Published online by Cambridge University Press: 14 October 2009
The reduction of soil moisture content during droughts lowers the plant water potential and leads to a decrease in transpiration. This in turn causes a reduction of cell turgor and relative water content in plants, which brings about a sequence of damages of increasing seriousness. After a discussion of the links between soil moisture and plant conditions, the mean crossing properties of soil moisture, analytically derived in Chapter 3, are used here to define an index of plant water stress that combines the intensity, duration, and frequency of periods of soil-water deficit. Plant water stress is then studied under different climatic conditions, to analyze how the interplay between plant, soil, and environment impacts on vegetation conditions. The analysis of plant water stress presented in this chapter closely follows the paper by Porporato et al. (2001).
Soil-water deficit and plant water stress
From the level of the single plant to that of the entire ecosystem, the action of climate, soil, and vegetation is linked to plant response by two fundamental processes: the first one is centered around the soil moisture dynamics and controls the intensity and duration of the periods of soil-water deficit, while the second one regulates the impacts of water deficit on plant physiology (Figure 4.1).
Since plants get their water from the soil, many of the impacts of climate and soil are felt by plants through the filter of soil moisture dynamics. Effective drought conditions for plants are determined by soil moisture availability and not necessarily by precipitation scarcity (Stephenson, 1990, 1998).
To save this book to your Kindle, first ensure coreplatform@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Find out more about the Kindle Personal Document Service.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.