Biology ETDs

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The Sandia Mountains are a block-fault range which attained the present height and topography during the Pleistocene epoch. The mountains are located just east of the Rio Grande in north-central New Mexico between 35° 05' N and 35° 18' N and between 106° 22' W and 106° 30' W. The general climate of the area is arid continental but there is much variation between the climate at the foot of the mountains and the climate at the crest ridge. There are four U. S. Weather Bureau weather stations within the area and a comparison is made among the weather records of these stations. The vegetation of the area has been much disturbed by fires and also by 250 years of grazing by domestic livestock. The study was made to determine the extent of vegetational disturbance as well as to determine, by inference, and to map the present and eventual distribution of the climax vegetational communities. The study was made as an aid to further studies of the biology of the Sandia Mountains area and as a part of a phytosociological study of New Mexico. The vegetational map was made from data obtained from field observations and from aerial photographs. Sampling of the forest communities was done in three strata using the 800-foot line transect method supplemented by 1-foot square quadrats. The grassland community was sampled using the 50-foot line intercept method. The area was separated into nine major communities: spruce-fir association between 10,000 and 10,600 feet elevation; mixed conifer association between 8,000 and 10,000 feet; white fir consociation occupying more mesic sites within the mixed conifer association; ponderosa pine association between 7,200 and 8,800 feet; pinyon-juniper association between 6,200 and 7,850 feet; aspen consocies in disturbed but relatively uneroded areas between 8,500 and 10,600 feet; oak consocies in disturbed and badly eroded areas above 6,800 feet; oak-grass association between 6,400 and 6,600 feet; and short-grass association between 6,000 and 6,600 feet. Bedrock on the west side of the mountains below 9,000 feet elevation is Precambrian granite and bedrock strata on the east side of the mountains are limestones, shales, mudstones, and sandstones. A correlation is indicated (1) between the SiO2-saturated bedrock and the ponderosa pine association and (2) between the fault-­controlled drainage of the east side and the seral stage of vegetational succession of disturbed areas.



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Department Name

UNM Biology Department

First Committee Member (Chair)

Loren David Potter

Second Committee Member

James Smith Findley

Third Committee Member

William Clarence Martin

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Biology Commons