NPP Study: Quadrat biomass data

Data Access: 

Unrestricted

Dataset status: 

Study number: 

11

Data set ID: 

2100011001

Date range: 

1989-05-09 to 2012-09-20

Original investigator: 

Laura Huenneke

Data contact: 

Abstract: 

These data sets contain calculated aboveground biomass values, by species, for each quadrat in each site for a given season.

They are constructed (as outlined below) from the field data which are measurements of the physical dimensions (horizontal cover, vertical height) of plants or plant parts in the quadrats.

Objective is to monitor patterns (both temporal and spatial) of aboveground biomass across a range of ecosystem types; to allow the estimation of net primary production and its variability in those ecosystems; and to provide a quantitative description of plant community structure over time in those ecosystems.

Please refer to these publications to evaluate the appropriateness of these data for your intended use prior to contacting Debra Peters, Responsible Investigator, with a data request.

    Attention: These data are not appropriate for estimates of percentage 
    cover. NPP-associated percent cover measurements were developed for 
    and are used solely to provide the best estimate of biomass production. 
    Becuase the methodology results in measurements of overlapping subcanopy 
    systems and canopies of adjacent individuals, NPP percent cover 
    measurements are not an appropriate measure of actual aerial plant cover. 
    Doing so will result in inflated numbers for the "actual" vegetative cover. 
 
    Attention: Data through 2003 was replaced online per below on 9/22/2011. 
    Analyses and results for ANPP differ from previous uses of the data from 
    1989-1998 (Huenneke et al., 2002) in three ways: 
      (1) Yucca elata was removed prior to analysis because its growth form 
          results in large errors in biomass estimates from year-to-year, 
      (2) regressions between biomass and plant volume used an intercept equal 
          to 0 to be consistent with a recent study in a similar system 
          (Muldavin et al., 2008), and 
      (3) reference harvests obtained in extreme years resulted in adjusted 
          regression coefficents through time that reflect year-to-year variation 
          in ANPP. These changes result in ANPP values that are smaller compared 
          (Peters et al. submitted) with previous studies (Huenneke et al., 2002).

Methods: 

Methods of recording (field data sheets, instrumental, etc.)
    Data set is produced by SAS program that processes field data
    sets (NPPQyys.DAT), as described below.
Methodology
    See documentation for NPP project for description of field
    sampling methods, site locations, etc.  The quadrat data from field
    sampling (NPPQxxy.dat; see dataset documentation) are used as input
    to SAS programs (NQBIOxxy SAS) that calculate the volume of each
    plant part in each quadrat as a rectangular volume (cm3) from the
    cover and height measurements; sum the volume of all plant parts
    for a species within a quadrat; use species-specific (and where
    appropriate site and/or season-specific) regressions to calculate
    aboveground live biomass for each species in each quadrat; and write
    a summary data file as output (the NQBIOxxy DAT files) that list the
    total cover, the total volume, and the calculated biomass of each
    species in each quadrat for each site.

Additional information: 

Site Location

    Fifteen sites (3 in each of 5 ecosystem types) were selected for
    monitoring of NPP.  Sites, abbreviations, and location summarized
    here and on LTER site map; directions are from stone pillars /
    gate marking entrance to Jornada Experimental Range, 6.6 mi north
    of US Hwy 70, east of Las Cruces, on North Jornada Road:

    Creosote - Caliche  C-CALI  From stone pillars, go 4.1 mi north
                                to South Well.  Turn left, drive 3.4 mi
                                to College Ranch HQ.  Turn left, drive
                                south 1.3 mi (going through gate and
                                crossing LTER transects); turn right
                                (this is 2nd right) and proceed 0.3 mi.
                                Turn left on small track; site is on
                                right (uphill) of road, 70 m from turn.

    Creosote - Gravel   C-GRAV  From stone pillars, go 4.1 mi north
                                to South Well.  Turn left, drive 3.4 mi
                                to College Ranch HQ.  Turn left, drive
                                south 3.4 mi (going through gate and
                                crossing LTER transects, passing Upper
                                Trailer).  Site is on left (E) of road.
                                OR - from stone pillars, turn left and
                                proceed 2.6 mi; turn right at gate and
                                go 0.6 mi along power line road, then
                                0.4 mi along right fork.  Site is on
                                right (E) of road.

    Creosote - Sand     C-SAND  From stone pillars, go 4.1 mi north
                                to South Well.  Turn left, drive 3.4 mi
                                to College Ranch HQ.  Turn left, drive
                                south 1.6 mi (going through gate and
                                crossing LTER transects).  Site is
                                on left (E) of road.

    Grassland - Basin   G-BASN  From stone pillars, go 4.1 mi north
                                to South Well.  Turn left, drive about
                                1 mi; park in pull-off on left adjacent
                                to fence.  Enter fence through gate;
                                site is uphill about 50 m.

    Grassland - IBP     G-IBPE  From stone pillars, go 4.1 mi north to
                                South Well.  Take 2nd left (i.e., AFTER
                                the well) and drive 8 mi (this is SW
                                boundary of Exp. Range).  IBP exclosure
                                is on left of road 0.2 mi after it
                                turns north away from boundary.
                                OR - from stone pillars, go 10.2 mi
                                north to JER HQ; past shop area, turn
                                left and go 6.4 mi to West Well.  Turn
                                left (S) and go 1.4 mi to exclosure.

    Grassland - Summerford G-SUMM       From stone pillars, go 4.1 mi
                                north to South Well.  Turn left, drive
                                3.4 mi to College Ranch HQ.  Turn left,
                                drive south 1. mi (going through gate
                                and crossing LTER transects). Turn
                                right (this is 1st right), drive 0.5 mi
                                to power line road, turn left.  Site is
                                0.3 mi from turn, uphill from power
                                line at base of rocks.

    Mesquite - North    M-NORT  From stone pillars, go 10.2 mi north to
                                JER HQ; past shop area, turn left and
                                go 2.4 mi to junction with pipe line
                                road, turn right.  Proceed 0.6 mi N.
                                Park; site is located about 400 m to
                                west inside fenced exclosure.

    Mesquite - Rabbit   M-RABB  From stone pillars, go 10.2 mi north to
                                JER HQ; past shop area, turn left and
                                go 3.4 mi to Rabbit Rain Gauge parking
                                area.  Site is to north (left) of road,
                                about 75 m, inside fenced exclosure.

    Mesquite - West     M-WELL  From stone pillars, go 10.2 mi north to
                                JER HQ; past shop area, turn left and
                                go 6.4 mi to West Well.  Stay on road
                                straight past well; site is about 150 m
                                west of well, on right of road.  OR -
                                from IBP grassland exclosure, drive
                                1.4 mi north, turn left at West Well,
                                site is about 150 m from well.

    Playa - College     P-COLL  From stone pillars, go 4.1 mi north
                                to South Well.  Turn left, drive about
                                2.5 mi to Lower Trailer (on left); park
                                there and continue on foot along road
                                to stiles over fence on right.
                                Concrete block paths lead to playa.
                                NPP grid is in western portion of
                                fenced area of playa, just east of
                                College Ranch HQ and pasture.

    Playa - Small       P-SMAL  From stone pillars, go 4.1 mi north
                                to South Well.  Turn left, drive about
                                3.4 mi to College Ranch HQ.  Proceed
                                through gate and HQ area; road jogs
                                north and then heads west again.
                                Proceed 3.8 mi from HQ; take small
                                road on left, downslope 0.4 mi
                                (through gate) to playa.

    Playa - Tobosa Tank P-TOBO  From stone pillars, drive 10.2 mi north
                                to JER HQ.  Jog to right past shop,
                                continue north 3.1 mi.  Site is to
                                right of road in fenced portion of
                                large depression.

    Tarbush - East      T-EAST  From stone pillars, drive 2.6 mi north.
                                Site is on right of road (E), in
                                fenced area.

    Tarbush - Taylor    T-TAYL  From stone pillars, go 4.1 mi north.
                                Turn right just before South Well.
                                Take jog to left (N) across cattle
                                guard, proceed east 2.3 mi.  Site is
                                on right (S) of road about 20 m in
                                fenced area.

    Tarbush - West      T-WEST  From stone pillars, go 2.4 mi north.
                                Site is on left (W) of road, in
                                fenced area.

        Each site is a grid of 49 quadrats, each 1 m x 1 m, located
        10 m from one another in a 7 x 7 square (quadrats make up
        a 60 m x 60 m square with 10 m buffer zones around boundary).
        Exception is P-COLL, where limited space forced us to use
        a 3 x 16 arrangement (48 quadrats).

Maintenance: 

Frequency of measurement

    Three times per year, February, May, and October

Long-term dataset: 

Signature dataset: 

LTER Core Area(s): 

Data category: 

LTER VI Proposal Category: