Physiological Ecology of Water Balance in Terrestrial Plants

by

Paul Barnes

• LAST REVIEWED: 04 January 2022
• LAST MODIFIED: 31 July 2019
• DOI: 10.1093/obo/9780199830060-0221

Introduction

Water is one of the most important environmental factors limiting the growth and production of terrestrial (land) plants. Although water is essential for a number of metabolic, physiological, and growth processes in plants (e.g., turgor maintenance and cell elongation, transport of nutrients and carbohydrates, energy dissipation, and photosynthetic electron transport), most plants consume and store very little water. The vast majority of water that is absorbed by a plant’s root system moves through its vascular tissue (xylem) and is lost to the atmosphere as water vapor in the process of transpiration. It is the net difference between this uptake and loss that determines the overall water balance of a plant. Plant species vary considerably in their abilities to capture soil water, how efficiently they utilize water, and their tolerances to desiccation, and this variation has a number of ecological consequences at scales from individual plants to ecosystems, landscapes, and the globe. Historically, plant physiological ecologists studied the water relations of plant cells, tissues, and organs to better understand the molecular, physiological, anatomical, and morphological mechanisms by which plants have adapted to survive drought and cope with limited water availability. For obvious reasons, these studies were concentrated on plants in extreme moisture-limited ecosystems such as deserts, but water relations research was also conducted in other systems that experience intermittent and seasonal drought. Over time, physiological ecologists began to study the water relationships between plants and soil, examined how plants interacted with one another for this resource, and explored how temporal and spatial variation in soil moisture availability influences species distributions and community organization. The study of ecohydrology is a relatively recent interdisciplinary discipline that seeks to study how hydrological processes influence biological communities and also how these systems, in turn, influence the water cycle. Plant physiological ecologists play an important role in ecohydrology research by studying how water influences ecosystem function and quantifying the role of vegetation in influencing hydrological processes. Finally, plant physiological ecologists are increasingly interested in how changes in water availability driven by climate change affects plants and terrestrial ecosystems, how global change factors (e.g., atmospheric CO₂) influence plant water relations, and what role vegetation itself plays in influencing the atmosphere and climate. Below are selected sources that highlight the full breadth of the study of the physiological ecology of water balance in plants. An emphasis is placed on terrestrial plants in non-hydric (i.e., non-flooded) environments and sources include a number of classical as well as contemporary publications.

General Overviews

There are a number of textbooks in plant physiology and plant physiological ecology that address the fundamentals of plant and soil water relations. These sources largely vary in whether they take a physiological or an ecological emphasis, how quantitative they treat the subject, and to what degree they examine processes at scales above the individual plant (i.e., canopies and vegetation). One of the best introductions to plant and soil water relations, from a physiological perspective, is that of Kramer and Boyer 1995. There are a number of textbooks on plant physiological ecology that cover plant water relations from more of an ecological perspective. Of these, Lambers, et al. 1998 is perhaps the most comprehensive, whereas Jones 2013 and Nobel 1999 are the most quantitative. Chabot and Mooney 1985 take a biome-based approach to the subject. Larcher 2003 focuses on stress physiology and is therefore a more traditional comparative physiology approach. By comparison, Chapin, et al. 2002 examines plants and water from an ecosystem and hydrological perspective. The Physiological Plant Ecology series of the edited volume Lange, et al. 1982 remains a solid source for these and other topics not often covered in many textbooks. The best sources for methods are Pearcy, et al. 1989 for whole plant physiological ecology and Sala, et al. 2000 for ecosystem science.

• Chabot, B. F., and H. A. Mooney, eds. 1985. Physiological ecology of North American plant communities. Dordrecht, The Netherlands: Springer.

  A biome-based synthesis that examines ecophysiological processes, including water relations, relevant to the major plant community types of North America.

• Chapin, F. S., III, P. A. Matson, and H. A. Mooney. 2002. Principles of terrestrial ecosystem ecology. New York: Springer-Verlag.

  An introductory text in ecosystem science that includes sections addressing the role of plants and vegetation in water and energy balance in terrestrial ecosystems.

• Jones, H. G. 2013. Plants and microclimate: A quantitative approach to environmental plant physiology. 3d ed. Cambridge, UK: Cambridge Univ. Press.

  DOI: 10.1017/CBO9780511845727

  A quantitative approach to plant water relations and gas exchange; an excellent resource for modelers.

• Kramer, P. J., and J. S. Boyer. 1995. Water relations of plants and soils. Academic Press.

  Emphasizes the physiological aspects of water relations from cells to whole plants, including soil water relations. Some attention is given to environmental and agricultural topics and a brief history of research developments in the field is provided.

• Lambers, H., F. S. Chapin III, and T. L. Pons. 1998. Plant physiological ecology. New York: Springer.

  DOI: 10.1007/978-1-4757-2855-2

  A comprehensive treatment of the subject including plant and soil-water relations from an ecological perspective. Includes sections on adaptations to drought and scaling water use from leaves to canopies and vegetation.

• Lange, O. L., P. S. Nobel, C. B. Osmond, and H. Ziegler. 1982. Physiological plant ecology II: Water relations and carbon assimilation. Vol. 12. Berlin and Heidelberg, Germany: Springer-Verlag.

  DOI: 10.1007/978-3-642-68150-9

  A solid source for information on a range of topics including modeling of water loss and photosynthesis, water and seed germination, responses to flooding, and other topics that are often not covered in standard textbooks.

• Larcher, W. 2003. Physiological plant ecology. Berlin and Heidelberg, Germany: Springer-Verlag.

  DOI: 10.1007/978-3-662-05214-3

  Provides background information that is similar to other sources but emphasizes the comparative stress physiology of plant functional groups.

• Nobel, P. S. 1999. Physicochemical and environmental plant physiology. San Diego, CA: Academic Press.

  Examines the environmental aspects of water in plants with a strong quantitative and biophysical perspective.

• Pearcy, R. W., J. R. Ehleringer, H. A. Mooney, and P. W. Rundel, eds. 1989. Plant physiological ecology: Field methods and instrumentation. New York: Chapman and Hall.

  One of the best sources for information on the methods and instrumentation used in field water relations research, and related topics.

• Sala, O. E., R. B. Jackson, H. A. Mooney, and R. W. Howarth, eds. 2000. Methods in ecosystem science. New York: Springer.

  An excellent source for methodology in ecosystem science, including the use of stable isotopes and measurement of water fluxes in whole plants and canopies.