ABSTRACT

1
Effects of Harvesting Intensity and Forest Cover
Type on White Spruce and Betulaceae Seed Rain and
Regeneration in Northwestern Alberta, Canada
Carrie A. Becker1 and Daniel W. Gilmore
1 1University of Minnesota, St. Paul, MN 55108
University of Minnesota
EMEND

• CURRENT FINDINGS
• 1999-2000 Seed Rain-Figure 3.
• White Spruce
• ? Less seed rain occurred overall under ADOM
  stands, with the 75 treatment being the greatest
  (149 seeds/m2).
• ? There was an increase in seed rain related to
  increasing residual material under CDOM stands.
• ? Across all cover types, the greatest amount of
  seed rain occurred under CDOM stands in the
  control treatment (2,850 seeds/m2).
• ? Compared to CDOM control treatments, MIX stands
  had 60 (1,147 seeds/m2) and 56 (1,248 seeds/m2)
  less seed rain in the control and 50 treatments,
  respectively.
• The greatest amount of seed rain under MIX
  stands occurred in the 75 treatment (2,172
  seeds/m2), which is only 24 less seed rain than
  what occurred in CDOM control treatments.
• The effects of cover type and treatment on seed
  rain was tested using Analysis of Variance
  (ANOVA) models. Differences among the means for
  cover type (Plt0.001) are evident. Treatment,
  cover type and treatment interaction, and block
  nested within that interaction were all
  insignificant.
• Betulaceae
• ? Less seed rain occurred overall under CDOM
  stands, with the 50 treatment being the greatest
  (38 seeds/m2).
• ? There is a slight increase in seed rain related
  to increasing residual material under ADOM
  stands.
• ? Across all cover types, the greatest amount of
  seed fall occurred under ADOM stands in the
  control treatment (507 seeds/m2 ).
• Compared to the ADOM control treatments, ADOM
  50 and 75 treatments had an approximate 92
  reduction in seed rain (16 and 30 seeds/m2,
  respectively).
• The least amount of seed rain, for all cover
  types, occurred under ADOM stand in the 0
  treatment (.33 seeds/m2 ).
• ANOVA was used and there were no differences
  detected among the means for cover type,
  treatment, and the cover type and treatment
  interaction. There were however, differences
  among the blocks.

Figure 2. Seed Trap and Regeneration Layout
ABSTRACT To practice good forest management, it
is essential to understand how timber harvesting
affects forest regeneration. Three replications
of six harvest intensity treatments (0-75
residual gradient and 100 residual control) in
three forest cover types of white spruce
dominated (CDOM), mixed conifer/deciduous species
(MIX), and aspen/balsam poplar dominated (ADOM)
were established during the winter of 1999. Seed
traps were installed to measure the quantity of
seed rain. White spruce seed rain was greatest
under CDOM stands in control treatments. In
comparison to these control treatments, MIX
stands showed a 60 reduction in seed rain in the
control treatments and a 56 reduction in the 50
treatments. Seed rain was greatest under MIX
stands in the 75 treatments. Betulaceae (paper
birch and alder) seed rain was greatest under
ADOM stands in the control treatments. Harvest
intensities of 75 and 50 showed approximately a
92 reduction in Betulaceae seed rain under ADOM
stands as compared to the control treatments.
Betulaceae seed rain was lowest in the 0
treatments at almost no seed fall/m2. Plots to
quantify germination were established in June of
2000 and monitored through August.
Interestingly, MIX stands had greater amounts of
white spruce germination in the control
treatments. CDOM stands however, had equal
amounts of germination in the control and 50
treatments. Additionally in the CDOM stands,
there was only a 25 reduction in germination in
the 75 and 20 treatments. No Betulaceae
germinants were found. In general, mean seed
rain was greatest under CDOM stands in the
control treatments (2,850 seeds/m2), while mean
number of germinants were greatest under MIX
stands in the control treatments (12.5
germinants/m2).
METHODS Study Area This project falls under the
umbrella of the Ecosystem Management by Emulating
Natural Disturbance Project (EMEND) and is
located In the P2 forest management area
(Township 90, Range 03, W6M), North of Hines
Creek, Alberta, Canada (Latitude 57N, Longitude
119W). Cover Type Before harvesting, forest
types were partitioned based on canopy
composition of stands 1) conifer dominated-CDOM
(gt70 white spruce), 2) mixed-MIX (conifer and
deciduous composition each 35-65), and 3)
deciduous dominated-ADOM(gt70 aspen and balsam
poplar). Treatments Blocks of 8-10 ha each were
harvested in stands of each Cover Type. Blocks
contain one of six proportions of residual
material. There are three replications of each
treatment for each Cover Type. Seed Trap
Installation and Collection Seed traps were
installed in July 1999 (Figure 1). Six 1 m2 seed
traps were placed within six predetermined plot
locations (P1-P6) for a select number of
treatments (50, 75, and 100) under all cover
types (Figure 2). Traps were emptied in fall
1999 and again in spring 2000. Collaboration
with the Canadian Forest Service allowed for
additional seed trap information for treatments
0, 50, and 75 under CDOM and ADOM cover types.
Regeneration Plot Set-up Two permanent 1 m2
regeneration plots were established in June 2000
five meters north and south of two randomly
selected seed traps (P1-P6) found in each
treatment under all cover types (Figure 2).
Germination and regeneration (up to 1.2 m) was
recorded in each plot for all boreal tree
species.
Figure 1. Seed Trap
COVER TYPECDOM
Block 854 Treatment 50
Block 856 Treatment 100
Block 855 Treatment 0
P3
Block 853 Treatment 75
P2
P5
P1
P6
P4
Two plots P4 P5
5 m
Four plots P1,P2,P3,P6
Seed Trap 1 m2
Seed Trap 1 m2
5 m
Regeneration plot 1 m2
Figure 3. 1999-2000 Seed Rain
OBJECTIVES Overall Objective of the EMEND
Project To determine which forest harvest and
regeneration practices best maintain natural
plant and animal communities when compared to
communities resulting from natural
disturbance. Specific Objectives of this
Study Collect and quantify the amount of seed
rain, quantify the amount of annual germination,
and compare the relationship between seed rain
and germination under different harvesting
intensities for three boreal cover
types. Central Hypothesis The quantity of
seed rain or germination is equal among cover
types (CDOMMIXADOM) and treatments
(05075100).
Figure 4. 2000 White Spruce Germination
White Spruce Germinant
AKNOWLEDGEMENTS Wed like to thank C.A. Buschena,
L.E. Frelich, D. Hawkins, J.C. Stewart, and J.C.
Zasada for assistance with experimental design.
Also C. Charman and T.N. Jones for assistance
with data collection. Research supported by the
Agricultural Experiment Station, University of
Minnesota and Canadian Forest Products Ltd.,
Daishowa-Marubeni International, Manning
Diversified Forest Products Trust, University of
Alberta, Canadian Forest Service, and the
Sustainable Forest Management Network Centres of
Excellence