I) 



many possible relationships resulting from retrogression." This acknowledges succession and 

 the complexity of possible community types due to site change. To help emphasize that these 

 changes are the rule rather than the exception in riparian environments, we have introduced 

 the term "site progression" which denotes major changes in the site. Site progression is not 

 intended to diminish or replace any of the concepts of community succession; rather, it is a 

 term to help those less familiar with the dynamics of riparian systems focus on the expecta- 

 tion for site change. Generally, site progression can be thought of as a site change which may 

 result in a different potential natural community for the site. An example of this would be a 

 site located on a flood plain consisting of fine substrate that imdergoes extreme incisement, 

 eventually changing the site from a moist to a very dry environment. The site progression is 

 also seen in the succession of a gravel bar to an eventual nonflooded, cottonwood dominated 

 terrace. In Figure 1, site progression would be seen as a site change between columns of the 

 site types (riparian and/or habitat types) or cones. Figure 2 is a representation of site progres- 

 sion. 



Additionally, for a classification or site description to be very useful to management it should 

 recognize and discuss site succession, site progression, and site potential and what makes 

 them occur, thereby offering managers a means for rational management. 



"It is important to remember tiiat not all the landscape is at its potential. In 

 fact, only relatively small amounts are. However, by knowing what the 

 potential is, a manager can understand the processes and how to best manage 

 for them." (Paul Hansen, pers. commim.) 



We refer to this as an understanding of "process pathways." Once the process pathways are 

 recognized, management can better understand cause and effect relationships. 



IV. Riparian Health and Ecological Site Status 



Riparian healtii has been related to ecological site status in recent years. This is a dangerous 

 and functionally impossible view of how riparian systems operate. The following paragraphs 

 discuss the concepts of ecological site status and riparian healUi in hopes that a more clear 

 understanding of riparian system function will result 



Ecological site status refers to the position on a successional pathway that a particular site 

 may be in. For example, a newly vegetated gravel bar may be covered with pioneering plant 

 species such as cottonwood and willow. This site is said to be in early serai stage because it 

 is at the beginning of its successional pathway. It is also in a frequentiy flooded state, 

 allowing deposition interspersed with scoured flow patterns. As vegetation succession occurs 

 and aggradation continues, young cottonwood trees may dominate an understory adapted to 

 frequent or occasional flooding. As long as the relationship with flooding frequency and 

 timing is maintained to allow cottonwood regeneration (not allowing the young cottonwoods 

 to effectively trap sediments or become older), vegetation succession cannot proceed and 

 could be considered in an advanced stage for that particular set of physical circumstances. 

 However, if aggradation has occurred far enough (which may be directiy related to the 

 presence of the cottonwoods) or stream channel migration relegates the site to a rarely 

 flooded or nonflooded state, the cottonwoods may persist to a decadent stand. Regardless of 

 the longevity of the cottonwoods at this location, site progression has evolved to a new state 

 allowing vegetation succession to proceed to a new potential dominated by ash or peitiaps 



