THE EFFECTS OF LOGGING AND PRESCRIBED FIRE ON FECUNDITY
AND SEED DISPERSAL OF SIERRAN CONIFERS
Ruth Ann Kern
Biology Department
California Sate University, Fresno
ABSTRACT
Seed rain is being monitored in
experimental forest treatment plots to
investigate the effects of thinning and
prescribed fire on seed production
and seed dispersal distances of Sierra
Nevada conifers. 18 1-ha forest
research plots, established in the
Teakettle Experimental Watershed,
Sierra National Forest, have been
manipulated in a 2 x 3 factorial design
(fire or no fire; shelterwood thinning,
California Spotted Owl protocol (CASPO)
thinning, or no thinning) with three
replicates of each treatment. 25 0.25m2
seed traps have been installed on a
25-m grid in each of the 18 plots. Seed
traps were installed in the control
plots in summer 2000 and 2001 and in the
treatment plots in summer 2001 and
2002, following completion of logging and
fire treatments in summer and fall
2001. Data from this long-term study
will be
used to understand the individual and
cumulative effects of the two methods of
logging and of prescribed burning on
seed production and seed dispersal
distances in White Fir, Red Fir, Sugar
Pine, Jeffrey Pine, and Incense Cedar.
Cabin
bn1
un1
uc1
uc2
bs2
bs3
bn3
us1
bc3
bc2
bn2
bs1
bc1
un2
us2
us3
un3
uc3
Garage
Teakettle Ecosystem Experiment
Sierra National Forest
• Approximate location of
seed traps within plot center
• Each
replicate plot is 4 hectares in area with the seed traps distributed at 25 m intervals within
the center
1-ha of the plot
• Seeds
are collected yearly just after snow melt, dried, separated from litter and tallied
by species for each seed trap location.
• All
trees in the 18 4-ha plots have been mapped and measured, allowing spatial analysis
of seed source and dispersal patterns
25 m
Plot Treatments
bs1
bs2
bs3
us1
us2
us3
Shelterwood Thinning
“s”
bc1
bc2
bc3
uc1
uc2
uc3
CASPO
Thinning
“c”
bn1
bn2
bn3
un1
un2
un3
No
Thinning
“n”
Control Burned
“b”
No Burn
“u”
Seed Trap Design
Seed Rain Collection
Teakettle
Ecosystem Experiment:
http://teakettle.ucdavis.edu/index.htm
Three-layer
design: bottom layer is attached to the ground, middle layer has fine screen
collection surface, top layer excludes seed predators and large litter via hardware
cloth. Layers are connected with
carriage bolts and wing nuts for easy separation to collect contents.
Data Analysis
•Effects of thinning and prescribed fire
treatments on fecundity and dispersal distances of each species will be
analyzed
•Dispersal curves created from model output may provide important clues regarding potential
rates of reproduction and forest spread.
Example results1 from pilot study in Sequoia National Park:
1Unpublished results. For description of analysis methods, see
Clark, et al. (1999). Seed dispersal near and far: patterns across temperate
and tropical forests. Ecology 80:1475-1494.
For more information contact:
Ruth Ann Kern
Biology Department
California State University, Fresno
2555 E. San Ramon Ave, M/S SB73
Fresno, CA 93704
559-278-4075
rakern@csufresno.edu
Funding for this research provided by
California State University Agricultural Research Initiative,
California State University, Fresno
College of Science and Mathematics, and USDA Forest Service.
