Carbon Isotope Discrimination and Foliar Nutrient Status of Larrea tridentata (Creosote Bush) in Contrasting Mojave Desert Soils

• Published in: Oecologia 2004-01, Vol.138 (2), p.210-215
• Main Authors: Hamerlynck, Erik P., Huxman, Travis E., McAuliffe, Joseph R., Smith, Stanley D.
• Format: Article
• Language: English
• Subjects: Alluvial soils; Animal and plant ecology; Animal, plant and microbial ecology; Autoecology; Biological and medical sciences; Carbon; Carbon isotopes; Carbon Isotopes - analysis; Desert soils; Deserts; Ecophysiology; Fundamental and applied biological sciences. Psychology; Larrea - physiology; Larrea tridentata; Micronutrients - metabolism; Nitrogen; Nutrient status; Plant Leaves - chemistry; Plants; Plants and fungi; Regression Analysis; Sand soils; Sandy soils; Soil; Soil horizons; Soil infiltration; Soil resources; Soil water; Stomatal conductance; Temporal distribution; Water; Water potential
• ISSN: 0029-8549; 1432-1939
• DOI: 10.1007/s00442-003-1437-7

We investigated the relationships between foliar stable carbon isotope discrimination (Δ), % foliar N, and predawn water potentials$(\psi_{\rm pd})$and midday stomatal conductance$(g_{\rm s})$of Larrea tridentata across five Mojave Desert soils with different age-specific surface and sub-surface horizon development and soil hydrologies. We wished to elucidate how this long-lived evergreen shrub optimizes leaf-level physiological performance across soils with physicochemical characteristics that affect the distribution of limiting water and nitrogen resources. We found that in young, coarse alluvial soils that permit water infiltration to deeper soil horizons, % foliar N was highest and Δ,$g_{\rm s}$and$\psi_{\rm pd}$were lowest, while %N was lowest and Δ,$g_{\rm s}$and$\psi_{\rm pd}$were highest in fine sandy soils; Larrea growing in older soils with well-developed surface and sub-surface horizons exhibited intermediate values for these parameters. Δ showed negative linear relationships with % N (R²;=0.54) and a positive relationship with$\psi_{\rm pd}$(R²;=0.14). Multiple regression analyses showed a strong degree of multicolinearity of$g_{\rm s}$and Δ with$\psi_{\rm pd}$and N, suggesting that soil-mediated distribution of co-limiting water and nitrogen resources was the primary determinant of stomatal behavior, which is the primary limitation to productivty in this shrub. These findings show that subtle changes in the soil medium palys a stroing role in the spatial and temporal distribution and nitrogen resources by this long-lived desert evergreen, and that this role can be detected throught carbon isotope ratios.