Forty Years of Forest Development in the Calvin College Ecosystem Preserve
Jonathan Knott, David Postma, and Dr. Randy Van Dragt
Department of Biology, Calvin College, Grand Rapids, MI
Background
• Identify, measure, and map all trees >2” DBH in the
original and new quadrats.
• Count saplings and shrubs in the original quadrats.
• Measure light level (PAR & Sunfleck) in the original
quadrats.
• Analyze growth, demographics, and composition based
on year (1974 vs. 2014) and location (new vs. original
quadrats) at the community level.
Methods
Area of study:
• The CCEP grid of 100 – 20x20 meter quadrats: 43 in
1974 (1.7 ha total), 7 added in 1989 (2.0 ha total), 50
added this year (4.0 ha total).
DBH Measurements:
• All trees >2” DBH were measured at 1.3m and 1.5m
above ground.
• Trees were recorded on maps by size class (2”-3.9”
DBH or >4” DBH) and quadrat (Original or New).
Sapling Counts:
• All woody-stemmed plants >12” tall and <2” DBH were
counted in the original quadrats and identified by
species to estimate future forest composition.
Light Measurements:
• PAR and Sunfleck were measured at four points in each
quadrat using a Decagon AccuPAR LP-80 ceptometer.
Percent Composition
Importance Value
30%
25%
20%
15%
10%
5%
0%
E
W
S
Four size classes: saplings (top left), 2”-3.9”
trees (top right), >4” trees (bottom left),
and >12” canopy trees (bottom right).
1974
Map of the CCEP grid (left): Green 1974 quadrats; Purple quadrats
added in 1989; Red quadrats added in 2014. Example quadrat map
(right): Past measurements in black, new data recorded in red.
1974
1206
23
0.834
2014-Original
1183
21
0.815
2014-New
1440
22
0.869
Table 1: Counts, Species Richness, and Simpson’s Diversity
Index for three samples: 1974, 2014 Original, and 2014 New
quadrats. Simpson’s Diversity Index and Species Richness
calculated based on trees >2” DBH.
60%
57% 55%
Fagus grandifolia (Beech)
50%
40%
30%
24%
20%
1974
20%
12%
2014
18%
10%
3%
8%
0%
Saplings
2"-3.9"
DBH
4"-11.9"
DBH
>12" DBH
Figure 1: PAR and Sunfleck maps. Four
measurements taken in each quadrat.
Darker areas represent lower PAR or
Sunfleck (more dense cover).
70%
60%
Quercus rubra (Red Oak)
56%
50%
42%
41%
40%
1974
30%
20%
15%
10%
19%
2014
11%
2%
2"-3.9"
DBH
Count Per Quadrat
2
1.5
1
0.5
0
1989
1994
1999
Year
2004
2009
2014 (New)
2014
Figure 5 (Left): Fraxinus
Americana (White Ash) count
per quadrat of >4”DBH trees
in the original area. Between
1994 and 1999, many F.
americana began dying from
Ash Yellows, followed by the
destruction of F. americana
by the Emerald Ash Borer.
Only 8 live >4”DBH F.
americana trees were
recorded in 2014.
Conclusions
• Areas of low shade found primarily around the ponds
and areas with recent large tree falls. These areas tend
to have more water-loving and shade intolerant
species.
• Higher Simpson’s Diversity Index for the new quadrats
in 2014 and the original quadrats in 1974 might be a
sign of earlier successional stages.
• Shifts from saplings to larger size classes occurred for
shade-intolerant species between 1974 to 2014.
• Importance values show a shift from early successional
to late successional species from 1974 to 2014, a trend
also seen when comparing the new quadrats (early
succession) to the original quadrats (late succession)
for 2014.
• Emerald Ash Borer and Ash Yellows destroyed most of
the >4”DBH population of F. americana after 1994;
however, F. americana was the most common <2” DBH
sapling, which may allow for future regeneration.
3%
0%
Saplings
2.5
1974
2014 (Original)
Figure 4: Percent Composition of major
species in 1974, 2014 Original, and
2014 New quadrats based on trees
>4”DBH.
3
Number Species Simpson's Diversity
Individuals Richness
Index
70%
1974
2014 (New)
F. americana (White Ash)
• 2623 trees >2” DBH measured:
• 1183 in original quadrats, 1440 in new quadrats.
• 8652 woody-stemmed plants <2” DBH counted in original quadrats.
• Light level readings show areas with gaps in the canopy, primarily from ponds
and recent large tree falls.
• The new quadrats had more earlysuccessional, shade-intolerant tree species
than the original quadrats, such as Q. rubra
and P. serotina.
• Shade intolerant species typically had a
smaller proportion of their population in
the sapling size class in 2014 compared to
1974.
• Highest diversity in the 2014 new quadrats,
compared to 2014 original and 1974.
Sample
2014 (Original)
Figure 3: Importance values of major
species in 1974, 2014 Original, and 2014
New quadrats based on trees >4”DBH.
Results
Percent Species in Size
Class
Objectives
0.70
0.60
0.50
0.40
0.30
0.20
0.10
0.00
Percent Composition of
35%
Top Species
N
Percent Species in Size
Class
• 1974: All trees >2” diameter at breast height (DBH) in
the old-growth woodlot (43 quadrats, 1.7 ha total) of
the Calvin College Ecosystem Preserve (CCEP) were
measured by a Calvin College professor and a recent
graduate.
• 1983 & 1987: The trees were partially re-measured
(and recorded, but excluded from the analyses).
• 1989 & 1994: 7 more quadrats were added, bringing
the total area to 50 quadrats (2.0 ha total).
• 1989-present: All trees were re-measured on a fiveyear interval.
• 2014: Trees were re-measured in the original census
area, 50 new quadrats were added to the study area
(4.0 ha total). 2014 data also included sapling counts
and light readings in the original sampling area.
Importance Values of
Top Species
0.80
4"-11.9"
DBH
>12" DBH
Figure 2: Size distribution of shade-tolerant F. grandifolia (left) and shade-intolerant Q. rubra (right) in the original
quadrats. Note the shift from saplings to larger size classes from 1974 to 2014 for both species, but with less sapling
regeneration for Q. rubra.
Acknowledgements
• Special thanks to Calvin College and the Calvin College
Ecosystem Preserve for funding this research.