The Intensively Managed Landscape Critical Zone Observatory: A Scientific Testbed for Understanding Critical Zone Processes in Agroecosystems

Abstract

In intensively managed landscapes, interactions between surface (tillage) and subsurface (tile drainage) management with prevailing climate/weather alter landscape characteristics, transport pathways, and transformation rates of surface/ subsurface water, soil/sediment, and particulate/dissolved nutrients. To capture the high spatial and temporal variability of constituent transport and residence times in the critical zone (between the bedrock and canopy) of these altered landscapes, both storm event and continuous measurements are needed. The Intensively Managed Landscapes Critical Zone Observatory (IML-CZO) is comprised of three highly characterized, well instrumented, and representative watersheds (i.e., Clear Creek, Iowa; Upper Sangamon River, Illinois; and Minnesota River, Minnesota). It is organized to quantify the heterogeneity in structure and dynamic response of critical zone processes to human activities in the context of the glacial and management (anthropogenic) legacies. Observations of water, sediment, and nutrients are made at nested points of the landscape in the vertical and lateral directions during and between storm events (i.e., continuously). The measurements and corresponding observational strategy are organized as follows. First, reference measurements from surface soil and deep core extractions, geophysical surveys, lidar, and hyperspectral data, which are common across all Critical Zone Observatories, are available. The reference measurements include continuous quantification of energy, water, solutes, and sediment fluxes. The reference measurements are complemented with event-based measurements unique to IML-CZO. These measurements include water table fluctuations, enrichment ratios, and roughness as well as bank erosion, hysteresis, sediment sources, and lake/floodplain sedimentation. The coupling of reference and event-based measurements support testing of the central hypothesis (i.e., system shifts from transformer to transporter in IML-CZO due to the interplay between management and weather/climate). Data collected since 2014 are available through a data repository and through the Geodashboard interface, which can be used for process-based model simulations.

The Power of Environmental Observatories for Advancing Multidisciplinary Research, Outreach, and Decision Support: The Case of the Minnesota River Basin

“…Over time, long‐term environmental research sites have been developed across a wide range of biomes through programs like the Long‐Term Ecological Research network and the National Ecological Observatory Network to focus on ecological and socioecological systems (e.g., S. L. Collins & Childers, ; Goodman et al, ; Hobbie et al, ; Redman et al, ; Utz et al, ). More recently CZOs focusing on the physical, biogeochemical, and ecological interactions within the Earth's critical zone have been developed, bringing more geoscience into the observatory platform (e.g., Anderson et al, ; White et al, ; Wilson et al, ). Many of these observatory efforts are funded for decades, with a goal of developing long‐term environmental data sets for cutting‐edge transdisciplinary science.…”

“…The goal of this paper is to present an integrated synthesis of these data sets and models, both as an example of how interdisciplinary science can inform key scientific and societal questions and to encourage additional research into IML as a prototype of coupled human‐natural systems undergoing change (Kumar et al, ). This data collection and analysis effort differs from some of the longer‐term observatory‐scale efforts (e.g., Goodman et al, ; Hobbie et al, ; Utz et al, ; White et al, ; Wilson et al, ) but provides an example of how leveraged publicly available data and previous studies can be optimally integrated to maximize science. Specifically, we demonstrate how targeted collection of biogeochemical data and repeat geomorphic data coupled with routine stream gage, meteorological, topography, and land use data can be used to make transdisciplinary advances in our understanding of how sediment, water, and nutrients move through and transform in IML.…”

The Role of Hydraulic Connectivity and Management on Soil Aggregate Size and Stability in the Clear Creek Watershed, Iowa

“…This study was conducted in southeastern Iowa within agricultural fields of the Clear Creek Watershed (CCW), Iowa (41.74 • N, −91.94 • W), which is part of the U.S. National Science Foundation Intensely Managed Landscapes Critical Zone Observatory [53] (Figure 2). In CCW, the mean annual precipitation is 889 mm/year and temperature is 9 • C, with convective storms dominating late spring-early summer months [54].…”

The impact of tillage row orientation on physical and chemical sediment enrichment

“…The upper 5 cm of the soil surface interface hosts a wide range of biogeochemical and hydrologic processes (Wilson et al., 2018). The structure of this interface is comprised of an arrangement of soil aggregates that vary in size, texture, and stability (Bronick & Lal, 2005; Jarvis, Larsbo, & Koestel, 2017; Jastrow, 1996; Six, Paustian, Elliott, & Combrink, 2000).…”