Pedodiversity
Encyclopedia
Pedodiversity can be generally defined as the variation of soil
properties (usually characterised by soil classes) within an area.
Pedodiversity studies were first started by analyzing soil series–area relationships (Beckett and Bie, 1978). According to Guo et al. (2003) the term pedodiversity was developed by McBratney (1992) who discussed landscape preservation strategies based on pedodiversity. Recently, examinations of pedodiversity using indices commonly used to characterize bio-diversity have been made
(Ibánez et al., 1995). Ibáñez et al. (1995) first introduced ecological diversity indices as measures of pedodiversity. They include
Species richness
, abundance
, and Shannon index
. Richness is the number of different soil types, which is the number of soil classes at particular level in a taxonomic system. Abundance is defined as the distribution of the number of soil individuals.
Just as biologists and ecologists talk about biodiversity
, geologists on geodiversity
, soil scientists can talk about pedodiversity. Pedodiversity has some overlap with biodiversity
as soil contains organisms. Pedodiversity is a measure of soil variation, and pedodiversity is a function of soil formation.
Pedodiversity can be thought as a way to preserve, or even reconstruct, the soil cover. Just as biologists argue that organisms need to be maintained, soil scientists can argue that preserving soil will maintain organisms as well as other unique soil materials equally crucial in insuring our future wellbeing. In areas which have been degraded it will become important to reconstruct the variation. A quantitative knowledge of natural pedodiversity will ease the task of the person who attempts to rebuild quasi-natural soil systems.
Soil scientists have pragmatically adapted the concept of biodiversity
and used diversity index
such as Shannon index
using taxa from well-accepted international soil classification
systems.
Jonathan Phillips showed that in eastern North Carolina
intrinsic variability within homogeneous landscape units is more important in determining the total pedodiversity of the study area than is the extrinsic variability associated with measurable differences in topography, parent material, and vegetation/land use.
In another study, they found that soils in Ouachita Mountains
of Arkansas
vary considerably within small more-or-less homogeneous areas, and richness–area analysis shows that the overall pattern of pedodiversity is dominated by local, intrinsic (within-plot) variability as opposed to between-plot variability. This is consistent with variation controlled mainly by individual trees and local lithological variations. Given the criteria used to distinguish among soil types, biomechanical as opposed to chemical and hydrological effects of trees are indicated. Results also suggest divergent evolution whereby the pedologic effects of trees are large and long-lived relative to the magnitude of the initial effects and lifespan of the plants.
Guo et al. recently explored quantitative aspects of pedodiversity for the USA based on the State Soil Geographic database (STATSGO). They found that the West USDA-NRCS geographical region has the highest soil taxa richness, followed by the Northern Plains. The South Central region has the highest taxa evenness, while taxa evenness in the West region is the lowest. The West or the South Central regions have the highest overall soil diversity in the four highest taxonomic categories, while the West or Northern Plains regions have the highest diversity in the two lowest taxonomic levels. The high diversity index in the West region results from high taxa richness while the high diversity index in the South Central region results from an evenness of taxa. As the taxonomic level decreases, the pattern of taxa abundance approaches a lognormal distribution. One of the key findings of this research is that at lower levels of soil taxonomic divisions (especially the series level), soil taxa increase continuously with increasing area, indicating considerable soil endemism in the USA (and likely around the world), a key consideration in conservation
and preservation
planning.
However conventional diversity measures, only measure the relative abundance of soil classes, and there is no information on the taxonomic similarity or differences between soil classes. New measures of pedodiversity, such as the mean soil taxonomic distance, which considers both information on the relative abundance and the taxonomic differences between soil classes have been developed and shown to be a better measure.
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...
properties (usually characterised by soil classes) within an area.
Pedodiversity studies were first started by analyzing soil series–area relationships (Beckett and Bie, 1978). According to Guo et al. (2003) the term pedodiversity was developed by McBratney (1992) who discussed landscape preservation strategies based on pedodiversity. Recently, examinations of pedodiversity using indices commonly used to characterize bio-diversity have been made
(Ibánez et al., 1995). Ibáñez et al. (1995) first introduced ecological diversity indices as measures of pedodiversity. They include
Species richness
Species richness
Species richness is the number of different species in a given area. It is represented in equation form as S.Species richness is the fundamental unit in which to assess the homogeneity of an environment. Typically, species richness is used in conservation studies to determine the sensitivity of...
, abundance
Abundance
Abundance may refer to:In science and technology:* Abundance , the opposite of scarcities* Abundance , growing food with plentiful resources that will not run out -- sunshine, CO2, and waste or brine water....
, and Shannon index
Shannon index
The Shannon index, sometimes referred to as the Shannon-Wiener Index or the Shannon-Weaver Index, is one of several diversity indices used to measure diversity in categorical data. It is simply the Information entropy of the distribution, treating species as symbols and their relative population...
. Richness is the number of different soil types, which is the number of soil classes at particular level in a taxonomic system. Abundance is defined as the distribution of the number of soil individuals.
Just as biologists and ecologists talk about biodiversity
Biodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...
, geologists on geodiversity
Geodiversity
Geodiversity is the variety of earth materials, forms and processes that constitute and shape the Earth, either the whole or a specific part of it. Relevant materials include minerals, rocks, sediments, fossils, soils and water. Forms may comprise folds, faults, landforms and other expressions of...
, soil scientists can talk about pedodiversity. Pedodiversity has some overlap with biodiversity
Biodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...
as soil contains organisms. Pedodiversity is a measure of soil variation, and pedodiversity is a function of soil formation.
Pedodiversity can be thought as a way to preserve, or even reconstruct, the soil cover. Just as biologists argue that organisms need to be maintained, soil scientists can argue that preserving soil will maintain organisms as well as other unique soil materials equally crucial in insuring our future wellbeing. In areas which have been degraded it will become important to reconstruct the variation. A quantitative knowledge of natural pedodiversity will ease the task of the person who attempts to rebuild quasi-natural soil systems.
Soil scientists have pragmatically adapted the concept of biodiversity
Biodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...
and used diversity index
Diversity index
A diversity index is a statistic which is intended to measure the local members of a set consisting of various types of objects. Diversity indices can be used in many fields of study to assess the diversity of any population in which each member belongs to a unique group, type or species...
such as Shannon index
Shannon index
The Shannon index, sometimes referred to as the Shannon-Wiener Index or the Shannon-Weaver Index, is one of several diversity indices used to measure diversity in categorical data. It is simply the Information entropy of the distribution, treating species as symbols and their relative population...
using taxa from well-accepted international soil classification
Soil classification
Soil classification deals with the systematic categorization of soils based on distinguishing characteristics as well as criteria that dictate choices in use.- Overview :...
systems.
Jonathan Phillips showed that in eastern North Carolina
North Carolina
North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...
intrinsic variability within homogeneous landscape units is more important in determining the total pedodiversity of the study area than is the extrinsic variability associated with measurable differences in topography, parent material, and vegetation/land use.
In another study, they found that soils in Ouachita Mountains
Ouachita Mountains
The Ouachita Mountains are a mountain range in west central Arkansas and southeastern Oklahoma. The range's subterranean roots may extend as far as central Texas, or beyond it to the current location of the Marathon Uplift. Along with the Ozark Mountains, the Ouachita Mountains form the U.S...
of Arkansas
Arkansas
Arkansas is a state located in the southern region of the United States. Its name is an Algonquian name of the Quapaw Indians. Arkansas shares borders with six states , and its eastern border is largely defined by the Mississippi River...
vary considerably within small more-or-less homogeneous areas, and richness–area analysis shows that the overall pattern of pedodiversity is dominated by local, intrinsic (within-plot) variability as opposed to between-plot variability. This is consistent with variation controlled mainly by individual trees and local lithological variations. Given the criteria used to distinguish among soil types, biomechanical as opposed to chemical and hydrological effects of trees are indicated. Results also suggest divergent evolution whereby the pedologic effects of trees are large and long-lived relative to the magnitude of the initial effects and lifespan of the plants.
Guo et al. recently explored quantitative aspects of pedodiversity for the USA based on the State Soil Geographic database (STATSGO). They found that the West USDA-NRCS geographical region has the highest soil taxa richness, followed by the Northern Plains. The South Central region has the highest taxa evenness, while taxa evenness in the West region is the lowest. The West or the South Central regions have the highest overall soil diversity in the four highest taxonomic categories, while the West or Northern Plains regions have the highest diversity in the two lowest taxonomic levels. The high diversity index in the West region results from high taxa richness while the high diversity index in the South Central region results from an evenness of taxa. As the taxonomic level decreases, the pattern of taxa abundance approaches a lognormal distribution. One of the key findings of this research is that at lower levels of soil taxonomic divisions (especially the series level), soil taxa increase continuously with increasing area, indicating considerable soil endemism in the USA (and likely around the world), a key consideration in conservation
Conservation ethic
Conservation is an ethic of resource use, allocation, and protection. Its primary focus is upon maintaining the health of the natural world: its, fisheries, habitats, and biological diversity. Secondary focus is on materials conservation and energy conservation, which are seen as important to...
and preservation
planning.
However conventional diversity measures, only measure the relative abundance of soil classes, and there is no information on the taxonomic similarity or differences between soil classes. New measures of pedodiversity, such as the mean soil taxonomic distance, which considers both information on the relative abundance and the taxonomic differences between soil classes have been developed and shown to be a better measure.