East and west boundary fence plant line intercepts - percent cover for all species beginning 1986

Data Access: 

Unrestricted

Dataset status: 

Study number: 

120

Data set ID: 

210120001

Date range: 

1986-09-24 to 2005-10-29

Original investigator: 

Walter G Whitford

Data contact: 

Abstract: 

BACKGROUND.

In the spring of 1982, as part of the establishment of the Jornada Long-Term Ecological Research site in southern New Mexico, a 135 ha portion of a 1500 ha, internally drained, watershed was exclosed from grazing by domestic livestock. Prior to exclosure the watershed, as well as the rest of the Jornada basin, had been moderately to heavily grazed for the past 100 years. Concurrent with grazing, the vegetation had undergone a dramatic change from desert grassland, with an almost continuous cover of C4 perennial grasses, to isolated patches of the original grassland in a mosaic with desert shrub dominated plant communities (Buffington and Herbel, 1965). The exclosure lies along a northeast facing piedmont slope at the base of a steep isolated mountain peak, and covers a variety of component landforms from the foot of the mountain to the basin floor. This provided the opportunity to investigate the response of vegetation with respect to landscape characteristics as well as release from grazing. This summary data set consists of percent cover of all perennial plant species from the plant line intercept measurements on either side of the LTER-I exclosure East and West boundary fence. Data is sorted by treatment (grazed, ungrazed), year, fence line, station, then species i.d. Along the East Boundary fence line, the east side is ungrazed (control) and the west side is grazed (treatment). Along the West Boundary fence line, the east side is grazed and the west side is ungrazed. Each plant line transect is divided into 6 5-meter segments. All perennials were measured at about 5 year intervals as the length of intercept for each species along a 30-meter line oriented perpendicular to the fence. Summary data presented in this data set is the average percent cover for the outer-most 2 5-meter segments for the respective treatment (grazed or ungrazed). The term outer-most is relative to the fence. The 5-meter segment on either side of the fence is not included in the cover estimates due to fence line effect disturbances; e.g., cattle trails, tumbleweeds trapped along fence, etc. This summary data does not include the first year of measurement in 1982 because of numerous problems with species codes used that could not resolved.

Data download: 

Methods: 

 1982 and 1986 data recorded using field data sheets.
 1992 and 1998 data recorded on audio tape and transcribed to floppy disk.
 2005 data recorded using Sony digital voice recorder

 METHODS
 1. Permanently marked 30m line transects were located at about

 50m intervals along the two parallel long axis fences of the LTER
 exclosure which begins immediately above the College Playa and extends
 toward Mt. Summerford. This is the northern portion of Pasture 10 of
 New Mexico State University Chihuahuan Desert Rangeland Research Center
 (formerly known as College Ranch). These fences run approximately north
 to south (NNE to SSW) up the slope of the watershed, traversing the
 component landforms characteristic of the bajadas of the Basin and Range
 Province. The line transects are perpendicular to the fences and cross
 them at a fence post (either T-post or wood post) on the downslope side.
 They are thus perpendicular to the direction of major drainage flow.
 The line transects are identified by an aluminum tag wired to the fence
 post. The letter on the tag i.d. identifies the fence (E=East or
 W=West); the number is the station number (East: 1-30; West: 1-31).

 Canopy cover of only perennial species intercepted by
 a line stretched the length of the 30-meter line transect are measured
 and recorded for each of 6 5-meter segments. The ends of the line
 are anchored by 3/8" rebar extending about 6 inches out of the ground.
 When measurements are to be made, a length of clothesline is stretched
 between the two rebar so it is taut. Before making readings, ensure
 the line is freed from obstructions so it is perfectly straight
 between the two rebar. This may require threading the line through
 large plants or lifting free where sections are snagged.

 The clothesline used is pre-stretched overnight when new to
 minimize changes in length when stretched tight in the field. It is
 marked in 5 meter increments with enamel paint to indicate segment
 lengths. The length of the line should be checked before beginning a
 new season of measurements to ensure that stretching has not distorted
 the line.

 Data is recorded by identifying the Station number (metal tag is

 located on fence post) and Segment number. The 5-meter segments are
 numbered 1 through 6 beginning at the west end of the line (right end if
 facing upslope). Length of each plant species that is intercepted by
 line is recorded. Multiple readings (intercept observation) can occur
 for a single plant if vegetation is broken up with open areas along the
 line intercept. Beginning and end of each new 5-meter line segment is
 identified as it is encountered. Plant species are recorded as a 4
 letter acronym consisting of first 2 letters of genus and first 2
 letters of species epithet. If a duplicate acronym results for 2
 different species, generally the 3rd letter of the species epithet is
 then used. Acronyms used are found in the Plant Checklist for the
 NSF/LTER Jornada Sites.

Quality assurance: 

 Data sheets were used to record the field data through Week 247.
 Analog tape recorders were used for Week 559 and 876. Sony digital
 voice recorders were used beginning with week 1240. This data was
 entered and processed using several programs. INPUT.EXE (Fortran) is
 used to input tape recorded data. CONVERT.EXE (Fortran) is used to
 convert the entered tape recorded data to a format that matches that
 entered from data sheets. SRELCHEK.EXE (QuickBasic) error checks data.
 Data is separated into 4 files consisting of the grazed and ungrazed
 segments 1, 2, 5, and 6 of both East and West fence lines. LTERCOVR.EXE
 (Fortran) is then used to process each of the 4 files, which calculates
 mean percent cover for each species for each treatment (grazed,
 ungrazed) on each 30-meter plant line transect based on the 2 5-meter
 segments furthest from the fence. The 2 5-m segments next to the fence
 (segments 3 and 4) were not included in the calcuations because of
 possible fence line effects resulting from cattle trails, tumbleweeds
 that pile up along the fence, etc.

Additional information: 

In the spring of 1982, as part of the establishment of the Jornada Long-Term Ecological Research site in southern New Mexico, a 135 ha portion of a 1500 ha, internally drained, watershed was exclosed from grazing by domestic livestock. Prior to exclosure the watershed, as well as the rest of the Jornada basin, had been moderately to heavily grazed for the past 100 years. Concurrent with grazing, the vegetation had undergone a dramatic change from desert grassland, with an almost continuous cover of C4 perennial grasses, to isolated patches of the original grassland in a mosaic with desert shrub dominated plant communities (Buffington and Herbel, 1965). The exclosure lies along a northeast facing piedmont slope at the base of a steep isolated mountain peak, and covers a variety of component landforms from the foot of the mountain to the basin floor. The northeast side of the exclosure is immediately upslope of the College Playa located near the NMSU College Ranch. Permanently marked 30m line transects were located at 50m intervals along the two parallel long axis fences of the exclosure. These fences run from north to south (more or less) up the slope of the watershed, traversing the component landforms characteristic of the bajadas of the Basin and Range Province. The transects are thus perpendicular to the direction of major drainage flow. There are 31 30-meter line intercepts located along the west boundary fence and 30 30-meter line intercepts located along the east boundary fence. Line intercepts are located at every 5th fence pole (except where noted) starting near the ranch headquarters access road which passes by the playa. Fence poles are not marked and transects E01 and W01 are located several fence poles south of the road. [W04 is 6 posts from W03; W19 is 4 posts from W18.]

Each line intercept is 30 meters in length and divided into 6 5-meter segments; 3 segments of each line (15 meters) are inside the fence and ungrazed, the other 3 segments are outside the fence and is subject to grazing when pastures are stocked. Segments are numbered 1 - 6 beginning from the west end of the line (or if facing upslope while standing at the fence, segment 1 begins at the end of the intercept line to your right).

Maintenance: 

6 year intervals

Long-term dataset: 

Signature dataset: 

LTER Core Area(s): 

Data category: 

LTER VI Proposal Category: 

DOI: 

10.6073/pasta/196c6ce34e