| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
CSIRO Land and Water, PMB Aitkenvale, Townsville, QLD 4814, Australia
* Corresponding author (Keith.Bristow{at}csiro.au).
Received for publication June 25, 2003.
THIS ISSUE OF Agronomy Journal contains a series of papers originating from the symposium titled "The Soil–Plant–Atmosphere Continuum: Gaps and Unresolved Issues," held at the 2001 ASA-CSSA-SSSA annual meetings in Charlotte, NC. The main purpose of the symposium and publication of these papers is to honor Professor Gaylon S. Campbell and to celebrate his achievements and contributions to ASA and SSSA and to science, education, instrumentation, business, and his fellow men and women.
Gaylon Sanford Campbell was born on 20 Aug. 1940, in Blackfoot, ID, the eldest son of Sanford and Rosalie Campbell. He received his B.S. in physics in 1965 and his M.S. in soil physics in 1966, both from Utah State University, before being awarded a National Science Foundation Graduate Fellowship to undertake his Ph.D in soils at Washington State University, which he completed in 1968.
Dr. Campbell was then appointed Assistant Professor at Washington State University, a position he held until 1969, when he moved to New Mexico to serve as Captain in the U.S. Army's Atmospheric Sciences Laboratory at White Sands Missile Range. At White Sands, Dr. Campbell worked with a micrometeorology group studying air movement as it affects missile launches, atmospheric diffusion, and the paths of laser beams. He returned to Washington State University in 1971 where he held, successively, the positions of Assistant Professor, Associate Professor, and Professor until 1998. Dr. Campbell now serves as Vice President of Engineering at Decagon Devices in Pullman, WA.
During his tenure at Washington State University, Dr. Campbell hosted and supervised more than 50 students, postdoctoral researchers, sabbatical scientists, and visiting scientists from numerous disciplines and countries. He also served, often as Chair, on numerous national and international committees and review teams and has served on the editorial boards of Agricultural Water Management, Journal of Theoretical and Applied Climatology, and Agricultural and Forest Meteorology.
Dr. Campbell is a highly sought-after speaker and has presented lectures, seminars, workshops, and presentations at scientific conferences in, amongst other countries, the USA, England, Scotland, Belgium, Israel, China, India, Germany, Spain, Portugal, South Africa, Australia, Japan, and Chile. He has been awarded a number of fellowship and visiting scientist positions and has served as a British Science Research Council Senior Visiting Fellow at the University of Nottingham in England (1977–1978); Visiting Scientist at Campbell Scientific in Logan, UT (1979); Visiting Professor at the University of Nottingham in England (1985–1986); Visiting Professor at Utah State University in Logan, UT (1993); and Visiting Scientist at Campbell Scientific in Logan, UT (1994).
With his exceptional knowledge and understanding across many disciplines (including mathematics, physics, chemistry, biology, computing, modeling, electronics, and instrumentation), Dr. Campbell has made major research contributions in the field of soil and environmental physics where he has led developments in a wide range of areas spanning the soil–plant–atmosphere continuum. These have included the hydraulic, thermal, and electrical properties of soils; heat, water, and solute transport; soil freezing; measurement of soil and plant water potential; crop residue and soil N dynamics; water uptake by plants; sap flow and plant water relations; canopy transport and soil–atmosphere coupling; radiation and energy balance; organism–environment interactions; mathematical modeling and computer simulation; and soil and environmental instrumentation.
Not only is Dr. Campbell able to identify, deconstruct, and analyze key processes, he is also able to reconstruct them in such a way as to improve our understanding of how various systems work. This ability to excel as both a reductionist and a synthesist is one of the characteristics that sets Dr. Campbell apart. This quality, combined with his skills in developing and coding computer models, has enabled him to analyze the dynamics of various components of the soil–plant–atmosphere system and the system as a whole and to carry out predictions in both space and time. His models, some of the first of their kind, are ideal teaching aids, with graphics that bring difficult concepts to life and help people without strong math and physics backgrounds greatly improve their understanding of the soil–plant–atmosphere system.
Dr. Campbell is also a disciplined and prolific writer, with an ability to express the complex in ways that are easily understood. He has authored and coauthored more than 250 publications, including three major text books (Campbell, 1977, 1985; Campbell and Norman, 1998), more than 100 refereed journal papers, and more than 30 book chapters. One of his better known and more highly cited papers, "A simple method for determining unsaturated conductivity from moisture retention data," was published in Soil Science (Campbell, 1974). One could argue that some of Dr. Campbell's greatest contributions to soil and environmental physics are his classic textbooks, used in universities and other teaching environments worldwide. It would be hard to guess just how many people have been influenced by these texts, some of which have been translated into foreign languages.
From early in Dr. Campbell's career it was clear that, in addition to his research skills, he had a special ability in instrumentation and recognized the interdependence of new measurements and instrumentation and new and improved understanding. Dr. Campbell's role in the development of leading-edge instrumentation has been exceptional. He has been the lead or a major player in the development of more than 15 new instruments, including the in situ soil psychrometer, in situ leaf psychrometer, dew point hygrometer, medical osmometer, laser anemometer, counting integrator, hydraulic press, ultrasonic anemometer, sample changer psychrometer, nanovolt meter, root analysis system, dew point water activity meter, sunfleck ceptometer, thermal property probes, grain flow sensor, weighing chain segment, and the water content reflectometer and Echo dielectric aquameter for estimating volumetric water content of soils.
In addition to playing a lead role in developing this instrumentation, Dr. Campbell also played a critical role in the establishment and success of a number of commercial companies that have marketed and supported application of these instruments worldwide. These include Wescor, Campbell Scientific (USA and UK), Decagon Devices, Harvest Master, and Juniper Systems. Other companies that have benefited from Dr. Campbell's input have included LI-COR, Delta T Devices, and Hansatech. While the instruments and companies have delivered benefits to thousands of scientists and technologists worldwide, there are also broader benefits that have resulted from Dr Campbell's efforts in these areas. These include employment of hundreds of people worldwide and spin-off benefits to a range of other private companies and state and federal organizations. Given the breadth and depth of influence, the real benefits and impacts of the intellect, ingenuity, and drive of Dr. Campbell will probably always be underestimated.
Dr. Campbell's professional accomplishments have been recognized in many ways, including through his appointments as Fellow of SSSA and Fellow of ASA.
The presentations made at the 2001 symposium and this series of papers cover a wide range of topics. They nevertheless all relate directly to areas of work in which Dr. Campbell has made significant contributions. For the purposes of this publication, the papers have been ordered to reflect a transition from the soil to various issues relating to plant canopies (such as xylem hydraulics, sap flow, and canopy exchange), to ongoing challenges and opportunities in instrumentation, and finally to a regional view of the soil–plant–atmosphere continuum.
The first paper, by Peter Ross (1352–1361), presents novel approaches to providing fast and robust measurements relating to the transport of water and solutes in soils using the Richards' and advection–dispersion equations. The speed and robustness of these approaches should help improve large-scale stochastic modeling of a range of hydrological processes.
The paper by John Sperry et al. (1362–1370) highlights the need to improve our understanding and representation of xylem hydraulics in models of crop water use to achieve a mechanistic link between soil water availability and canopy water use.
The first paper by Steve Green et al. (1371–1379) reviews the theory underpinning both the compensation and T-max heat pulse methods for measuring sap flow. They use a two-dimensional model of heat and water flow to derive a series of correction factors that account for the probe thermal properties and flow blockage due to wounding by the probes and show how these corrections improve the accuracy of measurements of transpiration.
The second paper by Steve Green et al. (1380–1387) reports on a field test of a three-dimensional model of light interception and transpiration. The results show good agreement between measured and modeled data and indicate that light interception is influenced mostly by changes in leaf area and leaf optical properties and that transpiration is influenced mostly by changes in leaf area and leaf conductance.
In his paper, Gaylon Campbell (1388–1392) provides another example of his ability to tackle a complex problem (canopy transport) and develop a simple and elegant model of the key processes. He does this by deriving transformations to minimize the interactions (the coupling) between latent and sensible heat fluxes in the canopy and using the transformations to produce an equivalent, but simple, one-layer canopy transport model that can be used as the upper-boundary condition for soil heat and water flow models.
The paper by Jay Ham and Jim Heilman (1393–1403) addresses the ongoing challenge to obtain accurate measurements of CO2 fluxes using open-path eddy covariance. The authors provide an analysis of the impacts of density corrections and adjustments for energy balance closure on daily C balances and conclude that additional research and improvements in the methodology are needed before eddy covariance may be routinely applied in agronomic research.
John Baker's paper (1404–1407) reminds us that the frontiers in any science, including that of soil and environmental physics, are generally defined by measurement limitations. He highlights some of the seminal contributions that Gaylon Campbell has made to the measurement and understanding of surface–atmosphere exchange, soil water and solute fluxes, and plant water status but stresses that we have a long way to go before we have routine, accurate measurement methods in these and related areas.
The final paper, by Martha Anderson et al. (1408–1423), tackles the difficult issue of scale when coupling soil–plant–atmosphere systems. It addresses upscaling (extracting information from models of isolated leaves and plants to predict behavior of landscapes) and downscaling (extracting information from regional models to predict landscape and field behavior). It highlights in particular a multiscale modeling framework currently being used to identify scale-relevant land–atmosphere feedbacks and to represent surface heterogeneity within regional modeling schemes.
I commend this series of papers to you and hope that it recognizes, at least in some small way, the many seminal contributions Professor Gaylon S. Campbell has made to the science of soil and environmental physics and the wide-ranging and beneficial impacts he has had on the minds and lives of people worldwide.
|
 |
REFERENCES |
|---|
 TOP REFERENCES |
|---|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| The SCI Journals | Crop Science | Vadose Zone Journal | |||
| Journal of Natural Resources and Life Sciences Education |
Soil Science Society of America Journal | ||||
| Journal of Plant Registrations | Journal of Environmental Quality |
The Plant Genome | |||
