River channel dynamics following extirpation of wolves in northwestern Yellowstone National Park, USA

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Gray wolves maintained a presence in the upper Gallatin Basin through the early 1900s and, with human hunting, affected elk populations until the 1920s.

“Gray wolves, a strongly interacting species (Soule et al., 2005), maintained a presence in the basin through the early 1900s and, in conjunction with widespread hunting by humans, affected elk populations up until the 1920s (Lovaas, 1970;Weaver, 1978).”

• cites Lovaas, 1970 sourcePartly supported

  The Introduction (page unavailable) documents elk hunting in the Gallatin Basin during the early 1900s and describes wolves as once important to Gallatin ecology. It does not establish that wolves remained in the basin through the early 1900s or affected elk populations alongside human hunters until the 1920s; it calls wolves’ effects on the herd conjectural or hypothetical. (LLM, conf=0.83)

  Experimental — accuracy not yet measured
• cites Weaver, 1978Not checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing).

Gray wolves were extirpated from nearly all of the contiguous 48 United States by the early 1900s due to hunting, trapping, and poisoning.

“By the early 1900s, the formerly wide-ranging North American gray wolf (Canus lupus) had been extirpated from nearly all of the contiguous 48 United States (US) due to an extensive and systematic program of hunting, trapping and poisoning (Musiani and Paquet, 2004).”

• cites Musiani and Paquet, 2004 sourcePartly supported

  The Abstract says wolves were extirpated from the conterminous 48 states except northern Minnesota by 1970, not by the early 1900s. “Foundations for historical and current killing of wolves” describes eradication programs involving trapping, shooting, and poisoning, but does not establish the earlier date. Page numbers are unavailable in our copy. (LLM, conf=0.87)

  Experimental — accuracy not yet measured

May combine two claims.

Reach A is outside the normal winter range and has no historical record of heavy willow browsing.

“Several factors indicated that the channel associated with reach A has been stable for many decades: (1) the reach is located outside the normal winter range of the upper Gallatin elk herd and there is no historical record (Lovaas, 1967, 1970) indicating that willows along this reach had been heavily browsed, either before or after the removal of wolves”

• cites Lovaas, 1967Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Lovaas, 1970 sourceCould not verify

  The Introduction describes the Gallatin elk winter range and records heavy willow browsing at named locations, including along the Gallatin River down to Black Butte Creek. Neither those passages nor searches for the range boundary and willow browsing identify reach A or establish its location relative to the winter range, so this copy cannot verify the reach-specific historical claim. (LLM, conf=0.72)

  Experimental — accuracy not yet measured

May combine two claims.

The planform morphology of the river channel along reach C was relatively straight in 1947 and remained similar in subsequent aerial photographs, although some localized widening and increases in unvegetated alluvial deposits were noted.

“The planform morphology of the river channel along reach C was relatively straight in 1947 and remained similar in subsequent aerial photographs, although some localized widening and increases in unvegetated alluvial deposits was noted.”

May combine two claims.

Field observations in 2004 indicated streambanks at reach A were well vegetated by sedges and willows and dense mature willows occurred across the floodplain.

“(2) field observations in 2004 indicated streambanks were well vegetated by both sedges and willows and that a dense community of mature willows occurred across the floodplain”

May combine two claims.

Average bankfull widths for reaches A and C were within the 99% confidence limits for mountain streams in western Montana, while the average bankfull width for reach B was well outside these limits.

“Although average bankfull widths for reaches A and C were within the 99 per cent confidence limits for mountain streams in western Montana, the average bankfull width for B was well outside these limits (Figure 5).”

• cites Parrett and Johnson, 2004 sourceNot checked — no full text of the source

May combine two claims.

For the extended period of record, annual peak discharges averaged 155 m3/s with a coefficient of variation of ±31%.

“For this extended period of record (Figure 3), annual peak discharges averaged 155 m 3 s -1 (coefficient of variation ±31 per cent).”

May combine two claims.

For discharges encountered in late August 2004, Manning's n ranged from 0.033 to 0.072 for individual cross-sections and averaged 0.052, 0.057, and 0.067 for reaches A, B, and C, respectively.

“For the discharges encountered in late August of 2004, Manning's n ranged from 0•033 to 0•072 for individual cross-sections and averaged 0•052, 0•057 and 0•067 for reaches A, B and C, respectively.”

May combine two claims.

Average return period of calculated bankfull discharges was 3.1 years at reach A, 32.4 years at reach B, and 10.6 years at reach C.

“The average return period of calculated bankfull discharges was 3•1 yrs for reach A but increased to 32•4 yrs and 10•6 yrs for reaches B and C, respectively.”

• Also stated in: § Floodplains and vegetation · plain

  “The average return period for bankfull discharge at reach A was 3•1 yr, much less than the 32•4 and 10•6 yr at reaches B and C, respectively (Table II).”

May combine two claims.

Post-1947 aerial photographs indicated increasing divergence in planform morphology and amount of unvegetated alluvial deposits along reaches B and C.

“However, post-1947 photographs indicated increasing divergence in planform morphology and the amount of area comprising unvegetated alluvial deposits.”

May combine two claims.

The complex hydraulic condition at reach B resulted in a wide gravel/cobble surface or secondary channel adjacent to the main channel, both of which carried water during high discharge.

“This situation resulted in a wide gravel/cobble surface or secondary channel adjacent to the main channel, both of which carried water during periods of high discharge.”

May combine two claims.

Tall saplings of lodgepole pine have become established at several locations on the floodplain immediately downstream of reach C, indicating this surface has become drier in recent decades.

“Similarly, tall saplings of lodgepole pine (Pinus contorta), a tree that typically occupies dry sites, have become established at several locations on the floodplain immediately downstream of reach C, indicating this surface has become drier in recent decades.”

May combine two claims.

Channel gradients measured in August 2004 ranged from 0.0032 to 0.0121 m/m for individual cross-sections and averaged 0.0074, 0.0056, and 0.0078 for reaches A, B, and C, respectively.

“Channel gradients measuered in August of 2004 (Table I) ranged from 0•0032 to 0•0121 m m -1 for individual crosssections and averaged 0•0074, 0•0056 and 0•0078 for reaches A, B and C, respectively.”

May combine two claims.

Average width/depth ratio at bankfull discharge for reach B (118 m/m) was significantly greater (p=0.02) than reach A (42 m/m), whereas reach C (39 m/m) was not significantly different (p=0.83) from reach A.

“The average width/depth ratio at bankfull discharge (Table II) for reach B (118 m m -1 ) was significantly greater ( p = 0•02) than the control reach A (42 m m -1 ), whereas reach C (39 m m -1 ) was not significantly different ( p = 0•83) from the control.”

May combine two claims.

The coefficient of variation for calculated bankfull discharges was similar for cross-sections within reaches A (21%) and C (22%) but much larger for reach B (78%).

“The coefficient of variation for calculated bankfull discharges was similar for cross-sections within reaches A (21 per cent) and C (22 per cent) but was much larger for reach B (78 per cent).”

May combine two claims.

Active beaver dams were present on the floodplain associated with reach A but absent from reaches B and C.

“In addition, active beaver dams were present on the floodplain associated with reach A, but absent from reaches B and C.”

May combine two claims.

Willow cover on floodplains averaged 85% at reach A, 26% at reach B, and 5% at reach C, with B and C significantly lower than A (p<0.01).

“Willow cover on floodplains averaged 85 per cent for reach A, but only 26 per cent and 5 per cent for reaches B and C, respectively.”

• Also stated in: § Floodplains and vegetation · hedged

  “Vegetation measurements in 2004 indicated significantly less ( p < 0•01) average willow cover associated with the floodplains of reach B (26 per cent) and reach C (5 per cent) in comparison to reach A (85 per cent).”

May combine two claims.

Sedges provided nearly continuous cover along each streambank at reach A and often extended several meters away from channel margins.

“Sedges provided nearly continuous cover along each streambank at Reach A and often extended for several meters away from channel margins.”

May combine two claims.

At reach A, calculated bankfull flows had a mean recurrence interval of 3.1 years; at reaches B and C, the mean intervals were about 10 years and three times larger, respectively.

“For the calculated bankfull flows, an average return period of 3•1 yr was obtained at reach A, whereas average return periods at reaches B and C were approximately 10 and three times larger, respectively.”

Probably not a substantial claim: may not pass S1 (asserted), S3 (load-bearing).

The period of low-to-moderate peak discharges and the 1930s drought coincided with the timing of deteriorating sedge-willow communities in the elk winter range.

“Since the period of low-to-moderate peak discharges, in conjunction with the general drought conditions of the 1930s, corresponds to the general timing of deteriorating sedge-willow communities within the elk winter range, it could be hypothesized that these hydrologic patterns are an important contributor to the degradation of these plants.”

May combine two claims.

For reaches B and C, bankfull water levels averaged 0.71 m and 0.65 m above the late summer water surface, respectively.

“However, for reaches B and C, where return periods of bankfull discharges were generally greater than those of the control reach, water surface elevations at bankfull discharge averaged 0•71 and 0•65 m, respectively, above the water surface in late summer.”

May combine two claims.

For most of reaches B and C, willows are still mostly missing and eroding banks are widespread.

“While the willows shown along the left side of the reach B photograph represent some that have begun to recover since wolves returned to this basin in the mid-1990s, willows remain largely absent and eroding banks are common for most of reaches B and C.”

May combine two claims.

Even with greater runoff from the 1970s to the 1990s, willow stature and canopy cover kept declining and channels grew more unstable.

“If so, then the increasing magnitude of runoff in the 1970s through the 1990s (Figure 3) should have initiated a resurgence of these plant communities, but such was not the case, and willows continued to decrease in stature and canopy cover while channels became increasingly unstable.”

May combine two claims.

The 1949 and 1961 photographs show increasing streambank erosion even though yearly peak flows from the 1920s to the 1960s never reached a 6-year event.

“In contrast, photographs for 1949 and 1961 (Figure 1(B) and 1(C)) indicate streambank erosion was becoming increasingly common even though annual peak discharges from the 1920s through the 1960s never exceeded the magnitude of a 6 yr event.”

May combine two claims.

After wolves came back to the basin in the mid-1990s, willow clumps started growing taller and appearing more often.

“Since wolves returned to this basin in the mid-1990s, clumps of willows have begun to grow taller and become more common as shown on the lower left portion of (D) (see also Ripple and Beschta, 2004b).”

• cites Ripple and Beschta, 2004bNot matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

The broad willow communities on the 1924 floodplain declined steadily by the 1949 photo and had mostly disappeared by 1961.

“Extensive riparian willow communities associated with the floodplain in 1924 show progressive decline in the 1949 photo and are largely absent by 1961.”

May combine two claims.

Despite seven peak discharges at or above a 6-year event between 1890 and 1919, the 1924 photograph shows little evidence that these flows harmed willow communities in the winter range or destabilized the channel.

“Streamflow records for the Gallatin River (Figure 3) indicate peak discharges greater than or equal to the magnitude of a 6 yr event occurred seven times from 1890 to 1919, yet the 1924 photograph (Figure 1(A)) provides little evidence that these flows adversely affected willow communities within the winter range or resulted in a destabilized channel.”

May combine two claims.

During overbank flow, hydraulic roughness of above-ground stems and branches of floodplain plants reduces water velocities and enhances deposition of fine sediment and organic matter.

“During overbank flow, the hydraulic roughness of above-ground stems and branches of floodplain plant communities reduces water velocities and enhances the deposition of fine sediment and organic matter (Sedell and Beschta, 1991;Darby, 1999;Gyssels and Poesen, 2003;Smith, 2004).”

• cites Sedell and Beschta, 1991Not checked — no full text of the source
• cites Darby, 1999 sourceNot checked — no full text of the source
• cites Gyssels and Poesen, 2003 sourceNot checked — no full text of the source

Classified as probably not a substantial claim. May combine two claims.

The study used an above/below experimental design with reach A as untreated control upstream of the elk winter range where heavy browsing does not occur, and reaches B and C as treatment within the winter range.

“We used an 'above' and 'below' experimental design.An untreated control reach (reach A) was selected upstream of the upper Gallatin elk herd winter range, where heavy browsing of deciduous woody plants does not occur.Treatment reaches B and C were located within the elk winter range”

Classified as probably not a substantial claim.

Riparian plant communities are often dependent upon hydrologic disturbance regimes.

“Since riparian plant communities are often dependent upon hydrologic disturbance regimes (Patten, 2000;National Research Council, 2002b), we utilized the historical record of annual peak discharges as an indicator of climatic influences in the upper Gallatin Basin.”

• cites Patten, 2000Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites National Research Council, 2002bNot matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

Root systems of riparian plants stabilize streambanks by slowing or preventing erosion, thereby reducing channel migration rates in floodplain systems.

“Additionally, the root systems of riparian plants help to stabilize streambanks by slowing or preventing streambank erosion (e.g.particle entrainment, mass wasting) (Simon and Collison, 2002;Murray and Paola, 2003), thereby reducing rates of channel migration for floodplain systems (Hickin, 1984;Micheli and Kirchner, 2002a).”

• cites Simon and Collison, 2002 sourceNot checked — no full text of the source
• cites Murray and Paola, 2003 sourceNot checked — no full text of the source
• cites Hickin, 1984 sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The drainage area above reach A was 92 km2, compared to 412 and 450 km2 for reaches B and C.

“Since reach A Edwards, 1941, andAllen, 1970). (control) lies upstream of the elk winter range, the drainage area above this reach was only 92 km 2 , in comparison to 412 and 450 km 2 for reaches B and C, respectively.”

Probably not a substantial claim: may not pass S3 (load-bearing).

An initiation of riparian willow and cottonwood recovery has been documented for winter range in the northeastern portion of Yellowstone National Park.

“An initiation of riparian willow and cottonwood recovery has similarly been documented for winter range in the northeastern portion of Yellowstone National Park (Ripple and Beschta, 2003).”

• cites Ripple and Beschta, 2003 sourceNot checked — no full text of the source

May combine two claims.

Long-term loss of streamside vegetation allowed channels to generally increase hydraulic capacity via increases in width, incision, or both, and to decrease hydrologic connectivity with adjacent floodplains.

“The long-term loss of streamside vegetation allowed channels to generally increase in hydraulic capacity (via increases in width, incision or both) and decrease their hydrologic connectivity with adjacent floodplains.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Historical photographs were inspected for land use or other factors that might affect channel characteristics.

“These photos were also inspected for land use or other factors that might affect channel characteristics.”

Probably not a substantial claim: may not pass S3 (load-bearing).

In 1919 the elk herd using the upper Gallatin winter range was estimated at 1600 animals (7 elk/km2).

“In 1919 the size of the elk herd using the upper Gallatin winter range was estimated at 1600 (7 elk km -2 ) animals (Graves and Nelson, 1919).”

• cites Graves and Nelson, 1919Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Classified as probably not a substantial claim.

High herbivory along streams and rivers can over time have large impacts on terrestrial and aquatic habitats.

“Furthermore, it is widely recognized that high levels of herbivory along streams and rivers can, over time, have potentially large impacts on terrestrial and aquatic habitats (Platts, 1991;Ohmart, 1996;Kauffman et al., 1997;Dobkin et al., 2002).”

• cites Platts, 1991Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Ohmart, 1996Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Kauffman et al., 1997Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Riparian plant communities can influence bank stability, moderate microclimates and water temperatures, cycle nutrients, and produce organic carbon important to food webs.

“Riparian plant communities can influence bank stability, moderate microclimates and water temperatures, cycle nutrients, produce organic carbon that is an essential component of food-webs for many terrestrial and aquatic organisms and others (Cummins, 1974;Gregory et al., 1991;Naiman and Decamps, 1997).”

• cites Cummins, 1974 sourceNot checked — no full text of the source
• cites Gregory et al., 1991 sourceNot checked — no full text of the source
• cites Naiman and Decamps, 1997 sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing).

In Sierra Nevada snowmelt systems, when banks stood more than 1 m above the low-flow water surface, dry-site vegetation dominated riparian habitats.

“In snowmelt systems of the Sierra Nevada range, Micheli and Kirchner (2002a) found that when streambank heights were >1 m above the low-flow water surface, riparian habitats became dominated by dry-site vegetation.”

• cites Micheli and Kirchner, 2002aNot matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing).

In southwestern Oregon, hydrophytic communities persisted on floodplain areas that flooded more often than once per five years.

“For example, Chapin et al. (2002) found that hydrophytic plant communities in southwestern Oregon were sustained on those portions of a floodplain where overbank flows occurred more frequently than once every five years.”

• cites Chapin et al., 2002Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing).

Graminoids such as sedges can add substantial root strength to streambank soils.

“Sedges and other graminoid species can also contribute considerable root strength to streambank soils (Micheli and Kirchner, 2002b).”

• cites Micheli and Kirchner, 2002bNot matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

Long-term heavy grazing or browsing by wild or domestic ungulates can impoverish plant communities, destabilize channels, and sever hydrologic connectivity, harming habitat quality and extent for many aquatic and terrestrial species.

“Persistent, heavy grazing/browsing of streamside vegetation by either wild or domestic ungulates can lead to impoverished plant communities, channel instability and loss of hydrologic connectivity, all of which adversely affect the quality and extent of habitats for a wide range of aquatic/terrestrial biota.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Severe geomorphic change in floodplain channels can produce major ecological harm.

“The catastrophic geomorphic transformation of floodplain channels (i.e.unraveling of streambanks via accelerated bank erosion and/or incision, sometimes in conjunction with channel aggradation in downstream reaches) can have serious ecological consequences (Smith, 2004).”

• cites Smith, 2004 sourceNot checked — no full text of the source

May combine two claims.

Many riparian hydrophytes, including willows and sedges, need moist sites to establish and grow and are suited to Rocky Mountain snowmelt runoff.

“Willows, sedges and related hydrophytic plants found in many riparian systems typically require moist-site conditions for their establishment and growth and thus are well adapted to the annual patterns of snowmelt runoff in the Rocky Mountains (Braatne et al., 1996;Patten, 2000).”

• cites Braatne et al., 1996Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Patten, 2000Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

On the Little Bighorn River in south-central Montana, removing streamside vegetation through grazing and mechanical means triggered faster channel adjustments: wider channels, incision, and less sinuosity.

“Along the Little Bighorn River in south-central Montana, Beschta (1998) found that the loss of streamside vegetation by grazing and mechanical methods initiated a period of accelerated channel adjustments, including increased channel widths, channel incision, and decreased sinuosity.”

• cites Beschta, 1998Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing).

In eastern Oregon snowmelt systems, roughly 0.5 m of channel incision was enough to change riparian communities from hydrophytic to mesophytic.

“In eastern Oregon's snowmelt systems, Otting (1998) concluded that channel incision of ~0•5 m in a floodplain was sufficient to shift riparian plant communities from hydrophytic to mesophytic species.”

• cites Otting, 1998Not checked — no full text of the source

May combine two claims.

In sum, removing wolves from the Yellowstone area triggered a trophic cascade along the Gallatin River in the elk winter range, affecting elk first and then willows.

“Overall, the extirpation of wolves from the Yellowstone area has had a cascading effect on lower trophic levels (first elk and then willows) along the Gallatin River, where it flows through the elk winter range.”

May combine two claims.

Although elk numbers fell over the long term after wolf removal because of hunting, other predators, and harsh winters, streamside vegetation still kept being destroyed.

“Even though the longterm trend in elk numbers following wolf extirpation was one of decline due to the annual harvest of elk via hunting, predation by other large carnivores and the periodic occurrence of mortality during severe winters, this situation was unable to prevent the continued decimation of streamside vegetation.”

May combine two claims.

Seasonal high runoff and overbank flows supply moisture and nutrients to hydrophytic plants and keep mesic or xeric communities from colonizing streambanks and floodplains.

“This annual disturbance regime of seasonally high runoff and periodic over-bank flows is not only an important source of moisture and nutrients for hydrophytic plants (Goodwin et al., 1997) but also prevents mesic or xeric plant communities from becoming established on streambanks and floodplains.”

• cites Goodwin et al., 1997Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

Less overbank flooding and lower groundwater tables help eliminate moist-site riparian plants and shift floodplain communities toward drought-tolerant species.

“Both of these factors contribute to the loss of moist-site riparian plants and a conversion of floodplain plant communities to species that can tolerate drier conditions (Rost and Rasmussen, 2004).”

• cites Rost and Rasmussen, 2004Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• AssumptionRests on an assumption: Incision lowers groundwater tables and makes overbank flooding less frequent on nearby floodplains.

May combine two claims.

Fast-eroding banks and wider channels raise stream temperatures and remove overhanging banks that fish use for cover and refuge.

“Rapidly eroding streambanks and wider channels allow for increased stream temperatures (due to shallower depths and lack of shading vegetation along the banks) and a loss of overhanging banks typically used as cover and refugia for fish (Platts, 1991).”

• cites Platts, 1991Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

The elk winter range floodplains are now hydrologically cut off from the Gallatin River's natural flow regime, with less frequent overbank flooding.

“This indicates that floodplains within the elk winter range have become hydrologically disconnected (i.e.reduced frequency of overbank flooding) from the natural flow regime of the Gallatin River.”

• AssumptionRests on an assumption: The Gallatin River's flow regime is natural or minimally altered by human activities.

Probably not a substantial claim: may not pass S3 (load-bearing).

High flows can cause channel adjustments such as widening, incision, and avulsion.

“Periods of flooding provide a high-energy environment for the detachment, transport and deposition of sediment, thus high flows can be a factor affecting channel adjustments such as widening, incision and avulsion (Rinaldi, 2003).”

• cites Rinaldi, 2003 sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing).

Native herbivore foraging can produce significant biophysical changes in riverine systems.

“Others (e.g.Naiman et al., 2000) have similarly noted that foraging by native herbivores can cause important biophysical effects to riverine systems.”

• cites Naiman et al., 2000Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

Peak-flow magnitude changes were not the main driver of sedge-willow decline in the upper Gallatin winter range or of the channel changes that followed.

“Collectively, these factors indicate that variations in peak-flow magnitudes were not the primary cause of sedgewillow decline in the upper Gallatin winter range or of initiating the channel changes that ensued.”