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ARS Home » Southeast Area » Dawson, Georgia » National Peanut Research Laboratory » Research » Publications at this Location » Publication #127308
Title: PHYSIOLOGICAL, MORPHOLOGICAL, AND ENVIRONMENTAL VARIATION AMONG GEOGRAPHICALLY ISOLATED COTTONWOOD (POPULAS DELTOIDES) POPULATIONS IN NEW MEXICO

Author
item Rowland, Diane
item BEALS, LUCILLE - UNIVERSITY OF MEXICO
item CHAUNDRY, AMINA - UNIVERSITY OF MEXICO
item EVANS, ANN - UNIVERSITY OF MEXICO
item GRODESKA, LARRY - UNIVERSITY OF MEXICO

Submitted to: Western North American Naturalist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/2/2002
Publication Date: 12/1/2002
Citation: -

Interpretive Summary: Cottonwood forests along the middle Rio Grande in New Mexico are expected to disappear within the next fifty years due to extensive damming and channelization. This study characterized the physiological stress that different populations within this river system are experiencing. There was large variability among populations in several environmental, gas exchange and leaf morphological characteristics. These observations are important for describing the ecology of these forests and may be used in future reclamation efforts.

Technical Abstract: Southwestern riparian areas have numerous plant species that are experiencing radical changes in water availability due to construction of dams in these areas, and thus, their ability to respond to such changes is critical. One such species likely to be greatly affected by these hydrological changes is Populus deltoides (cottonwood) because it relies heavily on groundwater and river surface volume, both of which have been extremely impacted by impoundments along southwestern rivers. To understand how New Mexico populations of cottonwood may respond to environmental changes, we quantified environmental, physiological, and morphological variation among four cottonwood populations. Significant differences among study sites in water availability were indicated by both soil and groundwater salinity and by groundwater depth and amount. The northernmost site, at Abiquiu, had the highest salinity levels in both soil and groundwater, followed by Bernardo, while San Antonio and Corrales sites had the lowest soil salinity. As expected, variation in physiological and leaf morphological characters existed among the tree populations, most likely in response to environmental factors. Midday xylem pressure potentials indicated that Abiquiu individuals suffered the greatest water stress and had the highest transpiration levels. Because of high specific leaf weights and high photosynthetic levels, cottonwoods at Corrales may better mitigate lower water availability. Such physiological and morphological trait variability among populations is