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Water use and carbon acquisition were examined in a northern Utah population of Juniperus osteosperma (Torr.) Little. Leaf-level carbon assimilation, which was greatest in the spring and autumn, was limited by soil water availability. Gas exchange, plant water potential and tissue hydrogen stable isotopic ratio (deltaD) data suggested that plants responded rapidly to summer rain events. Based on a leaf area index of 1.4, leaf-level water use and carbon acquisition scaled to canopy-level means of 0.59 mm day(-1) and 0.13 mol m(-2) ground surface day(-1), respectively. Patterns of soil water potential indicated that J. osteosperma dries the soil from the surface downward to a depth of about 1 m. Hydraulic redistribution...
Cottonwoods (Populus spp.) are adapted to ripar-ian or floodplain zones throughout the Northern Hemisphere; they are also used as parents for fast-growing hybrid poplars. We review recent ecophysiological studies of the native cottonwoods Populus angustifolia James, P. balsamifera L., P. deltoides Marsh., P. fremontii S. Watson and P. trichocarpa T. & G. in North America, and P. nigra L. in Europe. Variation exists within and across species and hybrids; however, all riparian cottonwoods are dependent on shallow alluvial groundwater that is linked to stream water, particularly in semi-arid regions. This conclusion is based on studies of their natural occurrence, decline following river damming and dewatering (water...
Juniper species are noted for long-lived foliage, low and persistent gas exchange activity and drought tolerance. Because leaves and roots of the same species are thought to be similar in structure and life history, we hypothesized that Juniperus osteosperma (Torr.) Little (Utah juniper) fine roots would reflect the persistent aboveground foliage characteristic of this species. We monitored fine roots, less than 1 mm in diameter, by minirhizotron imaging to a depth of 150 cm over two growing seasons from April 2002 to December 2003. We measured fine root numbers, lengths and diameters, and noted the time of birth and death of root segments. We correlated our root data with soil water potential measured by thermocouple...
    map background search result map search result map Carbon acquisition and water use in a Northern Utah Juniperus osteosperma (Utah juniper) population. Root turnover and relocation in the soil profile in response to seasonal soil water variation in a natural stand of Utah juniper (Juniperus osteosperma).