NPP Harvest Protocol: NPP Core Site Project, NPP Burn Project and Fertilizer
Plots
Generating Cover Range for Harvest Samples
After all NPP quad vegetation measurements are taken, plants of similar size classes are
harvested outside the permanent quadrats. These samples are sorted, dried and weighed
and the data is used to create regressions that estimate above ground biomass. Prior to
making harvest collections, a range of cover values is generated for each plant species
recorded at a site. In consecutive years, certain species may no longer be harvested.
Check with the PI to determine which species need to be collected. In all years and
seasons, Blue and Black grama as well as creosotebush will be harvested at their
repective sites regardless of how well the regressions do.
Collect plants from an area that is close to but not actually on the trapping webs or NPP
plots at each site. Avoid collecting plants near the roadside since these plants may have
morphologies that vary from plants on the NPP quadrats. Harvest collections are
combined for all NPP studies at the sevilleta including the NPP Burn project and the
Fertilizer plot project. Site P is collected by itself. For the rest of the sites, three types of
collections are made. Type “F” refers to forbs and is meant to represent species that do
not change growth form after fire and includes annual forbs and grasses and some short
lived herbaceous perennials. Type “U” refers to unburned hardy perennials, and type “B”
refers to hardy perennials that were burned in the 2003 fire.
A perl script, titled “npp_count_new”, looks through all the data in the palm top excel
files and creates a list of smallest and largest cover values of each species observed, as
well as the total number of individuals of each species. Make a note of species that have
only a few observations, as you will need to harvest a smaller number of samples (10) for
these species.
To run this script, first copy all excel files for a particular harvest into
pc_field/palmtop/npp. Make sure there are no other excel files in that folder. On an XWin terminal, go to this directory and type “perl npp_count_new” This will create and
output file titled “minmax”. The file can then be opened in excel. This list should be
presented to the PI to determine which species need to be harvested. Repeat this
procedure three times, once for the P data, once for the unburned sites and once for the
burned sites.
To produce a range for a species, first decide the number of samples you will be
collecting for that species. 15 samples will be collected for dominant or frequently
observed species and 10 samples will be collected for rare species. Next decide if you
will be making this range based on counts or cover measurements. The majority of
species will be based on cover measurements. Only seedlings will be based on count
measurements.
For ranges based on cover measurements, start by writing down the cover value one sizeclass below the smallest cover observed at a site. For example, if the smallest cover
observed at a site was 0.5 write down 0.25. If smallest cover value observed is 0.01 do
not go below this value. Next write down the cover value one size-class above the largest
cover value recorded at a site. These two numbers represent the largest and smallest
covers that will be harvested at a site. Within the bounds of these two numbers fill in
cover values. Ultimately you will need to end up with either 10 or 15 cover values
depending on the observed frequency of the species. Try and keep the numbers as
balanced as possible. Smaller covers will have more variability than larger covers and
thus it is best to collect duplicates of the smaller cover sizes. Also, as covers increase the
size-class increments between covers should also increase. When generating these ranges
keep in mind that the purpose of harvest samples is to produce a statistical linear
regression equation for each species at each site from which biomass will be estimated.
An example range for BOER4 that has a minimum cover of 0.05 and a maximum cover
of 11:
BOER4
1
2
3
4
0.01 0.01 0.05 0.05
5
0.1
Sample Number
6
7
8
9
0.1 0.25 0.5 0.75
10
1
11
2
12
3
13
6
14
9
For seedlings, collect multiple individuals in a single sample to account for the low
weight of each individual.
CRCR3
1
10
2
10
3
10
4
20
5
20
6
20
7
40
Sample Number
8
9 10 11
40 60 60
12
13
14
15
Bags for collections are made before you go into the field. One bag is made for each size
class or count. In general, harvests with covers between 0.01 and 0.25 are collected into
coin envelopes and larger covers are placed in paper bags. Label each bag or envelope
with the date, type (P, B, U, or F), plant species, sample number, and cover value. Leave
a blank spot for height. These labels can be generated in Microsoft and printed on
envelope labels.
Collecting Harvest Samples
Locate individual plants that correspond to the cover values written on a bag. Measure
the height of the plant to the nearest cm and write this height on the bag. For perennial
grasses, this does not include the inflorescence, but the inflorescence is put in the bag
with the rest of the sample. For shrubs and subshrubs, this does not include the bare
stems, only the foliage, but the stems are collected and placed in the bag with the rest of
the sample. Then with a pair of shears clip the foliage and place it in the bag. It is
important to collect all of the foliage and to clip it off as near to the base as possible. Do
not include any root material in the sample.
15
12
If you cannot find a natural clump of foliage of a particular cover value you may take a
sub-sample from a larger plant. This should be done only when absolutely necessary.
The most important thing to remember is that foliage harvests need to have a similar
morphology to plants measured on the quadrats. If a sub-sample must be taken try to
collect a sample that seems representative of a cover that would occur naturally on a
quadrat.
After a sample has been collected fold and/or staple the bag so that no portion of the
sample can fall out. When all the samples of a species have been collected, indicate that
the collection of that species is complete on the Harvest Data sheet. Place the samples
into a large plastic garbage bag and try to keep them in a cool location until you are able
to store them. Store the samples in refrigerators at 4° C until sorted.
Sorting Harvest Samples
Remove the stored bags from the refrigerator and empty the contents of a single bag onto
a large tray or newspaper. Make sure to empty the bags completely of all inorganic
material as well. Pick through the foliage and separate live stems, leaves and
inflorescence from dead material. For Winter, consider only green material as live and
discard yellow, brown and gray material. For Fall and Spring, consider green and yellow
material as live material and any brown or gray material as dead. All reproductive
material from the current year should remain with the sample. Winter measurements are
meant to represent baseline live material that stays active year-round. For shrubs, three
separate bags should be made, one for foliage, one for reproductive parts and one for
woody stems. When you have finished sorting live from dead, place the live material
back in the original bag and discard the dead material. Bags containing sorted material
are then placed in a drying oven located at the Sevilleta field station. Dry the bags for 46 days at 50° C or until completely dry. It usually takes 6-10 days for cacti to dry in the
oven and the samples should be dried separately from other samples. Before placing
cacti in the oven perforate them several times with a knife to promote the escape of
moisture. Remove the bags with the samples from the oven when they are completely
dry. The plants should be very brittle. Store the plants in a dry location until weighed.
Weighing Harvest Samples
Try to weigh the samples as soon after drying as possible so that the do not re-absorb any
moisture. Sort the bags by species and site so that these can be weighed at the same
sitting. Remove the sample from the bag and place it into a tarred tray. Make sure that
no portion of the plant remains in the bag. Weigh the sample to the nearest centigram.
Record the date of collection, type (P, B, U, or F), plant species, sample number, cover
value, height and weight into the Sevilleta LTER NPP Harvest Mass Data book. Set the
sample aside. For the dominant species at each site, combine the dry material and retain
50g for a voucher specimen. Discard any excess material. Place the voucher specimen
into a paper bag labeled voucher with the date of collection, type, plant species, and
approximate weight of the sample. Give these vouchers to the lab manager. Emptied
paper bags should be folded and kept for future reuse.
1) Plant Harvest Tools and Supplies:
regression lists
unknown plant code history log data book
plant species list
harvest protocol
labeled envelopes and paper bags
3-meter measuring tapes
Niners
plexiDecs
plant clippers (pruning shears, and grass-cutters)
garbage bags
Sharpie markers
Trap bags to carry supplies
2) Sorting, Drying, and Weighing Tools, Supplies, and Equipment:
weight data books
protocol description
refrigerator (large)
drying oven (large)
scale (0.01 gram)