Biology ETDs

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Cochiti and Bland canyons are adjacent steep-walled canyons in the Jemez Mountains. The canyons range in elevation from 6,000-8,500 ft and open into the Rio Grande Valley. The former has permanent water, the latter does not. Cochiti Canyon is constricted at its mouth and widest near its head.

The Canadian, Transition and upper Sonoran life zones are represented in the study area. Due to the variety of exposures these zones seldom occur exclusively over large areas. The varied topography, volcanic outcroppings, disturbance by man, and water supply all contribute to the extreme diversity and variety of the flora. The flora is developing under the relatively xeric influence of the Rio Grande Valley.

The local situations exposure has a greater effect on the flora than does altitude. This is indicated by the inversion of the normal altitudinal distributions of life zones. It is also indicated b the fact that opposing exposures of equal elevation usually support floras of different life zones.

Permanent water has the most immediate and dramatic effect on the flora. The mesic riparian community exists in sharp contrast, and adjacent, to the xeric communities of the canyon walls. Many species follow the riparian habitat to a point far below their normal minimal elevations. For example, Canadian zone species are found at 6,025 ft om elevation.

Cochiti Canyon is generally more mesic than Bland Canyon particularly at lower elevations. The greater mesicness of Cochiti Canyon is indicated by the comparison of the riparian floras of the two canyons. The following differences are noted: (1) the variety and frequency of mesic species is greater, (2) the width of the riparian community is greater, (3) the mesic species extend father from the stream, and (4) the mesic species occur at lower elevations in Cochiti Canyon than in Bland Canyon. The greater mesicness of Cochiti Canyon is due primarily to the protective constriction at its permanent water supply.



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Department Name

UNM Biology Department

First Committee Member (Chair)

William Clarence Martin

Second Committee Member

Howard J. Dittmer

Third Committee Member

Loren David Potter

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Biology Commons