Hackberry
Page 1.
Introduction: discussion of classification, seral assignment and monitoring.
Page 2.
Graph.
Page 3.
Instructions: plot setup and data collection using the Excel spreadsheet.
Page 4.
References.
Caution
Hackberry.xls is an Excel workbook containing the datasheet for field data collection. Copy the Excel file to a
PDA. The .xls file will be converted to a Pocket Excel file with a .pxl extension. The file contains a
spreadsheet with formulas that provide calculations necessary for classification of a site, using the variables
defined for this ecological type.
Be careful with the spreadsheet when loaded on a PDA. Although the formulas and cells are protected on the
PC version of Excel, protection of spreadsheets/worksheets is not an option on the Pocket version of Excel. It
is possible to erase formulas and stop the classification system. Be sure to make changes only within the empty
cells, and not in any of the calculation or formula cells such as cov%, probabilities, etc.
In addition, always:
•
Keep a backup copy of the original ‘Hackberry.pxl’ file on your PDA and,
•
Save the file under a new name after finishing data collection on each site, e.g. ‘Hackberry site1.pxl’,
‘Hackberry site2.pxl’…….. to avoid overwriting previous files with data.
Monitoring Seral Stages in Hackberry-Prunus-Snowberry Ecological Type
Classification, seral assignment, and monitoring of Hackberry-Prunus-Snowberry ecological type seral
stages is according to the method of Uresk (1990). Statistical analysis of field-collected data indicates the
presence of four seral stages: early, early intermediate (EINT), late intermediate (LINT) and late. A site is
classified, and assigned to a seral stage by entering a set of key plant measurements into the set of canonical
discriminant functions developed for this ecological type and estimating posterior probability for each seral
stage (SPSS, 1995). The site monitored is assigned to the stage with the highest posterior probability (See
Hackberry.xls program for methods).
For the Hackberry-Prunus-Snowberry ecological type the key variables are the basal area of trees in square
feet per acre for Celtis occidentalis (CEOC), and the percent canopy cover of Prunus spp. (PRUN) and
Symphoricarpos occidentalis (SYOC), using Daubenmire’s (1959) canopy cover method.
The seral stage assigned to a set of plant measurements is always associated with the greatest probability
value. If that value is 1, then succession is at the middle of the assigned seral stage. If the greatest probability
value is less than 1, then the second greatest probability value is used to determine the successional status
relative to middle of the assigned stage. For instance, if the second greatest probability is associated with an
earlier seral stage, succession is at the lower end of the assigned seral stage. On the other hand, if the second
greatest probability is associated with a later seral stage, succession is at the upper end of the assigned stage
(see example below).
When permanent macroplots are established to assess the vegetational trend of a site, re-sampling and
comparing the previously assigned seral stage to the current stage provides information about succession or
retrogression. On a finer scale, within-stage changes in vegetation successional status can be quantified by
comparing the probability values. For example, first-year field measurements collected for basal area of
hackberry and canopy cover of Prunus and snowberry on a site resulted in the following values: CEOC=4,
PRUN=15, and SYOC=17. Four years later the values obtained were: CEOC=4, PRUN=24, and SYOC=13.
Calculating the probabilities, we find:
CEOC PRUN SYOC
LATE LINT
EINT
EARLY
Stage
Year1
4
15
17
.000
.000
.689
.311
EINT
Year5
4
24
13
.000
.000
.982
.018
EINT
Difference
In both years, the site was classified and
assigned to the early intermediate seral stage;
the greatest probability values (.689 in Year1
and .982 in Year5) are associated with EINT.
Placement within the early intermediate seral
stage is at the lower end of the stage, as
indicated by the second greatest probability
values (.311 for Year1 and .018 for Year5)
which are associated with an earlier seral stage
(ERLY).
The site shows an upward
successional change of about .29, which is the
difference between the probabilities in Year1
and Year5.
.293
Late
Early
Year 1
1.0
.5
Late
1.0
.5
1.0
1.0
.5
Early Intermediate
.98
Late Intermediate
Early
Year 5
1.0
.5
Late
The figure to the right illustrates this example.
These quantitative changes in the probabilities
can be used to evaluate and monitor the effects
of management alternatives.
Early Intermediate
.69
Late Intermediate
1.0
.5
1.0
Early Intermediate
.29
Late Intermediate
1.0
.5
Early
Change
1.0
.5
1.0
.5
1.0
.5
1.0
Page 1 of 4
Monitoring Seral Stages in Hackberry-Prunus-Snowberry Ecological Type
Hackberry-Prunus spp-Snowberry
Ecological Type by Seral Stage
70
60
Basal Area>1"
Prunus Cover
Snowberry Cover
60
50
40
40
30
30
20
20
10
Canopy Cover (%)
2
Basal Area (ft /acre )
50
10
0
0
LATE
L.INTERMEDIATE E.INTERMEDIATE
EARLY
Mean Values
Hackberry BA (ft2/a)
*Prunus spp (%)
Snowberry (%)
51
7
8
1
64
0
3
24
7
7
17
32
Mean variables of plant species through four stages of succession in a Hackberry-Prunus spp.Snowberry ecological type. Smoothed lines connect the means for each key plant species at each
stage. Graph provides a guide for an approximate mixture of species variables at each seral stage.
*American plum (Prunus americana) and chokecherry (Prunus virginiana)
Page 2 of 4
Monitoring Seral Stages in Hackberry-Prunus-Snowberry Ecological Type
DATA COLLECTION,
30m
SUMMARIZATION
OR
40m
10m
20m
40m
40m
20m
30m
30m
AND
30m
CALCULATIONS
VEG TYPE LIMITS
Hackberry
Enter DBH only
1.2
3.1
1.4
2.7
7.1
3.2
3.4
1.5
1.5
2
3.6
1.9
3.4
Basal
Xsect Frm
1
8
2
6
40
8
9
2
2
3
10
3
9
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
4
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
PRUN SYOC
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
cov%
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
cov%
Mean
cov%
4
1
3
1
4
3
3
1
2
1
2
1
4
1
2
5
6
3
2
TRANSECT
1. Within the Hackberry-Prunus-Snowberry type, establish a
permanent plot with an area of 800m2. Ideal plot
dimensions are 20m x 40m; however, on some sites it may
be necessary to use two 10m x 40m plots. Along the plot
boundaries, establish two 30m transects, a minimum of
20m apart. (See figure above)
Enter Daubenmire classes 1 through 6
DBH BA
PLOT LIMITS
Recommendations are to monitor two sites per section
(640 acres) within the ecological type. Sites should be at
least ¼ mile apart.
2
5
2
4
1
1
2. Using the ‘Hackberry.xls’ spreadsheet (see figure at left)
installed on your PDA:
5
Record the DBH in inches of each Celtis occidentalis
(CEOC) tree 1” or greater diameter within the 800m2 plot.
2
2
Record canopy cover of Prunus spp. (*PRUN) and
Symphoricarpos occidentalis (SYOC) within a 20cm x
50cm quadrat at one-meter intervals along each transect
(30 readings/transect) using Daubenmire (1959) class
codes 1 through 6. *American plum (Prunus americana) and
3
1
1
1
1
19
2
4
1
2
5
6
3
1
1
12
1
chokecherry (Prunus virginiana).
Class Code
1
2
3
4
5
6
4
1
4
1
1
2
2
5
3
1
2
5
2
2
3
1
3
1
3
3
5
2
2
19
1
15
15
Seral Stage Classification Posterior Probability
LATE LINT
EINT
ERLY
0.00
0.00
0.69
0.31
Cover Class
>0 - 5%
5 - 25%
25 - 50%
50 - 75%
75 - 95%
95 – 100%
Mid Point
2.5%
15%
37.5%
62.5%
85%
97.5%
The spreadsheet calculates basal area for each tree and for the
site, and mean percent canopy cover for snowberry for each
transect and for the site. It also provides classification
probabilities by seral stage and the seral stage assignment.
‘Hackberry.xls’ Calculations
Basal area per tree (in inches) = DBH2 / 4 x 3.14.
17
BA (ft2 / acre) = Sum basal of all trees on plot, divided by 144 to
convert basal in inches to basal in feet. BA (ft) x 5.06 converts BA
per 800m2 to BA per acre.
Assigned Stage
EARLY INTERMEDIATE
Cover (%) = Sum of Daubenmire cover class midpoint values for
each species per transect, divided by 30. Site cover = mean cover of
the 2 transects.
Page 3 of 4
Monitoring Seral Stages in Hackberry-Prunus-Snowberry Ecological Type
REFERENCES
Daubenmire, R. 1959. A canopy-coverage method of vegetational analysis. Northwest Science.
33(1):43-64.
SPSS 12.0 for Windows. 1989-2003. SPSS Inc. 444 N Michigan, Ave, Chicago, IL 60611.
Uresk, D. W. 1990. Using multivariate techniques to quantitatively estimate ecological stages in a
mixed grass prairie. J. Range Mgt. 43(4):282-285.
Page 4 of 4