Does timber harvest influence the dynamics of marine-derived nutrients in Southeast Alaska streams?

2011 ◽  
Vol 68 (8) ◽  
pp. 1316-1329 ◽  
Author(s):  
Peter S. Levi ◽  
Jennifer L. Tank ◽  
Scott D. Tiegs ◽  
Janine Rüegg ◽  
Dominic T. Chaloner ◽  
...  
Keyword(s):  
Nutrient Concentration ◽  
Pacific Salmon ◽  
Timber Harvest ◽  
Nutrient Export ◽  
Southeast Alaska ◽  
Particulate Nitrogen ◽  
Nutrient Delivery ◽  
Before And After ◽  
Nutrient Subsidies ◽  
Marine Derived Nutrients

Streams often rely on nutrient subsidies, and variation in nutrient delivery may alter the ecosystem response. Pacific salmon (Oncorhynchus spp.) provide marine-derived nutrients to their natal streams but also cause benthic disturbance, with the net effect determined by watershed and stream characteristics. To understand the factors contributing to variation in salmon-derived nutrients (SDN), we studied nutrient concentration and export in seven streams with varying physical characteristics due to timber harvest (e.g., channel complexity) over three years in Southeast Alaska, USA. Salmon increased concentrations and export of dissolved and particulate nitrogen, phosphorus, and carbon, but the magnitude of increase varied up to 41-fold among streams. The density of live salmon best predicted the increase in nutrient concentration and export, whereas the density of carcasses had a negligible effect. Nutrient export was predicted by transient storage before and after the salmon run. Streams in harvested watersheds with simplified channels had greater nutrient export than those in pristine watersheds with complex channels. However, enrichment from salmon overrode the effect of timber harvest on export during the run. Our study demonstrates that enrichment via SDN is short-lived and related to run size, whereas timber harvest and carcasses exert little influence on SDN dynamics.

Comment on “Does timber harvest influence the dynamics of marine-derived nutrients in Southeast Alaska streams?” 1Original article by Levi et al. appears in Can. J. Fish. Aquat. Sci. 68(8): 1316–1329 and is available at http://www.nrcresearchpress.com/doi/full/10.1139/f2011-067. Reply by Levi et al. appears in Can. J. Fish. Aquat. Sci. 69: this issue, and is available at http://www.nrcresearchpress.com/doi/full/10.1139/f2012-106.

2012 ◽  
Vol 69 (11) ◽  
pp. 1894-1897 ◽  
Author(s):  
C. Rhett Jackson ◽  
Douglas J. Martin
Keyword(s):  
Temporal Variability ◽  
Nutrient Dynamics ◽  
Timber Harvest ◽  
Channel Morphology ◽  
Nutrient Concentrations ◽  
Spatial And Temporal Variability ◽  
Southeast Alaska ◽  
Channel Conditions ◽  
Sample Set ◽  
Marine Derived Nutrients

Levi et al. (2011, Can. J. Fish. Aquat. Sci. 68: 1316–1329) related nutrient concentrations before, during, and after spawning, as well as various measures of channel morphology, to levels of prior timber harvest in seven watersheds on Prince of Wales Island in Southeast Alaska, USA. They assumed that single reaches of seven streams were otherwise similar and that other controls on channel morphology and nutrient dynamics could be ignored relative to the effects of prior timber harvest. In this commentary we show that the seven watersheds were not similar and that the sample set was too small to address geomorphic variability unrelated to timber harvest. Levi et al. failed to consider adequately the natural drivers of spatial and temporal variability in channel morphology and to consider stronger alternate hypotheses for observed channel conditions.

Diet composition of Steller sea lions (Eumetopias jubatus) in Frederick Sound, southeast Alaska: a comparison of quantification methods using scats to describe temporal and spatial variabilities

2015 ◽  
Vol 93 (5) ◽  
pp. 361-376 ◽  
Author(s):  
D.J. Tollit ◽  
M.A. Wong ◽  
A.W. Trites
Keyword(s):  
Pacific Salmon ◽  
Biomass Energy ◽  
Eumetopias Jubatus ◽  
Steller Sea Lions ◽  
Southeast Alaska ◽  
Merluccius Productus ◽  
Sea Lions ◽  
Sampling Protocols ◽  
Dietary Indices

We compared eight dietary indices used to describe the diet of Steller sea lions (Eumetopias jubatus (Schreber, 1776)) from 2001 to 2004 in Frederick Sound, southeast Alaska. Remains (n = 9666 items) from 59+ species categories were identified from 1684 fecal samples (scats) from 14 collection periods. The most frequently occurring prey were walleye pollock (Theragra chalcogramma (Pallas, 1814) = Gadus chalcogrammus Pallas, 1814; 95%), Pacific herring (Clupea pallasii Valenciennes in Cuvier and Valenciennes, 1847; 30%), Pacific hake (Merluccius productus (Ayres, 1855); 29%), and arrowtooth flounder (Atheresthes stomias (Jordan and Gilbert, 1880) = Reinhardtius stomias (Jordan and Gilbert, 1880); 21%). These species, along with Pacific salmon (genus Oncorhynchus Suckley, 1861) and skate (genus Raja L., 1758), accounted for 80%–90% of the reconstructed biomass and energy contribution, with pollock contributing 37%–60%. Overall, 80% of fish were 14–42 cm long and mainly pelagic, though 40% of scats contained benthic-associated prey. Steller sea lions switched from adult pollock to strong cohorts of juvenile pollock, and took advantage of spawning concentrations of salmon in autumn and herring in late spring and summer, as well as a climate-driven increase in hake availability. Observed temporal and site differences in diet confirm the need for robust long-term scat sampling protocols. All major indices similarly tracked key temporal changes, despite differences in occurrence and biomass-energy-based diet estimates linked to prey size and energy-density effects and the application of correction factors.

Impact of Canada's Pacific Salmon Fleet Control Program

1979 ◽  
Vol 36 (7) ◽  
pp. 764-769 ◽  
Author(s):  
Peter H. Pearse ◽  
James E. Wilen
Keyword(s):  
Key Words ◽  
Statistical Data ◽  
Pacific Salmon ◽  
Control Program ◽  
Resource Rent ◽  
The Real ◽  
Before And After ◽  
Salmon Fishery

The available statistical data are analyzed to appraise the success of Canada's Pacific salmon fleet rationalization program, in terms of the extent to which it has prevented fishing costs from rising in pace with the value of the catch. It is found that while the fleet's revenues increased at about the same rate before and after the scheme was introduced in 1969, the real capital employed increased more slowly under the controls than earlier. The program has, nevertheless, failed in its purpose of preventing further expansion of redundant capital in the fleet. The reasons for this failure, and for certain apparent shifts in the structure of the fleet, are discussed. Key words: Pacific salmon fishery, capitalization, economic rationalization, resource rent

Short-term effects of timber harvest and forest edges on ground-layer mosses and liverworts

2005 ◽  
Vol 83 (6) ◽  
pp. 610-620 ◽  
Author(s):  
Cara R Nelson ◽  
Charles B Halpern
Keyword(s):  
Forest Management ◽  
Edge Effects ◽  
Management Practices ◽  
Timber Harvest ◽  
Ground Layer ◽  
Limited Information ◽  
Short Term ◽  
Before And After ◽  
Logging Effects ◽  
Structural Retention

Limited information exists on the effects of forest management practices on bryophytes, despite their importance to forest ecosystems. We examined short-term responses of ground-layer bryophytes to logging disturbance and creation of edges in mature Pseudotsuga forests of western Washington (USA). The abundance and richness of species were measured in four 1-ha forest aggregates (patches of intact forest) and in surrounding logged areas before and after structural retention harvests. One year after treatment, species richness, total cover, and frequency of most moss and liverwort taxa declined within harvest areas. Within forest aggregates, mosses did not show significant edge effects; however, richness and abundance of liverworts declined with proximity to the aggregate edge. Our results suggest that, over short time frames, 1-ha-sized aggregates are sufficient to maintain most common mosses through structural retention harvests but are not large enough to prevent declines or losses of liverworts. Thus, current standards for structural retention, which allow for aggregates as small as 0.2 ha, may be inadequate to retain the diversity and abundance of species found in mature, undisturbed forests.Key words: bryophyte, edge effects, forest borders, forest management, logging effects, structural retention harvest.

Advances in Understanding Landscape Influences on Freshwater Habitats and Biological Assemblages

2019 ◽  
Keyword(s):  
Forested Wetlands ◽  
Timber Harvest ◽  
Large Wood ◽  
Catchment Scale ◽  
Southeast Alaska ◽  
Riparian Management ◽  
Freshwater Habitats ◽  
Study Sites ◽  
Landscape Attributes ◽  
Landscape Influences

<i>Abstract.</i>—Currently, much is known about influences of landscape attributes, including timber harvest practices, on large wood dynamics in streams. Comparatively, much less is known about influences of catchment attributes on Southeast Alaska streams, in part because of a historical lack of consistent catchment-scale data available for the region. As in forested regions elsewhere, large wood is an important resource to stream habitats and fishes in Southeast Alaska. Therefore, the purpose of this study was to characterize catchment-scale influences, including various timber harvest practices, on large wood in Southeast Alaska stream sites. We delineated local catchment boundaries for all stream reaches in the region and summarized landscape influences, including natural and harvest-related attributes in local and network catchments. Relative amounts of variation in four large wood habitat variables explained by natural versus harvest practice-related landscape attributes were evaluated to compare different influences on 28 randomly selected study sites. We used those results to predict variation in large wood variables from our sites through use of both natural and harvest practice-related catchment attributes to identify those that may be most influential to large wood. Natural characteristics, including catchment area, deciduous forests, forested wetlands, and catchment slope, all had significant influences on large wood variables, as did various measures of contemporary and historical timber harvest practices. We found that large wood length was positively related to conventional harvest after 1990, suggesting the potential effectiveness of contemporary logging regulations in protecting large wood characteristics. In our study, both natural and timber harvest practice-related attributes had measureable influences on stream habitat, underscoring the importance of considering catchment-scale attributes, including riparian management schemes, for managing Southeast Alaska streams.

TIMBER HARVEST TRANSFORMS ECOLOGICAL ROLES OF SALMON IN SOUTHEAST ALASKA RAIN FOREST STREAMS

2008 ◽  
Vol 18 (1) ◽  
pp. 4-11 ◽  
Author(s):  
Scott D. Tiegs ◽  
Dominic T. Chaloner ◽  
Peter Levi ◽  
Janine Rüegg ◽  
Jennifer L. Tank ◽  
...  
Keyword(s):  
Rain Forest ◽  
Timber Harvest ◽  
Southeast Alaska ◽  
Ecological Roles ◽  
Forest Streams

scholarly journals A comprehensive biogeochemical record and annual flux estimates for the Sabaki River (Kenya)

2018 ◽  
Vol 15 (6) ◽  
pp. 1683-1700
Author(s):  
Trent R. Marwick ◽  
Fredrick Tamooh ◽  
Bernard Ogwoka ◽  
Alberto V. Borges ◽  
François Darchambeau ◽  
...  
Keyword(s):  
Suspended Sediment ◽  
Sediment Yield ◽  
Particulate Phosphorus ◽  
Poor Correlation ◽  
Inland Waters ◽  
Base Line ◽  
Nutrient Export ◽  
Wet Season ◽  
Particulate Nitrogen ◽  
Organic C

Abstract. Inland waters impart considerable influence on nutrient cycling and budget estimates across local, regional and global scales, whilst anthropogenic pressures, such as rising populations and the appropriation of land and water resources, are undoubtedly modulating the flux of carbon (C), nitrogen (N) and phosphorus (P) between terrestrial biomes to inland waters, and the subsequent flux of these nutrients to the marine and atmospheric domains. Here, we present a 2-year biogeochemical record (October 2011–December 2013) at biweekly sampling resolution for the lower Sabaki River, Kenya, and provide estimates for suspended sediment and nutrient export fluxes from the lower Sabaki River under pre-dam conditions, and in light of the approved construction of the Thwake Multipurpose Dam on its upper reaches (Athi River). Erratic seasonal variation was typical for most parameters, with generally poor correlation between discharge and material concentrations, and stable isotope values of C (δ13C) and N (δ15N). Although high total suspended matter (TSM) concentrations are reported here (up to ∼ 3.8 g L−1), peak concentrations of TSM rarely coincided with peak discharge. The contribution of particulate organic C (POC) to the TSM pool indicates a wide biannual variation in suspended sediment load from OC poor (0.3 %) to OC rich (14.9 %), with the highest %POC occurring when discharge is < 100 m3 s−1 and at lower TSM concentrations. The consistent 15N enrichment of the particulate nitrogen (PN) pool compared to other river systems indicates anthropogenic N loading is a year-round driver of N export from the Sabaki Basin. The lower Sabaki River was consistently oversaturated in dissolved methane (CH4; from 499 to 135 111 %) and nitrous oxide (N2O; 100 to 463 %) relative to atmospheric concentrations. Wet season flows (October–December and March–May) carried > 80 % of the total load for TSM (∼ 86 %), POC (∼ 89 %), dissolved organic carbon (DOC; ∼ 81 %), PN (∼ 89 %) and particulate phosphorus (TPP; ∼ 82 %), with > 50 % of each fraction exported during the long wet season (March–May). Our estimated sediment yield (85 Mg km−2 yr−1) is relatively low on the global scale and is considerably less than the recently reported average sediment yield of ∼ 630 Mg km−2 yr−1 for African river basins. Regardless, sediment and OC yields were all at least equivalent or greater than reported yields for the neighbouring dammed Tana River. Rapid pulses of heavily 13C-enriched POC coincided with peak concentrations of PN, ammonium, CH4 and low dissolved oxygen saturation, suggesting that large mammalian herbivores (e.g. hippopotami) may mediate the delivery of C4 organic matter to the river during the dry season. Given recent projections for increasing dissolved nutrient export from African rivers, as well as the planned damming of the Athi River, these first estimates of material fluxes from the Sabaki River provide base-line data for future research initiatives assessing anthropogenic perturbation of the Sabaki Basin.

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