scholarly journals Effects of Forest Harvesting on Warm-Season Low Flows in the Pacific Northwest: A Review

2020 ◽  
Vol 4 (1) ◽  
pp. 29
Author(s):  
R.D. (Dan) Moore ◽  
Stefan Gronsdahl ◽  
Richard McCleary
Keyword(s):  
Pacific Northwest ◽  
Forest Disturbance ◽  
Fish Habitat ◽  
Warm Season ◽  
Forest Harvesting ◽  
Low Flow ◽  
Post Harvest ◽  
Low Flows ◽  
The Pacific ◽  
Paired Catchment

Paired-catchment studies conducted on small (< 10 km2) rain-dominated catchments revealed that forest harvesting resulted in a period of increased warm-season low flows ranging from less than five years to more than two decades, consistent with the results of stand-level studies and process considerations. Of the five paired-catchment studies in snow-dominated regions, none revealed a statistically significant change in warm-season low flows in the first decade following harvest, although two exhibited non-significant higher flows in August and September and one had lower flows. Two studies, one of rain-dominated catchments and one of snow-dominated catchments, found that summer low flows became more severe (i.e., lower) about two decades or so following harvest. These longer-term results indicate that indices such as equivalent clearcut area, as currently calculated using monotonic recovery curves, may not accurately reflect the nature of post-harvest changes in low flows. Studies focussed on medium to large catchments (tens to thousands of km2 in area) found either no statistically significant relations between warm-season low flows and forest disturbance, or inconsistent responses. Attempts to synthesize existing studies are hampered by the lack of a common low-flow metric among studies, as well as detailed information on post-harvest vegetation changes. Further fieldresearch and process-based modelling is required to help elucidate the underlying processes leading to the results from these paired-catchment studies and to enhance the ability to predict streamflow responses to forest harvesting, especially in the context of a changing climate. KEYWORDS: streamflow; forestry; low flows; fish habitat; hydrologic recovery

Effects of forestry on summertime low flows and physical fish habitat in snowmelt‐dominant headwater catchments of the Pacific Northwest

2019 ◽  
Vol 33 (25) ◽  
pp. 3152-3168 ◽  
Author(s):  
Stefan Gronsdahl ◽  
R. Dan Moore ◽  
Jordan Rosenfeld ◽  
Rich McCleary ◽  
Rita Winkler
Keyword(s):  
Pacific Northwest ◽  
Fish Habitat ◽  
Headwater Catchments ◽  
Low Flows ◽  
The Pacific

Detecting forest disturbance in the Pacific Northwest from MODIS time series using temporal segmentation

2014 ◽  
Vol 151 ◽  
pp. 114-123 ◽  
Author(s):  
Damien Sulla-Menashe ◽  
Robert E. Kennedy ◽  
Zhiqiang Yang ◽  
Justin Braaten ◽  
Olga N. Krankina ◽  
...  
Keyword(s):  
Time Series ◽  
Pacific Northwest ◽  
Forest Disturbance ◽  
Temporal Segmentation ◽  
The Pacific

Characteristics and function of large woody debris in subalpine Rocky Mountain streams in northern Colorado

1995 ◽  
Vol 52 (8) ◽  
pp. 1789-1802 ◽  
Author(s):  
Ann D. Richmond ◽  
Kurt D. Fauseh
Keyword(s):  
Pacific Northwest ◽  
Woody Debris ◽  
Fish Habitat ◽  
Rocky Mountain ◽  
Large Woody Debris ◽  
Mountain Streams ◽  
Coastal Forests ◽  
The Pacific ◽  
And Function ◽  
Rocky Mountain Streams

Large woody debris has been well studied in coastal forests of the Pacific Northwest, but little is known of its role in Rocky Mountain streams. Large woody debris was measured in 11 undisturbed streams draining subalpine old-growth forests in north central Colorado to assess abundance, characteristics, and function. Although large woody debris in Colorado had smaller diameter, length, and volume than in the Pacific Northwest, its abundance and function were similar. The majority of pools (76%) were plunge and dammed pools formed by large woody debris, most of which spanned the channels perpendicular to stream flow. Smaller streams had a greater proportion of such perpendicular pool-forming pieces than larger streams. Four disturbed streams had significantly less and smaller large woody debris than undisturbed streams. Flows in larger undisturbed streams were capable of moving large woody debris, so pieces were more often located at the stream margins, oriented diagonally, or distributed in clumps than in smaller streams. Individual pools were larger and deeper in larger streams, but their size was not related to the size of large woody debris pieces forming them. Therefore, the function of large woody debris in forming fish habitat in small Rocky Mountain streams is strongly influenced by the stream's location within the watershed.

scholarly journals Both Forest Harvesting and Hydropower Dams Yielded Negative Impact on Low Flow Regimes in the Zagunao River Watershed, Southwest China

Forests ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 787
Author(s):  
Zhiwei Jiang ◽  
Mingfang Zhang ◽  
Yiping Hou
Keyword(s):  
Return Period ◽  
Negative Impact ◽  
Flow Regimes ◽  
Forest Harvesting ◽  
Forest Recovery ◽  
Low Flow ◽  
River Watershed ◽  
Low Flows ◽  
Hydropower Dams ◽  
The Impact

Forest harvesting and hydropower dams can significantly affect flow regimes (magnitude, timing, duration, frequency, and variability), resulting in changes in degraded aquatic ecosystems and unstable water supply. Despite numerous studies on the effects of forest harvesting on mean flows, the impact of forest harvesting on flow regimes has been less investigated. A great difficulty lies in separating the hydrological effect of forest harvesting from that of climate variability and other watershed disturbances such hydropower dams. In this study, the Upper Zagunao River watershed (2242 km2) was selected as an example to provide a quantitative assessment of the effects of forest harvesting and hydropower dams on low flow regimes. The key findings include: (1) Forest harvesting led to a significant reduction in the magnitude and return period of low flows, and a significant increment in the variability and duration of low flows; (2) the recovery of low flow regimes occurred 40 years after forest harvesting as forest recovery processed; and (3) hydropower dams caused significant impact on all components of low flow regimes, e.g., a reduction in the magnitude, return period, and timing of low flows, and an increment in the variability and duration of low flows. Our findings highlight the negative impact of both forest harvesting and hydropower dams on low flow regimes in the Upper Zagunao River watershed. A watershed management strategy for offsetting the negative effect of hydropower dams on low flow regimes by restoring hydrological functions of subalpine forests is highly recommended in subalpine watersheds of the Upper Yangtze River.

Riparian forest harvesting and its influence on benthic communities of small streams of sub-boreal British Columbia

2007 ◽  
Vol 37 (5) ◽  
pp. 907-918 ◽  
Author(s):  
K. Jill Melody ◽  
John S. Richardson
Keyword(s):  
Leaf Litter ◽  
Pacific Northwest ◽  
Riparian Forest ◽  
Benthic Communities ◽  
Forest Harvesting ◽  
Riparian Areas ◽  
The Pacific ◽  
Small Streams ◽  
Coastal Streams ◽  
Physical Features

Forest harvesting in riparian areas can alter the leaf-litter inputs, shading, and stability of small streams, and many of the details of these impacts are known for coastal streams of the Pacific Northwest. However, little is known about how small streams in the drier, continental areas of western North America respond to logging. We conducted a study of paired stream reaches (comparing one recently harvested (≤3 years) reach and two upstream, forested reaches in each of five streams) in which periphyton, detritus, macroinvertebrate abundance and biomass, and physical features were measured in summer and autumn. In general, recently harvested stream sections tended to be wider and contained more riffle areas than the upstream forested sections. The amounts of leaf litter and algae varied among streams and were not consistently greater or lesser in the forested sections than in the harvested sections. Though the variation in amounts within streams was mainly seasonal, amounts differed more among streams than between pairs of harvested and forested reaches. The communities of benthic invertebrates differed significantly between forested and harvested reaches, but often in opposite directions between streams. The magnitude and direction of differences observed between treatments, streams, or seasons were associated with the specific stream and the method of riparian harvesting used.

scholarly journals Importance of maximum snow accumulation for summer low flows in humid catchments

2016 ◽  
Vol 20 (2) ◽  
pp. 859-874 ◽  
Author(s):  
Michal Jenicek ◽  
Jan Seibert ◽  
Massimiliano Zappa ◽  
Maria Staudinger ◽  
Tobias Jonas
Keyword(s):  
Snow Water Equivalent ◽  
Warm Season ◽  
Snow Accumulation ◽  
Low Flow ◽  
Annual Variations ◽  
Low Flows ◽  
Snow Storage ◽  
Winter Snow ◽  
Lower Elevation ◽  
Alpine Catchments

Abstract. Winter snow accumulation obviously has an effect on the following catchment runoff. The question is, however, how long this effect lasts and how important it is compared to rainfall inputs. Here we investigate the relative importance of snow accumulation on one critical aspect of runoff, namely the summer low flow. This is especially relevant as the expected increase of air temperature might result in decreased snow storage. A decrease of snow will affect soil and groundwater storages during spring and might cause low streamflow values in the subsequent warm season. To understand these potential climate change impacts, a better evaluation of the effects of inter-annual variations in snow accumulation on summer low flow under current conditions is central. The objective in this study was (1) to quantify how long snowmelt affects runoff after melt-out and (2) to estimate the sensitivity of catchments with different elevation ranges to changes in snowpack. To find suitable predictors of summer low flow we used long time series from 14 Alpine and pre-Alpine catchments in Switzerland and computed different variables quantifying winter and spring snow conditions. In general, the results indicated that maximum winter snow water equivalent (SWE) influenced summer low flow, but could expectedly only partly explain the observed inter-annual variations. On average, a decrease of maximum SWE by 10 % caused a decrease of minimum discharge in July by 6–9 % in catchments higher than 2000 m a.s.l. This effect was smaller in middle- and lower-elevation catchments with a decrease of minimum discharge by 2–5 % per 10 % decrease of maximum SWE. For higher- and middle-elevation catchments and years with below-average SWE maximum, the minimum discharge in July decreased to 70–90 % of its normal level. Additionally, a reduction in SWE resulted in earlier low-flow occurrence in some cases. One other important factor was the precipitation between maximum SWE and summer low flow. When only dry preceding conditions in this period were considered, the importance of maximum SWE as a predictor of low flows increased. We assessed the sensitivity of individual catchments to the change of maximum SWE using the non-parametric Theil–Sen approach as well as an elasticity index. Both sensitivity indicators increased with increasing mean catchment elevation, indicating a higher sensitivity of summer low flow to snow accumulation in Alpine catchments compared to lower-elevation pre-Alpine catchments.

Sources of large wood in the main stem of a fourth-order watershed in coastal Oregon

2003 ◽  
Vol 33 (8) ◽  
pp. 1363-1370 ◽  
Author(s):  
Gordon H Reeves ◽  
Kelly M Burnett ◽  
Edward V McGarry
Keyword(s):  
Pacific Northwest ◽  
Fourth Order ◽  
Flow Channel ◽  
Main Stem ◽  
Low Flow ◽  
Large Wood ◽  
Coast Range ◽  
Riparian Management ◽  
The Pacific ◽  
Management Approaches

We compared the contribution of large wood from different sources and wood distributions among channel zones of influence in a relatively pristine fourth-order watershed in the central Coast Range of Oregon. Wood in the main stem of Cummins Creek was identified as coming from either (i) streamside sources immediately adjacent to the channel or (ii) upslope sources delivered by landslides or debris flows more than 90 m from the channel. About 65% of the number of pieces and 46% of the estimated volume of wood were from upslope sources. Streamside sources contributed about 35% of the number of pieces and 54% of the estimated volume of wood. The estimated mean volume of upslope-derived pieces was about one-third that of streamside-derived pieces. Upslope-derived pieces were located primarily in the middle stream reaches and in the zones of influence that had the most contact with the low-flow channel. Streamside-derived pieces were more evenly distributed among the examined reaches and were predominately in the influence zones that had the least contact with the low-flow channel. Our findings suggest that previous studies that examined only streamside sources of wood have limited applications when designing and evaluating riparian management approaches in landslide-prone areas. The failure to recognize the potential sources of wood from upslope areas is a possible reason for the decline of large wood in streams in the Pacific Northwest.

Temperature changes along the Gulf of Alaska and the Pacific Northwest coast modeled from coastal tree rings

1996 ◽  
Vol 26 (3) ◽  
pp. 474-481 ◽  
Author(s):  
Gregory C. Wiles ◽  
Rosanne D. D'Arrigo ◽  
Gordon C. Jacoby
Keyword(s):  
Pacific Northwest ◽  
Large Scale ◽  
Ring Width ◽  
Warm Season ◽  
Gulf Of Alaska ◽  
Maximum Latewood Density ◽  
Pacific Northwest Coast ◽  
Latewood Density ◽  
The Pacific ◽  
Temperature Records

Warm-season (April–September) temperature models based on a network of coastal ring-width and maximum latewood density tree-ring chronologies are the first reconstructions for coastal stations along the Gulf of Alaska and the Pacific Northwest. These well-verified temperature models are consistent with long climatic series from coastal stations and other proxy data from the Pacific coast. Cool summers during the 1850s and late 1800s in the Gulf of Alaska correspond to general glacier advance from the region. The Pacific Northwest reconstruction shows summer temperatures cooling in the early 1800s, coincident with a maximum of glacier activity in the coastal Olympic Mountains, Washington. The two warm-season temperature records show intervals when anomalies are opposite in sign, most notably during the 1850s, when cooling is inferred for the Gulf and warming is inferred for the Pacific Northwest. The records are coherent, however, during other intervals, with both showing cooling in the early 1800s and warming around 1870. The phase of these two records may reflect decadal changes in large-scale circulation in the northeastern Pacific. These land temperature reconstructions are strongly correlated with nearby sea surface temperatures, indicating large-scale oceanic–atmospheric influences.

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