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Attribute Name: Ecological Site Name <br />Ecological Site Name <br />Rating Options <br />An ecological site name provides a general description of a particular ecological site. For example, "Loamy Upland" is the name of <br />a rangeland ecological site. An "ecological site" is the product of all the environmental factors responsible for ita development. It has <br />characteristic soils that have developed over time; a characteristic hydrology, particularly infiltration and runoff, that has developed <br />over time; and a characteristic plant community (kind and amount of vegetation). The vegetation, soils, and hydrology are all <br />interrelated. Each is influenced by the others and influences the development of the others. For example, the hydrology of the site <br />is influenced by development of the soil and plant community. The plant community on an ecological site is typified by an <br />association of species that differs from that of other ecological sites in the kind and /or proportion of species or in total production. <br />Descriptions of ecological sites are provided in the Field Office Technical Guide, which is available in local offices of the Natural <br />Resources Conservation Service. Descriptions of those displayed in this map and summary table may also be accessed through <br />the Ecological Site Assessment tab in Web Soil Survey. <br />Ecological sites and their respective unique set of characteristics are uniquely identified by the Ecological Site ID. The same <br />Ecological Site Name may be assigned to multiple Ecological Site IDs. If you wish to display a map of unique ecological sites, it is <br />recommended that you select the Ecological Site ID attribute from the choice list. <br />Class: NRCS Rangeland Site <br />Aggregation Method: Dominant Condition <br />Aggregation is the process by which a set of component attribute values is reduced to a single value to represent the map unit as a <br />whole. <br />A map unit is typically composed of one or more "components ". A component is either some type of soil or some nonsoil entity, <br />e.g., rock outcrop. The components in the map unit name represent the major soils within a map unit delineation. Minor <br />components make up the balance of the map unit. Great differences in soil properties can occur between map unit components <br />and within short distances. Minor components may be very different from the major components. Such differences could <br />significantly affect use and management of the map unit. Minor components may or may not be documented in the database. The <br />results of aggregation do not reflect the presence or absence of limitations of the components which are not listed in the database. <br />An on -site investigation is required to identify the location of individual map unit components. <br />For each of a map unit's components, a corresponding percent composition is recorded. A percent composition of 60 indicates that <br />the corresponding component typically makes up approximately 60% of the map unit. Percent composition is a critical factor in <br />some, but not all, aggregation methods. <br />For the attribute being aggregated, the first step of the aggregation process is to derive one attribute value for each of a map unit's <br />components. From this set of component attributes, the next step of the aggregation process derives a single value that represents <br />the map unit as a whole. Once a single value for each map unit is derived, a thematic map for soil map units can be generated. <br />Aggregation must be done because, on any soil map, map units are delineated but components are not.The aggregation method <br />"Dominant Condition" first groups like attribute values for the components in a map unit. For each group, percent composition is set <br />to the sum of the percent composition of all components participating in that group. These groups now represent "conditions" rather <br />than components. The attribute value associated with the group with the highest cumulative percent composition is returned. If <br />more than one group shares the highest cumulative percent composition, the corresponding "tie- break" rule determines which value <br />should be retumed. The "tie- break" rule indicates whether the lower or higher group value should be returned in the case of a <br />percent composition tie. <br />The result returned by this aggregation method represents the dominant condition throughout the map unit only when no tie has <br />occurred. <br />Tie -break Rule: Lower <br />The tie -break rule indicates which value should be selected from a set of multiple candidate values, or which value should be <br />selected in the event of a percent composition tie. <br />USDA Natural Resources <br />Conservation Service <br />Application Version: 5.2.0016 05/22/2012 <br />31 <br />Page 2 of 2 <br />