Abstract
Ephemeral plant biomass and density on a Sonoran Desert hill near Cave Creek, Arizona, vary relative to shrub canopy type and shrub density. Higher shrub density associated with increased elevation appears to decrease both ephemeral biGmass productivity and density, while ephemeral growth is enhanced under a shrub canopy if it is not too dense or low-hanging. Phenology of ephemerals on the desert study site shows early cool-season germination, low tolerance to heat, and early flowering when compared to shrubs and succulents in the same area. INTRODUCTION The Sonoran Desert of North America is characterized by a hot, dry climate; small mountain ranges rising out of fairly level basins, and a vegetation of shrubs, small trees, cacti and associated ephemerals. Information on desert ephemerals includes studies of germination (Went, 1948, 1949; Went and Westergaard, 1949; Capon and Van Asdall, 1967), growth and longevity (Tevis, 1958; Beatley, 1967), responses to moisture stress (Klikoff, 1966; Adams, et al., 1970) and interspecific associations with herbs (both annual and perennial), shrubs and small trees (Went, 1942; Muller, 1953; Muller and Muller, 1956; McDonough, 1963; Beatley, 1966, 1969; Cable, 1969; Harris and Wilson, 1970). The prime objective of this study was to relate ephemeral productivity and density to varying densities of shrubs in the central Arizona portion of the Sonoran Desert; in addition, phenological observations were made. STUDY AREA This study was conducted on the N side of a small desert hill near Cave Creek which lies N of the Salt River Valley in central Arizona. The hill is approximately 1.2 km wide at its base and rises 162 m above a base of 610 m elevation. The geologic substrate is composed of schist of igneous origin, and the soils, typical Aridosols, generally are shallow with small amounts of organic matter, little clay development and a layer of caliche in the lower portion of the profile. The climate of this area is desert-like, but modified by itg proximity to mountainous terrain to the N. Data taken from the Weather Bureau at Cave Creek, Arizona, show a mean annual precipitation of approximately 300 mm. Precipitation peaks occur during the summer from 1 Present address: Department of Botany, University of Rhode Island,
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Claims 6
Claim · model-written summary
Ephemeral biomass and density varied with shrub canopy type and density.
- Taxon
- Ephemeral plante0
- Interactor
- shrube0other
- Outcome
- biomass and densitye0
- Setting
- Sonoran Desert hill near Cave Creek, Arizonae0
Not reportedDirection
Verbatim
e0“Ephemeral plant biomass and density on a Sonoran Desert hill near Cave Creek, Arizona, vary relative to shrub canopy type and shrub density.”
Claim · model-written summary
Higher shrub density appeared to decrease ephemeral biomass productivity and density.
Verbatim
e0“Higher shrub density associated with increased elevation appears to decrease both ephemeral biGmass productivity and density”
Claim · model-written summary
Shrub canopy enhanced ephemeral growth when it was not too dense or low-hanging.
Verbatim
e0“ephemeral growth is enhanced under a shrub canopy if it is not too dense or low-hanging.”
Claim · model-written summary
Ephemerals germinated early in the cool season.
Verbatim
e0“Phenology of ephemerals on the desert study site shows early cool-season germination, low tolerance to heat, and early flowering when compared to shrubs and succulents in the same area.”
Claim · model-written summary
Ephemerals had low tolerance to heat.
Verbatim
e0“Phenology of ephemerals on the desert study site shows early cool-season germination, low tolerance to heat, and early flowering when compared to shrubs and succulents in the same area.”
Claim · model-written summary
Ephemerals flowered earlier than shrubs and succulents.
Verbatim
e0“Phenology of ephemerals on the desert study site shows early cool-season germination, low tolerance to heat, and early flowering when compared to shrubs and succulents in the same area.”