Macroinvertebrates
Poff (1997) presents a hierarchical framework tool used to understand and predict species within a system based on environmental constraints at different scales. Poff’s framework outlines scales at which the environment drives the assemblage, in this case macroinvertebrates. The scales discussed include watershed/basin scale, valley/reach scale, the channel-unit scale and the microhabitat scale. The scale most relevant to our outline of process domains is the valley or reach scale, which highlights the impacts of lithology, slope, valley bottom morphology, confinement, and riparian conditions on assemblages. Poff’s framework tool could be used to better understand how macroinvertebrate populations in the Front Range are influenced by surrounding environmental conditions.
The purpose of the above discussions about macroinvertebrates has been to determine what influences macroinvertebrate populations in the stream systems of the Colorado Front Range. We conclude that the main drivers of invertebrate assemblages in the Front Range are the following: flow regime, shading amount, stream gradient, land use (and associated heavy metals, timber harvests, nutrient concentrations, sediment loads, and changes in grain size and bedform), and how nutrient retention may vary in different disturbance regimes and between process domains. Additionally, human impacts to stream systems in the Front Range cannot be ignored in this discussion. Human alterations of the landscape, both prehistorically, historically, and at present, have impacted macroinvertebrate assemblages in these stream systems.
With respect to the process domain schematic, macroinvertebrates occur throughout the stream systems of the Front Range and in all process domains. However, the influences outlined above will impact certain functional groups in different ways and will thus impact levels found in each domain. For example, shading amount will limit primary production, thus limiting grazers.
Vertebrates
The question resulting from the vertebrate discussion outlined on the page describing aquatic organisms is how these species fit into the process domain outline of stream systems in the Colorado Front Range.
The literature on vertebrate species of the Front Range is limited to discussions of species ranges relative to elevation ranges. Vincent and Miller (1969) note that fish habitats in the headwaters of the South Platte are not limited by geomorphic barriers. They thus propose temperature, as related to elevation, as a control on species distribution. Below is a table summarizing species common in the Front Range and their historic and present elevation distributions.
Table summarized from Vincent and Miller (1969) and Martin et al. (1994)
Based on the lack of classification of fish in the Front Range literature by geomorphic setting or process domain, we believe that it is safe to assume that species vary primarily in relation to elevation. Based on the elevation distributions above, we then assume that species are present in any perennial flow process domain within their respective elevation range.