©The Pellet Acre
Carolyn E. Eppler, Arizona, 1998

Purpose of the Pellet Acre: The purpose for creating this plant inventory method is not to replace other methods of evaluation. Rather, to step outside the transect to capture a representation of all plants within a site to display nature’s possibilities and diversity.

Method Used:
Modified Relevé – In our manuscript, we refer to this as the: “Pellet Acre” (PA)
The handbook used as a basis to create this modified plant inventory method: “A Handbook for collecting Vegetation Plot Data in Minnesota: The Relevé Method”.

PA Data sheets, GPS unit, Camera, field looking glass, 200 foot and 100 foot tapes to delineate measured sections within the plot.
The Pellet Acre – round to 210 ft. x 210 ft.
The ½ Pellet Acre – round to 105 ft. x 210 ft.

Classification of upland plant communities across different aspects and elevational gradients, including species abundance and relative basal plant species abundance and cover are recorded. In addition, species are classified over two seasons within the same year, Spring and Fall. Wetland plant communities may be evaluated using this method. A species unique multiplier is used where certain plants have numerous fruiting stems within a given area creating a unique patch.

For example, the bush muhly grass growth can be evaluated based on the number of times a square foot of plant material is observed. In the case of a subshrub such as false mesquite, the plants growth can be evaluated based on the number of times a 3x3 square foot section of plant material is observed, with an estimate of 35 fruiting stems per square foot or in a 3x3 square foot section, 315 fruiting stems.

Cover Determination:
Both ocular and mechanical measurements are used. Cover or abundance is determined by ocular estimates that are based on actual counts of fruiting stems per square foot (mechanical evaluation). In addition, plants that are easily counted are done so using mechanical measurements (tape delineation and actual counting of each plant).

Though some believe a broad category for recording cover is appropriate for describing species that vary greatly in cover from season to season (to avoid a false sense of exactness in an ephemeral variable); a finer scale is used in the Pellet Acre method to detect fine-scale variation in species cover over time, including a unique species multiplier. This multiplier, as described above is determined by individual species growth characteristics.

General Information:

Biotic Community types: Sonoran Desertscrub, Desertscrub, Semidesert grassland, Grassland, Interior Chaparral, Madrean evergreen woodland and/or chaparral, Montane Conifer Forest, Montane Conifer Forest and Montane Scrub, Great Basin Woodland, Subalpine Conifer Forest, Timberline, Alpine Tundra.

Plant Community Types:
(general characterization of vegetation)
Creosote/ambrosia, etc

Plant Species remarks codes:
DD = dead (litter or remnants) LU = luxurious growth
DY = dying 00 = poor vitality
EX = being driven out DT = Dormant
BU = budding MS = multiple stemmed
BR = browsed MW = mowed
DF = defoliated OG = open grown
FL = flowering PF = past fruiting
FR = fruiting SE = present as seed
FS = fire scattered ST = sterile
GE = germinating SD = seedling
GR = grazed  
IN = Introduced in Arizona OP = just outside plot (< 2 yards)
RA = rare in Arizona  
Life Form:
A = annual C = climbers
B = broadleaf evergreen D = broadleaf deciduous
E = needleleaf evergreen G = graminoids
H = forbs L = lichens & mosses
K = stem succulents P = biennial or perennial
X = epiphyte (grows upon another) R = half-shrub
T = cactus S = shrub
1 = growing singly 4 = small colonies, broken mat
2 = small dense clumps 5 = extensive mat
3 = large group, many plants 6 = thickets
Reliability Codes:
0 = very certain 4 = cf. species
1 = cf. var./subsp. 5 = Genus certain
2 = species certain 6 = cf. genus
3 = species complex 7 = Unknown
(cf. = confer or appears to be, shows likeness to)
It is not possible to identify with certainty all of the plant specimens in a study plot, because some of the plants will lack taxonomic characters (i.e. flowers, mature fruit).
Pellet Acre Cover Classes:
[PA] Pellet acre =1 sq. inch [K50A] Kilo50acre 50 x 50 or 2,500 sq. ft.
[MA] Milli1acre 1 sq. ft. [K100A] Kilo100acre 100 x 100 or 10,000 sq. ft.
[CA3] Centi33acre 3 x 3 or 9 sq. ft. [K225A] Kilo225acre 150 x 150 or 22,500 sq. ft.
[CA10] Centi1acre 10 x 10 or 100 sq ft. [K40A] Kilo40acre 200 x 200 or 40,000 sq. ft.
[CA25] Centi25acre 25 x 25 or 625 sq. ft. [KEA] entire acre (rounded)

Discussion: A review of the above mentioned handbook provided direction in the design of the Pellet Acre. With the objective of the study to describe or characterize vegetation:

in two seasons within the same calendar year;
within fragmented landscapes;
within minor plant community types – which are often undersampled in objective plot placement;
within minor plant community types – which are often undersampled in objective plot placement;
to capture variation and diversity within a particular management area;
and the influence of interactions within the natural environment to growth, natural mortality, recruitment, and resilience; and
within an anthropogenically disturbed area (cattle grazing or recreation) to demonstrate whether this disturbance is negative or positive;
Subjective Plot Placement
The use of subjective plot placement was selected with a focus on capturing the full range of variation in vegetation in the study areas.

Probability Statistics
With others’ data already available that is suitable for analysis using probability statistics, the study focused on classification techniques.

The data may be repeatable as the plot locations are recorded using GPS units, and landscape photos as well as plant species close-up photos are included in the data sets. The resolution of the data collected was according to the Pellet Acre method.

Need for Additional Plots
Upon completion of the data collection, we found that additional plots to document the numerous variations in vegetation and minor plant community types would be useful. Our hope is that other researchers will continue this effort to more distinctively classify and document plant diversity, resiliency, and response to change over time and within seasons.

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