Grizzly bear habitat analysis. Section 2: Evaluation of grizzly bear food plants, food categories and habitat
There are no author-identified significant results in this report.
Craighead, J. J.↗
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Grizzly bear habitat analysis. Section 3: LANDSAT-1 multispectral imagery and computer analysis of grizzly bear habitat
There are no author-identified significant results in this report.
Craighead, J. J.↗
An evaluation of the use of ERTS-1 satellite imagery for grizzly bear habitat analysis
Multispectral scanner images taken by the ERTS-1 satellite in August and October, 1972, were examined to determine if they would be useful in identifying and mapping favorable habitat for grizzly bears. It was possible to identify areas having a suitable mixture of alpine meadow and timber, and to eliminate those which did not meet the isolation requirements of grizzlies because of farming or grazing activity. High altitude timbered areas mapped from satellite imagery agreed reasonably well with the distribution of whitebark pine, an important food species. Analysis of satellite imagery appears to be a valuable supplement to present ground observation methods, since it allows the most important areas to be identified for intensive study and many others to be eliminated from consideration. A sampling plan can be developed from such data which will minimize field effort and overall program cost.
Varney, J. R.↗
An evaluation of the use of ERTS-1 satellite imagery for grizzly bear habitat analysis
Improved classification and mapping of grizzly habitat will permit better estimates of population density and distribution, and allow accurate evaluation of the potential effects of changes in land use, hunting regulation, and management policies on existing populations. Methods of identifying favorable habitat from ERTS-1 multispectral scanner imagery were investigated and described. This technique could reduce the time and effort required to classify large wilderness areas in the Western United States.
Varney, J. R.↗
Grizzly bear habitat analysis, section 1
There are no author-identified significant results in this report.
Craighead, J. J.↗
Radiogenic Ingrowth of 40CA from Decay of 40K Provides a Powerful Tracer for Understanding the Origins of Felsic Magmas
Over time high K/Ca continental crust produces a unique Ca isotopic reservoir, with measurable 40Ca excesses compared to Earth's mantle (ɛCa=0). Thus, values of ɛCai > 1 indicate a significant crustal contribution to a magma. Values of ɛCai (<1) indistinguishable from mantle Ca indicate that the Ca in those magmas is either directly from the mantle, or is from partial melting of newly formed crust. So, whereas 40Ca excesses clearly define crustal contributions, mantle-like 40Ca/44Ca ratios are not as definitive. Here we present Ca isotopic measurements of intermediate to felsic igneous rocks from the western United States, and two crustal xenoliths found within the Fish Canyon Tuff (FCT). The two crustal xenoliths found within the 28.2 Ma FCT of the southern Rocky Mountain volcanic field (SRMVF) yield ɛCa values of ~4 and ~7.5, respectively. The 40Ca excesses of these possible source rocks are due to long-term in situ 40K decay and suggest that they are Precambrian in age. However, the FCT (ɛCai ~0.3) is within uncertainty of the mantle 40Ca/44Ca. Together, these data indicate that little Precambrian crust was involved in the petrogenesis of the FCT. Nd isotopic analyses of the FCT imply that it was generated from 10- 75% of an enriched component, and the Ca isotopic data appear to restrict that component to newly formed lower crust, or enriched mantle. However, the Ca isotopic data do permit assimilation of some crust with low Ca/Nd; decreasing the 143Nd/144Nd without adding much excess 40Ca to the FCT. Several other large tuffs from the SRMVF and from Yellowstone have ɛCai indistinguishable from the mantle. However, a few large tuffs from the SRMVF show significant 40Ca excesses. These tuffs (Wall Mountain, Blue Mesa, and Grizzly Peak) are likely sourced from near, or within the Colorado Mineral Belt. New isotopic measurements of Mesozoic and Tertiary granites from across the northern Great Basin show a range of ɛCai from 0 to ~3. In these samples ɛCai is generally correlated with ɛSri and is broadly negatively correlated with ɛNdi. However, for granites with similar ɛNdi at a given general location ɛCai can vary significantly (1 to 2 epsilon units). In rocks where low ɛNdi could also be due to melting from enriched reservoirs in the mantle lithosphere, the combination of high ɛCai with low ɛNdi clearly identifies crustal melts.
Mills, Ryan D.↗