Author : Paul Joseph Soltesz
Publisher :
ISBN 13 :
Total Pages : 141 pages
Book Rating : 4.:/5 (9 download)
Book Synopsis Large Wood Dynamics in Central Appalachian Hemlock Headwater Ravines by : Paul Joseph Soltesz
Download or read book Large Wood Dynamics in Central Appalachian Hemlock Headwater Ravines written by Paul Joseph Soltesz and published by . This book was released on 2014 with total page 141 pages. Available in PDF, EPUB and Kindle. Book excerpt: Large wood (LW) is a critical component of forested mountain headwater streams that significantly contributes to geomorphic and ecological processes including channel structure, sediment and nutrient dynamics, flow regimes, and habitat formation for fish and aquatic macroinvertebrates. The character of LW is a function of valley recruitment processes that influence LW entering the channel and instream retention processes that influence LW transport through the channel reach. In the central Appalachian Mountains, US, LW dynamics in eastern hemlock-dominated ravines may change due to the invasive insect Hemlock Wooly Adelgid (HWA). However, quantitative LW studies are lacking for this region, yet are necessary for effective management of ecosystem health and processes regarding projected HWA-associated change. We examined LW dynamics across central Appalachian headwater streams (drainage area 20 km2) to identify: 1) the current state of LW loading, 2) the environmental factors that influence LW loading, 3) potential signs of HWA impact on LW dynamics, and 4) functional grouping patterns of LW pieces in these systems. A field study was conducted in 24 streams across southeastern Ohio, West Virginia, and western Virginia that represent a gradient of HWA infestation from 0 (uninfested) to 23 years. At each site, channel morphology, in-stream wood load, and wood recruitment potential were recorded. Mean wood density was 36 pieces/100m ± 21 and mean wood volume was 5.6 m3/100m ± 3.5. Most pieces were less than bankfull width suggesting high transportability, but large pieces (10m) contributed significantly to wood volume, jam formation (>3 LW pieces touching), and geomorphic function. Central Appalachian LW loading was on the lower end of mountain headwater streams reported elsewhere in the world, although comparable to similar stream types in the northeastern US. A mixture of recruitment and retention processes influenced LW dynamics, but channel retention processes better explained LW jam dynamics. Specifically, higher LW load was associated with lower forest basal area, smaller channel dimensions, and lower hydraulic driving forces, which is consistent with other studies. We did not detect a significant influence of HWA infestation even in moderately advanced infestation (e.g., ~20 years) on LW load, which may reflect a lag period between tree mortality, toppling, and LW load. Pieces clustered in three functional groups of: 1) larger, stable pieces that store sediment, stabilize the bank, and create pools, 2) relatively stable pieces that deflect flow and dissipate energy, and 3) smaller pieces associated with flow deflection and energy dissipation composed of mixed stability. This study provides quantitative information on LW dynamics in the central Appalachian region prior to expected environmental change associated with HWA. This information may aid land managers in regulating LW loads and environmental processes influenced by LW including sediment dynamics, aquatic habitat creation, and flow regimes.
