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Geology topics

M. L. Scott

Publications and source records attributed to M. L. Scott.

At least 37 records · Page 2Linked to original sources
USGS1997

Constraints on establishment of plains cottonwood in an urban riparian preserve

Plot sampling and hydraulic modeling were combined to investigate establishment and survival of plains cottonwood along Boulder Creek, an urban stream on the Colorado Plains. We tested the hypothesis that establishment is limited to bare, moist surfaces produced by spring flooding in the current year. No cottonwood germination was observed in 1989 when peak flow was low. A moderate peak of 11.9 m 3 /s in 1990 resulted in cottonwood establishment on surfaces inundated by discharges less than 15 m 3 /s. Surviving sapling cottonwoods established before 1989 occurred on surfaces inundated by discharges of 15–31 m 3 /s and dated to years with peak flows over 15 m 3 /s. Since 1969, establishment of cottonwood has been limited to a floodplain 21 m wide. Flow regulation and channel stabilization upstream and downstream of the study area have reduced the channel movement and overbank flooding that otherwise would have created bare, moist sites suitable for cottonwood establishment across a wider area. GIS analysis of aerial photographs shows that between 1937 and 1992 the channel has not moved and forest has encroached upon formerly open areas near the channel. A terrace, 317 m wide, is now dominated by trees that can reproduce in the absence of disturbance, especially the exotic crack willow.

Colorado↗
USGS1990

Synthesis of soil-plant correspondence data from twelve wetland studies throughout the United States

This report synthesizes the information collected for the U.S. Fish and Wildlife Service in a series of 12 studies designed to describe the relation between soils and vegetation in wetlands located in 11 States throughout the United States. Results of the study demonstrated almost complete agreement between hydric soils and hydrophytic vegetation. However, agreement between nonhydric soils and nonhydric vegetation was not as high because most nonhydric soils lay adjacent to the wetland boundary. There was some evidence that various vegetation layers describe the hydrophytic nature of the vegetation differently than others. Herbaceous species seem to reflect current hydrologic conditions while trees may reflect past hydrologic conditions. Wetland indicator categories for some plants listed in the Fish and Wildlife Service national list of plant species that occur in wetlands may need to be reevaluated as additional data become available. Similarly, soils listed in the Soil Conservation Service hydric soils of the United States list should always be verified in the field prior to assigning them to a hydric category. While wetland hydrology is the critical factor determining wetlands, the use of soils and vegetation are frequently adequate for designating wetland conditions.

Report↗
USGS1985

Plant water status relationships among major floodplain sites of the Flathead River, Montana

Water status measurements of dominant species from major floodplain plant community types of the North Fork Flathead River, Montana were used to test the accuracy of site moisture gradient relationships postulated from floristic ordinations and site water balance estimates. Analysis of variance tests showed significant differences among the average predawn xylem pressure potential (ψp) of species in several community types. However, additional analyses failed to indicate a significant degree of association between averaged predawn Yp measurements and either floristic ordination or site water balance results. Sixty eight percent of 22 trials comparing the diurnal average ψp of the same species in different community types on the same day were less negative for a species in the wetter community types as predicted by floristic ordinations. Similarly, 64% of the trials indicated that the diurnal average stomatal conductance was higher for a species in the wetter type. These results suggest that although a floodplain moisture gradient exists, it alone does not limit the distribution of floodplain plant communities in the North Fork.

Montana↗
USGS1983

Methionine and cystine requirements of rainbow trout

Methionine and cystine requirements of rainbow trout (Salmo gairdneri) were studied by supplementing a 35% protein semipurified basal diet with these amino acids at graded levels in a factorial design. In experiment 1 (initial average weight of fish, 1.5 g), methionirie levels were 0.30, 0.45, and 0.60% of the diet and cystine levels were 0.04, 0.15, 0.30, 0.45, and 0.60%. In experiment 2 (initial average weight of fish, 8.8 g), methionine levels were 0.55, 0.75, and 0.95% and cystine levels were 0.04, 0.08, 0.12, 0.16, 0.24, and 0.32%. Methionine requirement was estimated to be between 0.55 and 0.75% in the presence of adequate dietary cystine and the cystine requirement was about 0.30% with a diet marginally deficient in methionine. The requirement for both sulfur amino acids was, therefore, between 0.85 and 1.05% of the diet or 2.50 and 3.00% of the protein. Molar efficiency of conversion of dietary methionine to cystine was highest (80%) when the diet was deficient in methionine; this efficiency decreased as levels of dietary methionine increased. Bilateral cataracts occurred in methionine‐deficient but not in cystine‐deficient trout.

Progressive Fish-Culturist↗