Limits...
Predicting maximum tree heights and other traits from allometric scaling and resource limitations.

Kempes CP, West GB, Crowell K, Girvan M - PLoS ONE (2011)

Bottom Line: In addition to predicting maximum tree height in an environment, our framework can be extended to predict how other tree traits, such as stomatal density, depend on these resource constraints.Furthermore, it offers predictions for the relationship between height and whole canopy albedo, which is important for understanding the Earth's radiative budget, a critical component of the climate system.Because our model focuses on dominant features, which are represented by a small set of mechanisms, it can be easily integrated into more complicated ecological or climate models.

View Article: PubMed Central - PubMed

Affiliation: Department of Earth Atmosphere and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America. ckempes@mit.edu

ABSTRACT
Terrestrial vegetation plays a central role in regulating the carbon and water cycles, and adjusting planetary albedo. As such, a clear understanding and accurate characterization of vegetation dynamics is critical to understanding and modeling the broader climate system. Maximum tree height is an important feature of forest vegetation because it is directly related to the overall scale of many ecological and environmental quantities and is an important indicator for understanding several properties of plant communities, including total standing biomass and resource use. We present a model that predicts local maximal tree height across the entire continental United States, in good agreement with data. The model combines scaling laws, which encode the average, base-line behavior of many tree characteristics, with energy budgets constrained by local resource limitations, such as precipitation, temperature and solar radiation. In addition to predicting maximum tree height in an environment, our framework can be extended to predict how other tree traits, such as stomatal density, depend on these resource constraints. Furthermore, it offers predictions for the relationship between height and whole canopy albedo, which is important for understanding the Earth's radiative budget, a critical component of the climate system. Because our model focuses on dominant features, which are represented by a small set of mechanisms, it can be easily integrated into more complicated ecological or climate models.

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Related in: MedlinePlus

The size-based resource gathering capabilities of a tree.The above-ground canopy is shown in green and the below-ground root mass in blue. The essential dimensions of the tree are indicated, where  is the radius of the canopy,  is the height of the canopy, and  is the radius of the root mass. Each of these features scales with height, , where  [41],  and . The number of leaves scales as  [28]. The scaling of the canopy features determines the collection of solar radiation and the heat exchange with the atmosphere, which can be used to solve for . The rate of moisture absorption, , is related to the scaling of the root system and incoming precipitation. Please see Supplement S1 for a more detailed treatment of these scaling relationships along with derivations for the associated tree physiology.
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pone-0020551-g003: The size-based resource gathering capabilities of a tree.The above-ground canopy is shown in green and the below-ground root mass in blue. The essential dimensions of the tree are indicated, where is the radius of the canopy, is the height of the canopy, and is the radius of the root mass. Each of these features scales with height, , where [41], and . The number of leaves scales as [28]. The scaling of the canopy features determines the collection of solar radiation and the heat exchange with the atmosphere, which can be used to solve for . The rate of moisture absorption, , is related to the scaling of the root system and incoming precipitation. Please see Supplement S1 for a more detailed treatment of these scaling relationships along with derivations for the associated tree physiology.

Mentions: We investigate the survival of an idealized tree with features determined primarily by its size. These features include the number of leaves, canopy shape and size, and the root mass, all of which interact with the environment via the tree's requirements for light and water (Fig. 3). Trees rely on their phloem and xylem for the internal distribution of nutrients and water. This circulation is a process of trees extracting moisture from the soil and making it available for evaporation, which drives the flow at the leaves. Accordingly, the rate of fluid flow through the vascular system has been a long-standing focus of environmental tree physiology [50], [51].


Predicting maximum tree heights and other traits from allometric scaling and resource limitations.

Kempes CP, West GB, Crowell K, Girvan M - PLoS ONE (2011)

The size-based resource gathering capabilities of a tree.The above-ground canopy is shown in green and the below-ground root mass in blue. The essential dimensions of the tree are indicated, where  is the radius of the canopy,  is the height of the canopy, and  is the radius of the root mass. Each of these features scales with height, , where  [41],  and . The number of leaves scales as  [28]. The scaling of the canopy features determines the collection of solar radiation and the heat exchange with the atmosphere, which can be used to solve for . The rate of moisture absorption, , is related to the scaling of the root system and incoming precipitation. Please see Supplement S1 for a more detailed treatment of these scaling relationships along with derivations for the associated tree physiology.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3113805&req=5

pone-0020551-g003: The size-based resource gathering capabilities of a tree.The above-ground canopy is shown in green and the below-ground root mass in blue. The essential dimensions of the tree are indicated, where is the radius of the canopy, is the height of the canopy, and is the radius of the root mass. Each of these features scales with height, , where [41], and . The number of leaves scales as [28]. The scaling of the canopy features determines the collection of solar radiation and the heat exchange with the atmosphere, which can be used to solve for . The rate of moisture absorption, , is related to the scaling of the root system and incoming precipitation. Please see Supplement S1 for a more detailed treatment of these scaling relationships along with derivations for the associated tree physiology.
Mentions: We investigate the survival of an idealized tree with features determined primarily by its size. These features include the number of leaves, canopy shape and size, and the root mass, all of which interact with the environment via the tree's requirements for light and water (Fig. 3). Trees rely on their phloem and xylem for the internal distribution of nutrients and water. This circulation is a process of trees extracting moisture from the soil and making it available for evaporation, which drives the flow at the leaves. Accordingly, the rate of fluid flow through the vascular system has been a long-standing focus of environmental tree physiology [50], [51].

Bottom Line: In addition to predicting maximum tree height in an environment, our framework can be extended to predict how other tree traits, such as stomatal density, depend on these resource constraints.Furthermore, it offers predictions for the relationship between height and whole canopy albedo, which is important for understanding the Earth's radiative budget, a critical component of the climate system.Because our model focuses on dominant features, which are represented by a small set of mechanisms, it can be easily integrated into more complicated ecological or climate models.

View Article: PubMed Central - PubMed

Affiliation: Department of Earth Atmosphere and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America. ckempes@mit.edu

ABSTRACT
Terrestrial vegetation plays a central role in regulating the carbon and water cycles, and adjusting planetary albedo. As such, a clear understanding and accurate characterization of vegetation dynamics is critical to understanding and modeling the broader climate system. Maximum tree height is an important feature of forest vegetation because it is directly related to the overall scale of many ecological and environmental quantities and is an important indicator for understanding several properties of plant communities, including total standing biomass and resource use. We present a model that predicts local maximal tree height across the entire continental United States, in good agreement with data. The model combines scaling laws, which encode the average, base-line behavior of many tree characteristics, with energy budgets constrained by local resource limitations, such as precipitation, temperature and solar radiation. In addition to predicting maximum tree height in an environment, our framework can be extended to predict how other tree traits, such as stomatal density, depend on these resource constraints. Furthermore, it offers predictions for the relationship between height and whole canopy albedo, which is important for understanding the Earth's radiative budget, a critical component of the climate system. Because our model focuses on dominant features, which are represented by a small set of mechanisms, it can be easily integrated into more complicated ecological or climate models.

Show MeSH
Related in: MedlinePlus