Maintaining high rates of water loss during times of high resource availability could allow establishing woody desert perennials to grow quickly by allowing them to take advantage of the fleeting but abundant monsoonal moisture typical of warm deserts like the Chihuahuan. However, a plant cannot endlessly increase water loss in order to grow faster --there are hydraulic constraints on rates of water loss. The hydraulic properties of each particular plant xylem and soil microsite, as well as the AR:AL absorbing root area to transpiring leaf area ratio) interact to set limits on rates of water loss. If transpiration rates become too high, cavitation may limit the ability of the xylem to supply water to the leaves. The main objective of this study was to test two hypotheses on a population of Larrea tridentata at the Sevilleta LTER in central New Mexico (1) do small plants grow faster and use water less conservatively than large, and (2) are there differences in the hydraulic constraints on small and large plants. Measurements were made every six weeks in the spring, summer and fall from April 2002 - August 2003. Field measurements of shoot growth, gas exchange and plant and soil water potentials were made to determine growth rates and water use. Measurements of leaf specific conductance determined the ability of the xylem to supply water to the leaves. Excavation findings were used to estimate (AR:AL). Xylem vulnerability curves and soil texture analysis were used to determine the hydraulic properties of the plant xylem and soil. A model determined where the limiting conductance occurred in the plant-soil continuum.
Knowledge Network for Biocomplexity (KNB) Identifier
Data Policies: This dataset is released to the public and may be freely downloaded. Please keep the designated Contact person informed of any plans to use the dataset. Consultation or collaboration with the original investigators is strongly encouraged. Publications and data products that make use of the dataset must include proper acknowledgement of the Sevilleta LTER. Datasets must be cited as in the example provided. A copy of any publications using these data must be supplied to the Sevilleta LTER Information Manager. By downloading any data you implicitly acknowledge the LTER Data Policy (http://www.lternet.edu/data/netpolicy.html).
2002-07-01 - 2003-08-01
Location: The Five Points area emcompasses both the Five Points Black Grama and Five Points Creosote study sites. Five Points falls along the transition between the Chihuahuan Desert Scrub and Desert Grassland habitats. Both core sites are subject to intensive research activities, including NPP measurements, phenology observations, pollinator diversity studies, and ground dwelling arthropod and rodent population assessments. There are rain-out shelters for drought studies in both the Five Points Black Grama and Five Points Creosote sites.Vegetation: The Five Points Creosote site is characterized as Chihuahuan Desert Scrub, dominated by a creosote overstory, with broom snakeweed, purple pricklypear (Opuntia macrocentra), and soapweed yucca as co-occurring shrubs. The site is also characterized by numerous, dense, grass-dominated patches, reflecting proximity to the Five Points Black Grama Site. Dominant grasses are black grama, fluffgrass (Dasyochloa pulchellum), burrograss (Scleropogon brevifolia), bushmuhly (Muhlenbergia porteri), and galleta (Pleuraphis jamesii). Notable forbs include field bahia (Bahia absinthifolia), baby aster (Chaetopappa ericoides), plains hiddenflower (Cryptantha crassisepala), Indian rushpea (Hoffmannseggia glauca), Fendlers bladderpod (Lesquerella fendleri), and globemallows (Sphaeralcea spp.), siteid: 3
Medeiros, Juliana (2010): Hydraulic Constraints on Two Life History Stages of Larrea tridentata in a Chihuahuan Desert Creosote Shrubland at the Sevilleta National Wildlife Refuge, New Mexico (2002-2003). Long Term Ecological Research Network. http://dx.doi.org/10.6073/pasta/88ae09e69e69afbf54152a5d8f512ee9