Arbuscular mycorrhizal fungal abundance in the Mojave Desert: Seasonal dynamics and impacts of elevated CO2

• Published in: Journal of arid environments Vol. 73; no. 9; pp. 834 - 843
• Main Authors: Clark, N.M, Rillig, M.C, Nowak, R.S
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier 01.09.2009
• Subjects: Ambrosia dumosa; Animal and plant ecology; Animal, plant and microbial ecology; arid soils; Biological and medical sciences; carbon dioxide; deserts; elevated atmospheric gases; Fundamental and applied biological sciences. Psychology; glomalin; Larrea tridentata; microbial colonization; mycorrhizal fungi; population size; proteins; roots; seasonal variation; shrubs; Synecology; Terrestrial ecosystems; vesicular arbuscular mycorrhizae; Mojave Desert; Nevada; Mojave Desert; Carbon dioxide; Larrea tridentata; Ambrosia dumosa; Compositae; Fungi; Medium enrichment; Zygophyllaceae; Dynamics; Seasonal variation; Dicotyledones; Angiospermae; Root colonization; Ecological abundance; Root; Arid environment; Increase; Glomalin-related soil protein; Woody plant; Symbiont; Protein; Extra-radical hyphae; Soils; Endomycorrhiza; Mycorrhiza; Spermatophyta; Colonization
• ISSN: 0140-1963; 1095-922X
• DOI: 10.1016/j.jaridenv.2009.03.004

Arbuscular mycorrhizal fungi (AMF) play important roles in ecosystem processes. However, little is known about AMF abundance in arid, nutrient-poor environments like the Mojave Desert of North America. We conducted two AMF studies: one examined AMF responses to elevated atmospheric CO2 at the Nevada Desert FACE (Free-Air-Carbon dioxide-Enrichment) Facility (NDFF), and the second examined seasonal dynamics at nearby sites. In both studies, AMF measurements (root colonization, extra-radical hyphal [ERH] length, and two measures of glomalin-related soil protein [GRSP]) and environmental factors (root length, soil water content, and precipitation) were measured across microsites (beneath shrubs, shrub interspaces) for two species (Larrea tridentata, Ambrosia dumosa). Elevated CO2 did not significantly affect AMF measurements. Other NDFF studies show no change in fine root production under elevated CO2 but show increased available nitrogen. We infer that additional fixed carbon under elevated CO2 is not allocated to soil resource foraging. However, AMF varied seasonally. ERH seasonally declined across species and microsites, but GRSP declined only beneath L. tridentata. Our results combined with previous results indicate that drought negatively affects AMF root colonization. Robust inter-relationship among AMF measurements only occurred between the two measures of GRSP, indicating that resources are independently allocated to different AMF structures.