Application of Reference Data for Assessing and Restoring Headwater Ecosystems

Abstract

Attributes of 25 headwater streams and their associated wetlands were quantitatively sampled in the inner coastal plain of eastern North Carolina. Data from these sites were used to construct and test one functional assessment model (biogeochemical cycling) using the hydrogeomorphic (HGM) approach. Of the 25 sites sampled, 16 unaltered sites were used to establish standards against which field indicators could be compared (indexed). Nine altered sites were used to examine the sensitivity of the model to assess the types of alterations typically inflicted upon headwater ecosystems in eastern North Carolina: channelization, logging, construction of cross‐floodplain ditches to shunt water directly from uplands to the main stream channel, and conversion of stream floodplains and buffer zones to cropland. Of 30 field indicators measured that potentially could be used to model alterations to hydrologic regime and biomass stocks, we found six were robust in assessing conditions related to biogeochemical cycling. Hydrologic indicators used in the model included: (1) presence/absence of channelization, (2) presence/absence of cross‐floodplain ditches, and (3) a measure of buffer condition (using width and quality). Biomass indicators included: (4) total basal area of trees, (5) percent litter cover, and (6) volume of coarse woody debris. Our preliminary biogeochemical cycling model using these six variables was sensitive to alterations in nine altered sites and to a suite of hypothetical restorations of the most altered site. However, in order to improve accuracy of our preliminary model, it should be validated with studies designed to measure how alterations of various types and magnitudes affect biogeochemical processes.

Riparian Management: Alternative Paradigms and Implications for Wild Salmon

“…Process-based restoration is increasingly used in river management (Beechie & Bolton 1999, Rheinhardt et al 1999 and has been suggested to be relevant for Atlantic salmon rivers (Hendry et al 2003, Solomon et al 2003. In particular, the restoration of natural flow regimes has become an important goal in river conservation and restoration, with the expectation that restoring this key process will result in across-the-board improvements in habitat conditions for a wide range or riverine and riparian species (Poff et al 1997).…”

“…Nislow et al (1999) found that additions of LWD increased the amount of suitable habitat for age-0 salmon in rearing streams of the Connecticut River basin, USA. However, in the absence of appropriate reference systems (Rheinhardt et al 1999), we have little idea how the LWD levels achieved by these habitat manipulations relate to existing loads, or to future loads associated with specific riparian management strategies.…”

The Pace of Ecosystem Development of Constructed Spartina Alterniflora Marshes

“…To reduce this variability, each constructed marsh was paired with a nearby natural marsh of the same geomorphic position, salinity, and vegetation (S. alterniflora) to serve as a reference against which to measure ecosystem development of individual constructed marshes. Reference wetlands were used to set performance goals for created and restored wetlands (Aronson et al 1993a, b, 1995, Brinson and Rheinhardt 1996, Rheinhardt et al 1999, Whigham 1999). There was some concern, however, that using one or two references site does not capture the dynamic spatial variability among ecosystems of the same type (Pickett and Parker 1994).…”

Use of Ecohydraulic-Based Mesohabitat Classification and Fish Species Traits for Stream Restoration Design

“…IBI are broadly used in state biomonitoring programs to biologically assess environmental from poor water quality and habitat alteration [233][234][235][236]. It compresses categorical metrics for various fish traits (i.e., feeding and reproductive guilds, physiological tolerance) and other ecological indicators (i.e., richness and diversity) into a single score, in which the assessment score is compared with state reference condition scores [237]. The single IBI score is valuable as a screening tool to scope potential restoration projects, but is inadequate for design purposes.…”

“…By identifying the target species, traits and strategies can be summarized from available databases [113,245]. The suggested target community relies on professional judgement, which is supported by fish surveys from both local reference conditions and ecologically impaired streams, in addition to recolonization potential of different species [211,237,281,282]. After the target fish assemblage (community) has been identified, procedures utilizing species functional traits for restoration design are suggested as follow:…”