**Author details**

and feedbacks between hydrological, geochemical, geomorphological, microbial, and ecological processes that control landscape form and function, and to formalize this knowledge into distributed coupled-process models and closure relations at the hillslope-scale. The threefold replication of initial landscape conditions and climate treatment will thereby allow to develop and rigorously test (i.e., to accept or reject) laws of fundamental natural processes (e.g., flow and transport) at space-time scales relevant for prediction. In later phases, varying experimental treatments across the replicate slopes (e.g., different rainfall

jectories, which allow further evaluation and refinement of the knowledge and predictive

The LEO infrastructure is designed as a community resource with open data availability and seeks to foster broad interdisciplinary collaboration and science planning. During the next 10 years, scientists from across the world will have the opportunity to propose smaller research projects that can be implemented without loss of objectives of the institutional experiment. For instance, researchers who would like to study certain rainfall-runoff dynamics can propose a sequence of rain events, or those commanding specific measurement or analysis capabilities are welcome to integrate those into existing efforts. Similarly, the reader is encouraged to contact the authors to share their ideas about research opportunities with respect to the planned evolutionary forcing of the landscapes. For example, the composition of the seed pool for the upcoming vascular plant colonization is still under debate. By rapidly iterating dense experimental measurement with community-based planning, data analysis, and model development, we envision that our understanding and ability to predict the coevolution of hydrological, biogeochemical, and ecological processes and their interactions under variable climate can be significantly improved. This vision will be tested when we ultimately extrapolate our understanding of abiotic-biotic system coevolution into the complex reality of natural environments to meet the challenge of predicting landscape-scale

The authors gratefully acknowledge support from the Philecology Foundation of Fort Worth Texas, the National Science Foundation (NSF; NSF-funded project 1344552, NSF-funded Hydrologic Synthesis Project: Water cycle dynamics in a changing environment: advancing hydrologic science through synthesis, NSF grant EAR-0636043, NSF grant EAR-1340912, NSF grant EAR-1417097), and the Department of Energy (Joint Genome Institute small scale Community Science Program grant 502880). Additional funding support was provided by the Office of the Vice President of Research at the University of Arizona and by the Technology and Research Initiative Fund (TRIF) Water, Environmental, and Energy Solutions (WEES) initiative at the University of Arizona (Shared Equipment Enhancement Funds). PT is grateful for financial support from the

levels) may drive divergent landscape evolutionary tra-

distribution, temperature or CO<sup>2</sup>

64 Hydrology of Artificial and Controlled Experiments

capabilities gained.

response to global change.

**Acknowledgements**

Agnese Nelms Haury Program.

Till H. M. Volkmann<sup>1</sup> \*, Aditi Sengupta1 , Luke A. Pangle<sup>2</sup> , Katerina Dontsova<sup>1</sup> , Greg A. Barron-Gafford<sup>3</sup> , Ciaran J. Harman<sup>4</sup> , Guo-Yue Niu<sup>5</sup> , Laura K. Meredith<sup>6</sup> , Nate Abramson<sup>1</sup> , Antonio A. Meira Neto<sup>5</sup> , Yadi Wang<sup>7</sup> , John R. Adams<sup>1</sup> , David D. Breshears6,8, Aaron Bugaj1 , Jon Chorover6,7, Alejandro Cueva1 , Stephen B. DeLong<sup>9</sup> , Matej Durcik5 , Ty P. A. Ferre<sup>5</sup> , Edward A. Hunt1 , Travis E. Huxman¹<sup>0</sup> , Minseok Kim<sup>4</sup> , Raina M. Maier<sup>7</sup> , Russell K. Monson<sup>6</sup> , Jon D. Pelletier<sup>11</sup>, Michael Pohlmann<sup>7</sup> , Craig Rasmussen<sup>7</sup> , Joaquin Ruiz1,11, Scott R. Saleska<sup>8</sup> , Marcel G. Schaap7 , Michael Sibayan1 , Markus Tuller7 , Joost L. M. van Haren<sup>1</sup> , Xubin Zeng<sup>5</sup> and Peter A. Troch1,5

\*Address all correspondence to: tillv@email.arizona.edu

1 University of Arizona, Biosphere 2, Tucson, AZ, USA

2 Georgia State University, Department of Geosciences, Atlanta, GA, USA

3 University of Arizona, School of Geography and Development, Tucson, AZ, USA

4 Johns Hopkins University, Department of Geography and Environmental Engineering, Baltimore, MD, USA

5 University of Arizona, Department of Hydrology and Atmospheric Sciences, Tucson, AZ, USA

6 University of Arizona, School of Natural Resources and the Environment, Tucson, AZ, USA

7 University of Arizona, Department of Soil, Water and Environmental Science, Tucson, AZ, USA

8 University of Arizona, Department of Ecology and Evolutionary Biology, Tucson, AZ, USA

9 United States Geological Survey, Menlo Park, CA, USA

10 University of California at Irvine, Center for Environmental Biology, Irvine, CA, USA

11 University of Arizona, Department of Geosciences, Tucson, AZ, USA
