Temperature, water availability, and nutrient levels at various soil depths-consequences for shallow-rooted desert succulents, including nurse plant effects. [Agave deserti; Ferocactus acanthodes; hilaria rigida]

Journal Article · Sun Oct 01 04:00:00 EDT 1989 · American Journal of Botany; (USA)

DOI:https://doi.org/10.2307/2444436· OSTI ID:7028182

Nobel, P S ^[1]

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1. Univ. of California, Los Angeles (USA)

Soil conditions were evaluated over the rooting depths for Agave deserti and Ferocactus acanthodes from the northwestern Sonoran Desert. These succulents have mean root depths of only 10 cm when adults and even shallower distribution when seedlings, which often occur is association with the nurse plant Hilaria rigida, which also has shallow roots. Maximum soil temperatures in the 2 cm beneath bare ground were predicted to exceed 65 C, which is lethal to the roots of A. deserti and F. acanthodes, whereas H. rigida reduced the maximum surface temperatures by over 10 C, providing a microhabitat suitable for seedling establishment. Water Availability was defined as the soil-to-plant drop in water potential, for periods when the plants could take up water, integrated over time. Below 4 cm under bare ground, simulated Water Availability increased slightly with depth (to 35 cm) for a wet year, was fairly constant for an average year, and decreased for a dry year, indicating that the shallow rooting habit is more advantageous in drier years. Water uptake by H. rigida substantially reduced Water Availability for seedlings associated with this nurse plant. On the other hand, a 66-90% higher soil nitrogen level occurred under H. rigida, possibly representing its harvesting of this macronutrient from a wide ground area. Phosphorus was slightly less abundant in the soil under H. rigida compared with under bare ground, the potassium level was substantially higher, and the sodium level was substantially lower. All four elements varied greatly with depth, N and K decreasing and P and Na increasing. Based on the known growth responses of A. deserti and F. acanthodes to these four elements, growth was predicted to be higher for plants in soil from the shallower layers, most of the differences being due to nitrogen.

• OSTI ID: 7028182
• Journal Information: American Journal of Botany; (USA), Journal Name: American Journal of Botany; (USA) Vol. 76:10; ISSN 0002-9122; ISSN AJBOA
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540210* -- Environment
Terrestrial-- Basic Studies-- (1990-)
AVAILABILITY
DEPTH
DIMENSIONS
ECOLOGY
GROWTH
HYDROGEN COMPOUNDS
METABOLISM
NUTRIENTS
OXYGEN COMPOUNDS
PLANT GROWTH
PLANTS
ROOTS
SOILS
TEMPERATURE EFFECTS
WATER