The characteristics of woody debris and sediment distribution in headwater streams, southeastern Alaska

2001 ◽  
Vol 31 (8) ◽  
pp. 1386-1399 ◽  
Author(s):  
Takashi Gomi ◽  
Roy C Sidle ◽  
Mason D Bryant ◽  
Richard D Woodsmith

Large woody debris (LWD), fine woody debris (FWD), fine organic debris (FOD), and sediment deposition were measured in 15 steep headwater streams with five management and disturbance regimes. Clear-cut channels logged in 1995 contained large accumulations of logging residue that initially provided sites for sediment storage. Half of the LWD in clear-cut channels was recruited during and immediately after logging. Woody debris from logging activities remains in young growth conifer channels 37 years after logging. Numbers of LWD in clear-cut and young conifer channels were significantly higher than in old-growth channels, although numbers of FWD pieces were not significantly different because of higher recruitment from old-growth stands. Channels that experienced recent (1979 and (or) 1993) and earlier (1961 and (or) 1979) scour and runout of landslides and debris flows contained less LWD and FWD, although large volumes of LWD and FWD were found in deposition zones. The volumes of sediment stored in young alder and recent landslide channels were higher than in the other channels. Because of the recruitment of LWD and FWD from young alder stands, the ratio of sediment stored behind woody debris to total sediment volume was higher in young alder channels compared with recent landslide channels. Numbers of LWD and FWD pieces in all streams were significantly correlated with the volumes of sediment stored behind woody debris. Timber harvesting and soil mass movement influence the recruitment, distribution, and accumulation of woody debris in headwater streams; this modifies sediment storage and transport in headwater channels.

2021 ◽  
Vol 4 ◽  
Author(s):  
Jeffrey Opoku-Nyame ◽  
Alain Leduc ◽  
Nicole J. Fenton

Clear cut harvest simplifies and eliminates old growth forest structure, negatively impacting biodiversity. Partial cut harvest has been hypothesized (1) to have less impact on biodiversity than clear cut harvest, and (2) to encourage old growth forest structures. Long-term studies are required to test this hypothesis as most studies are conducted soon after harvest. Using epixylic bryophytes as indicators, this study addresses this knowledge gap. Fourteen years after harvest, we examined changes in epixylic bryophyte community composition richness and traits, and their microhabitats (coarse woody debris characteristics and microclimate) along an unharvested, partial cuts and clear cuts harvest treatment in 30 permanent plots established in the boreal black spruce (Picea mariana) forests of northwestern Quebec, Canada. Our results were compared to those of an initial post-harvest study (year 5) and to a chronosequence of old growth forests to examine species changes over time and the similarity of bryophyte communities in partial cut and old growth forests. Coarse woody debris (CWD) volume by decay class varied among harvest treatments with partial cuts and clear cuts recording lower volumes of early decay CWD. The epixylic community was richer in partial cuts than in mature unharvested forests and clear cuts. In addition, species richness and overall abundance doubled in partial and clear cuts between years 5 and 14. Species composition also differed among treatments between years 5 and 14. Furthermore, conditions in partial cut stands supported small, drought sensitive, and old growth confined species that are threatened by conditions in clear cut stands. Lastly, over time, species composition in partial cuts became more similar to old growth forests. Partial cuts reduced harvest impacts by continuing to provide favorable microhabitat conditions that support epixylic bryophytes. Also, partial cut harvest has the potential to encourage old growth species assemblages, which has been a major concern for biodiversity conservation in managed forest landscapes. Our findings support the promotion of partial cut harvest as an effective strategy to achieve species and habitat conservation goals.


2012 ◽  
Vol 286 ◽  
pp. 73-80 ◽  
Author(s):  
Ryan M. Burrows ◽  
Regina H. Magierowski ◽  
Jason B. Fellman ◽  
Leon A. Barmuta

1991 ◽  
Vol 48 (12) ◽  
pp. 2499-2508 ◽  
Author(s):  
Robert E. Bilby ◽  
James W. Ward

Amount of large woody debris (LWD) surveyed in 70 stream reaches flowing through old-growth, clear-cut, and second-growth forests decreased with increasing stream size for all stand types but was greatest at old-growth sites. Average piece volume was larger at old-growth sites than at other stand types in streams >10 m wide, but no differences were seen in smaller streams. Scour pools accounted for 90% of the wood-associated pools at second-growth and clear-cut sites but only 50% at old-growth sites, which contained more pools than other stand types, particularly for larger streams. Pool size was similar for all stand types in smaller streams, but averaged 10 m2 in streams >10 m wide at old-growth sites and 4 m2 for other stand types. Pool size was similar for all stand types in smaller streams. Sediment and fine organic matter retained by woody debris decreased with increasing stream size for ail stand types, but old-growth sites contained greater amounts of both materials than other stand types. The frequency of pool formation, the type of pool formed, and sediment accumulation were influenced by the amount of fine debris associated with LWD. Changes in LWD amount, characteristics, and function occurred very rapidly following removal of streamside vegetation.


2009 ◽  
Vol 39 (1) ◽  
pp. 131-142 ◽  
Author(s):  
Ulrike Hagemann ◽  
Martin T. Moroni ◽  
Franz Makeschin

Deadwood (woody debris (WD), standing dead trees (snags), stumps, and buried deadwood) abundance was estimated in Labrador humid high-boreal black spruce (Picea mariana (Mill.) BSP) forests regrown following natural and anthropogenic disturbances. Aboveground deadwood (DW) abundance in Labrador was similar to values observed in other boreal forests experiencing drier or warmer climates. Clear-cut harvest generated large amounts of WD, which had almost completely decomposed 34–36 years following harvesting, with a fitted volume reduction rate of –0.058 year–1. Total WD in all harvested stands was composed of predominantly <10 cm pieces, which should be included in DW inventories of disturbed coniferous boreal forests. Postfire WD likely peaked ∼20 years following disturbance, as a result of the collapse of snags, and was dominated by large amounts of medium-sized logs (10.0–19.9 cm). Buried DW stocks considerably exceeded total aboveground DW stocks in old-growth, middle-aged, and older harvested stands. Old-growth stands contained 179.3 m3·ha–1 of buried DW, a vast amount indicative of long-term accumulation requiring significantly depressed rates of WD decomposition following burial. DW stocks could be significantly underestimated if buried DW is excluded from DW inventories in cool and moist coniferous forests with long fire-return intervals.


1986 ◽  
Vol 43 (8) ◽  
pp. 1521-1533 ◽  
Author(s):  
Michael L. Murphy ◽  
Jonathan Heifetz ◽  
Scott W. Johnson ◽  
K V. Koski ◽  
John F. Thedinga

To assess short-term effects of logging on juvenile Oncorhynchus kisutch, Salvelinus malma, Salmo gairdneri, and Salmo clarki in southeastern Alaska, we compared fish density and habitat in summer and winter in 18 streams in old-growth forest and in clearcuts with and without buffer strips. Buffered reaches did not consistently differ from old-growth reaches; clear-cut reaches had more periphyton, lower channel stability, and less canopy, pool volume, large woody debris, and undercut banks than old-growth reaches. In summer, if areas had underlying limestone, clear-cut reaches and buffered reaches with open canopy had more periphyton, benthos, and coho salmon fry (age 0) than old-growth reaches. In winter, abundance of parr (age > 0) depended on amount of debris. If debris was left in clear-cut reaches, or added in buffered reaches, coho salmon parr were abundant (10–22/100 m2). If debris had been removed from clear-cut reaches, parr were scarce (< 2/100 m2). Thus, clear-cutting may increase fry abundance in summer in some streams by increasing primary production, but may reduce abundance of parr in winter if debris is removed. Use of buffer strips maintains or increases debris, protects habitat, allows increased primary production, and can increase abundance of fry and parr.


2006 ◽  
Vol 36 (3) ◽  
pp. 725-737 ◽  
Author(s):  
Takashi Gomi ◽  
Adelaide C Johnson ◽  
Robert L Deal ◽  
Paul E Hennon ◽  
Ewa H Orlikowska ◽  
...  

Factors (riparian stand condition, management regimes, and channel properties) affecting distributions of wood, detritus (leaves and branches), and sediment were examined in headwater streams draining young-growth red alder (Alnus rubra Bong.) – conifer riparian forests (< 40 years old) in southeast Alaska. More riparian red alder were found along streams affected by both timber harvesting and mass movement than in streams affected by timber harvesting alone. Young-growth stands produced little large wood material (diameter ≥10 cm) and had little effect on altering the size distribution of functional large wood in channels, although more alder wood pieces were found in streams with greater numbers of riparian alder trees. Legacy wood pieces (>40 years old) remained in channels and provided sites for sediment and organic matter storage. Despite various alder–conifer mixtures and past harvesting effects, the abundance of large wood, fine wood, and detritus accumulations significantly decreased with increasing channel bank-full width ( 0.5–3.5 m) along relatively short channel distances (up to 700 m). Changes in wood, detritus, and sediment accumulations together with changes in riparian stand characteristics create spatial and temporal variability of in-channel conditions in headwater systems. A component of alder within young-growth riparian forests may benefit both wood production and biological recovery in disturbed headwater stream channels.


Geosciences ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 253
Author(s):  
Tomáš Galia

Mountain headwater streams are still somewhat on the boundary of interest regarding possible human impact on their morphology or geomorphic processes, which may be caused by our perception of mountains as islands of relatively preserved natural conditions. This paper summarizes the past and present human pressure on the headwater streams that drain the highest mountain ranges of the Outer Western Carpathians in Czechia. Anthropogenic pressure began in this region in the 16th century during a colonization of the mountains and continued by timber harvesting, timber floating, and construction of torrent control works until present. Each of these interventions produced a morphological response of the channels in relation to altered sediment or water fluxes at the whole catchment scale or within longitudinal stream profiles. Because it is highly unlikely to reach pre-settlement conditions of the channels, the management effort should be concentrated to achieve realistic restoration targets under the present socioeconomic circumstances by taking into consideration the morphodynamical specifics of mountain headwater streams.


2016 ◽  
Vol 46 (7) ◽  
pp. 914-923 ◽  
Author(s):  
Jonathan L.W. Ruppert ◽  
Marie-Josée Fortin ◽  
Eldon A. Gunn ◽  
David L. Martell

The fragmentation and loss of old-growth forest has led to the decline of many forest-dwelling species that depend on old-growth forest as habitat. Emblematic of this issue in many areas of the managed boreal forest in Canada is the threatened woodland caribou (Rangifer tarandus caribou (Gmelin, 1788)). We develop a methodology to help determine when and how timber can be harvested to best satisfy both industrial timber supply and woodland caribou habitat requirements. To start, we use least-cost paths based on graph theory to determine the configuration of woodland caribou preferred habitat patches. We then developed a heuristic procedure to schedule timber harvesting based on a trade-off between merchantable wood volume and the remaining amount of habitat and its connectivity during a planning cycle. Our heuristic can attain 84% of the potential woodland caribou habitat that would be available in the absence of harvesting at the end of a 100 year planning horizon. Interestingly, this is more than that which is attained by the current plan (50%) and a harvesting plan that targets high volume stands (32%). Our results indicate that our heuristic procedure (i.e., an ecologically tuned optimization approach) may better direct industrial activities to improve old-growth habitat while maintaining specified timber production levels.


Author(s):  
Dennis Knight ◽  
Daniel Tinker

In forest ecosystems, the decomposition of coarse woody debris, woody roots, twigs, leaves and micro-organisms is a primary source of mineral soil organic matter. Primary productivity, the accumulation of nutrients, and other important ecosystem processes are largely dependent on the mineral soil organic matter that has developed during hundreds or thousands of years. Large quantities of coarse woody debris are typically produced following natural disturbances such as fires, pest/pathogen outbreaks, and windstorms, and make a significant contribution to the formation of soil organic matter (SOM). In contrast, timber harvesting often removes much of the coarse woody debris (CWD), which could result in a decrease in the quantity and a change in the quality of mineral soil organic matter.


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