An example 



of an ecological unit follows: 



Soil 



Vegetation 



Landform descriptor 



Order: Mollisol 



Class: Herbaceous 

 vegetation 





Suborder: Aquoll 



Subclass: Medium- 

 tall grassland 





Great Group: 

 Natraquoll 



Group: Without 

 woody layer 





Subgroup: Typic 

 Natraquoll 



Formation: Mainly 

 sodgrass 





Family: Fine, 

 montmorillonitic, 

 frigid typic 

 Natraquoll 







Series: Heil 



Series: Agropyron 

 smithii (Western 

 wheatgrass) 







Association: 

 Agropyron 

 smithii/spartina 

 pectinata 

 (Western wheat- 

 grass/Prairie 

 cordgrass) 



Shallow closed 

 depression 



Generally, elements are integrated to form ecological 

 units by merging classes or attributes from the respective 

 parent systems. A process using only the soil and vegeta- 

 tion elements is illustrated below. 



The name of the above unit would be Agropyron smithii/ 

 Spartina /?ecf/>?ata-Heil-shallow closed depression eco- 

 logical unit. It would be described as a western wheat- 

 grass/prairie cordgrass association occurring in shallow 

 closed depressions, with deep, fine textured, moderately 

 alkaline soils with a thick, dark gray surface layer. Water 

 occurs at or near the surface in the spring and summer. 

 This description characterizes the ecological unit so it 

 may be recognized whenever similar conditions exist. 

 More detailed information about the units, such as pro- 

 duction, amount and kind of vegetation, size of the area, 

 depth of the soil, and other features required for manage- 

 ment decisions may be obtained through review of exist- 

 ing information, including published soil surveys or other 

 information, or through additional inventories. 



A description of a broader unit, within which the 

 above unit would be included, can be provided at a more 

 general level. An example, using the above information, 

 would be sodgrass communities in seasonally ponded or 

 wet areas, receiving about 16 inches (400 mm) of precipi- 

 tation per year, mostly in the spring and summer. Soils 

 are formed in alluvium and are calcareous throughout; 

 groundwater is shallow during most of the year, and cap- 

 illary rise of water results in salt concentrations near the 

 surface. This description characterizes an ecological unit 

 at the formation level of vegetation. Inventory would be 

 needed to obtain more detailed information about the 

 unit. 







Vegetation Classes 





s, 



v, v 2 





s,v, 





s 2 





Soil 



S3 





Classes 



— 





v, 



SjVi 



With the vegetation classes identified as V, V s and 



the soil classes identified as S, S:, the resultant 



classes (Vj S:) have key attributes of V; and S- and the eco- 

 logical unit is formed. Thus, a new set of classes are rec- 

 ognized that defines an ecological unit rather than just 

 parts of that unit. In application, the vegetation and soil 

 integrations may be at any level of their parent systems. 

 Additional integration is often needed within an 

 overall framework to assist in land partitioning for cer- 

 tain objectives. The individual element and ecological 

 unit classification provides a basic framework for dealing 

 with grasslands, shrublands, and forestlands, with their 

 associated features of soil and topography as entities in 

 themselves, to determine features such as grassland pro- 

 duction, tree volumes, or opportunities to increase spe- 

 cific standing crop biomass. Spatial organization of 

 ecological units provides an adition to the classification 

 framework to help interpret cause and effect relation- 

 ships and make analyses of interdependence of such 

 values as wildlife, fisheries, and recreation opportunities. 

 Also, analyses of juxtaposition and interspersion may be 

 made to determine interrelationships among the relatively 

 pure ecological units to management decisions. For ex- 

 ample, few wildlife species or species groups obtain total 

 life requirements from only the forest or grassland. Con- 

 sequently, simultaneous evaluations of both are required 

 to understand the animal/habitat relationships. Also, 

 activities such as timber harvesting, livestock grazing, or 

 road building in a watershed composed of a complex of 

 ecological units, affect water in the stream and fisheries. 

 Therefore, analysis of activities in the whole watershed is 

 needed to assess their impacts on water quality and 

 quantity. 



15 



