore and seepage water can be collected; and soil gas concentrations of CO₂ and O₂ can be measured through gas-permeable membrane tubes at three different depths within each lysimeter. Additionally, soil temperature and moisture can be measured at four different depths within each lysimeter.
The system is innovative and allows for targeted process studies under controlled conditions. Its strengths include the ability to monitor the total water balance, pore and seepage water quantity and quality, and soil gas concentrations, as well as the ability to modulate environmental conditions over a wide range. The system's weaknesses are the small size and shallow depth of the lysimeters; the lack of soil temperature control, which prevents a natural vertical soil temperature gradient; the inability to freeze; and a lighting system that provides only about 25% of full sunlight intensity.
This paper will be of interest to readers who use or plan to use ecotrons and lysimeters for experiments or intend to use data from such experiments for modeling purposes. While the paper is generally easy to understand, it lacks some detail regarding technical specifications and equipment. The data presented in the Results section seem somewhat arbitrarily selected. It would be helpful to include example data from different climatic conditions. The discussion highlights the system's potential and limitations. However, it also includes a section about perspectives that is a bit far-fetched. Overall, this is an interesting paper, but it requires revision before publication can be recommended. I have made specific comments and edits in the attached annotated manuscript.