Regional reference sites: a method for assessing stream potentials

Abstract

Field assessments of impacted streams require a control or at least an unbiased estimate of attainable conditions. Control sites, such as upstream/downstream or wilderness sites, have proven inadequate for assessing attainable ecological conditions where the control streams differ naturally from the impacted streams to a considerable degree or where different disturbances exist than those being studied. Relatively undisturbed reference sites with watersheds in areas having the same land-surface form, soill potential natural vegetation, and land use as are predominant in large, relatively homogeneous regions are suggested as alternative control sites. These areas are considered typical of the region and therefore the sites also are considered typical of the region because their watersheds exhibit all the terrestrial variables that make that region a region. The logical basis for developing regional reference sites lies in the ability to group watersheds and common stream types into regions by integrating available maps of terrestrial variables that influence streams. Relatively undisturbed reference sites can be selected from typical areas of the regions and from transition zones where one or two of the terrestrial variables are not the predominant one(s) of the region. These reference sites are useful for estimating attainable conditions, for evaluating temporal and spatial changes in ecological integrity, for classifying attainable uses of streams, and for setting biological and environmental criteria.

Predicting assemblages and species richness of endemic fish in the upper Yangtze River

“…The upstream-downstream gradient is probably the most well-known large-scale pattern in stream fish assemblages, and correspondingly the flow regime, temperature, food availability and substrate conditions of the river also vary from upstream to downstream areas (Rahel and Hubert, 1991;Belliard et al, 1997;Marchetti and Moyle, 2001;Grubbs et al, 2007). Any change in expected assemblages could indicate environmental changes in the area (Hughes et al, 1986), which can provide a useful framework for studying and managing streams in different subgeographic areas of certain drainage basins (Céréghino et al, 2001;Oberdorff et al, 2001).…”

Theoretical predictions of observed to expected ratios in RIVPACS-type predictive model assessments of stream biological condition

“…Wright et al (1984) is the single most frequently cited paper that specifically addresses prediction of the local biota expected under different natural environmental conditions. Of the remaining 16 papers, 10 built on Wright et al (1984) and described aspects or refinements of the modeling approach, 3 explored aspects of the regionalization or typology approaches to setting reference expectations (Hughes et al 1986, Hawkins et al 2000a 1 ; Fig. 1), 1 treated the overall challenges in identifying reference conditions and applying them in a uniform manner (Stoddard et al 2006), 1 paper described how paleolimnological data could be used in lakes to identify historical conditions for individual sites (Dixit et al 1999), and 1 compared the performance of different types of biotic indices (Reynoldson et al 1997; Fig.…”

“…Three of the 18 influential papers identified in Table 3 were published in J-NABS, but we identified 5 other J-NABS papers that either have influenced reference-condition ideas or that we think probably will do so in the future. Barbour et al (1996) built on the pioneering paper of Hughes et al (1986) in describing the implementation of a regionalization approach for setting biological expectations. Eleven years after Hughes et al (1986), Reynoldson et al (1997) described the first rigorous evaluation of the performance of 2 different index types (both of which depend on comparison with reference conditions).…”

“…Barbour et al (1996) built on the pioneering paper of Hughes et al (1986) in describing the implementation of a regionalization approach for setting biological expectations. Eleven years after Hughes et al (1986), Reynoldson et al (1997) described the first rigorous evaluation of the performance of 2 different index types (both of which depend on comparison with reference conditions). Three years later, Hawkins et al (2000a) synthesized the results of several papers published in a special issue of J-NABS on landscape classification (volume 19, issue 3) that evaluated how well regionalizations and typologies accounted for natural biological variation among streams.…”

“…Landscape regionalizations.-In an effort to produce ecological assessments broadly based on the design elements of control and replication, Hughes et al (1986) advocated use of a regional reference site 2010] THE REFERENCE CONDITION 319 approach. In the regional reference site approach, some set of ecologically least-disturbed sites is identified within a relatively homogeneous terrestrial landscape (the controls), and the range of biotic attributes observed across this population of sites (the replicates) is used to estimate the range of natural variability that presumably would occur at an individual test site (a site of unknown condition) assuming it was in reference condition.…”