Land-atmosphere interactions at different temporal and spatial scales are important for our understanding of the Earth system and its modeling. The Landscape Evolution Observatory (LEO) at Biosphere 2, managed by the University of Arizona, hosts three nearly identical artificial bare-soil hillslopes with dimensions of 11 × 30 m 2 (1 m depth) in a controlled and highly monitored environment within three large greenhouses. These facilities provide a unique opportunity to explore these interactions. The dataset presented here is a subset of the measurements in each LEO’s hillslopes, from 1 July 2015 to 30 June 2019 every 15 minutes, consisting of temperature, water content and heat flux of the soil (at 5 cm depth) for 12 co-located points; temperature, relative humidity and wind speed above ground at 5 locations and 5 different heights ranging from 0.25 m to 9–10 m; 3D wind at 1 location; the four components of radiation at 2 locations; spatially aggregated precipitation rates, total subsurface discharge, and relative water storage; and the measurements from a weather station outside the greenhouses.

Understanding the process interactions and feedbacks among water, porous geological media, microbes, and vascular plants is crucial for improving predictions of the response of Earth’s critical zone to future climatic conditions. However, the integrated coevolution of landscapes under change is notoriously difficult to investigate. Laboratory studies are limited in spatial and temporal scale, while field studies lack observational density and control. To bridge the gap between controlled laboratory and uncontrollable field studies, the University of Arizona built a macrocosm experiment of unprecedented scale: the Landscape Evolution Observatory (LEO). LEO comprises three replicated, heavily instrumented, hillslope-scale model landscapes within the environmentally controlled © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Biosphere 2 facility. The model landscapes were designed to initially be simple and purely abiotic, enabling scientists to observe each step in the landscapes’ evolution as they undergo physical, chemical, and biological changes over many years. This chapter describes the model systems and associated research facilities and illustrates how LEO allows for tracking of multiscale matter and energy fluxes at a level of detail impossible in field experiments. Initial sensor, sampler, and soil coring data are already providing insights into the tight linkages between water flow, weathering, and microbial community development. These interacting processes are anticipated to drive the model systems to increasingly complex states and will be impacted by the introduction of vascular plants and changes in climatic regimes over the years to come. By intensively monitoring the evolutionary trajectory, integrating data with mathematical models, and fostering community-wide collaborations, we envision that emergent landscape structures and functions can be linked, and significant progress can be made toward predicting the coupled hydro-biogeochemical and ecological responses to global change.

Understanding the process interactions and feedbacks among water, porous geological media, microbes, and vascular plants is crucial for improving predictions of the response of Earth's critical zone to future climatic conditions. However, the integrated coevolution of landscapes under change is notoriously difficult to investigate. Laboratory studies are limited in spatial and temporal scale, while field studies lack observational density and control. To bridge the gap between controlled laboratory and uncontrollable field studies, the University of Arizona built a macrocosm experiment of unprecedented scale: the Landscape Evolution Observatory (LEO). LEO comprises three replicated, heavily instrumented, hillslope-scale model landscapes within the environmentally controlled Biosphere 2 facility. The model landscapes were designed to initially be simple and purely abiotic, enabling scientists to observe each step in the landscapes' evolution as they undergo physical, chemical, and biological changes over many years. This chapter describes the model systems and associated research facilities and illustrates how LEO allows for tracking of multiscale matter and energy fluxes at a level of detail impossible in field experiments. Initial sensor, sampler, and soil coring data are already providing insights into the tight linkages between water flow, weathering, and microbial community development. These interacting processes are anticipated to drive the model systems to increasingly complex states and will be impacted by the introduction of vascular plants and changes in climatic regimes over the years to come. By intensively monitoring the evolutionary trajectory, integrating data with mathematical models, and fostering community-wide collaborations, we envision that emergent landscape structures and functions can be linked, and significant progress can be made toward predicting the coupled hydro-biogeochemical and ecological responses to global change.

84Understanding the multitude of processes, feedback, and interactions among water, microbes, plants, and porous geological media is crucial for obtaining better predictions about the behavior of Earth's critical zone in the face of future climatic conditions. Current studies often suffer from the limitations of the spatial scale in which they are performed. By not considering the effects brought by the heterogeneity while moving from pore to landscape scales, important feedback and integrated behavior may be missed, rendering predicted behavior different from that of the natural systems. The time span in which such experiments are executed might also not be suitable for the observation of phenomena typically occurring over years in natural settings. Studying naturally occurring phenomena in situ carries with it the uncertainty about the initial state of the system, and the fact that observations require destructive sampling, which will interfere with the processes under investigation. The investigation of hydrological and biogeochemical evolution of natural systems is thus a challenging task for Earth scientists. The Landscape Evolution Observatory (LEO), a research facility managed by the University of Arizona and located at Biosphere 2, allows for the interdisciplinary investigation of the evolution of artificial hillslopes containing an initially naive mineral assemblage that will be subjected to controlled climate experiments. The LEO's unique set of instrumentation allows for exceptional observations of energy, water, and carbon fluxes across the three 330 m3 hillslopes. Within the time frame of 10 years of interdisciplinary research, scientists will be able to address important questions related to the interactions among hydrology, geochemistry, and ecology. The LEO project maintains a database open to scientists and practitioners from different domains to address different research questions in a collaborative way. The research done at the LEO has the potential to be a milestone in terrestrial ecosystem research infrastructures.

Zero-order drainage basins, and their constituent hillslopes, are the fundamental geomorphic unit comprising much of Earth's uplands. The convergent topography of these landscapes generates spatially variable substrate and moisture content, facilitating biological diversity and influencing how the landscape filters precipitation and sequesters atmospheric carbon dioxide. In light of these significant ecosystem services, refining our understanding of how these functions are affected by landscape evolution, weather variability, and long-term climate change is imperative. In this paper we introduce the Landscape Evolution Observatory (LEO): a large-scale controllable infrastructure consisting of three replicated artificial landscapes (each 330m2 surface area) within the climate-controlled Biosphere 2 facility in Arizona, USA. At LEO, experimental manipulation of rainfall, air temperature, relative humidity, and wind speed are possible at unprecedented scale. The Landscape Evolution Observatory was designed as a community resource to advance understanding of how topography, physical and chemical properties of soil, and biological communities coevolve, and how this coevolution affects water, carbon, and energy cycles at multiple spatial scales. With well-defined boundary conditions and an extensive network of sensors and samplers, LEO enables an iterative scientific approach that includes numerical model development and virtual experimentation, physical experimentation, data analysis, and model refinement. We plan to engage the broader scientific community through public dissemination of data from LEO, collaborative experimental design, and community-based model development.

The Landscape Evolution Observatory (LEO) at the Biosphere 2 consists of three 333 m2 hillslope landscapes, constructed inside an environmentally controlled greenhouse facility. LEO aims to address today's challenges in Earth science by studying the effects of physical, biological, and chemical systems in response to climate change. Each landscape holds approximately one meter depth of basaltic tephra ground, crushed to form a homogenous loamy sand, that will evolve into structured soil over many years. To help monitor the evolution, the landscapes contain a spatially dense sensor and sampler network capable of resolving meter-scale lateral heterogeneity and sub-meter scale vertical heterogeneity in moisture, energy, and carbon states and fluxes. The density of sensors and frequency at which they can be polled allows for measurements to be made that are impossible in natural field settings. Additionally, each landscape has an engineered rain system that allows precipitation rates to vary between 0.003 and 0.045 m/hr in spatially homogeneous or heterogeneous patterns, and with enough capability to produce full hillslope-scale hydrological steady-state conditions. Specifically for this presentation, we explore the results and challenges of coupling an electrical resistivity monitoring program with other sensors in an effort to bridge the understanding of averaging point-scale measurements with larger volume-scale geophysical methods.