-
A LIDAR‐DERIVED EVALUATION OF WATERSHED‐SCALE LARGE WOODY DEBRIS SOURCES AND RECRUITMENT MECHANISMS: COASTAL MAINE, USA
-
In‐channel large woody debris (LWD) promotes quality aquatic habitat through sediment sorting, pool scouring and in‐stream nutrient retention and transport. LWD recruitment occurs by numerous ecological and geomorphic mechanisms including channel migration, mass wasting and natural tree fall, yet LWD sourcing on the watershed scale remains poorly constrained. We developed a rapid and spatially extensive method for using light detection and ranging data to do the following: (i) estimate tree height and recruitable tree abundance throughout a watershed; (ii) determine the likelihood for the stream to recruit channel‐spanning trees at reach scales and assess whether mass wasting or channel migration is a dominant recruitment mechanism; and (iii) understand the contemporary and future distribution of LWD at a watershed scale. We utilized this method on the 78‐km‐long Narraguagus River in coastal Maine and found that potential channel‐spanning LWD composes approximately 6% of the valley area over the course of the river and is concentrated in spatially discrete reaches along the stream, with 5 km of the river valley accounting for 50% of the total potential LWD found in the system. We also determined that 83% of all potential LWD is located on valley sides, as opposed to 17% on floodplain and terrace surfaces. Approximately 3% of channel‐spanning vegetation along the river is located within one channel width of the stream. By examining topographic and morphologic variables (valley width, channel sinuosity, valley‐ side slope) over the length of the stream, we evaluated the dominant recruitment processes along the river and often found a spatial disconnect between the location of potential channel‐spanning LWD and recruitment mechanisms, which likely explains the low levels of LWD currently found in the system. This rapid method for identification of LWD sources is extendable to other basins and may prove valuable in locating future restoration projects aimed at increasing habitat quality through wood additions.
key words: large woody debris; lidar; river restoration; habitat
Located in
Resources
/
Climate Science Documents
-
Biotic Drivers of Stream Planform: Implications for Understanding the Past and Restoring the Future
-
Traditionally, stream channel planform has been viewed as a function of larger watershed and valley-scale physical variables, including valley slope, the amount of discharge, and sediment size and load. Biotic processes serve a crucial role in transforming channel planform among straight, braided, meandering, and anabranching styles by increasing stream-bank stability and the probability of avulsions, creating stable multithread (anabranching) channels, and affecting sedimentation dynamics. We review the role of riparian vegetation and channel-spanning obstructions—beaver dams and logjams—in altering channel–floodplain dynamics in the southern Rocky Mountains, and we present channel planform scenarios for combinations of vegetation and beaver populations or old-growth forest that control logjam formation. These conceptual models provide understanding of historical planform variability throughout the Holocene and outline the implications for stream restoration or management in broad, low-gradient headwater valleys, which are important for storing sediment, carbon, and nutrients and for supporting a diverse riparian community.
Keywords: stream planform, riparian vegetation, beaver, old-growth forest, restoration
Located in
Resources
/
Climate Science Documents
-
Challenges in the conservation, rehabilitation and recovery of native stream salmonid populations: beyond the 2010 Luarca symposium
-
– In May 2010, I chaired a session on challenges to salmonid conservation at the international symposium
‘Advances in the population ecology of stream salmonids’ in Luarca, Spain. I suggested that in addition to scientific challenges, a major challenge will be improving the links between ecologists, conservationists and policy makers. Because the Luarca symposium focused mainly on ecological research, little time was explicitly devoted to conservation. My objective in this paper is to further discuss the role of ecological research in informing salmonid conservation. I begin with a brief overview of research highlights from the symposium. I then use selected examples to show that ecological research has already contributed much towards informing salmonid conservation, but that ecologists will always be faced with limitations in their predictive ability. I suggest that conservation will need to move forward regardless of these limitations, and I call attention to some recent efforts wherein ecological research has played a crucial role. I conclude that ecologists should take urgent action to ensure that their results are availableto inform resource managers, conservation organisations and policy makers regarding past losses and present threats to native, locally-adapted salmonid stocks.
Located in
Resources
/
Climate Science Documents
-
Channel, Bank, & Riparian Restoration to Improve Habitat and Water Quality in Kings River, AR
-
The natural course and riparian corridor of the Kings River have been significantly modified by various landowners over several decades, leading to channel instability and decreased habitat and water quality. The Nature Conservancy (TNC) purchased a preserve on the Kings River that includes nine miles of river. To protect and restore river and riparian habitat, TNC has created a stream channel and floodplain restoration project along 0.5 miles of the river.
Located in
Resources
/
Whitewater to Bluewater W2B
-
Chipola River Watershed Restoration Listed Mussels and Black Bass Initiative
-
A Chipola River watershed partnership between the U.S. Fish and Wildlife Service (Service) and Florida Fish and Wildlife Conservation Commission (FWC) have been initiated since 2006. The purpose was to develop and lead a research-based platform for environmental restoration and conservation. The Service, along with FWC, West Florida RC&D; Council and others developed a Chipola River Watershed Management Plan (CRWMP) to achieve management and conservation of fish and wildlife resources. This proposal is for the next steps toward management activities under the CRWMP.
Located in
Resources
/
Whitewater to Bluewater W2B
-
Copper Creek In-Stream Habitat Restoration Project
-
This project improved riparian zones, water quality, appropriate sediment flows and restoring physical habitat for multiple listed aquatic species in the Copper Creek watershed, within the Upper Tennessee River Basin.
Located in
Resources
/
Whitewater to Bluewater W2B
-
Copper Creek In-Stream Habitat Restoration Project
-
This project improved riparian zones, water quality, appropriate sediment flows and restoring physical habitat for multiple listed aquatic species in the Copper Creek watershed, within the Upper Tennessee River Basin. (Photo: The low water bridge that was removed and replaced with a new bridge that spans the river. )
Located in
Projects
/
SARP
-
Crabtree Swamp Habitat Restoration
-
The restoration of Crabtree Swamp is an innovative, "first of its kind" project, in which a previously channelized drainage basin is being returned to a blackwater hardwood swamp in which the floodplain is being recreated via earthmoving and replanting into functional habitat for fish, invertebrates and other wildlife. To match resources, the restoration project has been subdivided into 10 reaches.
Located in
Resources
/
Whitewater to Bluewater W2B
-
Develop Artificial Estuarine Habitats in SC to Increase Abundance of Recreationally-Important Fish
-
This project will develop artificial estuarine habitats to increase abundance of recreationally important fish within South Carolina.
Located in
Resources
/
Whitewater to Bluewater W2B
-
Distribution and characterization of in‐channel large wood in relation to geomorphic patterns on a low‐gradient river
-
A 177 river km georeferenced aerial survey of in‐channel large wood (LW) on the lower Roanoke River, NC was conducted to determine LW dynamics and distributions on an eastern USA low‐gradient large river. Results indicate a system with approximately 75% of the LW available for transport either as detached individual LW or as LW in log jams. There were approximately 55 individual LW per river km and another 59 pieces in log jams per river km. Individual LW is a product of bank erosion (73% is produced through erosion) and is isolated on the mid and upper banks at low flow. This LW does not appear to be important for either aquatic habitat or as a human risk. Log jams rest near or at water level making them a factor in bank complexity in an otherwise homogenous fine‐grained channel. A segmentation test was performed using LW frequency by river km to detect breaks in longitudinal distribution and to define homogeneous reaches of LW frequency. Homogeneous reaches were then analyzed to determine their relationship to bank height, channel width/depth, sinuosity, and gradient. Results show that log jams are a product of LW transport and occur more frequently in areas with high snag concentrations, low to intermediate bank heights, high sinuosity, high local LW recruitment rates, and narrow channel widths. The largest concentration of log jams (21.5 log jams/km) occurs in an actively eroding reach. Log jam concentrations downstream of this reach are lower due to a loss of river competency as the channel reaches sea level and the concurrent development of unvegetated mudflats separating the active channel from the floodplain forest. Substantial LW transport occurs on this low‐gradient, dam‐regulated large river; this study, paired with future research on transport mechanisms should provide resource managers and policymakers with options to better manage aquatic habitat while mitigating possible negative impacts to human interests
Located in
Resources
/
Climate Science Documents
