Abstract
Overlap areas between encinal and pinyon-juniper woodlands on three mountain ranges in southeastern Arizona were studied in terms of selected physiographic (slope, aspect, soil coarse fragments, and soil pH) and vegetative (overstory number of stems, basal area, volume; regeneration counts and stocking) variables. Overlap areas, defined arbitrarily in this study, were those areas where oak and pinyon-juniper types mix in space, but, basal area per acre of one species group must not have equaled nor exceeded 80 percent of the total basal area recorded at the area. The purpose of the study was to find and describe factors and relationships that might account for the occurrences of overlap areas. Findings of the study might be used by natural resource managers to better understand and manage these important woodlands, including the overlap area. Slope and aspect, although not critical factors in the occurrence of overlap areas, must be carefully considered before harvesting trees on warm and steep sites because juniper is known to have higher tolerance for xeric conditions than oak. Hence, tree harvesting operations in overlap areas located on warm, steep slopes might induce the dominance of pinyon-juniper over oak in the area. Overlap areas were stonier at the soil surface than encinal and pinyon-juniper types. If a field manager wanted an overlap area to re-establish itself after tree harvesting operations, then he must look for overlap areas with stony to very stony soil surfaces. Basal area and volume of oak in overlap areas appeared to dominate over those of pinyon-juniper at some study areas. Oak trees apparently were more mature and established than pinyon-juniper trees in the overlap areas. The smaller and perhaps younger pinyon-juniper trees might indicate recent occupation of the area. It should be noted, however, that data from which this inference was based upon involved no long-term tree measurements. Regeneration of oak generally was more abundant than that of pinyon-juniper in the overlap area. If sheer numbers of plantlets or stocking would indicate eventual establishment and dominance of a species in the overlap area at a given time, then oaks might dominate over pinyon-juniper in time.
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Claims 10
Claim · model-written summary
Slope and aspect were not critical to overlap area occurrence.
Verbatim
e0“Slope and aspect, although not critical factors in the occurrence of overlap areas”
e1“oak and pinyon-juniper types mix in space”
Claim · model-written summary
Overlap areas had stonier soil surfaces than the other woodland types.
Verbatim
e0“Overlap areas were stonier at the soil surface than encinal and pinyon-juniper types”
e1“oak and pinyon-juniper types mix in space”
Claim · model-written summary
Oak basal area exceeded pinyon-juniper basal area at some overlap sites.
QuercusOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Basal area and volume of oak in overlap areas appeared to dominate over those of pinyon-juniper at some study areas”
Claim · model-written summary
Oak volume exceeded pinyon-juniper volume at some overlap sites.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Basal area and volume of oak in overlap areas appeared to dominate over those of pinyon-juniper at some study areas”
Claim · model-written summary
Oak trees appeared more mature and established than pinyon-juniper trees in overlap areas.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Oak trees apparently were more mature and established than pinyon-juniper trees in the overlap areas”
Claim · model-written summary
Smaller pinyon-juniper trees might indicate recent occupation of overlap areas.
Not reportedDirection
Verbatim
e0“The smaller and perhaps younger pinyon-juniper trees might indicate recent occupation of the area”
Claim · model-written summary
Oak regeneration was generally more abundant than pinyon-juniper regeneration.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Regeneration of oak generally was more abundant than that of pinyon-juniper in the overlap area”
Claim · model-written summary
The authors advised selecting stony to very stony overlap areas for re-establishment after harvesting.
Verbatim
e0“If a field manager wanted an overlap area to re-establish itself after tree harvesting operations, then he must look for overlap areas with stony to very stony soil surfaces”
e1“oak and pinyon-juniper types mix in space”
Claim · model-written summary
The authors advised caution when harvesting warm, steep slopes because pinyon-juniper could become dominant.
Verbatim
e0“tree harvesting operations in overlap areas located on warm, steep slopes might induce the dominance of pinyon-juniper over oak in the area”
Claim · model-written summary
The authors suggested oak might eventually dominate pinyon-juniper in overlap areas.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“oaks might dominate over pinyon-juniper in time”