Sampling design and laboratory analysis
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This data was collected in 1986 as part of the Jornada Basin LTER
program.
Five plots, approximately 1 ha in size and labeled A-E, were randomly
selected from a 1.0 by 0.5 km area within a creosotebush stand. The
site area was situated on a gradually sloping east-facing alluvial
slope below the Dona Ana mountains. Creosotebush was the dominant
shrub in the area, associated with less abundant subshrubs and a
variety of small annual forbs. Thirty shrubs were selected for
sampling from each of the five plots. To test for differences in
foliage characteristics and arthropod densities between nutrient-rich
and nutrient-poor shrubs, 10 high nutrient shrubs and 10 low nutrient
shrubs were selected in each plot. Shrub nutrient status was
determined on the basis of the relative size of leaf litter
accumulations on the ground beneath shrub canopies. Ten shrubs were
selected at random from each plot prior to selecting different shrub
types in order to provide measurements of natural variability of shrub
characteristics and foliage arthropods.
Foliage arthropods were sampled from each of the 150 shrubs on May 2,
1986. Three branches were selected randomly from each shrub and shaken
into an insect sweep net. A consistent-sized branch of 50 cm in length
was sampled each time to provide a standardized sample from each
shrub, regardless of shrub size. The contents of three branch samples
per shrub were combined into one zip-lock plastic storage bag and
taken to the lab, frozen, and later sorted. Field sampling was done in
the morning at sunrise. Arthropods were classified into trophic
groups, or guilds of taxa that had similar morphological feeding
mechanisms and fed on similar food resources.
Additional Files
An additional metadata file - ltrophic.dsd.txt - from the earlier
Jornada information management system is included and may contain
useful metadata.
REFERENCES
Lightfoot, David C., and Walter G. Whitford. 1989. Interplant
variation
in creosotebush foliage characteristics and canopy arthropods.
Oecologia 81: 166-75.